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Technical and economical feasibility of integrated salmon and kelp production system Tabrizi, Kamran Mazhari 1992

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TECHNICAL AND ECONOMICAL FEASIBILITY OF INTEGRATEDSALMON AND KELP PRODUCTION SYSTEMByKAMRAN MAZHARI TABRIZIB.A.Sc., The University of British Columbia, Canada, 1989A THESIS SUBMITTED IN PARTIAL FULFILMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMASTER OF APPLIED SCIENCEinTHE FACULTY OF GRADUATE STUDIES(BIO-RESOURCE ENGINEERING DEPARTMENT)We accept this thesis as conformingto the required standardTHE UNIVERSITY OF BRITISH COLUMBIAApril 1992©KAMRAN MAZHARI TABRIZIIn presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that the Library shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives. It is understood that copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.(Signature)Department of  P _ Pp_ccit A rc_e 	neerThe University of British ColumbiaVancouver, CanadaDate )2Yri	 /46112DE-6 (2/88)ABSTRACTThe purpose of this study was to evaluate the technical andeconomical feasibility of Laminaria saccharina culture near asalmon netpen farm. A computer model was developed to make thisassessment. The availability of ammonia nitrogen from the netpensand its diffusion into the kelp were included in the model.Laminaria production is based on nitrogen availability, light andwater temperature. Light intensity, including its availability andattenuation, was incorporated into a submodel. This submodel couldbe used to manage the light intensity on a kelp farm (i.e. bychanging the depth of kelp ropes).Based on model predictions, a Laminaria farm containing 10 60m ropes on each end of a salmon netpen farm is technically feasibleand is fertilized by the salmon farm. A yearly production of 1600kg of kelp (dry basis) and a net profit of $20,000 are expected bythis size of farm (selling price = $35 per kg dry mass). Kelpproduction on multiple salmon farms or with more kelp ropes couldincrease the overall net revenue of the owner. Larger-sized kelpfarms may, however, need artificial fertilizer.The average rate of light radiation for good kelp growthshould not exceed 100 AE rfl-2 s-1 and should not be less than 30 AEm-2 5-1. Light intensity for different depths and attenuationcoefficients can be predicted by the light submodel, and thisinformation can be used as a kelp farm management tool. Lightavailability depends on the season of the year and water condition.ii.By using this submodel, the optimum depth of a kelp raft for growthcan be determined. A 47% reduction in light intensity is observedwhen light travels from a depth of 2 to 7 m (attenuationcoefficient = 0.1 m-1). A set of experiments was conducted at theDepartment of Fisheries and Oceans facilities (July-August 1991) toexamine Laminaria growth at different salmon-effluent nitrogenconcentrations and to validate the Laminaria growth model. Theexperiment was a model of an actual kelp farm near a netpen (i.e.similar water velocity and tidal effects). The model was validatedfor ammonia nitrogen concentrations of less than 5 AM. A directrelationship between growth rate, and ammonia nitrogen and nitrateavailability was found. For a combined nitrogen concentration ofammonia nitrogen and nitrate of 9.7 ,M, a specific growth rate of9% d-1 was obtained.A second set of experiments was conducted to measure theoxygen consumption rate of the kelp. The results were used in thecomputer model to determine if kelp farms would cause an oxygendeficit for fish in the netpens at night. The consumption rate wasfound to be 0.024 mg 02 g kelp-1 h-1 . This result was used in themodel to compare oxygen availability versus oxygen consumptionrate. The results from the model were used to show that for a 10x 60 m rope kelp farm, oxygen consumption at night was less than 1%of the oxygen available to the fish in the netpens. Therefore,oxygen consumption at night by a 10 x 60 m rope farm would notcause significant oxygen depletion for fish.iiiTABLE OF CONTENTSABSTRACT 	 iiLIST OF FIGURES 	 viLIST OF TABLES 	 viiiACKNOWLEDGEMENTS 	 ixI INTRODUCTION 	 1II. OBJECTIVES 	 3III. LITERATURE REVIEW 	 53.1 Kelp Characteristics 	 53.2 Kelp Growth Studies 	 63.3 Nutrients and Water Motion 	 73.4 Temperature 	 83.5 Light 	 93.6 Kelp Production and Integrated Culture 	 143.7 Netpens and Fish Growth 	  16	3.8 Fish Growth Models   19	3.9 Nutrient Loading   193.10 Uptake and Growth Models 	  20	3.11 Production Models   21IV MODEL DEVELOPMENT 	  244.0 Conceptual Model 	  244.1 Fish Farm and Nutrient Availability 	  284.2 Kelp Farm and Productivity 	  344.3 Interrelationships and Formulations 	  36	4.4 Economic Considerations   40	4.4.1 Fixed Capital Costs   40	4.4.1.1 Storage Shed   424.4.1.2 Boat 	  424.4.1.3 Light Sensor 	  44	4.4.2 Operating Costs   44	4.4.2.1 Seedling Costs   444.4.2.2 Labour Cost for Planting and	harvesting   444.4.2.3 Management Cost 	  444.4.2.4 Light Control and MaintenanceCosts 	  45	4.4.2.5 Land Cost   454.4.2.6 Transportation Cost 	  454.4.3 Indirect Operating Costs 	  46	4.4.3.1 Depreciation   46	4.4.3.2 Financing   46	4.4.4 Revenue   46	4.4.5 Pay-Back Period   47iv4.5 Kelp Production and Economical	Model Formulation   474.6 Calculation and Outputs of KelpProduction Model 	  49V	 MODEL VALIDATION AND PARAMETER ESTIMATION 	  505.1 Materials and Methods 	  505.1.1 Growth Experiment 	  505.1.2 Oxygen Experiment 	  535.2 Results and Discussion 	  545.2.1 Results of Nutrient Experiment 	  545.2.2 Discussion of Nutrient Experiment 	  615.2.3 Results of Oxygen Experiment 	  635.2.4 Discussion of Oxygen Experiment 	  67VI PRODUCTION MODEL ANALYSIS 	  696.1 Fish and Kelp Production 	  696.2 Ammonia Nitrigen 	  71	6.3 Phosphorus   75	6.4 Oxygen   75VII LIGHT MANAGEMENT TECHNIQUE 	  817.1 Inputs of Light Model 	  817.2 Outputs of Light Model 	  827.3 Light Model Analysis 	  83VIII ECONOMIC FEASIBILITY 	  87IX CONCLUSIONS AND SUGGESTIONS FOR FURTHER WORK 	  91BIBLIOGRAPHY 	  94Appendix 1 GROWTH CALCULATIONS 	  100Appendix 2 PHOSPHATE CALCULATIONS 	  101Appendix 3 COMPUTER GROWTH MODEL 	  102Appendix 4 LIGHT SUBMODEL	  108LIST OF FIGURESFigure 1. Solar radiation path from sun to an ocean depth. 	 11Figure 2. Schematic of the proposed integrated salmon/Laminaria farm. Current on the site changesdirection with tidal pattern. 	 27Figure 3. Flow diagram of an integrated salmon/Laminariasystem representing components and environmentalinputs. It includes nutrient loading (ammonianitrogen + phosphorus) from the netpens, Laminariagrowth, environmental parameters affecting Laminariagrowth and economics 	 29Figure 4. Ammonia nitrogen production rate using twodifferent models. At time = 1, initial massof fish = 0.040 kg.	 Final individual fishmass= 3.0 kg	 33Figure 5. Description of the experimental layout. Itincludes salmon culture tank, 3 Laminaria raceways,3 Laminaria tanks for oxygen experiment. 	 51Figure 6. Average daily ammonia and nitrate concentrationsin the fish tank. The error bars represent 1standard deviation with n = 32. Days 1, 2, 3 and 4represent the days that the samples were taken(July 18, 23, 28 and August 2). 	 57Figure 7. Average daily total nitrogen and phosphorusconcentrations in the fish tank. The error barsrepresent 1 standard deviation with n = 32.Days 1, 2, 3 and 4 represent the days that thesamples were taken (July 18, 23, 28 and August 2). ..58Figure 8. Daily water temperature in the Laminaria racewaysduring the Laminaria growth experiment(July 18 - August 3).	 59Figure 9. Average daily light intensity reaching theLaminaria throughout the growth experiment(July 18 - August 3). 60Figure 10. Relationship between mass and surface areaof the Laminaria. 	 66Figure 11. Ammonia nitrogen availability for an integratedSalmon/Laminaria farm (netpens = 2, 50 ropesLaminaria farm).	 72viFigure 12. Ratio of total ammonia nitrogen consumed by theLaminaria to ammonia nitrogen produced by salmonfarm. The drops represent the harvesting periodsin the Laminaria farms. 	73Figure 13. Ammonia nitrogen availability for an integratedSalmon/Laminaria farm (netpens = 1, 20 ropesLaminaria farm). 	 74Figure 14. Ratio of ammonia nitrogen consumed by theLaminaria to ammonia nitrogen produced bysalmon farm. The drops represent the harvestingperiods in the Laminaria farms. 	 76Figure 15. Phosphate available from the Fish Farm(netpens = 12, Fish Feeding Rate = 1%). 	 77Figure 16. Phosphorus consumption by different Laminariasized farms. 	 78Figure 17. Oxygen consumption by different Laminariasized farms. 	 79Figure 18. Light intensity reduction due to differentextinction coefficients. 	 85Figure 19. Light intensity reduction as a function ofwater depth. 	 86Figure 20. Break-even analysis for a 20 x 60 m Laminariafarm. 	 90viiLIST OF TABLESTable 1.Table 2.Table 3.Table 4.Table 5.Table 6.Table 7.Table 8.Table 9.Table 10.Mathematical expressions relating growth (% day-1)to temperature (°C) were obtained fromAustreng et al., 1987. 	 30Cost of materials for one 60 m long cultivationrope (Druehl, 1980. 	 42Breakdown of initial capital investment. Thisincludes the capital investment, initial constructioncapital, and initial operating capital. 	 43Observed and calculated specific growth ratesof kelp (L. saccharina) grown in differentnitrogen concentrations from July 18 to August 3.The different nitrogen concentrations were madeby the dilution of effluent from a salmon culturewith seawater. (Errors represent 1 standarddeviation, sample size = 128).	 55Average daily nitrate, ammonia nitrogen, andphosphate concentrations in the fish tank.Samples were taken over a 24 hour period(day and night). (Error represents 1 standarddeviation, sample size = 32) 	 56The theoretical specific growth rate of Laminariais compared with the actual kelp growth in thethree raceways. A t-test (95% confidencelevel) was used. Sample size or number of plantsin each raceway = 7, S = standard deviation ofsamples in each raceway. 	 62Oxygen drop (mg 1-1) in different Laminaria tanksduring night (8 h). Average kelp mass in tank 1 = 0.20kg; tank 2 = 0.18 kg ; tank 3 = 0.13 kg. 	 64Oxygen uptake rate in different Laminaria tanks overexperimental period (July 12 to July 25). Cumulativeoxygen drop is the total (i.e. 14 nights) in each22 1 bucket. 	 65Summary of typical Laminaria production model inputvalues. Average monthly water temperatures(1921-1991) of Race Rocks (latitude = 48.18 °N,longitude = 123.32°W) was used in this model. 	 70Cash flow analysis for two 10 rope Laminaria farmsfor a 5 year period. 	 89viiiACKNOWLEDGEMENTSAll praises are for Almighty God who gave us strength, health,knowledge, opportunity, and patience.I would like to thank the Department of Fisheries and Oceansfor funding this project through the Subvention Program. I wouldlike to express my special gratitude and appreciation to Dr. R. J.Petrell for introducing me to this topic and for her guidance, helpand encouragement throughout the present study. Appreciation isalso extended to Dr. P. J. Harrison for being very helpful andunderstanding. I would also thank Dr. K. V. Lo for sitting on thecommittee, providing valuable advice and reviewing this thesis. Iappreciate the comments and suggestions of Dr. R. Foreman duringthe Defense.I must thank the Department of Fisheries and Oceans WestVancouver Marine Laboratory and the University of British Columbiafor the use of their facilities. Great appreciation is extended toK. Abbaspour, K. Behnam, C. Savage, S. Mattice and K. Chui fortheir technical assistance.I would like to express my sincere appreciation and feeling ofindebtedness to my father, mother, brother and brother-in-law fortheir care, love, understanding, and moral and spiritual supportspecially during the hard times.I wish to express my special gratitude to my beloved fiance,for her whole-hearted love, encouragement and patience in the lasteighteen months.ixI. INTRODUCTIONWorld demand for fish as a source of food for humanconsumption has been continuously growing since the end of thesecond World War. The demand is projected to increase by around 2to 2.4% per annum (Beveridge, 1987). The British Columbia SalmonFarmers Association projected a farmed salmon harvest of about16,500 tonnes in 1992. This production generates an environmentalnutrient loading (i.e. nitrogen in the form of ammonia nitrogen)and reduces the concentration of the dissolved oxygen around thesalmon net pen farm (Phillips et al., 1985).The cultivation of kelp outside a fish farm could utilize thereleased nitrogen for tissue growth, increase the dissolved oxygenlevel through photosynthesis and bring an economical return. Kelphas economic value for its food value (i.e. kombu), chemicalcontent, particularly iodine, and to lesser extent for its vitaminand alginic acid content (Glicksman, 1987; Druehl, 1988a).Alginate has a large application in the food industry, where it ismostly used as a thickener and stabilizer for different frozen,dairy and bakery products. Kelp accounts for 66% of the totalcultured seaweed production of Asia and the Pacific in 1988 (FAO,1990). The total cultured seaweed production globally reached 3.6million tons in 1988. Kelp has been cultivated for many years inSouth East Asia and recently in British Columbia (Druehl et al.,1988b).1Kelp cultured on fish culture effluent receives the benefit offree fertilizer. Lobban and Wynne (1981) discuss the need ofapplying fertilizer to the body of water to enhance kelp growth.The fish farm replaces the need for artificial fertilization. Todate, this type of integrated system has not been modelled ortested.Mathematical models were developed in this thesis in order todetermine technical and economical feasibility of kelp culture neara salmon netpen farm. Laminaria species was chosen to be studiedbecause it is a cold temperate species, which grows in BritishColumbia; it can be grown in raft culture in waters beside salmonnetpens, and it has a commercial value as kombu. With a fewmodifications in the model, Nereocystis and Macrocystis culturefeasibility can be substituted.2II. OBJECTIVESThe objectives of this study were :1) to examine the relationship between growth rate ofLaminaria saccharina and ammonia nitrogen concentrationfrom salmon effluent through a set of experiments andcomputer simulations.2) to examine phosphorus limitation in the integratedsalmon and kelp culture.3) to analyze oxygen consumption by kelp due torespiration at night.4) to analyze light intensity in different water conditions(i.e. different attenuation coefficients) at differentwater depths. This would enable farmers to alter thecultivation depth of kelp for maximum growth.5) to develop a computer model to simulate the following:i) fish growth in netpensii) ammonia nitrogen production in netpensiii) phosphate production in netpensiv) ammonia nitrogen and phosphate concentration in thekelp raft.3v) kelp growth rate at different ammonia nitrogenconcentration with different water temperatures.vi) mass of kelp produced for different farm sizes.6) to estimate the economical feasibility of the kelp farmbeside a netpen operation (i.e. selling kombu).4III. LITERATURE REVIEW3.1 Kelp Characteristics Seaweeds are large marine algae, which can be divided intothree major groups: green, brown and red algae. Seaweeds grow inintertidal and subtidal habitats; they vary in form fromfilamentous, simple to branched blades. Seaweeds require sunlightfor photosynthesis. They absorb nutrients directly from the waterthrough cell walls, since they do not have a root system. Seaweedsreproduce either by fragments or by mobile or immobile microscopicspores (Cheney and Mumford, 1986).Kelp (or brown algae) grow around Vancouver. Different typesof kelp, such as Macrocystis integrifolia and Laminaria saccharina,can be found in coastal waters of British Columbia. The technologyfor extensive culture of Laminaria saccharina has been proven inB.C. (Druehl et al., 1988).Laminaria is important for its food value (i.e. kombu) as wellas its chemical content (e.g. alginate and iodine). Laminaria isused to prepare different food dishes. Powdered kelp and kelpstrips can be utilized as tea or as the base for various soups,broths and marinades (Druehl, 1988a). Dried kelp (1 m long and0.40 to 0.50 m wide) were sold to health food stores in Vancouverfor $32 per kg dry mass in 1988 (Lloyd, Pers. Comm.).On the other hand, alginate, extracted from kelp, is used asa stabilizer (e.g. for cream cheese and whipped cream) and as athickener for bottled salad dressings (Glicksman, 1987). Food5demand for edible seaweed is increasing, on the other hand; thealginate market is nearly saturated (Csavas, 1990).3.2 Kelp Growth Studies Different environmental parameters such as nutrientavailability, irradiance and water temperature influence kelpgrowth. In nature, seasonal growth patterns, due to differentcombinations of environmental factors, can be observed. In winter,because of low water temperature, respiration is minimal,therefore; the carbonic compensation point is low and aphotosynthetic surplus could be achieved despite low lightintensities (Gagne et al., 1982). In summer, growth is nitrogen-limited, so Laminaria lingicruris builds up reserves ofcarbohydrates. In fall, respiration is maximum; light intensitydecreases, and growth is minimum (Gagne et al., 1982).Druehl (1967) mentioned two growth seasons for Laminaria grownin British Columbia, namely, the season of rapid growth (January-June) (i.e. due to upwelling) and the season of slow growth (July-December). Gagne et al. (1982) suggested that Laminaria did nothave a typical seasonal pattern of growth and it respondsdifferently to different environmental factors. When a Laminariapopulation is sufficiently exposed to a particular combination ofenvironmental parameters, it can genetically change and lose thepotential to respond to other environmental combinations.63.3 Nutrients and Water MotionNitrogen is a limiting factor in oceanic environment.Harrison et al. (1986) concluded that Laminaria groenlandicautilized ammonium as well as nitrate. Subandar (1991) found thatammonium and nitrate contributed equally to nitrogen uptake byLaminaria saccharina cultured in tanks receiving salmon cultureeffluent. The nutrient uptake by a seaweed depends both uponconcentration of the nutrient in the surrounding water and theamount of water movement. Dunton (1985) stated that the periods ofhighest growth in Laminaria solidungula and L. saccharina occurredduring the periods when high concentrations of inorganic nitrogenwere available in water.Phosphorus is one of the nutrients required by kelp.Phosphorus is generally not considered to be a limiting nutrient inthe marine environment (Lobban and Wynne 1981). The major form inwhich algae acquire phosphorus is as orthophosphate ions. Amaximum uptake rate (i.e. V, ) of 0.47 moles g dry mass-1 11-1 wasobtained for the red algal Agardhiella subulata (DeBoer, 1981).Nutrient uptake by marine plants is related to water motion.The effect of water motion on growth and production of Laminariahas extensively been studied. Some studies concluded that apositive relationship between water current and growth orproduction exists (Pace, 1972; Markham, 1973; Kain, 1977; Parker,1981). Gerard (1987) observed that plants in turbulent habitatsgrew faster than the plants in still habitats. Dayton (1975)7indicated that wave action (i.e. high water current environment)could limit predatory or competitive species.Gerard (1987) reported that plants subjected to constantlongitudinal tension had significantly narrower blades and higherrates of blade elongation than plants with no stress on them. Lowflow velocities can limit boundary layer transport of essentialdissolved gases and nutrients and thus result in reduced growth andproduction (Wheeler, 1980; Parker, 1981 and 1982). "The Japanesefeel that water motion is an important factor influencing thequality of cultivated kombu (edible kelp)" (Druehl, 1967).3.4 TemperatureTemperature is one of the environmental parameters affectingkelp growth rate. It is also the single most important factordetermining the geographic distribution of benthic marinemacroalgae (Gerard and DuBois, 1988). The growth rate of seaweedsis affected by the surrounding temperature. Generally, individualenzyme reactions have a peak above or below the optimum-temperaturerange. Bolton and Luning (1982) concluded that optimal growth (15to 18% d-1 in length) of Laminaria saccharina occurred at atemperature range between 10 to 15°C. They also observed that thespecific growth rate of Laminaria saccharina was reduced by 50 to70% when the surrounding temperature reached 20°C, and it wasreduced to 60 to 70% of the optimum when the temperature reached50C .83.5 LightLight intensity is an controlling factor for photosynthesis inseaweeds. Photosynthesis consists of two reactions, namely lightand dark reactions.	 The light reactions consist of energyabsorption, energy trapping and ATP generation. In the darkreactions, ATP and NADPH are used to fix inorganic carbon. Boden(1979) concluded that irradiance controlled Laminaria saccharinaproduction. The saturation irradiance for Laminaria is between 30to 100 AE m-2 s-1 (Harrison and Druehl, 1982).The photosynthetic rates of the kelp also affect oxygenproduction. King and Schramm (1976a) measured the photosyntheticrate for Laminaria digitata to be 1.19-3.97 mg 02 g dry mass-1 h-1 .King and Schramm (1976b) concluded that for Laminaria saccharinathe maximum photosynthetic rate was 2.0 mg 02/g dry mass-1 h-1 (i.e.for Millipore-filtered (0.22 Am) natural seawater of salinity15°/oo and, temperature 15°C).The parameters which affect solar-light intensity arediscussed next, because they help explain light-limited growthpatterns of seaweed. The intensity of solar radiation at the plantcanopy depends on different factors such as time of year, plantspacing, water depth, water clarity (i.e. phytoplankton blooms) andlatitude. Dunton (1985) observed very little growth in Laminariasaccharina during the dark period. Growth is delayed until lightis available, irregardless of nutrient concentrations.As solar radiation passes through the atmosphere, some energyis scattered and some is absorbed (i.e. transferred to heat)9(Figure 1). The solar radiation reaching the earth's surface iscomposed of direct and diffuse radiation. Dry-air molecularabsorption, scattering and absorption from dust, selectiveabsorption by water vapour and other gases (e.g. CO and CO2), andreflection and absorption in cloud layers are the parameters givenby Kreith and Black (1980) to reduce solar intensity. Theavailability of solar radiation on the earth depends on latitude,season and weather. The dependency on latitude and season isbecause of the elliptical path of the earth around the sun.Light penetration in water depends on the amount of scatteringand absorption in the water column. Scattering can be divided intotwo components, namely, scattering by pure water (molecularscattering) and particle scattering. The attenuation of light inwater is a function of water depth and the size and concentrationof particulate matter in the sea. Ingmanson and Wallace (1989)defined attenuation as a lessening of the amplitude of a wave withdistance from the origin.If the light intensity at different locations and periods areknown, the optimum depth for the kelp raft can be determined. Themathematical equations to compute light availability in the watercolumn are described in this section. Daily extraterrestrial10sunshine hourangleSEASONAL	 angular positionVARIATION	 of sun at polarnoon w.r.t. planeof equatorSOLAR RADIATIONCLOUDINESS INDEXdry air, COcloud layersozone layer	1DIURNAL VARIATIONIo, SOLAR RADIATION ATTHE SEA COMPOSED OFIbeam and IdiffuseI,SOLAR RADIATION BELOWWATER SURFACEmean dailysolar radiationATTENUATION OF LIGHT BEAMwater turbidityphytoplanktonparticleswater depthId, SOLAR RADIATION ATDEPTH dFigure 1. Solar radiation path from the sun to an ocean depth.11radiation on a horizontal surface can be computed using thefollowing equation:H0= 24	 71,(sinasin0)+cos8costiminwj	 (1)where	 'Sc = solar constant = 1367 W/m2.Solar constant is the rate of solar energy incident in per unitarea exposed normally to sun rays at one AU or mean sun earthdistance. Parameter E0 is eccentricity and is mathematicallydescribed below:E0=(:°)2 = 1 + 0.033 [cos  365 ])	 (2)where	 r0 = mean sun to earth distance,r = sun to earth distance on a particular date, and= day number (e.g. on Jan 1 do = 1).Sunrise hour angle ws is calculated using the followingequation:= cos -1 [ -tan8 tan$]	 (3)Solar declination is defined as follows by Iqbal (1983):Daily diffuse radiation, Hd, is needed to calculate the hourly128 = sin -1 [0.4 sin ( 365 (dA - 82) )360	 (4)diffuse radiation in Equation 6. Parameter Hd is calculated asfollows (Iqbal, 1983):	H d = H (0.958 - 0.982 140	 (5)where H is the global daily radiation and is obtained by summingthehourly solar radiations from Canadian Climate Normals. Cloudinessindex KT is the ratio of global to extraterrestrialradiation (Iqbal, 1983).Kr Ho	 (6)The hourly diffuse radiation Id is computed by equation 7.Hourly global radiation (from Canadian Climate Normals) is composedof beam and diffuse radiation. Hourly beam radiation is calculatedusing Equation 8 (Iqbal, 1983).Id _ A 	cosy - cosnyiBC/	24 aim", - (	 )I 180—'beam = Iglobal	 Idwhere	 Ibeam = hourly beam radiationId	 = hourly diffuse radiation, andw	= solar hour angle.( 7 )(8)13Below the water surface, radiant energy decreases exponentially asit penetrates through optically uniform water (Riley and Skirrow,1975).1z = I0 e-kz	 (9)where	 I0 = intensity of light crossing the water surfaceIz = intensity at depth z, andk = vertical attenuation coefficient.In order to convert the units from watts m-2 to gE m-2 s-1 , thefollowing approximation for sunlight for the photosyntheticallyactive range of 400-700 nm can be used (Brock, 1981)1W m -' = 4.6 ILE ni-3 /3 -1	 (10)A summary of the light model algorithm is presented in Chapter 7.This algorithm describes different parameters which affect lightintensity from the sun to a point in the water column.3.6 Kelp Production and Integrated CultureAs competition for coastal waters increases and demand foredible kelp increases, a greater importance will be given toextensive cultivation methods. In Asia and the Pacific regionswhere the seaweed production was 3.6 million tonnes in 1988, 90% ofthe harvested seaweeds comes, for instance, from aquaculturalpractices (Csavas, 1990). At present most of the cultured seaweedproduction in the world is in Asia and the Pacific regions. In the14rest of the world, seaweed production comprises only 1% of thetotal aquaculture production.Farming involves the cultivation in the sea of smallsporophytes of Laminaria until they reach the desired size ofapproximately 1 m. Floating kelp farms constructed of anchoredropes are buoyed at the surface by floats. In South East Asia twokinds of floating arrangements are used to construct a cultivationraft in offshore areas (Lobban and Wynne, 1981). One type ishorizontal where the rope lies parallel to the sea surface and isbuoyed by commercial rafts. The second method is the hanging type,where series of ropes lie perpendicular to the sea surface.Clusters of Laminaria are inserted in the twist of the ropes every30 cm. The distance between the ropes is at least 5 m, in orderfor boats to pass and in order to enhance nutrient availability.Boats are used to spray fertilizer on the farm every few days(Lobban and Wynne, 1981).Different fertilizer application methods have evolved toenhance the kelp growth. Lobban and Wynne (1981) mentioned theporous container method as well as the spraying method. Bothmethods are used in China to apply nitrogen to the kelp. In theporous container method, the clay bottles containing nitrogenousfertilizer, usually ammonium sulphate, are hung at certainintervals from the rope. Fertilizer application using the spraymethod is not very laborious and is more efficient. In either thehorizontal or vertical type farming arrangement when the kelp grow15to their harvesting age, the ropes are pulled into the boat andtransferred to shore. Once on shore, the kelp is dried and sold.In British Columbia the duration of Laminaria saccharinacultivation is approximately 8 months. In a set of experimentsconducted by Druehl et al. (1988b) the final wet mass of Laminariasaccharina ranged from 192 to 435 g after 8 months of cultivation.In these experiments, production started in February and ended inSeptember. The farming practice was the horizontal cultivationtype. Seedlings were inserted in the twist of the ropesapproximately every 30 cm. The ropes laid horizontally in thewater column. At the harvest time ropes were transferred to theshore by boats, and the clusters were detached from the ropes. InBritish Columbia, air drying is not permitted, so either greenhouses or commercial dryers must be used to process the product.3.7 Netpens and Fish GrowthNetpen or cage culture provides low cost alternatives toconventional land-based grow-out facilities. A cage is a type ofrearing unit which is screened on all sides (except the top) bymesh or netting, through which water exchange is facilitated.Netpens are sometimes preferred to land-based structures because oftheir simple technology, ease of management and lower cost. Netpensare floating structures which are used to grow different marinespecies. Salmon ranging in size between 10 and 60 g are put in thenetpens. Final stocking density is approximately 10 kg.m-3 inBritish Columbia, and the final fish size ranges from 1.8 to 3 kg.16The growout period for Atlantic salmon is up to 18 months(Laird and Needham, 1988). The number of the netpens per farm inBritish Columbia ranges from 6 to 60 netpens (Tillapaugh, Pers.Comm.). The typical size of the netpens in British Columbia is2250 m3 (15 x 15 x 10 m) for Atlantic salmon and 3375 m 3 (15 x 15x 15 m) for Pacific salmon (Tillapaugh, Pers. Comm.).Cage finfish aquaculture is the most common method ofintensively reared marine fish species (Kuo and Beveridge, 1990).Water quality determines to a great extent the success or failureof a fish production operation. Oxygen requirements of fish dependon species, stage of development and size. At most sites,dissolved oxygen concentrations of surface waters are close tosaturation levels (i.e. 8 to 9 mg 1-1). As long as cages aremaintained free from fouling organisms and current is sufficient,no oxygen depletion should occur (Beveridge, 1987).Oxygen, being the second most abundant gas in water afternitrogen, is needed by fish for digestion and assimilation of food,maintenance of osmotic balance and their activities. Oxygen uptakeby fish occurs by diffusion. The governing parameter in diffusion(gas exchange process) is the oxygen tension gradient betweentissues and the external medium (i.e. water). Oxygen diffusesacross the gills into the blood down an oxygen gradient of 40 to100 mm Hg. Stewart et al. (1967) concluded that low concentrationsof oxygen would decrease food conversion efficiency. Whitmore etal. (1960) observed that juvenile chinook salmon showed avoidanceto oxygen concentrations of 1.5 to 4.5 mg 1 -1 in summer, but showed17little avoidance in winter. Randall (1970) mentioned that fishbecame more active in hypoxic (i.e. low oxygen concentration) waterand tried to move away from the low oxygen level zone. Oxygenconcentrations below 6.0 mg 1-1 are not recommended.The environmental parameters such as water current and watertemperature affect oxygen availability in the net pens. Gormican(1989) compared dissolved oxygen values in two different fish cageswith the same stocking densities. The cage with slower current hada larger dissolved oxygen value compared to the cage with fastercurrent. He suggested that a faster current speed may necessitatea greater swimming speed, and hence an increase in the metabolicrate. The optimum current speed depends on fish size and stockingdensity; however, it is assumed that the current velocity shouldnot be lower than 0.10 m s-1 in the cages (Aarsens et al., 1990).Braaten and Saerre (1973) suggested that the sites with a tidalcurrent range of 0.1 to 0.6 m s -1 were appropriate for cage culture.The fluctuations of dissolved oxygen level in water columndepend on water temperature and water salinity (see Beveridge,1987). Oxygen solubility declines with increasing salinity.Seawater contains, therefore less dissolved oxygen than freshwater. As water temperature increases, 02 solubility in waterdecreases. Fish living in warm water should pump more water tomaintain a constant oxygen level.183.8 Fish Growth Models There are different approaches to simulate fish growth.Stauffer (1973) developed the following equation to predict cohoand chinook salmon growth.w = (Wos 4, ABt ) inwhere W = final fish mass (g),Wo = initial fish mass (g),t = time (days),B = 1/3, andA = a polynomial function of temperature.Iwama and Fidler (1989) developed a growth equation for salmonbased on initial mass and temperature (valid between 4 to 18°C).wt0-33 = w °33 + Gc (T/1000 ) twhere	 Wt = fish mass at time t (g),Wo = fish mass at t = 0 (g),t = time (days),T = temperature (°C), andGc = variable growth coefficient.Austreng et al. (1987) produced tables of fish (salmon and rainbowtrout) growth rate in sea cages for different fish sizes anddifferent temperatures.3.9. Nutrient LoadingWeston (1986) proposed three sources of nutrient loading fromthe netpens. They include: the dispersion of the soluble endproducts of the salmonid metabolism, the excretory products offouling organisms on the nets and the decomposition of theexcessive feed and faeces deposited beneath a netpen.19Enell (1982) concluded that nitrogen concentration increasedby 0.05 mg 1-1 in a fish farm with an annual production of 20 to 44tons per year. He measured the total nitrogen load from the farmto be 86 kg ton-1 of fish produced per season (N-content in fishfood = 8.45% of dry weight). Enell (1982) found that about 78% oftotal nitrogen was in the dissolved form.Phillips et al. (1985) stated that phosphorus and nitrogenwere the two important nutrients which cause nutrient loading.Phosphorus, being an important element for fish growth, is added tothe fish diet. Beveridge and Muir (1982) reported the dietaryphosphorus requirements of fish to be from 0.29% to 0.90% of themass of the diet. Ackefors and Enell (1990) estimated 2.2 kgdissolved phosphorus and 7.3 kg particulate phosphorus per ton offish were produced in a cage farm operation. Their estimate wasbased on a feed containing 0.9% phosphorus and a feed conversionratio of 1.5. The particulate matters will accumulate beneath thefish netpens. The pattern of sedimentation beneath the netpensdepends on current velocity, water depth and total particulatematter output from the fish netpens (Iwama, 1991).3.10. Uptake and Growth Models Different growth models have been developed to estimate thenutrient removal rate. Monod equation for bacterial growth is(Ymaxg) Y- K. + S20	where y	 = uptake or growth rate,ymax = maximum uptake or growth rate,	S	 = limiting substrate concentration (MM), andKs = half saturation concentration (MM).In nature, production depends on growth as well as loss. For kelpthis loss could be due to predators and other limitingenvironmental parameters (i.e. limiting light or nutrient).The following equation describes the production (Charpa andReckhow, 1983) :R = Rgrowth - RWoo	where R	 = phytoplankton production,R 0 = phytoplankton growth, andRgtorso:= phytoplankton mass loss.For multiple nutrient limitation, the reduction in growth due toall limiting nutrients should be considered (Charpa and Reckhow,1983):R=R1 xR2 xR3 x ... sitiwhere R = fractional limitation for multiple nutrientlimitation, andRi= fractional limitation for individual nutrients.3.11. Production ModelsThis section gives a brief description of two recentproduction models for kelp. To date all models that were developedwere used on natural populations. Different approaches were taken21to develop the models. Since a model is a simplification of asystem, naturally each model has its own limitations. Morepowerful models should be developed to enhance our ability topredict the growth of kelp and its sensitivity to variations ofenvironmental parameters.The models which are discussed are as follows :1) A stage structured, stochastic population model for the giantkelp Macrocystis pyrifera by Burgman and Gerard (1990).2) Growth and harvest yield of the giant kelp Macrocystispyrifera by Jackson (1987).The above mentioned models are for kelp growth in the naturalstate. Computer models of kelp farm production have not beendeveloped.i) Burgman and Gerard (1990) developed a stage-structuredstochastic population model for the giant kelp Macrocystispyrifera. The model predicts monthly changes of population in anarea of 1000 m2. The model is a function of environmentalstochasticity. Environmental stochasticity can be defined as therandom variation in population parameters due to variability ofenvironmental conditions. Environmental stochasticity isrepresented in Burgman's model by a coefficient of variation , CV.Environmental parameters include temperature (at sea surface andbottom), irradiance (at the bottom in open water) and gametophytedensity. Coefficient of variation for each of these parameters isinput data in the model. The model predicts the density of eachsporophyte stage (population is divided into 5 life-history stages)22monthly for up to 20 years. The model uses temperature to simulatethe effects of both temperature and nitrogen supply.In order to consider mortality, specific monthly survivalprobabilities for each life-history stage are used. A coefficientof variation CV is specified by the user for each mean survivalprobability. The output of the model is the mean density for eachsporophyte stage as a function of time. Monthly mean values ofcanopy frond density, irradiance on the bottom (under the kelpcanopy), temperature (at sea surface and bottom), as well asextinction probability for the adult sporophyte can also beobtained from the model.ii) Jackson (1987) introduced a model for growth and harvest yieldof Macrocystis pyrifera. The model calculates plant biomass andproduction as a function of environmental parameters. All of theenvironmental parameters affect the growth by affecting the lightflux. The environmental parameters include water clarity, bottomdepth, latitude, harvesting activity and photosynthetic response(i.e. Pmax vs I). Plant growth is obtained using daily netproduction (i.e. photosynthesis - respiration).Jackson (1987) compared light limitation versus nutrientlimitation for the growth of kelp. Chapman and Craige (1978)observed that winter growth for various seaweeds is light-limited(i.e. high nutrient winter condition) and nutrient-limited duringsummer conditions. Jackson (1987) suggested that a combination oflight and nutrient limited models should be considered.23IV. MODEL DEVELOPMENT4.0 Conceptual Model. Few adequate near-shore sites for Laminaria exist in BritishColumbia. Laminaria saccharina requires a site with the followingcharacteristics: an optimum water temperature range of 10 to 15 °Cand good water clarity. Saturation irradiance range from 30 to 100AE I11-2 s-1 (Harrison and Druehl, 1982). Sites should be chosen inupwelling zones or any place that nutrients can be addedartificially.Salmon netpen farms meet most of these criteria. The waterclarity in terms of water on salmon farms is good, because itranges from 6.5 m in summer to 11 m in winter (from records of theFisheries and Oceans Canada). These translate into extinctioncoefficients of 0.26 and 0.15 m-1. The low values of extinctioncoefficients indicate that the ropes should be laid deep in waterto avoid photoinhibition.	 The rate of irradiance in BritishColumbia from January to June ranges from 300 to 1330 AE 111-2The depth of cultivation ropes, therefore, should be between 2 to3 m in winter and 6 to 7 m in summer. As the kelp grow, therewould be a self-shading effect of kelp plants, and therefore, theycan be brought up closer to the surface.The conventional kelp mooring system would, however, need tobe redesigned, and the drying facilities, if not located on thesalmon farm, would have to be remotely located. One advantage ofthe integrated system is that fertilization costs do not applyhere, because the nutrients stemming from the salmon farm fertilize24the kelp. In a conventional system, fertilizer is applied to akelp farm every other day. The fertilizer application requires agreat deal of labour, because it is a continuous operation. In anintegrated system, labour would be required during the harvestingperiod to pull out the ropes and to insert the new seedlings in theropes. Daily inspections lasting 15 to 120 minutes would also berequired.Another advantage to integrated culture is the ability of thekelp to improve water quality for the salmon farm in terms ofoxygen and nutrient removal. The salmon farmer may be able torenegotiate lease agreements based on the "on site filtering"system.One possible concern of kelp production beside a netpen is theability of the seaweeds to withstand a current velocity of 0.1 m/s.The interaction between hydrodynamic forces in the ocean and thestructure of the seaweeds have been studied. The primaryhydrodynamic force exerted on macroalgae is drag, which acts in thedirection of flow. Carrington (1990) suggested that the survivalof intertidal macroalgae (i.e. Laminaria) depended on their abilityto withstand large hydrodynamic forces generated by breaking waves,an ability that is a function of both morphology and the size ofthe plants. Jackson and Winant (1983) found that for a tidalcurrent of 0.10 m s-1 , the drag force was given as 15.5 N on atypical Macrocystis plant. They concluded that the structure ofthe plant and its holdfast are sufficiently strong to withstandloads of this magnitude.25Another possible concern to integrated culture is the nightlyoxygen requirements of kelp. The oxygen production in a kelp farmbeside netpens could provide continuous oxygen supply during thedaylight hours, but in the dark, kelp consume oxygen. Respirationrates for Laminaria saccharina were measured to be between 0.1 to0.3 gmol cm-2 h-1 (Gerard, 1988).The integrated salmon/kelp system was conceptualized to becomposed of different components, namely, the fish farm andnutrient availability, kelp farm and productivity, and theeconomical component (Figure 2). Horizontal-type kelp farms areviewed being located on both ends of a salmon netpen farm. Ahorizontal type was chosen over the vertical type because it wastested in British Columbia (Druehl et al. 1988b). In theconceptual system, the rope spacing between the ropes is 3 m,whereas in practise, fertilized kelp farms have 5 m rope spacingsto facilitate the movement of the boats used for fertilizerapplication. In the conceptualized integrated system, nutrientsare transferred by water current, and hence the spacing between theropes are reduced. The smallest rope spacings in this integratedsystem could possibly be as small as 1 m. The spacing could be thesmallest before light impedance limits growth.The fish farm used in the conceptualized model contains 12 (15m x 15 m x 10 m deep) netpens. The cages are arranged 4 by 3, withthe current passing through the side with the largest number ofcages. The species chosen for culture is Atlantic Salmon. Thefinal stocking density in the netpens is 10 kg m-3, which is260.30 mrope NETPENS IBMEll10 mKELP FARMcurrentFigure 2. Schematic of the proposed integrated salmon/Laminariafarm. Current on the site changes direction with tidalpattern.27currently typical in British Columbia. The initial fish mass inthe model is 40 g. The fish production schedule follows a single-year class scheme. A 10% mortality throughout the production cycleis assumed.Tidal currents would bring waste nutrients to one of the kelpfarms, and when the tidal currents change direction, nutrientswould bring nutrients to the other farm. A distance of 10 mbetween the kelp and salmon farms was considered ideal for boatmovement.A mathematical model was developed using mathematicalexpressions of netpen nutrient release, kelp nutrient uptake andkelp growth. These expressions were interrelated in order topredict seasonal kelp production and economics (Figure 3). Thekelp farm size for this study was limited to the size expected tobe fertilized by the netpen farm and not expected to be lightlimited. The payback period of the resulting farm was calculated.The mathematical expressions, interrelations and economicalassumptions used to develop the production model are discussed inthis Chapter. The model with small changes can be used to studythe economics of different netpen clusters, fish species, kelpfarming methods, kelp species and kelp farm sizes.4.1 Fish Farm and Nutrient AvailabilityA netpen salmon farm produces valuable nutrients for kelp,ammonia, urea, nitrate and phosphate. These nutrients are neededfor rapid kelp growth. The nutrient in the system model will be28NUMBER OF FISHNUTRIENT LOADING FROM NETPENSAVAILABLE NUTRIENT FOR KELPA ELP GROWTH Ix	/ 1	TEMPERATURE LIGHT IOXYGEN CONSUMPTIONBY KELP 1 ECONOMICSFigure 3. Flow diagram of an integrated salmon/Laminariasystem representing components and environmentalinputs. It includes nutrient loading (ammonianitrogen + phosphorus) from the netpens, Laminariagrowth, environmental parameters affecting Laminariagrowth and economics.29restricted to ammonia nitrogen, because more than 60% of salmonnitrogen waste is found in this form (Fivelstad et al., 1990).In this section, parameters which affect the supply of nutrients tothe kelp farm and kelp growth are discussed.The supply of nutrients depends on the number and size offish. In order to simulate fish production, the growth rateestimates for cultured Atlantic salmon in sea cages by Austreng etal. (1987) are used (section 3.9). Their approach was preferredover other models, because they have used actual data from seacages. They produced tables of Atlantic salmon growth rate (% massday-1) for different fish sizes at different temperatures.Mathematical expressions relating growth to temperature wereobtained from this growth data (Table 1). The expressions wereobtained with linear correlation.The available nutrient in the netpens depends also on thedesired final stocking density, mortality, individual fish mass,the volume of each netpen, as well as the number of netpens inoperation. Total fish mass in netpens at any time can becalculated using the following equation :total fish mass = ((initial fish number in netpens) x (fishmass at time t)) x (1 - (% daily mortality x days afterstart of production)	 (3.1)initial fish number in netpens = netpen volume (0) x number ofnetpens x final stocking density (kg/m3) / final fish mass/ (1 - % mortality)fish mass at time t = (fish mass at time t = 0) ectwhere	 G = specific growth rate, in % day-1, Table 1,t = time in days.30Table 1. Mathematical expressions relating growth (% day -1) totemperature (°C) were obtained from Austreng et al., 1987.Fish Size	 (g) Growth Equations	 (% day-1) R230 - 150 Growth = 0.15 * Temp + 0.10 1.0150 - 600 Growth = 0.12 * Temp - 0.014 0.996600 - 2000 Growth = 0.079 * Temp + 0.014 0.992>	 2000 Growth = 0.05 * Temp 1.031Different ammonia nitrogen and Phosphorus production modelsexist (Liao, 1974 and Fivelstad et al., 1990. Liao (1974) usedfeeding rate as the parameter determining ammonia nitrogen andphosphate production, whereas Fivelstad et al., (1990) relatedammonia nitrogen production to fish growth rate:1) Fivelstad's modelammonia produced = 0.1525 * Growth - 0.0078	 (12)ammonia produced = mg ammonia / kg fish / min, andGrowth = is obtained from equations (Table 1).2) Liao's modelammonia produced = (0.0289)(Feeding rate)(TFM)(0.01)	 (13)phosphate produced = (.0162)(Feeding rate)(TFM)(0.01)	 (14)where	 Feeding rate	 = kg feed per 100 kg fish,ammonia produced = kg per day, andTFM	 = total fish mass, kg from equation 11.In order to evaluate which of the two previously mentionedmodels would be most useful in the production model, they werecompared (Figure 4). The comparisons were made assuming a 1%feeding rate. Monthly water temperatures for comparison of modelsvaried from 7.3 to 10.9°C.Liao's (1974) equation resulted in a higher ammonia nitrogenproduction rate than Fivelstad et al's. (1990) equation. Liao(1974) based his equation on fish feeding rate, whereas Fivelstad'smodel is based directly on fish growth rate.The results of the two models were very close for the firsteight months, assuming a 1% feeding rate. The model is simulated3290.0-rt.' 80.0 -50	 -70.0 -60.00C.) 50.0 -0a, 40.0 -E(.4	 • 0- 34.40	 -E- 20.0 -10.0Liao's model	  Fivelstad's model00.0 1 11111111111114	 8	 12Time	 (months)16Figure 4. Ammonia nitrogen production rate using twodifferent models. At time = 1, initial massof fish = 0.040 kg.	 Final individual fishmass = 3.0 kg.Based on Fivelstad's model, the increase in ammonia nitrogenproduction would not exceed 30 kg day-1 (Figure 4).Contrary to Liao's model, which is widely cited in theliterature, Fivelstad's model is very recent. No evaluation of itsprecision has been reported. Therefore, Liao's equation was chosenfor the kelp production model.4.2. Kelp Farm and ProductivityEnvironmental parameters, such as temperature, light andnutrient availability affect kelp growth (see literature review).In order to consider kelp mortality in the model, only 5plants in each cluster are assumed to survive (initially 10plants). This assumption was based on Druehl et al. (1988b), wherethey measured the mass of individual plants as well as total massof each cluster in a kelp production system.The following three equations for Laminaria saccharina growthare used. These equations represent the reduction of kelp growthat extreme temperatures (i.e. 60% reduction at 20°C and 40%reduction at 5°C, from section 3.3). The following equationsrelate ammonia nitrogen concentration and temperature of water toLaminaria growth. The assumptions for equation 16 are as follows:1) There is a direct relationship between nutrient concentrationand Laminaria saccharina growth up to 10 AM NH4+(Chapman et al., 1978b).2) At the optimum temperature (i.e. 10 to 15°C), growth is 1.5times the available ammonia nitrogen concentration (Gerard etal., 1987).343) A 60% reduction in growth occurs when temperature increasesfrom 15 to 20°C (see section 3.3).4) A 40% reduction in growth occurs when water temperaturedecreases from 10 to 5°C (see section 3.3).5) Phosphorus is not a limiting nutrient.6) Light is not considered a limiting factor, because lightintensity would be controlled by changing the depth of theropes, (see chapter 7).Assumptions concerning growth were partially validated (seeChapters 5) and assumption 5 was validated using computersimulations.The growth equations, which are used in the production model areas follows (see Appendix 1 for sample calculations):T = 5 to 10°C	 G = 1.5 [ammonia nitrogen] ((0.08 T) + 0.2)T = 10 to 15°C G = 1.5 [ammonia nitrogen]T = 15 to 20°C G = 1.5 [ammonia nitrogen] ((-0.12 T) + 2.8) (15)where	 T = Temperature in °C, and[nitrogen] = ammonia nitrogen concentration within the kelpfarm in AM.Ammonia nitrogen and phosphate consumption in the model iscalculated by the following equation :35rate of ammonia uptake = 10 gmol g dry mass-1 11-1 x (m)	 (16)(Harrison et al., 1986)mass of phosphorus consumed = 42 g dry mass-1 x (m)	 (17)(Druehl, 1988a)where	 m = dry mass of kelp.4.3. Interrelationships and Formulations Although kelp farms and fish netpens are two physicallyseparate components, they are interrelated through current and flowconditions. The size of the fertilized kelp farm will depend onthe availability of the nutrients, and availability depends ondilution. The fish depend on oxygen-rich water, so oxygenconsumption by kelp during dark hours could have a negative impacton them. In this section three interrelationships, namely,nutrient dilution effect, nutrients and oxygen concentrations aredescribed.Ammonia nitrogen from the fish farm is the main input to thekelp farm. One of the problems in the model was to relate ammonianitrogen concentration in the netpens to ammonia nitrogenconcentration in the kelp farm. Three reports focused on thedistribution of nitrogen around netpens. Black (1987) took watersamples at a number of depths both in the netpens and at pointsalong a line down current from the pens. Current velocity in thefour different sites ranged from 0.0008 to 0.015 m s -1 . Black(1987) found no significant difference in ammonia nitrogenconcentration with water depth. The average total ammonia nitrogen36concentration in the netpens ranged from 0.7 AM (total biomass in8, 12 m2 x 6 m deep netpens, was 28,300 kg) to 2.3 gM (totalbiomass in 13, 36 m2 x 6 m deep netpens was 12,500 kg). Typicalocean background level for ammonia concentration ranged from 0.6 to0.9 AM (Black, 1987). Weston (1986) measured ammonia concentrationin a netpen (with an approximate biomass of 27,000 kg) to be 1.0AM, whereas 30 m downcurrent the concentration was 0.7 AM.On the other hand, Korman (1989) found that ammonia nitrogenconcentration decreased with distance from the netpens up to adistance of 10 m. After 10 m and up to 35 m, he found that theconcentration fluctuated. The total ammonia nitrogen concentrationwithin the netpens and at the outer stations (i.e. 25 m away) was2.0 to 5.6 gM (with an annual production of 65 tonnes of salmon)and 1.4 to 3.4 AM (with an annual production of 52 tonnes),respectively.A River-run mathematical model was initially used to accountfor the change in the nutrient concentration between fish cage andkelp farm. A River-Run model where both advection and diffusionare important could not be used to model the unsteady andcomplicated flow pattern around the netpen structure. The flowpattern also varies with site and actual current direction.Instead Korman's data was used to predict the dilution effect.The dilution effect on ammonia nitrogen concentration was mostevident within 10 m of the netpen. A random variation in nitrogenconcentration was observed from 10 m to 40 m away from the netpens(i.e. at 35 m away the concentration was higher than 15 m away).37In the conceptualized Laminaria production system, a 30 m widemixing zone after the initial 10 m was assumed to be fertilized.Any portion of a kelp farm extending beyond 40 m from the salmonfarm may, therefore, have to be artificially fertilized. The sizeof one of the kelp production areas (e.g. for one end of a netpenfarm, 4 cages wide and 15 m wide per cage) was calculated using thefollowing formula:Kelp production area per netpen end =1,800 m2= 30 m of fertilized distance x 4 cages x 15 m, thenumber of kelp ropes = 10 = 30 m of fertilized distance/3 mspacing,number of surviving kelp = 10,000 = number of ropes * 4 cages *15 m * 5 plants per cluster / 0.3 m.Mathematical expressions were obtained using Korman's datawhich related dilution with distance from netpen up to 10 m. Ninedata points from Korman's data were used (i.e. 3 concentrations inthe netpens, 3 concentrations at 3 m away from the netpens, and 3concentrations at 10 m away from the netpens) to calculate thisdilution rate. Ammonia nitrogen concentration decayed as a linearfunction of initial ammonia nitrogen concentration and as afunction of distance from the netpen (see Equation 18). At 10 mfrom the netpens, a 48% decrease in concentration was evident.Decay = 1.02-0.056 d	 r2 = 0.92	 (18)38where	 decay = Ammonia Nitrogen Concentration Decay (Fractionof initial concentration), andd = distance from Netpen.In order to interrelate the two components (i.e. nutrientavailability and kelp growth as discussed in sections 4.1.1 and4.1.2), the ammonia nitrogen production rate is converted toammonia nitrogen concentration using the current speed and the flowarea of the netpens (Inoue, 1972).Ammonia = Ammonia nitrogen / (area x speed * 1000)	 (19)where	 Ammonia production =Ammonia =area =speed =kg h-1, equations 13, 18gM,netpen depth x netpen width re,current velocity m/s.Ammonia nitrogen is rapidly diluted on a netpen farm (Korman,1989). Based on Korman's data the ammonia nitrogen concentrationdecay as a function of distance was obtained.kelp raft concentration = Ammonia x dilution	 (20)where	 kelp raft concentration = ammonium concentration at thekelp raft in gM,Ammonia = ammonia nitrogen concentration in the netpens,anddilution = dilution effect due to distance from thenetpens, obtained from equation (18).Oxygen is another interrelationship between fish netpen andkelp farm. Oxygen consumption in the kelp farm at night could39cause oxygen depletion in the netpens. Oxygen consumption in thekelp farm was calculated by the following equation:oxygen consumption = uptake rate x mass of kelp	 (21)where	 oxygen consumption = kg per day,mass of kelp = kg, anduptake rate = mass of oxygen per mass of kelp pertime (experimentally obtained, section (5.2.2).4.4. Economic Considerations In order to determine the economical feasibility of theoperation of the two 10 60 m rope areas, a breakdown of inputcosts was first established. The cost of the operation includescapital costs, direct costs and indirect costs. Subsequently, therevenue and the break-even point were determined.4.4.1. Fixed Capital costs The fixed costs are the equipment costs and initial workingmoney needed to begin an operation up to first harvest. Capitalcost includes the cost of all materials needed to construct a kelpfarm. Initial working money is the total amount needed until firstsale. Initial capital costs include costs of rope, steel cable,galvanized chain, thimbles, buoys, floats, cement bags andshackles. Druehl (1980) outlined the material costs for one 60 mlong cultivation rope (Table 2). An industry price index of 4.7%per year was used to inflate the 1980 costs to 1992 costs40Table 2. Cost of materials for one 60 m long cultivation rope(Druehl, 1980).MATERIALS COST125 m, 0.5" polyprop rope $ 47.006 m, 0.5" cable (steel) 13.604 m, 3/8" chain (galvanized) 20.686 thimbles (galvanized) 9.602	 #40 buoys 41.303, 6600-20 floats 8.851.4 bags cement for anchors 10.002, 7/16" shackles (galvanized) 4.20TOTAL 155.2341(Anonymous, 1992). The adjusted material cost due to inflation(i.e. from 1980 to 1992) is $270 for a 60 m long rope. A lifeexpectancy of 3 years is assumed for each rope. A life expectancyof 5 years and a salvage cost of $20 is assumed for other materialsneeded to put up each rope (e.g. buoys, floats). A complete listof initial fixed capital costs is shown in Table 3.4.4.1.1 Storage Shed A small shed is needed for the storage of the kelp. The shedhas to be dark and dry. The price of a storage shed is highlyvariable depending on material. A price of $2500 for a 3 x 5 mshed (i.e. wood framing) is assumed.A greenhouse is needed to dry the kelp. A price of $2900 fora 6 x 10 x 3 m3 plastic greenhouse is assumed. A heater ($ 700) isneeded in the greenhouse to maintain high temperature (25 to 30 °C)throughout the year. The salvage value and life expectancy of thegreenhouse and the heater are $400 and 10 years.4.4.1.2 BoatA boat is needed to perform routine operations in the kelpfarm. The boat is needed mainly for planting and harvestingperiods, which usually takes 4 to 6 weeks a year for the farm. Thecost of a 4 m aluminum boat is set at $2,433. The salvage valueand expected life expectancy of the boat are $300 and 10 years.42Table 3. Breakdown of initial capital investment. This includesthe capital investment, initial construction capital, and initialoperating capital.1. Fixed investment Price1.1 cost of 20 x 60 m ropes $ 5400(see table 10 for itemized list)1.2 cost of boat for transportation $ 24331.3 cost of storage shed $ 25001.4 cost of greenhouse $ 29001.5 cost of heater $	 7001.6 cost of light sensor $ 34001.7 cost of mooring system installation $ 11501.8 land lease $ 1500(for 3 months, before first harvest)2. Initial construction capital	2.1	 interest payment during installationperiod (compound interest rate = 11%)	2.2	 insurance policies(10% of material cost)3. Initial operating capital$ 9590$ 1340	3.1	 labour for seedling production	 $ 4147and planting	3.2	 management of the operation	 $ 18000	3.3	 cost of seedling production	 $ 600	3.4	 overhead (60% of total labour cost)	 $ 2488	3.5	 cost of gas and oil for boat	 $ 200	3.6	 cost of transportation to the site	 $ 800	3.7	 cost of marketing (5% of fixed cost)	 $ 1040	3.8	 contingency (10% of initial operating	 $ 2728cost)434.4.1.3 Light SensorA light sensor is needed to measure light intensity atdifferent depths. The cost of a light sensor with underwaterprobes is $3400.4.4.2 Operating Costs The factors which contribute to direct operating cost are thecost of seedling, labour cost and management costs.4.4.2.1 Seedling Costs In order to produce the seedling, space has to be rented for4 months at a Marine Station (Lloyd, Pers. Comm.). The rental costis approximately $600 for four months. Eight hour weekly labour isneeded to look after the seedling production (Lloyd, Pers. Comm.).The labour cost (i.e. $12 h-1 + 20% benefits) is $1843 (i.e. 128working hours).4.4.2.2 Labour Cost for Planting and HarvestingTwo workers are needed for four weeks annually for harvestingand insertion of seedlings in the ropes. The annual labour cost($12 h-1 + 20% benefits) totals $4608 (a total of 320 working hoursis assumed).4.4.2.3 Management CostA monthly salary of $1500 is chosen for the manager of thekelp farm. Therefore, $18,000 annual salary is assumed for the44manager. The duties of the manager include daily inspections ofthe farm and marketing for the products.4.4.2.4 Light Control and Maintenance Costs The depth of kelp ropes in water can be varied monthly toobtain the optimum light intensity (Chapter 7). A labour cost isassociated with the operation. An annual cost of $1150 isestimated for light control operation (i.e. eight hours everymonth, $12 h-1 + benefits).An annual maintenance cost of $100 is assumed for the boat(i.e. gas and oil). This assumption is based on the fact that theboat travels 600 km annually (i.e. a distance of 10 km to theshore, four weeks a year for transportation of seedlings andharvested material). An annual maintenance cost of $100 is assumedfor the heater in the greenhouse.4.4.2.5 Land CostLand to put the greenhouse and storage shed is needed. Onsome fish farms, space may be available, but for this study land isincluded. A yearly rent of $5000 is assumed for a quarter acreland (a minimum of 5 year lease).4.4.2.6 Transportation Cost The product (after being dried) should be brought to themarket. A yearly transportation cost of $400 is considered.454.4.3 Indirect Operating Costs Indirect costs arise from work that is beneficial to the farmand include: taxes, administrative and financing costs. Since theoperation is small (i.e. less than $200,000 income), and is forproduction purposes a 18% tax is used in the calculations. A 10%annual rate (10% of equipment cost) is assumed for the insurance ofthe equipment.4.4.3.1 Depreciation Depreciation cost is used for tax purposes. Depreciation costdepends on the lifespan of the equipment as well as the salvagevalue (Lee, 1988):Linear Depreciation = (initial cost - Salvage value) / Life span4.4.3.2 FinancingInterest rate will accrue on the capital cost, at an annualrate that can be set by the user. It is assumed that 50% of therequired fixed cost is paid by the owner (Chapter 8). For thisstudy a the compounded interest rate is set at 11% per annum.4.4.4 Revenue Revenue depends on the mass of kelp produced annually as wellas the selling price of kelp. The selling price of kombu (ediblekelp) in Vancouver Health Food Stores is between $4.50 to $5.00 per2 ounce (i.e. $79 to $88 per kg). A selling price of $35 per kg isassumed for the dry mass of kelp. This assumption is based on a46selling price of $32 per kg in Vancouver in 1988 (Lloyd, pers.comm.).4.4.5 Pav-Back Period This point is reached when a surplus of cash is established(i.e. total initial cost is equal to total net revenue). Thefollowing procedure is used to determine the break-even point :1) Calculation of total annual revenue (TAR) (i.e. mass ofharvested product x price of product).2) Tax = (TAR - operating cost - depreciation - interest payment)x 0.18After Tax Revenue (ATR) = Total Revenue - Tax - operating cost -total bank payment3) The pay-back period is when the sum of annual profits is equalto the initial cost of the operation (i.e. the cost to startthe operation).4.5 Kelp Production and Economical Model Formulation A computer model was written using Turbo-C language (Appendix3). It related the mathematical expressions of netpen nutrientrelease, kelp nutrient uptake and kelp growth in order to estimatekelp production, kelp oxygen uptake and nutrient removal. Thepayback period of the resulting production was calculated. Thefollowing parameters can be changed, depending on environmentalconditions, to determine the feasibility of the operation. A47summary of the necessary inputs and the typical outputs is givenbelow.Typical Inputs:1) initial fish mass : The mass of fish as they are put in thenetpens (unit : g)2) pH : The pH of seawater is 8.2 (Equation 14)3) number of netpens4) the final stocking density (unit : kg m-3).5) volume of each netpen (unit : m3).6) % annual mortality.7) current velocity : The current speed at the end of the netpens(unit : m s-1).8) flow area : Netpen flow area (i.e. width x depth) (unit : m2).9) plant number : number of clusters of kelp in each m of rope(one cluster every 30 cm).10) Cluster : average number of surviving plants on each cluster(5 plants per each cluster).11) kelp mass : initial kelp mass on the rope. (unit : g).12) salinity : (unit : °/00).13) temperature : Average monthly water temperature14) oxygen concentration : The dissolved oxygen concentration ofthe surrounding water is an input. This concentration can beused to compare the available oxygen to the netpens with theamount of oxygen consumed by the kelp farm at night (unitmg 1-1).15) feeding rate : mass of feed (in kg) per 100 kg of fish.4816) phosphorus uptake : The consumption of phosphorus by thekelp is 42 mg per 100 g dry mass (Druehl 1988a).4.6. Calculation and Outputs of Kelp Production Model 1) fish mass : fish mass increases with time and temperature(Table 1).2) Total fish mass : Total fish mass (i.e. kg) in the netpens atany period of time (Table 1, equation 11).3) ammonia nitrogen produced : Mass (i.e. kg) of ammonia producedin the netpens per day (equation 13).4) ammonia nitrogen consumed : Mass (i.e. kg) of ammonia nitrogentaken up by the kelps in the kelp farm per day (equations 16).5) kelp growth : The specific growth rate of kelp (unit : % perday) (equation 15).6) harvest : Number of harvests during one fish productionperiod. The kelps are harvested when the final kelp massreaches 400 g.7) kelp raft concentration : The ammonia nitrogen concentration atthe kelp farm (unit : mg/1) (equation 20).8) phosphate production : The rate of phosphate production in thenetpens is simulated in the model (unit : kg per day)(equation 14).9) phosphorus uptake : The phosphorus uptake rate of kelp iscalculated in the model (unit : kg per day) (equation 17).10) Oxygen consumption : Oxygen uptake by the kelp is measured(unit : kg per day) (equation 21).49V. MODEL VALIDATION AND PARAMETER ESTIMATION5.1. Materials and Methods Two sets of experiments were conducted at the Department ofFisheries and Oceans at West Vancouver from June 16 to August 7,1991. Laminaria saccharina was collected at Stanley Park on June14 and 15 (during the low tide). Kelp were put in a styrofoamcooler covered with seawater, and were transferred to theexperimental site immediately.5.1.1 GROWTH EXPERIMENT A set of growth experiments was conducted to relate kelpgrowth to salmon-effluent nitrogen concentration and temperature.In order to measure the growth rate of kelp, they were put in threeparallel, 2 m raceways (Figure 5). Effluent water from a salmontank was siphoned through three hoses to the three raceways.Another three hoses delivered fresh seawater into the raceways, inorder to dilute the effluent from the fish tank. Seven kelp, withdifferent coloured pins in their holdfast, were trimmed to 0.15 mand were put into the raceways. In order to simulate the actualcurrent condition around fish netpens, the height of water in theraceways was set so that the water velocity was 0.08 m Thekelp was kept in place with small stones on their holdfast.Green meshes were laid on top of the raceways in order tomaintain the light intensity below 100 AE m-2 s-1 and to reducephotoinhibition in the kelp. Irradiance was measured (Licor Li185B, Li 190 SA quantum sensor) and recorded on a portable computer(IBM 286) every50kelp tankfor oxygenexperimentkelp racewayIIIIsea waterI IIIIIfish tankIIIIFigure 5. Description of the experimental layout. Itincludes salmon culture tank, 3 Laminaria raceways,3 Laminaria tanks for oxygen experiment.510.5 h. The kelp was conditioned to the effluent from the salmontank for two weeks before the start of experiment.A set of measurements was done (24 samples during a 24 hperiod) to estimate nitrogen (ammonia + nitrate) concentration inthe fish tank. The average total nitrogen concentration from thefish tank (nitrate + ammonia nitrogen) was 38.6 AM; standarddeviation was 28.4. A preliminary set of growth experiments wereconducted from June 28 to July 12. The results showed no variationin kelp growth in three raceways; therefore, the dilution rateswere changed for the second set of experiments.A second set of growth experiments started on June 18 andended on August 3. Diurnal samples were taken on June 19, 24, 29and August 3 (i.e. 32 samples throughout each day). Kelp in threeraceways received effluent with different dilution ratios (i.e.seawater : effluent) (raceway one, 3 : 1; raceway two, 8 : 1 andraceway three, 20 : 1) for 12 h daily. The dilution rate werechosen so that nitrogen concentration (ammonium+ nitrate) would bebelow 10 AM. The purpose of introducing fish effluent for 12 hdaily was to simulate the tidal effect. The effluent hose wasturned on at 8 A.M. and was disconnected at 8 P.M. The temperaturewas recorded by two copper constant thermocouple (i.e. at thebeginning and the end of the raceway) using a computerized dataacquisition system. The mass of the kelp was measured weekly,before they were trimmed to 0.15 m.Water samples were collected from the inlet of the kelpraceways. Each sample was taken with a 60 ml syringe, and then it52was injected into a 30 ml bottle through a 934 AH Whatman filterheld by a Swinnex 25 mm Millipore filter holder. The first 10 mlwas always discarded, and the next 10 ml was used for rinsing thebottle; 25 ml of the sample was injected to the bottle, and theremaining 15 ml was discarded. All the bottles were washed in 10%HC1 solution before sampling. Ammonia nitrogen, nitrate andphosphorus analyses were done at the Oceanography Department,U.B.C. using a Technicon Auto Analyzer II using the standardprocedure as described in Harrison et al. (1986).5.1.2. Oxygen Experiment A set of experiments was conducted to measure the oxygenconsumption rate (i.e. mass of oxygen consumed per mass of kelp pertime) of the Laminaria at night. Three different kelp densitieswere put into three 25 1 buckets. A fourth bucket was used as thecontrol (i.e. no kelp). The kelp densities were as follows :bucket 1, 9.1 kg ITI - 3; bucket 2, 8.0 kg/m-3; and bucket 3, 5.4 kg m-3.A set of preliminary experiments was conducted from July 6 to14 to ensure that the oxygen drop would be more than the error ofthe dissolved oxygen meter. From July 12 to 25 the drop in thedissolved oxygen concentration from 2130 to 0530 was measured usinga YSI 50 D.O. meter. The probe was calibrated before eachmeasurement. The temperature and the salinity (YSI model 57) ofeach bucket were also measured. Samples were taken at thebeginning and end of the dark period (i.e. 8 h interval).Oxygen consumption has been expressed in the literature bothin terms of mass as well as surface area. In order to have this53flexibility in this study, mass and surface area were determined.The outline of the kelp was traced on a piece of paper (usingAutocad software). The wet mass of the kelp (i.e. the kelp in thetanks) was measured at the beginning and at the end of theexperiment.5.2. Results and Discussion 5.2.1 Results of Nutrient Experiment The growth rate of the kelp varied proportionally with thenitrogen concentration (Table 4). Total nitrogen concentrationvaried between 3.3 to 9.7 AM in the raceways, while the specificgrowth rate varied from 3.3 to 8.9 AM.Nitrate concentration varied between 5.5 to 10.7 gM andammonium concentration varied between 5 to 16 AM during theexperiment in the salmon culture tank (Table 5). Nitrateconcentration was relatively constant (i.e. compared to ammoniumconcentration) (Figure 6). Phosphorus concentration varied between2.8 and 4.5 AM in the fish tank (Figure 7).The average temperature in the tanks was less than 10°C(Figure 8). The maximum water temperature during the experimentwas 11.5°C, and the minimum water temperature was 6.8°C. The shadeson the raceways prevented water temperatures from rising higher onsunny days.Light intensity was reduced because of the shading panels(Figure 9). The average daily light intensity did not exceed 58 AEm- 2 s -1 (Figure 9). The average light intensity (from June 19 toAugust 3) before 7 A.M. and after 7 P.M. was less than 20 AE 111-254Table 4. Observed and calculated specific growth rates of kelp(L. saccharina) grown in different nitrogenconcentrations from July 18 to August 3. Thedifferent nitrogen concentrations were made by thedilution of effluent from a salmon culture withseawater. (Error represents 1 standard deviation,sample size = 128).RACEWAY 1 RACEWAY 2 RACEWAY 3INITIAL MASS (g)(July 18) 44 44 59FINAL MASS	 (g)(August 3) 161 120 93OBSERVED SPECIFICGROWTH RATE% PER DAY9 7 3DILUTION RATEeffluent:seawater 1:	 3 1:	 8 1:	 20AVERAGE TOTALNITROGEN (ammonium+ nitrate)CONCENTRATION(July 18 - August 3)AM9.7 ± 1.1 5.3 ± 0.8 3.2	 ± 0.6CALCULATED SPECIFICGROWTH RATE% PER DAYUSING Eqn. 1512.1 6.5 4.055Table 5. Average daily nitrate, ammonia nitrogen, and phosphateconcentrations in the fish tank. Samples were takenover a 24 hour period (day and night). (Error represents1 standard deviation, sample size = 32).NitrateAMAmmoniumAMPhosphategMSamplesizeJULY 18 25.9 ± 2.2 8.2 ± 2.0 4.5 ± 0.5 32JULY 23 25.8 ± 0.3 16.4 ± 3.2 3.6 ± 0.04 32JULY 28 21.4 ± 0.2 5.2 ± 2.4 2.8 ± 0.04 32AUGUST 2 21.2 ± 0.6 11.4 ± 0.7 4.9 ± 0.5 32561	 2	 3	 4time (days)all nitrate ammoniumFigure 6. Average daily ammonia and nitrate concentrationsin the fish tank. The error bars represent 1standard deviation with n = 32. Days 1, 2, 3 and 4represent the days that the samples were taken(July 18, 23, 28 and August 2).50— 40 -302010 -01	 2	 3	 4Time (days)ON phosphorus	 total nitrogenFigure 7. Average daily total nitrogen and phosphorus	 -concentrations in the fish tank. The error barsrepresent 1 standard deviation with n = 32.Days 1, 2, 3 and 4 represent the days that thesamples were taken (July 18, 23, 28 and August 2).17.06.512.011.511.0	 average temperature   minimum temperature00000 maximum temperature10.510.0(J1^ - .• 8.0 1(71 . .7.5 -=:14 N;7)7' \ •n NN0	 2	 4	 6	 8	 10	 12	 14	 16	 18	 20	 22	 24Time	 (hours)Figure 8. Daily water temperature in the Laminaria racewaysduring the Laminaria growth experiment(July 18 - August 3)40.0H7E.' 30.0 -1720.0J70.0 -•60.0 -/10.0. . .-1---------_--e-""V0.0	 ;	1	 I	 i	 1	 1	 i	 1	 (	 1	 '-r-	i0	 2	 4	 6	 8	 10	 12	 14	 16	 18	 20	 22	 24	Time	 (hour)Figure 9. Average daily light intensity reaching theLaminaria throughout the growth experiment(July 18 - August 3).5.2.2 Discussion of Nutrient Experiment The results of the nutrient experiment confirmed the linearrelationship between kelp growth rate and the available nitrogen.The average water temperature was between 8.3 to 9.5 °C, which waslower than the optimum range of 10 to 15°C (Bolton and Luning,1982). The experimental results were compared with the expectedvalues using Eq.20 (Table 5). The experimental and empiricalresults were tested for a significant difference using the t-test(null hypothesis : no significant difference between the actual andestimated growth). Number of samples (plants) in each raceway wasseven (n=7, inTable 5). In raceway 1 (i.e. highest ammonia nitrogenconcentration) the null hypothesis was rejected (Table 6). Inraceways 2 and 3 the null hypothesis was not rejected (Table 6).Therefore, the developed equation (i.e. equation 16) is valid forlow (i.e. less than 7 AM) nitrogen (ammonia nitrogen + nitrate)concentrations.Since the raceways were covered by the shades, the maximumlight intensity did not reach more than 60 AE m-2 s-1 (Figure 9),which was lower than the expected 80 to 90 AE rn-2 s-1 . The lowirradiance could be a possible explanation for low growth of kelpin the raceways. The relationship between light intensity and kelpgrowth rate was not considered directly in the model (Chapter 7).During the experiments the phosphorus concentration wasbetween 2.8 and 4.9 AM. The calculations (Appendix 1) show thatthe kelp were not phosphorus limited throughout the experiment61Table 6. The theoretical specific growth rate of Laminaria (Eq. 15)is compared with the actual kelp growth in the threeraceways. A t-test (95% confidence level) was used.Sample size or number of plants in each raceway = 7,S = standard deviation of samples in each raceway.Raceway S t t0.05(2),6 ActualGrowth% /dayTheor.Growth% /daysignificantdifference1 2.1 3.8 2.45 9 12 Yes2 1.1 1.3 2.45 7 6.5 No3 1.3 2.0 2.45 3.3 4 No62This was expected, because in the marine environment phosphorus isnot considered to be a limiting nutrient (Lobban and Wynne, 1981).5.2.3 Results of Oxygen ExperimentThe oxygen drop in the three tanks was different (Table 7).The maximum oxygen drop was 2.2 mg 1-1 in the tank with the largestmass (i.e. Tank 1). The results of the experiment showed that theoxygen drop was proportional to the kelp mass in the tanks (Table8). The oxygen drop in tank 1 varied between 1.6 and 2.2 mg 1-1.The oxygen drop in tank 2 was between 1.4 and 1.8 mg 1 -1 . Tank 3,having the lowest mass, had an average oxygen drop of 1.10 mg 1-1 .The salinity of water was between 20 and 26 o/oo with an averagevalue of 24 0/00. The water temperature was always lower at thebeginning of the experiment than at the end. Maximum and minimumincrease in water temperature in one night was 3 and 1.5 °Crespectively.The oxygen drop per unit mass of kelp was 0.026, 0.024, and0.026 mg 02 per wet gram kelp per hour in tanks 1, 2, and 3respectively (Table 8). The summary of the results from the oxygenexperiment is presented in Tables 7 and 8.The surface area for Laminaria used in the experiment (Figure10) was found to be relative to wet mass (in the range of 0.008 to0.023 kg) by the following equation :Area = 1.37 mass - 0.0004	 r2 = 0.91	 (22)where	 Area : kelp surface area in m2, andmass : kelp mass in kg.63Table 7. Oxygen drop (mg 1-1) in different kelp Laminaria duringnight (8 h). Average kelp mass in tank 1 = 0.20 kg;tank 2 = 0.18 kg ; tank 3 = 0.13 kg.TANK 1 TANK 2 TANK 3 CONTROLJULY 12 1.99 1.82 1.21 0.13JULY 13 1.56 1.47 0.86 -0.27JULY 14 1.90 1.64 1.21 -0.01JULY 15 1.62 1.36 1.02 0.15JULY 16 1.77 1.42 1.07 0.13JULY 17 2.09 1.67 1.41 0.13JULY 18 1.78 1.35 1.17 -0.03JULY 19 1.77 1.43 1.08 0.13JULY 20 1.86 1.43 1.01 0.13JULY 21 2.11 1.51 1.01 -0.04JULY 22 2.20 1.69 1.17 -0.03JULY 23 1.93 1.59 1.01 0.04JULY 24 2.12 1.52 1.17 0.22JULY 25 1.95 1.35 1.09 0.2464Table 8. Oxygen uptake rate in different Laminaria tanks overexperimental period (July 12 to July 25). Cumulativeoxygen drop is the total (i.e. 14 nights) in each 22 1bucket.TANK CUMULATIVEOXYGENDROPmgINITIALMASS(g)FINALMASS(g)AverageMass(g)02 dropper gramwet massMg gl h-11 42 188 210 199 0.0262 33 158 193 176 0.0243 24 107 130 119 0.026650.03 -,area = 1.37 mass - 0.00040.02- 0.015 -0.01 	0.006 0.008	 0.01	 0.012 0.014 0.016 0.018	 0.02	 0.022 0.024MASS (kg)Figure 10. Relationship between mass and surface areaof the Laminaria.5.2.4. Discussion of Oxygen ExperimentOxygen concentration is essential for fish farms. Theintroduction of the kelp farm near sea cages could cause oxygenconcentration depletion in the sea cages at night. In the oxygenexperiment, the rate of oxygen consumption at night was measured tobe 0.026 mg 02 g wet mass kelp-1 11-1 . The oxygen consumption canalso be expressed as 0.81 AM 02 cm-2 h-1 .King and Schramm (1976b) calculate the maximum photosyntheticrate for Laminaria saccharina to be 2.0 mg 02 g db-1 Druehl(1967) obtained an average ratio for photosynthesis to darkrespiration ratio of 13.36. Assuming a 10% dry mass/ wet massratio for the kelp, King and Schramm's (1976b) results can beconverted to a respiration rate of 0.015 mg 02 g db-1The two respiration rates, 0.015 and 0.026 02 g db-1 h-1 , werevery close. Basically two assumptions were used to convert Kingand Schramm's (1976b) photosynthetic rate to respiration rate.First, a 10% wet to dry kelp mass ratio was used, and secondly thephotosynthesis to respiration rate ratios of Druehl (1967) wereused.Gerard (1988a) measured dark respiration rates for Laminariasaccharina to be between 0.1 to 0.3 Amol cm-2 h-1 , which is lowerthan this experiment (i.e. 0.8 Amol cm-2 h-1). Higher oxygenconsumption in the experiment could be partially explained byBiochemical Oxygen Demand (i.e. BOD). The bacteria in water couldconsume oxygen.67The uniqueness of the oxygen experiment, beside measuring theoxygen consumption, was the method of the experiment. In all theabove mentioned references, the oxygen consumption was measuredusing small portions of kelp, whereas in this experiment the oxygenconsumption of the whole seaweed was measured.68VI. PRODUCTION MODEL ANALYSISA number of computer simulations were run. They were run inorder 1) to test if the kelp could be Phosphorus limiting, 2) topredict the ammonia nitrogen removal by the kelp, 3) to predict thenumber and amount of kelp harvests with a comparison to a nofertilized situation, and 4) to predict the amount of oxygenconsumed by kelp. A summary of typical kelp production model inputvalues used is given (Table 9). The schematic of the proposedintegrated salmon/kelp farm is shown in Figure 2. One 10 60 m ropekelp farm lies on each side of the fish farm (Figure 2). Based onempirical data this size of farm would be fertilized and it isassumed and not to be light limited.6.1. Fish and Kelp ProductionTotal mass of fish in the 12 netpens after 16 months is250,000 kg. Ammonium concentration from the fish farm after 16months was about 1.5 AM. An ambient nitrogen concentration of 1 to2 AM is assumed. Three kelp harvests were expected within 16months of operation. A wet mass of 8000 kg was expected at eachharvest from each 10 60 m rope kelp farms. The dried mass of kelpfrom each harvest is 800 kg. A minimum of 2 annual harvests witha yield of 16000 kg of kelp is expected. According to the model,during the same period, a non-fertilized farm would produce 8000 kgof kelp (one half of a fertilized farm).69Table 9. Summary of typical kelp production model inputvalues. Average monthly water temperatures(1921-1991) of Race Rocks (latitude = 48.18 °N,longitude = 123.32V, water depth = 1 m) wasused in this model.number	 of netpens = 12 ,	 final stocking density = 10 kg m-3netpen volume = 2250 m3,	 fish mortality = 10% per yearfinal fish mass = 3.0 kg,	 current velocity = 0.1 m s-1feeding rate = 1% of fish mass,	 initial fish mass = 40 gkelp farm = 10	 60 m ropes,	 final kelp mass = 400 g/plantmonthly water Temperature = 7.3, 7.3, 7.6, 8.4, 9.4,	 10.2,10.8,	 10.9,	 10.6,	 9.7,	 8.7,	 8.0	 °C# kelps per cluster = 5,	 flow area = 300 m2706.2. Ammonia NitrogenAmmonia nitrogen production in the netpens as well as ammonianitrogen consumption in the Laminaria farm was simulated by themodel. A mass balance was used to estimate the production andconsumption values. The consumption rate was computed by twodifferent approaches. In the first method, the nitrogen uptake wasbased on the nitrogen content of Laminaria (Figure 11). This valuehas been estimated to be about 2% dry mass (Harrison et al. 1986,Asare and Harlin, 1983). In the second method, an uptake rate of10 Amol 11-1 dry mass g-1 (i.e. based on Harrison et al. 1986 ) wasassumed (Figure 12). The results indicate that for a 10 60 m ropekelp farm, the ratio of consumed ammonia nitrogen to the total(i.e. particulate and dissolved) ammonia nitrogen was never morethan 0.5%. For a 100 x 60 m rope farm the above ratio could reachas high as 5.4%. If the dissolved ammonia nitrogen produced isconsidered, the above ratio could reach 9.6% for a 100 x 60 m ropefarm (Figure 14). The results indicate that throughout theproduction cycle no nitrogen limitation exists. The results alsosuggest that a larger kelp farm operation could bring down thenutrient loading significantly. Ammonia nitrogen production rateranged between 6.6 and 13.2 kg day-1 for 1 and 2 netpensrespectively (Figures 11 and 13) and the nitrogen consumption ratereached 0.2 and 1.0 kg day for a 40 and 100 rope kelp farmrespectively.In order to observe the efficiency of kelp farms to decreasethe nutrient loading from the sea cages, the ratio of total and71200 5Time10	 15(months)6.04.0•2.0 -0.014.0////V//	 •-......-.•-• ammonium consumption by 100 x 60 in rope farm.n•••••n-^	 ammonium production by 2 netpens.Figure 11. Ammonia nitrogen availability for an integratedSalmon/Laminaria farm (netpens = 2, 50 ropesLaminaria farm).8.0 -1.06.05.004.00c.)3.0 7:(7.5a)- 10 x 60 m ropes- 100 x 60 m ropes20(1)0	 5	 10	 15	 20Time	 (months)Figure 12. Ratio of total ammonia nitrogen consumed by theLaminaria to ammonia nitrogen produced by salmonfarm. The drops represent the harvesting periodsin the Laminaria farms.2010	 15(months)5Time7.0Ammonium consumption 20 x 60 rope farm	  Ammonium production in 1 netpen6.0COLS	 -_5'°4.0Figure 13. Ammonia nitrogen availability for an integratedSalmon/Laminaria farm (netpens = 1, 20 ropesLaminaria farm).dissolved ammonia nitrogen loading (from 12 netpens) to ammonianitrogen consumption by kelp was obtained (Figures 12, 14). Forthe 10 60 m rope farm, the percentage consumption did not reachmore than 1.0%. On the other hand, for a 100 60 m rope farm thisrate could reach up to 9.4% (Figure 14).6.3. Phosphorus Phosphorus production and consumption were analyzed in thekelp production model using equation 14. The model predicted amaximum phosphate production of 4.8 kg per day (Figure 15), whereasthe maximum phosphorus consumption by kelp would be 0.0026 kg perday for a 10 60 m rope kelp farm (Figure 16).On one hand the phosphate production rate by fish was high,and on the other hand the phosphorus content of kelp was low.Therefore, phosphorus limitation could not be observed in the kelpfarm. Ammonia nitrogen production rate in one netpen is higherthan phosphate production rate in twelve netpens (Figures 14 and15). The ambient phosphate concentration was neglected in thecomputer model.6.4. OxygenUsing the oxygen consumption rate from the oxygen experiment,the expected oxygen consumption for 10, 100 and 1000 x 60 m ropekelp farms was simulated (Figure 17). It can be seen that exceptfor the largest farm (i.e. 1000 x 60 m rope farm) the oxygenconsumption rate was below 2.0 kg h-1. This can be compared to aminimum oxygen transfer rate of 140 kg h -1 (i.e. with a current7510.08.06.0 10 x 60 m ropes100 x 60 m ropes74.032.00.0 ,710	 5	 10	 15	 20Time	 (months)Figure 14. Ratio of ammonia nitrogen consumed by theLaminaria to ammonia nitrogen produced bysalmon farm. The drops represent the harvestingperiods in the Laminaria farms.5.0›,4.0CO1:153.0O 2.001.00.0 	 ;	 1	 1	 1	 1	 1	 1	 f	 i	 ;	 i ; ) f	 111111	 10	 5	 10	 15	 20Time	 (month)Figure 15. Phosphate available from the Fish Farm(netpens = 12, Fish Feeding Rate = 1%).0.03000.0250 1:0.0200 "7H	 - 100 x 60 m rope farm- 0.0150   10 x 60 m rope farm•-0.0100 -0.00500.00000	 5	 l0	 15	 20Time	 (month)Figure 16. Phosphorus consumption by different Laminariasized farms.11.0 -310.0 ---i.......m 9.0 -3,..... ...!	„t1D B.0 -1	 i	 I.......	 7 /...-	- 7.0 3	I...,	.., 	 i	 iI--	 -	 i	 !..	 ..--5.0 	-	 ,/i !-,	 /;..: 4.0 --' if 1 1,	n	 n	 i'	 i	 I.....)	 .-I,	 i	 f	 1ILZ	 IMt	 .	 .:	!- ..., 3.0 -,	 ,/	 1	 /-.....,,--,.  ,	 /	 /	I 	 !1	 /,	!..!	 A	 4'	 1	 A	 !	 A/A I/ - 	 ,;!. .....,/ \	 71 \	 4, \	....-! 	\ i.' N.,-... ''l	\ ,t............,..7............,,,,..,7,---".1	\ ‘,..........70.0I1100	 60 in rope farm1000	 60 in rope f arm10	 60 in rope farm0	 5	 10	 15	 20Time	 (months)Figure 17. Oxygen consumption by different Laminariasized farms.speed = 0.1 m s-1 and [02] = 5.0 mg 1-1); therefore, oxygenconsumption was less than 1% of the available oxygen.The oxygentransfer to the netpens depends on oxygen concentration, as well ascurrent speed. As the current speed increases, the rate of oxygentransfer also increases.Oxygen production by the kelp through photosynthesis wouldbenefit the fish in the netpens. As discussed above, the rate ofphotosynthesis is 13 times higher than the respiration rate.According to the model, the rate of oxygen production isconsiderably higher than the consumption rate. The results shouldnot imply that all of this extra dissolved oxygen reaches thenetpens. Mixing, current direction, and dilution rates determinethe percentage of the produced oxygen reaching the net pens.80VII. LIGHT MANAGEMENT TECHNIQUEA computer model was developed to analyze the light intensityat different depths and different extinction coefficients (Appendix4). This model could be used as a tool to manage the kelp farm.The attenuation of solar radiation from the sun to the water columnin the ocean was calculated. The solar radiation arriving at theearth's surface is composed of a direct and a diffuse component.This occurs because some of solar radiation is scattered in theatmosphere. Different parameters, such as cloudiness index,seasonal variation and diurnal variation, affect the attenuation ofsolar radiation from the sun to air/water interface.The water surface, latitude and hour of the day affect thereflectance of the diffuse and the direct light. In the watercolumn, the attenuation of light beam depends on water depth andthe extinction coefficient. Mean hourly solar radiation totalsfrom Canadian Climate Normals (1951 - 1980) for the Vancouver, UBCstation were used in the model. In this climate normal, the hourlysolar radiation of a typical day of the month, which represents theaverage hourly solar radiation for that month in the last 30 years,is used.7.1 Inputs of Light Model The following input parameters are used to compute the lightintensity in the water column at different periods. Theseparameters can be varied depending on the site location.811) latitude : latitude of the desired location.2) depth : the water depth (unit : m).3) attenuation : attenuation coefficient of water (unit : m-1).4) hourly solar radiation : Hourly global solar radiation on ahorizontal surface for a typical day of each month. This datacan be obtained from Canadian Climate Normals(unit : Mega Joules m-2).5) day number : Typical day number of each month is input as aone dimensional array.7.2. Outputs of Light Model 1) cloudiness : cloudiness index, which determines whatpercentage of extraterrestrial radiation reaches theatmosphere.2) day length : The length of a typical day of each month iscalculated (unit : h).3) depth intensity : light intensity at a certain water depth(unit : AE m-2 s-1).4) diffuse intensity : diffuse light intensity reaching watersurface (unit : AE m-2 s-1).5) beam intensity : beam light intensity reaching water surface(unit : AE m-2 s-1).6) transmission : percentage of light transmission at air/waterinterface during different hours.827.3. Light Model Analysis Different simulations were done to analyze light intensity atvarious depths with different attenuation coefficients. Addey andLoveland (1991) listed attenuation coefficients for a variety offresh and marine waters to be 0.03 to 0.7 m-1 . A wide range ofattenuation coefficients from 0.1 to 0.8 m-1 was used in thesimulations. The attenuation coefficient was calculated using thefollowing equation (Parsons et al., 1988).attenuation coefficient, Kd = 1.7 / visibilitywhere : in summer	 visibility = 6.5 m	 hence Kd = 0.26 m-1in winter	 visibility = 11 m	 hence Kd = 0.15 m-1At a water depth of 2 m, depending on the attenuation coefficient,the maximum monthly light intensity varies between 240 and 690 gErft-2 s-1 (Figure 18). As expected, the maximum light intensity occursin June.	 Figure 18 is based on the range of attenuationcoefficients between 0.11 and 0.60 re l . The sharp reduction oflight intensity due to an increase in light extinction coefficientemphasizes the importance of measuring attenuation coefficient forthe desired site (Figure 18). At a water depth of 2 m, lightintensity was reduced from 690 to 240 gE ra-2 s-1 when attenuation wasincreased from 0.11 m-1 to 0.60 m-1 (Figure 18).The effect of water depth on light intensity is also examinedin the light model. As water depth increases, light intensitydecreases. For an attenuation coefficient of 0.1 m -1, light83intensity was reduced by 47% when travelling from a depth of 2 to7 m (Figure 19). The kelp should be grown at a depth, where theywould not be photoinhibited or light-limited. Using the computersimulations for light intensity, kelp farmers can determine theoptimum depth. In different months of the year the depth of kelprafts should be changed (i.e. adding or removing floats attached tothe ropes) to use the available sunlight. For example, in thesummer, the kelp raft should be placed deeper in the water to avoidany photoinhibition.84800.0400.0—	 extinction coeff. 0.104-4—i- 4- 1 extinction coeff.	 0.30 m_ ier-e-e-E-E extinction coeff. 0.60 mCOUlon 200.0600.0E0.0 	0	 2	 4	 6	 8	 10	 12	 14Time	 (hours)Figure 18. Light intensity reduction due to differentextinction coefficients.110.0100.0c.) 90.0 7480.0==-1. 70.001 —c);60.050.0 t141attenuation coeff = 0.1 rn - '1	 2	 3	 4	 5	 6	 7	 8Water Depth (m)Figure 19. Light intensity reduction as a function ofwater depth.VIII ECONOMIC FEASIBILITYSeaweed farming can be viewed as an additional income forsalmon farmers. Two 10 60 m ropes would produce 1600 kg of drykelp annually. Two 30 60 m rope kelp farms (distance between eachrope is 1 m) are the nominal size of the operation. The nominalproduction rate based on a computer simulation would be 4800 kg ofdry kelp each year. The yearly production of an unfertilized farmwould be one half of the production of a fertilized farm. Thiscase study analysis is based on 33% of maximum possible production(i.e. % real/nominal usage level of facility is 33%). The sellingprice of kelp is $ 35 dry kg-1 . A minimum yearly revenue of $56,000 can be expected from these farms.In the case study, a manager would receive $18,000 to marketthe product and oversee production. The cost analysis of theoperation shows that the operation is economically feasible (Table9). In this case study half of the initial capital is borrowedfrom the bank (11% compound interest, 5 annual payments). It isalso assumed that the operator invests $ 26000 (50% of the fixedinitial investment) in the project.The investment amount required for the implementation of theproject includes fixed investment, initial construction capital,and initial operating capital (Table 9), and it is $60,000. Thepay-back period is 6 years from the start of the operation and 5years after the first sale (Figure 20). The owner starts to investon the operation one year before the first harvest (i.e. t = -1, onFigure 20). In four years after the start of the operation, the87Figure 20). In four years after the start of the operation, thetotal profit exceeds $41,000.More kelp ropes could result in higher net revenues for theowners, but yield at a higher density needs to be experimentallytested in order to test for light limited growth. Larger sizedfarms could also be operated, but yield at this option too must betested in order to test for nitrogen availability. The best optionfor a manager at this date would be to manage more than one site.This option would give the manager/owner more income.A larger kelp farm could also reduce the nutrient loading inthe surrounding environment more effectively. The number ofnetpens in each fish farming site could then be increased. Thisadditional income (i.e. more fish production) could be anotherjustification for this type of integrated production unit.88Table 10. Cash flow analysis for two 10 rope Laminaria farmsfor a 5 year period.YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6Revenue 0.00 56,000 57,120 58,262 59,428 60,616TAX 0.00 3,680 3,510 3,329 3,144 3,017AFTER TAXINCOME0.00 52,320 53,610 54,933 56,284 57,599FIXEDCAPITALCOST19,983 0.00 0.00 0.00 0.00 0.00DIRECTCOSTS30,000 31,503 33,078 34,732 36,468 38,292INDIRECTCOSTS10,930 10.930 10,930 10,930 10,930 0.00TOTALCOST60,910 42,433 44,008 45,662 47,398 38,292ANNUALPROFIT9,887 9,602 9,271 8,886 19,3078920000 -pay back period ti	 I ICI-2fixed costtime2	4	 6	 8-20000-1\ 2-40000\211initialoperatingcapital -60000-7i/-80000 first harvestFigure 20. Break-even analysis for a 20 60 m LRminariafarm.IX. CONCLUSIONS AND SUGGESTIONS FOR FURTHER WORKThe purpose of this study was to assess the feasibility of anintegrated kelp and salmon culture. Laminaria culture positionedup to 40 m away from fish netpens would enhance kelp growth andreduce nutrient loading. Two 10 60 m kelp farms, each positionedat one end of a fish farm, would produce 1600 kg (dry mass) of kelpannually. The kelp farms begin 10 m from the netpens. Freefertilizer from the netpens is a very important parameter inencouraging fish farmers to consider this integrated system,because the kelp production could be double that of an unfertilizedkelp site. The kelp farm can be considered as an additional incomefor fish farmers. It could bring in a net profit of $20,000.0/year, plus reduce the nutrient loading by 1%.In order to model the kelp growth, nutrients, temperature, andlight were considered. Equations were developed relating watertemperature and nitrogen to kelp growth. A set of experiments wereconducted to relate growth and nitrogen availability. Theexperiments confirmed a linear relationship between kelp growth andnitrogen availability. Therefore, as fish grew and excreted morewaste, more nitrogen is available for the kelp growth. Ammonianitrogen production rate in one netpen reached up to 6 kg day-1,whereas nitrogen consumption rate for a 10 60 m rope kelp farm wasabout 0.2 kg day-1 .A submodel was developed to calculate light availability atdifferent depths and attenuation coefficients. This model servedas a management tool to change the depth of kelp rafts with respect91to available light intensity. As light availability decreased(i.e. in the winter), the ropes should be raised higher to avoidlight limited growth.The experiments and the model confirmed that phosphorus wasnot a limiting factor for kelp growth. Phosphorus excretion byfish in the netpens provided a continuous source for the kelp farm.On the other hand, phosphorus uptake was minimal. For a 10 60 mrope kelp farm, the maximum calculated uptake rate is less than 4.0g day-1 . Therefore, the ratio of N:P taken up by the kelp was 50:1.One of the considerations in this study was to check oxygenlimitation for the fish at night. The results of the experimentand the model show that for a 10 60 m rope kelp farm, oxygenconsumption was less than 1% of the available oxygen. Therefore,no oxygen depletion would occur in the netpens for this farm size.Kelp production 10 m from a netpen farm could also be lookedupon as a method to decrease the nutrient loading of water. Thefish farmers could apply for new licences (i.e. to increase thenumber of their netpens) and hence more revenue. This could be apossible opportunity revenue for fish farmers.Suggestions for Further Work :1. A pilot scale integrated kelp and salmon culture should bedeveloped to assess the actual feasibility of this project.2. Actual current patterns across the netpens should beanalyzed, in order to have a better assessment of nutrientdilution at different distances from the netpens.923. The feasibility of larger kelp farms could be analyzed. Thisdepends on nitrogen concentration at different positionsbeside fish netpens. Large sized Laminaria farms could beintroduced as a waste management system, which reduce nitrogenloading from the netpens.4. The effect of kelp size and density on light penetration in thewater column should be considered in order to find the properspacing of ropes.5. The Laminaria nutrient and growth model should be validated atdifferent temperature conditions.6. The economical feasibility of larger kelp farms on differentsites should be investigated.7. The effect of netpen arrangement to current direction and kelpfarm position should be studied.8. The nutrient release by netpens should be validated.93BIBLIOGRAPHYAarsens, J.V., H. Rudi and G. Loland, 1990. Current Forces onCage, Net Deflection. pp.137-152, in Engineering for OffshoreFarming, Thomas Telford Ltd, London, 137-152 pp.Ackefors, H. and M. Enell, 1990. Discharge of Nutrients fromSwedish Fish Farming to Adjacent Sea Areas. Ambio, 19(1):28-35.Addey, W.H. and K. Loveland, 1991. Dynamic Aquaria, BuildingLiving Ecosystems. 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GROWTH CALCULATIONSThe procedure to develop equation 16 is as follows :At T = 10 to 15°C growth(1) = 1.5 x ammonium concentrationAt T > 15 to T = 20°C, growth decreases so thatT = 16	 growth(2) = 0.88 growth(1)T = 18	 growth(2) = 0.64 growth(1)T = 20	 growth(2) = 0.40 growth(1)Therefore, a linear relationship between temperature and growth isobtained.growth(2) = growth(1) x ((-0.12 T) + 2.8)At T < 10 to T = 5°C, growth again decreases so thatT = 9	 growth(3) = 0.92 growth(1)T = 8	 growth(3) = 0.84 growth(1)T = 6	 growth(3) = 0.68 growth(1)T = 5	 growth(3) = 0.60 growth(1)Therefore, another linear relationship between temperature andgrowth is obtained.growth(3) = growth(1) x ((0.08 T) + 0.2)100APPENDIX 2. PHOSPHATE CALCULATIONSA set of calculations are done to compare phosphateavailability (from the salmon effluent) and phosphate consumptionby the kelp in the raceways.volume of water in each raceway = 2.7 m x .25 m x 0.05 m= 0.0338 m3water flow rate in each raceway = water velocity x area= 0.1 m s-1 x (0.05 m x 0.25 m)= 1.25 x 10-3 re s-1water exchange rate = volume / flow rate= 0.0338 / 1.25 x 10-3 = 27 sNumber of water exchanges per hour = 3600 s / 27 s = 133 h -1phosphate concentration in each raceway (see section 5.2.1) is asfollows :Raceway 1 : 1 : 3 dilution : 0.71 gMRaceway 2 : 1 : 8 dilution : 0.31 gMRaceway 3 : 1 : 20 dilution : 0.14 gMSample Calculation for raceway 3 :Phosphate requirement per hour = uptake rate x mass of kelpuptake rate = 0.47 gmol g db-1 h-1 (see section 3.3)dry mass of kelp = 9.3 g (Table 3)Phosphate requirement per hour = 0.47 x 9.3 = 4.4 gmol h-1phosphate available in the raceway per hour =0.14 AM x 33.8 1 x 133 h-1 = 630 gmol h-1101Appendix 3. COMPUTER GROWTH MODEL#include<stdio.h>#include<math.h>#include<conio.h>/* This program calculates kelp growth and harvest based on*//* the available ammonia nitrogen concentration from a fish farm*1OXYGEN_CONC 5CURRENT_SPEED 0.05INITIAL_FISH_WT 0.04PH 8.2time 30mort 10NETPENS 12FEED 1Rope 10ambient 0length 60FEEDING_RATE 2ATTRITION_P .0011ATTRITION_Q 2.9E-6PLANT_NUM 4#define#define#define#define#define#define#define#define#define#define#define#define#define#define#define/*	 mg/1 *//* current speed m/s *//* initial fish mass *//* days *//* percent per year	 *//* FEEDING RATE %	 *//* number of ropes *//* ambient ammoniumconcentration in micromols*//* length of each rope *//* number of clusters in eachm of rope */#define NETPEN_VOL#define FLOW AREA*/#define STOCK_DENkg/m3	 */2.25E330010/* volume of each netpen	 *//* net pen flow area in	 m2/* final stocking density#define SALINITY 25#defineclusterCLUSTER*/5 /* surviving plants in each#definepelletsPHOSP*/1.1 /* % phosphorous content of dry#define fish_phosp 0.4 /* % phosphorous content of fishmass */#define INITIAL KELPint flag;float Temp[363 = (8,	8,	 7,	 7,	8,	 7,	 7,107,8,8,7,9,9,8,10,10,/*	 initial kelp mass	 */9,	 10,	 11,	 11,	 12,	 11,	 10,9,	11,	 11,	 12,	 11,	 10,9,	11,	 11,	 12,	 11,	 10,9);102main()float fish weight;	 /* mass of each fish in kg*/float Total_fish_mass[18];	 /* total fish mass in kgfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloatfloat*/Total_ammonium[18];Total_ammonia[18];percent_ammonium[18];ammonium_concen[18];ionized_ammonia[18];kelpraft_concen[18];kelp_growth[18];oxy_consumpt;kelp_mass;new_kelp_mass;PERCENTAGE;phosph_prod;total_kelp_mass;initial_fish number;KILO_AMMONIA;	 /*NH4_consumpt;	 /*PO4_consumpt;	 /*old kelp_mass;ambient;	 /*KG ammonia produced per day */kg ammonia consumed per day */kg phosphor consumed per day */ambient nitrogen concentrationfloat new_fish_wt;float old_fish_mass[18];float kelp_raft_conc[18];float Ammon_uptake;float Ammon_mol_hr;float GROWTH1[18];150 g */float GROWTH2[18];600 g */float GROWTH3[18];2000 g */float GROWTH4[18];2000 g */int month, temp, harvest;/* specif. G for fish between 30 &/* specif. G for fish between 150 &/* specif. G for fish between 600 &/* specif. G for fish larger thanfor (month = 0; month <= 17; month++){flag	 = 0;Total_fish_mass[month] = 0;Total_ammonium[month]	 = 0;Total_ammonia[month]	 = 0;initial_fish_number	 = 0;percent_ammonium[month] = 0;ammonium_concen[month] = 0;ionized_ammonia[month] = 0;kelpraft_concen[month] = 0;103kelp_growth[month] = 0;old_fish_mass[month] = 0;harvest = 0;kelp_mass = 0;phosph_prod = 0;total_kelp_mass = 0;Ammon_uptake = 0;Ammon_mol_hr = 0;kelp_raft_conc[month] = 0;GROWTHl[month] = 0;GROWTH2[month] = 0;GROWTH3[month] = 0;GROWTH4[month] = 0;clrscr();/*	 printf("temp=%f\n",Temp[2]); */dummy = pow(10, (9.245 + 0.002 * SALINITY));fish_weight = INITIAL_FISH_WT ;kelp mass = INITIAL KELP;/* calculating the initial fish number/* for a final fish mass of 3 kg	 *1initial_fish_number = NETPEN_VOL * NETPENS * STOCK_DEN *(1 + (mort * 1.5/1000))/3;printf(" KELP FARM IN m2 = %f\n",FARM_ABEA);printf(" INITIAL FISH NUMBER = %f\n",initial_fish_number);for (month = 0; month <= 17; month++){GROWTHl[month] = ((0.15 * Temp[month] + 0.1)/100) + (2 *ambient);/* printf(" GROWTH1 = %f\n",GROWTHl[month]); */GROWTH2[month] = ((0.12 * Temp[month] - 0.014)/100) + (2 *ambient);/* printf(" GROWTH2 = %f\n",GROWTH2[month]); */GROWTH3[month] = ((0.079 * Temp[month] + 0.014)/100) + (2 *ambient);printf(" GROWTH3 = %f\n",GROWTH3[month]); */GROWTH4[month] = ((0.050 * Temp[month])/100) + (2 *ambient);printf(" GROWTH4 = %f\n",GROWTH4[month]);	 */flag = time * month;if (fish_weight > 0.03 && fish_weight <= 0.15 )new_fish_wt = fish_weight * pow(2.71,(GROWTH1 [month] *time));104if (fish_weight > 0.15 && fish_weightnew fish_wt = fish_weight * pow(2.71time));if (fish_weight > 0.60 && fish_weightnew fish_wt = fish_weight * pow(2.71time) );if (fish_weight > 2.0)new fish_wt = fish_weight * pow(2.71,time));<= 0.60 ),(GROWTH2[month] *<= 2.0 ),(GROWTH3[month] *(GROWTH4(month] *fish_weight = new_fish_wt;	 /* new mass of one fish in kg*/printf(" FISH MASS = %f\n",fish_weight);printf(" month = %i\n",flag);Calculating total fish mass in the net pens */and ammonia produced	 */old_fish_mass[month] = Total_fish_mass[month];Total_fish_mass[month] = initial_fish_number * fish_weight*( 1 - (mort* time * month)/36000);printf(" total fish mass %f\n",Total_fishmass[month]);/* total ammonia in mg per sec */Total_ammonia[month] = 0.0289 * Total_fish_mass[month] *FEED * 0.116;PHOSPHATE PRODUCTION IN KG/DAY	 */PHOSPHOROUS PHOSPHOROUS PHOSPHOROUS	 *//* phosphorous production , 23% in dissolved form , 52% 	 *//* reaches the kelp farm	 */phosph_prod = 0.23* 0.52 * 0.0162 * Total_fish_mass[month]* FEED / 100.0;printf(" phosphorous in the kelp farm	 kg/day=%f\n",phosph_prod);KILO_AMMONIA = Total_ammonia[month] * 3600 * 24/1E6;printf(" kilo ammonia per day = %f\n",KILO_AMMONIA);percent_ammonium[month] = 100;/**//*	 ammonium flow rate in kelp raft in micromol per liter perhour */Ammon_mol_hr = KILO_AMMONIA * percent_ammonium[month]* 1.0E+9 * 0.52 * 0.056 / 24.0;printf("NH4	 production	 by	 fish	 miromol/hr=%f\n",Ammon_mol_hr);105/* total ammonium in mg per second */Total_ammonium[month] = percent_ammonium[month] *Total_ammonia[month] / 100 ;/*	 printf(" total ammonium in mg per s=%f\n",Total_ammonium[month]);*//*	 PHOSPHORUS PHOSPHORUS PHOSPHORUS *//* phosphorus production , 23% in dissolved form , 52%/* reaches the kelp farmprintf(" phosphorous in the kelp farm kg/day=%f\n",phosph_prod);/* ammonium concentration in mg/1 */ammonium_concen[month] = Total_ammonium[month] /(FLOW AREA * CURRENT_SPEED * 1000);/* [ammonium] in micromols at the kelp raft */kelpraft_concen[month] = ammonium_concen[ month] * 0.52* 55.56;printf(" kelp raft concentration =%f\n",kelpraft_concen[month]);if (Temp[month] >= 5 && Temp[month] <= 10)kelp_growth[month] = 1.5 * kelpraft_concen[month]*((0.08 * Temp[month]) + 0.2);if (Temp[month] > 10 && Temp[month] <= 15)kelp_growth[month] = kelpraft_concen[month] * 1.5;if (Temp[month] > 15 && Temp[month] <= 20)kelp_growth[month] = 1.5 * kelpraft_concen[month] *((-0.12 * Temp[month]) + 2.8);/*	 printf("KELP	 GROWTH	 percent	 per	 day%f\n",kelp_growth[month]);*//* NUMBER OF HARVESTS */if (kelp_mass >= 400){harvest = harvest + 1;kelp_mass = 10;printf("harvest number =	 %i\n", harvest);old_kelp_mass = 0;total_kelp_mass = 0;/* individual kelp mass in grams *//* considering ambient concentration */if (kelp_growth[month] < 1.0){106kelp_growth[month] = 1.0;new_kelp_mass = kelp_mass * pow(2.72,(kelp_growth[month]*time/100));kelp_mass = new_kelp_mass;printf("new_kelp_mass = %f\n",new_kelp_mass);	 *//* total kelp mass in the farm in kg */old_kelp_mass = total_kelp_mass;total_kelp_mass = Rope x length * CLUSTER/PLANT_NUM *kelp_mass/1000;NH4_consumpt = (0.002*(total_kelp_mass -old_kelp_mass))/(30.0);PO4_consumpt = (0.000042*(total_kelp_mass -old_kelp_mass))/(30.0);printf("total kelp mass%f\n",total_kelp_mass);/* ammonium consumption by the kelp farm *//* UPTAKE RATE 7 to 10 micromol/g dry wt/hr */Ammon_uptake = total_kelp_mass * 1000.0;PERCENTAGE = 100.0 * (Ammon_uptake/Ammon_mol_hr);printf("NH4 CONSUMPTION BY KELP miromol/hr =%f\n",Ammon_uptake);printf("PERCENTAGE AMMONIUM CONSUMPTION =stf\n",PERCENTAGE) ;printf("Phosphorus CONSUMPTION BY KELP kg/day=%f\n",PO4_consumpt);/* oxygen consumption at night by the kelp kg/hr */oxy_consumpt = total_kelp_mass*0.026*0.001;printf("OXYGEN CONSUMPTION BY KELP kg/hr=%f\n",oxy_consumpt);)107Appendix 4. LIGHT SUBMODEL#include <math.h>#include <stdio.h>#include <io.h>#include <stdlib.h>/* This program calculates monthly solar intensity at different *//* water depths and for different water clarities	 */solar_constant 4.921latitude	 49.3water_depth	 2attenuation	 0.11pigoofymonthshoursconstant3.1401123284i,j;val;declination;hour_angle[24];sun_angle[24];cloudiness_index[12];cloudiness_ind;AVERAGE R[12];I global[12][24];(from data file)*/float	 I_beam[12][24];float	 I_underwater[2][24];radiation */float	 beam transmit[24];float	 I_deptli112][24];dept h d*/float	 AVG BOTTOM R[12];float	 I_diffuse[12)-C-24];*/float	 H_beam[12];float	 H_diffuse[12];*/float	 H extra[12];radiation *7float	 H_global[12];float	 H_underwater[12];depth d */float	 I_beamwater[12][24];float	 I diffusewater[12][24float	 Tlay_length[12];/* mega joules per m2 *//* degrees	 *//* depth of water in m*//* attenuation coefficient/* declination angle *//* in radians *//* hourly global radiation/* hourly beam radiation *//* hourly underwater/* hourly underwater rad. at/* hourly diffuse radiation/* daily beam radiation *//* daily diffuse radiation/* daily extraterrestrial/* daily global radiation *//* daily underwater rad. at/* day length at each#define#define#define#define1/m */#define#define#define#define#defineintfloatfloatfloatfloatfloatfloatfloatfloat1;108typical day */float	 day_angle;float	 ws,wsl;	 /* sunrise hour angle */float	 Eo,k,m;i	 n	 tday_number[12]=(17,47,75,105,135,162,198,228,258,288,318,334);main(){FILE *inp;inp = fopen("global.dat","r");/* INITIALIZATION */for(i=0; i<=months; i++) (H_beam[i]	 = 0;H_diffuse[i]	 = 0;H_extra[i]	 = 0;H_global[i]	 = 0;day_length[i]	 = 0;AVG_BOTTOM_R[i] = 0;cloudiness_index[i] = 0;for (j = 0; j <= hours; j++)	 {hour_angle[j] = 0;I_beam[i][j] = 0;I_diffuse[i][j] = 0;Ibeamwater[i][j]	 =0;I_diffusewater[i][j] =0;for(i=0; i<=months; i++) {for(j=0; j<=hours; j++)	 (fscanf(inp,"%f ", &I_global[i][j]);/* I_global[i][j]= I_global[i][j] * pow(10,6); *//*	 printf("ghi=%f\n",I_global[i][j]); */H_global[i] = H_global[i] + I_global[i][j];)/* printf("H_global=%f\n",H_global[i]); */)/* calculating daily extraterrestrial radiation */printf("water depth= 2m , attenuat = 0.11\n");for(i=0; i<=months; i++) {day_angle = 2 * pi * day_number[i] / 365 ;Eo = 1 + 0.033*cos(day_angle);printf("Eo=%f\n",Eo);109val = sin((day_number[i]- 82)*(0.986)*pi/180);/ *	 printf("value=%f\n",val);	 */declination = asin(0.4*val)*180/pi ;printf("decli angle=%f\n",declination);ws=acos(tan(declination*pi/180)*tan(latitude*pi/180)*(-1)) ;printf("ws=%f\n",ws);day_length[i] = 2 * ws * 180 / (pi * 15);printf("day length=%f\n",day_length[i]);Hextra[i] = (24/pi)*(solar_constant*Eo)*((ws*sin(declination*pi/180)*sin(latitude*pi/180))+cos(declination*pi/180)*cos(latitude*pi/180)*sin(ws ));/*	 printf("EXRTATER=Af\n",H_extra[i]);	 *//************* calculating cloudiness index */cloudiness_index[i] =H_global[i]/H_extra[i];/*	 printf("cloudiness=%f\n",cloudiness_index[i]); *//************ calculating diffuse daily radiation */H_diffuse[i] = (0.958 - 0.982 * cloudiness_index[i]) *H_global[i];printf("Diffuse=%f\n",H_diffuse[i]);	 *1for(j=0; j<=hours; j++) (hour_angle[j] = pi - (j*pi/12);/*	 printf("hourangle=%f\n",hour_angle[j]); */sun_angle[	 j	 ]sin(declination*pi/180)*sin(latitude*pi/180) +cos(declination*pi/180)*cos(latitude*pi/180) *cos(hour_angle[j]);/* printf("sunangle=%f\n",sun_angle[j]); *//************ calculating diffuse hourly radiation */if( I_global[i][j] > goofy) (I_diffuse[i][j]	 =	 H_diffuse[i]	 *	 pi	 *(cos(hour_angle[j]) -cos(ws))/(sin(ws)-ws*cos(ws))/24;/*	 printf("Diffuse Hourly=%f\n",I_diffuse[i][j]); *//************ calculating beam hourly radiation */I_beam[i][j] = I_global[i][j] - I_diffuse[i][j];110/ * printf("BEAM RADIATION=%f\n",I_beam[i][j]); *//****************************************************//****************************************************//*	 WATER SURFACE REFLECTION OF THE BEAMS	 */I_diffusewater[i][j] = 0.934 * I_diffuse[i][j];beam_transrait [j]	 =	 0. 30 54 4	 +9.9798*pow((pi/2-sun_angle[j]),2)+12.044*pow((pi/2-sun_angle[j]),3) -6.8773*pow((pi/2-sun_angle[j]),4) +1.4872*pow((pi/2-sun_angle[j]),5);printf("transmission= %f\n",beam_transmit[j]);I_beamwater[i][j] = I_beam[i][j] * beam_transmit[j] /100;I_underwater[i][j]	 =	 I_beamwater[i][j]	 +I_diffusewater[i][j];/*	 printf("underwaters= %f\n",I_underwater[i][j]);	 *//****************************************************//****************************************************//***** LIGHT ATTENUATION DUE TO WATER DEPTH ********/k = -1 * water depth * attenuation;I_depth[i][j] = 4.6 * pow(10,6)*I_underwater[i][j] *pow(2.72,k) / 3600;if(I_depth[i][j] >= 0){AVERAGE_R[i] = AVERAGE_R[i] + I_depth[i][j];)))AVG_BOTTOM_R[i] = AVERAGER[i] / day_length[i] ;printf("average bottom in microEin.is=%f\n",AVG_BOTTOM_R[i]);))111BIOGRAPHICAL INFORMATION NAME: kavy, raw	 VY) oak c\i'l	 lc\ 6rMAILING ADDRESS: qO 7 -. 222.,2 gelli:'-vue flw-03,0a,L, \1V- iC 7PLACE AND DATE OF BIRTH:	 ri_tCzi	 fp/)West Vok ocouver e.c,EDUCATION (Colleges and Universities attended, dates, and degrees):aii've a-sitf,Oir gPOSITIONS HELD:PUBLICATIONS (if necessary, use a second sheet):i — u rn-te- j rate/ CO310-10v, ow-14 ke/p pr-cci 1-i.) c.--e	 klc " . •	 ' 17-)17 116? ;1 j, F-‘t L is-- d 1Ell. 1; ' neer1 n 0 Os p2c=t1 01 10 te 0 ,---.-; v c fl-icti_ka,c LA i t.:,:tre, ,Prc. c -'_zl_..) Cti-Iti ry trern tfae r-ky.VAGLOT-Ure lfripr I Li- 6 	 rt--AWARDS:Complete one biographical form for each copy of a thesis presentedto the Special Collections Division, University Library.i tAOE-5

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