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Life on the Edge : A Comparison of Vancouver’s Intertidal Systems with Recommendations for Biodiversity… Walton, Tamara; Donohue, Marie; Wang, Weihao; Li, Qin 2019-04-16

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Life on the Edge:   A Comparison of Vancouver’s Intertidal Systems  with Recommendations for Biodiversity Enhancement in Northeast False Creek    Tamara Walton, Marie Donohue, Weihao Wang, and Qin Li  16/04/2019 ENVR 400 University of British Columbia, Vancouver  Dr. Michael Lipsen and Dr. Tara Ivanochko Angela Danyluk, City of Vancouver and Ileana Costrut, CityStudio Executive Summary  Background  The shorelines of Northeast False Creek (NEFC) are getting an eco-makeover. The City of Vancouver has plans to transform the shores into flourishing intertidal zones equipped with seaweeds, shellfish and sea stars. With breathtaking views of the City, 10km of waterfront pathway, and beautiful, vibrant shorelines, NEFC could soon become Vancouver’s most popular outdoor attraction.     Proposed area of development in Northeast False Creek (NEFC). Development will involve transforming portions of NEFC’s shoreline into healthy intertidal zones.   Healthy intertidal zones, however, will bring much more than just natural beauty to NEFC. They have substantial ecological value as they provide food and spawning habitat for a diverse suite of organisms—including Great Blue Herons, Dungeness Crabs, and Pacific Herring. In addition, healthy shorelines house a variety of microbes which help breakdown the toxic substances found in urban run-off. This helps to maintain good water quality, which benefits both marine life and humans.   Healthy intertidal zones will also bring significant societal value to NEFC. They are one of the most easily-accessible marine ecosystems and provide visitors the opportunity to connect with the ocean and discover its fascinating critters. In addition, intertidal zones provide irreplaceable outdoor classrooms for students learning about marine species and their habitats.   Ecological and societal value of healthy intertidal zones.  Study Objectives Transforming NEFC’s shorelines into an intertidal wonderland, however, will be no easy task. Currently, these shores are steep, filled with artificial rip-rap, and home to only a handful of hardy intertidal creatures. As a result, the City is seeking recommendations for shoreline design that will help to promote intertidal biodiversity in NEFC. The primary objective of our study was to provide the City with such recommendations. To do this, we compared the biological and physical characteristics of Creekside Park (CP)— which is located in NEFC—with those of David Lam Park (DL) and Third Beach (TB). These sites differ significantly in terms of species diversity, seaweed cover, substrate, and slope. By comparing these sites, we were able to identify the shorelines features most strongly correlated with intertidal biodiversity, which provided the foundation for our shoreline design recommendations.   Healthy Intertidal ZonesImportant Spawning HabitatImportant Feeding GroundsGood Water QualityOutdoor ClassroomConnecting with natureEcological ValueSocietal ValueDAVID LAM PARKCREEKSIDE PARKTHIRD BEACHSTANLEY PARKFALSE CREEKLocation of our three study sites. By comparing the physical and biological features of these sites, we were able to identify the shoreline features most strongly correlated with intertidal biodiversity. Results  Site Comparisons   The results from our site comparisons show that species richness is greatest at TB, followed by DL then CP. We found a total of 12 invertebrate species and six seaweed species at TB. In contrast, we found only seven invertebrate species and three seaweed species at CP, and eight invertebrate species and two seaweed species at DL. Additionally, our results show that the intertidal communities of CP and DL are dominated by Acorn barnacles and Blue mussels, while TB’s intertidal community is more balanced        Biological and physical features of our three study sites. Creekside Park and David Lam Park are located in False Creek, while Third Beach is located in Stanley Park.   Our study also showed that CP, DL and TB differ considerably in terms of seaweed cover, substrate and slope. Roughly one-half of TB’s shoreline is covered in seaweed, while it covers only one-tenth of CP’s and DL’s shoreline. This suggests that environmental conditions are more stressful at CP an DL as seaweeds provide cool, moist refuges for intertidal organisms during low tide. Furthermore, TB’s shoreline has a gradual slope and mostly large boulders, while the shorelines of CP and DL are steep and consists primarily of smaller substrates, like pebbles and cobble. These findings indicate that substrates are turned over more frequently at greater at CP and DL—which can hinder the growth of slow-growing species, like seaweeds.  Although the sites differ in a large number of shorelines features, we did not find significant differences in water temperature, pH or salinity between CP, DL and TB. This suggests that False Creek’s current water conditions should be able to support the types of intertidal organisms found in TB.   Features of Biodiverse Shorelines   The results of our analysis indicate that the top three defining features of Vancouver’s biodiverse intertidal zones are large substrates, abundant Rockweed (a common green seaweed), and limited amounts of Acorn barnacles. Acorn barnacles can multiply and grow quickly, which allows the species to take-over intertidal zones when there are few constraints on its population growth. This leaves little room for other intertidal species to grow, resulting in lower biodiversity. Furthermore, large substrates and Rockweed both create shaded moist habitats sheltered from predators. This enhances intertidal biodiversity by reducing competition among organisms for suitable living space. Larger substrates are also less frequently rolled over than smaller substrates, which helps prevent fast-growing barnacles from dominating and promotes growth of slower-growing species, like seaweed.     Top three defining features of biodiverse intertidal zones.  Shoreline Design Recommendations Our study shows that biodiverse intertidal zones are characterized by large substrates, high Rockweed abundance, and limited Acorn barnacle dominance. These features can be incorporated into NEFC by reducing the slope of its shorelines and replacing its current rip rap with larger, more rugged boulders. Large substrates will help promote Rockweed growth by providing stability, while rugged textures will aid the growth and survival of Rockweed spores. As Rockweed becomes more abundant, Acorn barnacle should become less dominant. This is because when Rockweed brushes against substrate, it disrupts settling Acorn barnacle larvae, opening up space for other intertidal species.  In addition to intertidal biodiversity, our shoreline design recommendations will improve public access to the shoreline. A more gradual shoreline will allow people to safely walk along NEFC’s shores—encouraging them to explore the intertidal zone and its fascinating creatures. Thus, if the City were to incorporate these shoreline designs into NEFC, we recommend that they designate an area to our three shoreline recommendations and another for public access. The former would include mostly larger substrates to minimize the effects of human disturbance on intertidal biodiversity, while the latter would include mostly sand, interspersed with large boulders, to encourage interaction and safe exploration.   Depiction of shoreline design recommendations for NEFC. To enhance intertidal biodiversity, we suggest the City reduces the slope of NEFC’s current shoreline and replaces its rip rap with large, rugged boulders.  GRADUAL SHORELINELARGE, RUGGEDBOULDERS About the Authors   Tamara Walton: Tamara is a fourth year student in the Environmental Sciences program at the University of British Columbia (UBC); her area of concentration is in Ecology and Conservation. Tamara has significant experience with species surveys through completion of university ecology courses and two ecology field schools. Furthermore, throughout university, Tamara has had ample experience in analyzing biological data using Microsoft Excel and R.   Marie Donohue: Marie is a fourth year Environmental Science student at the UBC with a concentration in Ecology and Conservation. Marie has always been passionate about environmental conservation; for the past two summers, she has enjoyed working with Alberta Parks, providing education to visitors on the care and protection of the environment. Through her BSc, she has developed data analysis skills through laboratory analysis and interpretation of biological data through programs like R and Microsoft Excel. About the Contributors  Weihao Wang: Weihao is a fourth year student in the Environmental Sciences program at UBC. His area of concentration is in Ecology and Conservation and has thus completed many university courses focused on ecology. Through these courses, he has accumulated experience working in the field and learned how to use GIS and fundamental techniques for biological data analysis.   Qin Li: Qin is a fourth year undergraduate student in the Environmental Science program at UBC. His area of concentration is in Land, Air, and Water. Through the requirements of his degree, he has acquired substantial knowledge on ecology and learned how to use GIS, Microsoft Excel and R. This knowledge and skills helped him to identify intertidal species and analyze the abiotic and biotic data collected in this study.    Table of Contents Executive Summary ....................................................................................................... 2 Background ............................................................................................................................................ 2 Study Objectives ................................................................................................................................... 3 Results .................................................................................................................................................... 4 Site Comparisons ............................................................................................................................................. 4 Features of Biodiverse Shorelines ................................................................................................................. 5 Shoreline Design Recommendations ................................................................................................ 5 About the Authors .......................................................................................................... 7 About the Contributors .................................................................................................. 7 List of Figures ............................................................................................................... 10 List of Tables ................................................................................................................ 11 Acronyms and Abbreviations ..................................................................................... 12 1. Introduction ........................................................................................................... 13 1.1. Rocky Intertidal Zones of the Pacific Northwest ................................................................ 13 1.1.1. Abiotic and Biotic Characteristics .............................................................................................. 13 1.1.2. Ecological Importance ................................................................................................................. 14 1.1.3. Human Importance ...................................................................................................................... 15 1.1.4. Rocky Intertidal Zones in Vancouver ........................................................................................ 16 1.2. History of False Creek ........................................................................................................... 16 1.3. False Creek in 2019 .............................................................................................................. 17 2. Methods ................................................................................................................. 18 2.1. Study Objectives .................................................................................................................... 18 2.2. Site Description ...................................................................................................................... 18 2.3. Data Collection ....................................................................................................................... 20 2.3.1. Species and Substrate Features ............................................................................................... 20 2.3.2. Water Quality ................................................................................................................................ 23 2.3.3. Shoreline Slope ............................................................................................................................ 23 2.4. Data Analysis .......................................................................................................................... 24 2.4.1. Species Relative Abundance, Diversity and Evenness ......................................................... 24 2.4.2. Substrate Size, Diversity and Evenness .................................................................................. 24 2.4.3. Macroalgae and Bare Rock Cover, Water Quality, and Shoreline Slope ............................ 25 2.4.4. Site Comparisons ........................................................................................................................ 25 2.4.5. Shoreline Features of Biodiverse Intertidal Zones .................................................................. 25 3. Results ................................................................................................................... 26 3.1. Species Relative Abundance, Diversity and Evenness .................................................... 26 3.2. Substrate Size, Diversity, and Evenness ........................................................................... 28 3.3. Bare Rock and Macroalgae Cover ...................................................................................... 29 3.4. Water Quality .......................................................................................................................... 29 3.5. Shoreline Slope ...................................................................................................................... 30 3.6. Shoreline Features of Biodiverse Intertidal Zones ............................................................ 31 4. Discussion ............................................................................................................. 32 4.1. Site Comparisons ................................................................................................................... 32 4.2. Features of Biodiverse Intertidal Zones .............................................................................. 33 4.3. Recommendations for Shoreline Design in Creekside Park ........................................... 34 4.4. Recommendations for Future Research ............................................................................ 35 5. Conclusion ............................................................................................................. 36 Acknowledgements ...................................................................................................... 37 References .................................................................................................................... 38 Appendix ....................................................................................................................... 43                  List of Figures  Figure 1. Food web typical of a rocky intertidal zone in the Pacific Northwest.   Figure 2. Map of Downtown Vancouver’s intact intertidal habitats, which are primarily found along Stanley Park. Intertidal habitats are also found in False Creek but have significantly altered through shoreline development (Adapted from Vancouver Board of Parks and Recreation, 2018). Figure 3. Proposed area of development under the City of Vancouver’s Northeast False Creek Plan. The orange box encloses Creekside Park, which makes up Xkm of False Creek’s shoreline (Adapted from City of Vancouver, 2018).  Figure 4. Map of sites used for intertidal data collection. All sites are located in Downtown Vancouver, adjacent to waterfront pathways (Photos by Tamara Walton). Figure 5. Depiction of transect setup at Creekside Park (CP), David Lam Park (DL), and Third Beach (TB).  Figure 6. Photo of quadrat (25x25cm) used in this study that has been divided into 100 equal squares (2.5x2.5cm). The orange tape marks the 25 randomly selected intersection points under which species counts were recorded (Photo by Weihao Wang).  Figure 7. Positions relative to middle intertidal transect in which water samples for temperature, pH and salinity measurements were collected  Figure 8. Visual of variables needed for shoreline slope calculations. Figure 9. Relative abundance (RA) of macrobenthos and macroalgae species found in the intertidal zones of Creekside Park (CP), David Lam Park (DL), and Third Beach (TB). Species with RAs less than 1.5% have been grouped into ‘Other Species’.   Figure 10. Relative Percent-cover of each substrate size class found in the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). Error bars indicate the 95% confidence interval.   Figure 11. Average percent-cover of bare rock and macroalgae found in the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). Error bars indicate the 95% confidence interval.  Figure 12. Average shoreline slope of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). CP’s (0.51 ± 0.34) and DL’s (0.36 ± 0.11) shoreline slope did not significantly differ but were both significantly steeper than that of TB (0.05 ± 0.02).    Figure 13. Factor coefficients (cos2) between each variable and Dimensions 1 and 2. Variables with arrows in the same or opposite quadrants are strongly correlated with one another; thus, Species Diversity is most strong correlated with Acorn Barnacle RA, Rockweed RA and Substrate Size. (RA, Relative Abundance).  Figure 14. Correlations between each variable considered in the Principle Component Analysis and Species Diversity. Larger circles indicate stronger correlations, while circle colour indicates the direction of correlation (red: positive; blue: negative). Thus, Acorn Barnacle RA (r = -0.81), Rockweed RA (r = +0.57), and Substrate Size (r = +0.41) are most strongly correlated with Species Diversity. (RA, Relative Abundance).  Figure 15. Photos of each intertidal collection site (CP: Creekside Park; DL: David Lam Park; TB: Third Beach). TB’s shoreline was more gradual, contained larger substrates, and had greater species diversity than the shorelines of CP and DL (Photos by Tamara Walton). List of Tables   Table 1. List of species commonly found in Pacific Northwestern rocky intertidal zones.  Table 2. Shoreline features of the three study sites.  Table 3. Substrate classification system based on diameter. Table 4. List of macrobenthos and macroalgae species found at each site through the intertidal quadrat surveys.  Table 5. Species diversity indices for the macrobenthos and macroalgae communities of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB).  Table 6. Weighted Average Substrate Sizes for the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB).  Table 7. Substrate diversity indices for the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB).  Table 8. Average difference in water temperature, pH and salinity between Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). None of these differences are statistically significant (p £ 0.05).     Acronyms and Abbreviations   CoV: City of Vancouver  CP: Creekside Park site  DL: David Lam Park site  H: Shannon-Wiener Index  LT: Lower intertidal transect  MT: Middle intertidal transect  Macrobenthos: Benthic macroinvertebrates   NEFC: Northeast False Creek  PCA: Principle Component Analysis   PNW: Pacific Northwest  RIZ: Rocky intertidal zone  TB: Third Beach site  VCC: Vancouver City Council                    1. Introduction   1.1. Rocky Intertidal Zones of the Pacific Northwest  1.1.1. Abiotic and Biotic Characteristics  Rocky intertidal zones (RIZs) are regions of the ocean that experience the effects of tidal currents and breaking waves (Raffaelli & Hawkins, 1999). They are typically broken into three zones: the high intertidal (highest amount of air exposure), the middle intertidal (intermediate amount of air exposure), and the low intertidal (lowest amount of air exposure; Snelgrove, 2008). Compared to other intertidal zones, such as sandflats and mudflats, RIZs are characterized by hard, stable substrate of varying size (Branch, 2008).  As noted above, RIZs are subjected to daily tidal fluctuations; thus, the organisms that live within these regions are repeatedly exposed to alternating periods of seawater immersion and emersion (Snelgrove, 2008). As a result, the organisms that live within RIZs must be adapted to withstand regular fluctuations in salinity, temperature, pH and light exposure.   Despite their harsh environmental conditions, the number of species inhabiting RIZs is large compared to other coastal ecosystems (CRD, n.d.a). This is primarily a result of RIZs’ substrate complexity, which creates various habitats capable of supporting a wide range of niches (Kostylev et al., 2005). However, the distribution of organisms is not even across RIZs as periods of emersion (and thus salinity, thermal and desiccation stress) increase with shoreline elevation (Raffaelli & Hawkins, 1999). As a result, the lower intertidal zone generally has the greatest biodiversity, followed by the middle intertidal zone and then the upper intertidal zone.  In the Pacific Northwest (PNW), the majority of species permanently inhabiting RIZs fall into one of two groups: algae and marine invertebrates (ODFW, 2016). Examples of intertidal algae include benthic microalgae, algal mats and macroalgae (seaweeds), while examples of intertidal invertebrates include zooplankton, marine worms, crustaceans, molluscs, echinoderms and cnidarians (Table 1).             Table 1. List of species commonly found in Pacific Northwestern rocky intertidal zones. Group Type Organisms (Lamb & Hanby, 2005) Algae Microalgae Unicellular phytoplankton  Algal Mats Colonial phytoplankton Macroalgae  Multicellular green, brown and red seaweeds Invertebrates  Zooplankton N/A Marine Worms Ribbon, flat, and tube worms Crustaceans Barnacles, fleas, isopods, shrimp and crabs Molluscs Chiton, limpets, oysters, clams, cockles, mussels, winkles, whelks, snails and nudibranchs Echinoderms Sea stars, cucumbers and urchins Cnidarians Sea anemones  1.1.2. Ecological Importance   RIZs in the PNW are very productive ecosystems; this is largely due to their high nutrient levels and light exposure. For RIZs located on the outer coasts of the PNW, high nutrient levels are sustained by coastal upwelling—which draws cold, nutrient-rich water from the deep ocean up to the surface (CRD, n.d.a). For RIZs near Vancouver, run-off from the Fraser River and seasonal turnover maintain high nutrient levels. The substrate features of RIZs also help to promote high levels of primary productivity. RIZs typically have large amounts of hard, stable substrate, which provide an ideal place for seaweeds to anchor their holdfasts (Branch, 2008). As a result, most RIZs can support large amounts of primary producer biomass.  With high levels of primary productivity, RIZs in the PNW can support a rich community of aquatic and terrestrial consumers (CRD, n.d.a). The aquatic consumers feed primarily during high tides and include organisms such as fish, octopus, and squid (Horn & Martin, 2006; Figure 1). In contrast, the terrestrial consumers feed primarily during low tides and include both bird (crows, brants, oystercatchers, and seagulls) and mammal species (squirrels, rats, voles, coyotes and black bears; Canning et al., 2016; Carlton & Hodder, 2003; Nature Vancouver, 2009; U.S. Fish & Wildlife Service, 2008; Figure 1).        Figure 1. Food web typical of a rocky intertidal zone in the Pacific Northwest.  In addition to feeding grounds, RIZs serve as important nursing and spawning habitat for various subtidal species (Horn & Martin, 2006). For example, many crab species, such as Dungeness crab, use RIZs as nursing grounds for their secondary larval stage (Dethier, 2006). The RIZ provides the developing crabs with refuge from predation and desiccation. RIZs serve a similar function rockfish and prickle backs. These species spawn in the tidal found within RIZs, which provide the developing fish with abundant food and protection from predation. Pacific herrings, on the other hand, often spawn on the seaweed beds found in RIZs (CRD, n.d.b). These mass spawning events typically attract large numbers of shorebirds, fish and marine mammals—which prey on both the herring and their eggs.   1.1.3. Human Importance   RIZs have long been an important food source for humans living in the PNW (CRD, n.d.a). RIZ organisms most commonly eaten by humans include mussels, clams, oysters and crabs. More recently, RIZs have come to serve an important role in education; this is primarily due to their accessibility and biodiversity (ODFW, 2016). For example, many school groups visit RIZs to learn about marine species and their interactions. Furthermore, a great deal of scientific research is conducted in RIZs in attempt to understand the health and ecology of coastal environments. This is because many of species residing in RIZs can be used as bioindicators for water quality and/or pollution (Andrews et al., 2015; Nuñez et al., 2012).  1.1.4. Rocky Intertidal Zones in Vancouver   Vancouver’s most natural RIZs are found outside the city center, along the Stanley Park Seawall (Nowell et al., 2018; Figure 2). However, other, less natural RIZs exist within Vancouver’s downtown neighbourhoods, such as those found along False Creek. These RIZs have been either partially or wholly human-manufactured and significantly affected by pollution and recreational use. Compared with the RIZs of Stanley Park, False Creek’s RIZs are steeper and have lower species and substrate diversity.     1.2. History of False Creek  False Creek’s intertidal zones were not always poorly diverse RIZs. Prior to the 20th century, False Creek was a large, muddy tidal flat with thick beds of eelgrass and clams and provided abundant resources for the Coast Salish (City of Vancouver, n.d.; Hatcher & Hulbert, n.d.). In 1913, however, parts of the flats were filled to build rail yards and stations for the Great Northern Railway and the Canadian Northern Pacific Railway (City of Vancouver, 2018). This was followed by the construction of the Georgia viaduct and two major shipping building plants. These developments led to False Creek becoming one of Vancouver’s primary industrial centers.   Industrial development continued in False Creek in the first half of the 20th century. The area became densely packed with piggeries, slaughter houses, boat builders, lumber mills, and other industries, which led to severe pollution of False Creek’s waters (Hatcher & Hulbert, n.d.). In 1968, however, Vancouver City Council (VCC) voted to remove False Creek’s industrial designation, and the area has since been replaced with neighbourhoods and sustainable light industry. : IntactFalse CreekStanley ParkIntertidal HabitatFigure 2. Map of Downtown Vancouver’s intact intertidal habitats, which are primarily found along Stanley Park. Intertidal habitats are also found in False Creek but have significantly altered through shoreline development (Adapted from Vancouver Board of Parks and Recreation, 2018).  1.3. False Creek in 2019 In 2015, VCC approved development in Northeast False Creek (NEFC), which includes replacement of the Dunsmuir and Georgia viaducts with a new diverse and active waterfront neighbourhood (Figure 3). Guiding this development is the City of Vancouver’s (CoV) NEFC Plan, which aims to ensure the development “contribute[s] toward the sustainability and resiliency of Vancouver” (City of Vancouver, 2018). Specifically, the plan will ensure that development in NEFC leads to the “enhancement of biodiversity [in] the intertidal zones of False Creek”, such as those found along Creekside Park (City of Vancouver, 2018). The CoV is currently looking for recommendations for shoreline design that will help them to achieve this goal.   Figure 3. Proposed area of development under the City of Vancouver’s Northeast False Creek Plan. The orange box encloses Creekside Park, which makes up 0.5km of False Creek’s shoreline (Adapted from City of Vancouver, 2018).  Currently, Creekside Park’s shoreline is not conducive to intertidal biodiversity. The steep slope has resulted in a compressed intertidal zone, which intensifies competition amongst species. Further intensifying this competition is the shoreline’s substrate—which consists almost exclusively of rip rap. This substrate type is small, uniform in size, and often has many broad flat surfaces. Consequently, rip rap shorelines provide few refuges from thermal and desiccation stress. In addition, this substrate-type is frequently turned over by waves, which prevents slow-growing, late-maturing species (such as brown macroalgae) from establishing populations. Intense species composition, stressful abiotic conditions, and high disturbance frequency in Creekside Park have contributed to an Acorn Barnacle-dominated intertidal zone—with limited abundance of other species, such as Blue mussels and Rockweed.   The major objective of this study was to provide the CoV with shoreline design recommendations that will help them to increase biodiversity in Creekside Park. This was achieved by comparing the physical (substrate, slope, water quality) and biological features (species frequencies, macroalgae cover) of three intertidal zones of varying biodiversity: Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). 2. Methods  2.1. Study Objectives  This study has three major objectives. The first objective is to examine if and how the intertidal zones of Third Beach, David Lam Park, and Creekside Park differ in terms of benthic macroinvertebrate (macrobenthos) and macroalgae species (relative abundance, richness, and diversity), substrate (size and diversity), macroalgae cover, bare rock cover, shoreline slope, and water characteristics (temperature, salinity, and pH). The second objective is to identify which shoreline features correlate best with macrobenthos and macroalgae diversity. The third objective is to make shoreline design recommendations for Creekside Park that would be expected to increase its intertidal biodiversity.   2.2. Site Description  In this study, biotic and abiotic data was collected from three intertidal zones: CP, DL, and TB. CP and DL are located on the north-eastern and northern side False Creek, respectively, while TB is located on the western side of Stanley Park (Figure 4). Although all three sites are situated within areas of relatively high human activity, they differ in a wide variety of shoreline features (Table 2).  Figure 4. Map of sites used for intertidal data collection. All sites are located in Downtown Vancouver, adjacent to waterfront pathways (Photos by Tamara Walton). Table 2. Shoreline features of the three study sites. Shoreline Feature Creekside Park David Lam Park Third Beach Species Diversity Low Low High Macroalgae Cover Low Very Low High Substrate Primarily angular rip rap Primarily small, round cobble Primarily boulders of varying size Slope Steep Intermediate Gradual Degree of Human Modification High High Low   DAVID LAM PARKCREEKSIDE PARKTHIRD BEACHDOWNTOWN VANCOUVERSTANLEY PARKFALSE CREEKCP was chosen as a study site as it will be developed under the NEFC Plan. By having a detailed understanding of the NEFC’s current shorelines, the researchers were able to provide the CoV with valid recommendations for future shoreline design. DL and TB were chosen as study sites as they differed in a wide variety of shoreline features from CP and had been studied by former students. This facilitated the researchers’ ability to identify the shoreline features most strongly correlated with intertidal biodiversity and allowed them to compare their results with those of previous studies.   2.3. Data Collection  Data was collected by all four researchers from TB on December 4th and January 6th. Data was simultaneously collected from CP (by Marie and Tamara) and from DL (by Weihao and Qin) on December 5th and January 5th. All four of these dates fell on or near the dates of low tide during the Spring Tide sequence (DFO, 2018; DFO, 2019).    2.3.1. Species and Substrate Features   Stratified random quadrat sampling was used to obtain species counts and percent-covers of varying substrate sizes, macroalgae, and bare rock (Gonor & Kemp, 1978). In total, 40 quadrats were sampled at each site.   Transect and Quadrat Placement  In each site, two transects were laid that ran parallel to the shore, one in the middle intertidal (MT) and another in the lower intertidal (LT) (R. DeWreede, personal communication, October 3rd, 2018). The MT was laid along the densest band of Fucus gardneri (estimated visually) at all three sites (Nowell et al., 2018). The LT was laid along the lower edge of the RIZ at TB, while it was laid along the land-water interface 30-minutes before low-tide at DL and CP (low-tide height was 0.5m on both nights of DL and CP data collection; DFO, 2018; DFO, 2019). The position of the LT varied among sites due to the fact that TB’s RIZ was fully exposed during low-tide, while the same was not true for DL or CP (Figure 5).  Figure 5. Depiction of transect setup at Creekside Park (CP), David Lam Park (DL), and Third Beach (TB).  Ten gridded quadrats (0.0625m2) were placed along each transect using a table of random numbers. For consistency, the quadrats were placed on side of the transect furthest from the water, with the top of the quadrat lined up with the position indicated by the random number table.  On each night of data collection, quadrat sampling began roughly 1 hour before low-tide and began with the MT. When the LT became exposed, researchers immediately began sampling the LT. Once all of the LT’s samples had been completed, researchers returned to the MT and completed any remaining samples.   Substrate Percent-cover  Each site’s substrate features were measured by visually estimating the percent-cover of different substrate size classes found in each quadrat. The size classes were based on the classification system presented in Greene et al. (1999), which classifies substrate according to diameter (Table 3). The percent-cover of bare rock and macroalgae in each quadrat were also visually estimated. Densest band of Fucus gardneriLow tide markMiddle intertidal transect Lower intertidal transect Rocky intertidal zoneSandLegendTBDLCPTable 3. Substrate classification system based on diameter.  (Source: Greene et al., 1999)  Biological Counts  Species counts were recorded using the point-intercept method (Lutes et al., 2006). For this study, 25 of each quadrat’s 100 intersection points were selected to record species counts under using a table of random numbers (R. DeWreede, personal communication, October 3rd, 2018). To ensure data was recorded under the same the intersection points for every sample, the 25 intersection points were identified using flagging tape (Figure 6).    Figure 6. Photo of quadrat (25x25cm) used in this study that has been divided into 100 equal squares (2.5x2.5cm). The orange tape marks the 25 randomly selected intersection points under which species counts were recorded (Photo by Weihao Wang).  Counts for macroalgae and macrobenthos on the surface were recorded first. For macroalgae, individuals were only counted if their holdfasts fell below an intersection point (R. DeWreede, personal communication, October 3rd, 2018). The macroalgae on the surface layer was then lifted and counts for macroalgae and macrobenthos underneath were recorded. A complete list of species considered in this study can be found in the Appendix.   2.3.2. Water Quality   On each night of data collection, three water samples were collected from each site for temperature, salinity and pH measurements. Water samples were first collected from CP by two researchers (Marie and Tamara). Once completed, they moved to DL and the two other researchers (Qin and Weihao) moved to TB. The two pairs of researchers then collected water sample simultaneously from their respective sites. For consistency, the three samples were taken from the same positions relative to the MT at each site (Figure 7).   Figure 7. Positions relative to middle intertidal transect in which water samples for temperature, pH and salinity measurements were collected.  At each location of water sample collection, researchers first collected a water sample for temperature measurements using a glass jar that had been rinsed three times with sea water (Nowell et al., 2018). The temperature of this sample was measured three times on-site using a thermometer. The water was then discarded from the jar and a new sample was collected. This sample was stored overnight in a refrigerator and its pH and salinity were measured in triplicate the following morning using a pH probe and refractometer, respectively. In total, 12 water samples for temperature, pH and salinity measurements were collected from each site.   2.3.3. Shoreline Slope  In this study, slope was taken as the change in elevation between the upper-limit of F. gardneri and the LT (rise) divided by the horizontal distance between these two points (run; Figure 8). At each site, rise and run were measured using an elevation rod (5m) and distance laser measurer at the same three locations of water sample collection (Figure 7). These measurements were collected from DL and CP on January 4th, 2019 and from TB on January 5th, 2019.   Figure 8. Visual of variables needed for shoreline slope calculations. 2.4. Data Analysis   The analysis outlined in sections 2.4.1. – 2.4.5 were performed in Microsoft Excel, while the analysis outlines in section 2.4.6. was performed in R. Furthermore, the level of significance (p) for all analyses was 0.05.   2.4.1. Species Relative Abundance, Diversity and Evenness   A species was deemed ‘present’ at a site if it had a count greater than zero in at least one quadrat. The number of species present at each site was summed to give its species richness (N). The relative abundance of each species was calculated using Equation A, where TCn is the total count of species ‘n’ (Gotelli, 2008).  Equation A. RA# = %&'∑ %&')'*+ 	 ∗ 100%  Each site’s species diversity was calculated using the Shannon-Wiener Index (HSD; Equation B), while its species evenness (ESD) was calculated using Equation C (Gotelli, 2008).   Equation B. H23 = 	−∑ RA# ∗ ln	(RA#)9#:;   Equation C. E23 = =>?@#	(9)  2.4.2. Substrate Size, Diversity and Evenness   For each site, the average percent cover (APC) of each substrate size was generated by averaging data across the 40 quadrats. The relative percent cover (RPC) of each substrate size was then calculated using Equation D (Gotelli, 2008). In this equation, ‘i' denotes the quadrat number and ‘j’ denotes the size class.  Equation D. RPCC = DE&F∑ DE&FGF*+    To calculate the average substrate size (AS) found at each site, the size classes listed in Table 3 were first assigned the following values: Mud = 1; Sand = 2; Granule = RunRockweedLower intertidal transectLegendRise Fu us gar neri 3; Pebble = 4; Cobble = 5; Boulder = 6; Large Boulder = 7. Each site’s average substrate size was then calculated using Equation E (Porter & Rosenfeld, 1999).   Equation E. AS = ∑ j ∗ RPCCJC:;    The substrate diversity (HSSC) and evenness (ESSC) of each site were calculated in the same manner as species diversity and evenness. However, for this calculation, ‘RAn’ was replaced with ‘RPCj’.   2.4.3. Macroalgae and Bare Rock Cover, Water Quality, and Shoreline Slope  The average macroalgae and bare rock at each site was calculated using data from all 40 quadrats. Likewise, each site’s average water temperature, pH and salinity on a given night were calculated using data from all 3 water samples. The difference in water temperature between CP, DL and TB on a given night was then calculated using the averaged values. This yielded a total of four values for each site comparison, which were averaged to give the mean difference in temperature between CP and DL, CP and TB, and DL and TB. A similar analysis was repeated for water pH and salinity. Lastly, shoreline slopes were calculated by dividing the change in elevation between the upper limit of F. gardneri and the LT (rise) by the horizontal distance between these two points. This yielded three values of shoreline slope for each site, which were averaged to give the mean shoreline slope of each site.  2.4.4. Site Comparisons  Species RA and percent-cover of each substrate size class, macroalgae, and bare rock were compared amongst the sites using z-tests, while their species and substrate diversity were compared using Hutcheson t-tests. Furthermore, a t-test was used to test whether mean differences in water temperature, pH, and salinity amongst the sites were different than zero, while a paired t-test was used to determine whether the sites differed in shoreline slope.   2.4.5. Shoreline Features of Biodiverse Intertidal Zones  After data collection was complete, the following variables were calculated for each quadrat: RAs of each species, species diversity, substrate size and substrate diversity.  This data was then combined with values for macroalgae and bare rock cover and cleaned by removing species with poor representation across the three sites (found in less than 50% of all quadrats). As a result, the final data had 8 columns (Acorn barnacle RA, Blue mussel RA, Rockweed RA, species diversity, substrate size, substrate diversity, bare rock cover, and macroalgae cover) and 120 rows (quadrats).  Principle Component Analysis (PCA) was used to identify the shoreline features most strongly correlated with species diversity. PCAs sort large datasets into groups of variables that tend to vary together (i.e. are strongly correlated; Pennsylvania State University, 2018). These groups are known as dimensions, with the first dimension explaining the greatest variability in the data, followed by the second, and so on. The researchers identified the dimension most strongly correlated with species diversity first. Variables that were also most strongly correlated this dimension were then identified as being most strongly correlated with species diversity. The Pearson correlation coefficients between these variables and species diversity were then calculated to determine the strength and direction of each relationship.  3. Results   3.1. Species Relative Abundance, Diversity and Evenness  For all three sites, Acorn barnacle (Balanus glandula) was the most dominant species, followed by Blue mussel (Mytilus trossulus). However, the degree of Acorn barnacle and Blue mussel dominance varied amongst the sites. The combined RA of Acorn barnacles and Blue mussels was 95.2%, 85.9%, and 67.9% in CP, DL and TB, respectively (Figure 9). The third most dominant species in all three sites was Rockweed (Fucus gardneri), but its RA varied amongst the sites. The RA of Rockweed was 1.8% in CP, 5.4% in DL and 11.0% in TB (Figure 9).     Figure 9. Relative abundance (RA) of macrobenthos and macroalgae species found in the intertidal zones of Creekside Park (CP), David Lam Park (DL), and Third Beach (TB). Species with RAs less than 1.5% have been grouped into ‘Other Species’.   In addition to the three species described above, 15 other species were found at TB, while only seven other species were found at CP and DL (Table 4). With exception of Checkered Periwinkle (Littorina scutulata, which had a RA of 11% at TB; Figure 9), the RAs of these species were all less than 5%. Furthermore, TB contained 5 species 0%10%20%30%40%50%60%70%80%90%100%CP DL TBRelative Abundance, RA (%)Other speciesShield limpetMasked limpetSea lettuceCheckered periwinkleRockweedBlue musselAcorn barnaclenot found at either CP or DL, while all species found at CP and DL were also found at TB (Table 4).   Table 4. List of macrobenthos and macroalgae species found at each site through the intertidal quadrat surveys. Species Common Name CP DL TB Ulva lactuca Sea lettuce X X X Cladophora spp. Sea moss X  X Fucus gardneri Rockweed X X X Mastocarpus papillatus Turkish washcloth   X Mazzaella splendens Iridescent seaweed   X Polysiphonia spp. Filamentous red seaweed   X Balanus glandula Common Acorn barnacle X X X Pentidotea wosnesenskii Rockweed Isopod X  X Calliostoma ligatum Blue topsnail   X Crassostrea virginica Pacific oyster X X X Littorina scutulata Checkered periwinkle  X X Lottia digitalis Ribbed limpet X  X Lottia pelta Shield limpet   X Mytilus trossulus Pacific blue mussel X X X Nucella lamellosa Wrinkled dogwinkle  X X Tectura persona Masked limpet X X X Tresus capax Fat gaper  X X Paranemertes peregrina Mud nemertean X X X  Species diversity (HSD) differed significantly amongst the three sites; it was greatest at TB, followed by DL then CP (Table 5). The difference in HSD between CP and TB stemmed from differences in both species richness (S) and evenness (ESD), while the difference in HSD between DL and TB stemmed primarily from differences in S (Table 5). Furthermore, the differences in HSD between CP and DL were caused solely by differences in ESD, as the two sites had the same S (Table 5).         Table 5. Species diversity indices for the macrobenthos and macroalgae communities of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). Site Species Richness, S Evenness, ESD Shannon's Diversity Index, HSD HSD 95% Confidence Interval CP 10 0.24 0.56 (0.51, 0.60) DL 10 0.46 1.06 (1.00, 1.12) TB 18 0.56 1.61 (1.55, 1.67)  3.2. Substrate Size, Diversity, and Evenness   TB had the largest weighted average substrate size, followed by CP then DL (Table 6). This is because TB was dominated by large boulders, while CP was dominated by boulders and cobble, and DL was dominated by cobble and pebbles (Figure 10). No sites, however, had significant amounts of mud, sand or granule—which accounted for less than 6% of the substrate types at all three sites.    Table 6. Weighted Average Substrate Sizes for the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). Site Weighted Average Substrate Size Substrate Size Class CP 5.5 Between Cobble and Boulder DL 4.9 Just smaller than Cobble TB 6.6 Between Boulder and Large Boulder    Figure 10. Relative Percent-cover of each substrate size class found in the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). Error bars indicate the 95% confidence interval.  0%10%20%30%40%50%60%70%80%90%Mud Sand Granule Pebble Cobble Boulder LargeBoulderRelative Percent-cover, RPC (%)Substrate Size ClassCPDLTBSubstrate diversity (HSSC) was greatest at DL, followed by CP then TB (Table 7). However, the differences in substrate diversity between the sites were not statistically significant.   Table 7. Substrate diversity indices for the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). Site Substrate Richness, SSC Evenness, EVSSC Shannon’s Substrate Diversity Index, HSSC HSSC 95% Confidence Interval CP 6 0.68 1.22 (1.06, 1.39) DL 7 0.68 1.32 (1.09, 1.55) TB 6 0.42 0.77 (0.43, 1.11)  3.3. Bare Rock and Macroalgae Cover   On average, CP and DL had significantly more bare rock cover than TB, while TB had significantly more macroalgae cover than CP and DL (Figure 10). CP and DL, however, did not significantly differ in their bare rock or macroalgae covers (Figure 11).    Figure 10. Average percent-cover of bare rock and macroalgae found in the middle and lower intertidal zones of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). Error bars indicate the 95% confidence interval.  3.4. Water Quality   Average water temperature ranged from approximately 6 – 8˚C at all three sites, with coldest temperatures recorded on December 6th and the warmest temperatures recorded on January 4th. Furthermore, average water pH ranged from approximately 7.5 0%10%20%30%40%50%60%Bare Rock Cover Algae CoverAverage Percent-cover (%)CPDLTBAverage Percent Cover (%) Bare Rock Macroalgae – 7.7 at DL and CP, while it ranged from approximately 7.6 – 7.8 at TB. The ranges of average salinity, however, differed considerable amongst the sites. Average salinity ranges were largest at TB (17566 – 25444 ppm), followed by CP (20889 – 27333ppm) then DL (23111 – 25333 ppm). This variation is likely due to tidal flux and local water run-off (Uncles & Stephens, 2011).   The average water temperature, pH and salinity did not significantly differ between the sites (Table 8). Thus, the three sites are similar in terms of water conditions.   Table 8. Average difference in water temperature, pH and salinity between Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). None of these differences are statistically significant (p £ 0.05). Variable CP - DL CP - TB DL - TB Average Difference in Water Temperature (˚C) 0.122 0.133 0.011 Average Difference in Water pH -0.007 -0.096 -0.090 Average Difference in Water Salinity (ppm) 416.667 1979.167 1562.500* *This difference was marginally significant (p = 0.08)  3.5. Shoreline Slope   The shoreline slopes of CP (0.51 ± 0.34) and DL (0.36 ± 0.11) did not significantly differ but were both significantly steeper than that of TB. (0.05 ± 0.02; Figure 12).   Figure 12. Average shoreline slope of Creekside Park (CP), David Lam Park (DL) and Third Beach (TB). CP’s (0.51 ± 0.34) and DL’s (0.36 ± 0.11) shoreline slope did not significantly differ but were both significantly steeper than that of TB (0.05 ± 0.02).  00.10.20.30.40.50 1Rise, a (m)Run, b (m)CPDLTB3.6. Shoreline Features of Biodiverse Intertidal Zones  Principle Component Analysis (PCA) is a linear dimension reduction technique which transforms data by projecting it onto a set of orthogonal dimensions (Lever et al., 2017). The first dimension (Dimension 1) accounts for the greatest amount of variability in the data, followed by the second dimension, and so on. Variables that are strongly correlated (i.e. have large factor coefficients, cos2) with the first dimension are thus strongly correlated with one another and account for the greatest amount of variability in the data.  The PCA results show that 37% and 17.3% of the variability in the data is retained by Dimension 1 and 2, respectively. Species diversity, Acorn barnacle RA, Rockweed RA, and Substrate size are strongly correlated with Dimension 1, while Bare rock cover and Macroalgae cover are strongly correlated with Dimension 2 (Figure 13). Thus, the variables most strongly correlated with species diversity are Acorn barnacle RA (r = -0.81), Rockweed RA (r = +0.57), and Substrate size (r = +0.41; Figure 14).  Figure 13. Factor coefficients (cos2) between each variable and Dimensions 1 and 2. Variables with arrows in the same or opposite quadrants are strongly correlated with one another; thus, Species Diversity is most strong correlated with Acorn Barnacle RA, Rockweed RA and Substrate Size. (RA, Relative Abundance)    4. Discussion  4.1. Site Comparisons  The results showed that the shorelines of CP, DL and TB differed significantly in terms of slope and substrate size. This finding reflects the sites’ developmental histories. For instance, TB’s intertidal zone has been left in a relatively natural state, while the intertidal zones of CP and DL have been human-manufactured. Man-made intertidal zones are commonly constructed with steep gradients to allow more room for water-front walkways (CRD, n.d.c). As a result, these shorelines contain smaller substrates as larger substrates would not be stable on such steep gradients. This explains why the intertidal zones of CP and DL, which are located directly adjacent to walking paths, have steeper slopes and smaller substrates than TB.   The results also showed that CP and DL had significantly less intertidal biodiversity and macroalgae cover than TB. This finding aligns with the results of other studies, which compare the intertidal communities between human-manufactured and natural shorelines (Toft, 2005; Dugan et al., 2008; Sobocinski et al., 2010). For example, Toft (2005) found that natural shorelines with gradual slopes had greater biodiversity of macrobenthos than steep, human-manufactured shorelines. Likewise, in their metanalysis of the effects of shoreline development on intertidal communities, Gittman et al. (2016) found that shorelines constructed with rip rap had significantly fewer species of intertidal flora than did shorelines containing natural substrates.  Figure 14. Correlations between each variable considered in the Principle Component Analysis and Species Diversity. Larger circles indicate stronger correlations, while circle colour indicates the direction of correlation (red: positive; blue: negative). Thus, Acorn Barnacle RA (r = -0.81), Rockweed RA (r = +0.57), and Substrate Size (r = +0.41) are most strongly correlated with Species Diversity. (RA, Relative Abundance). Although the sites differed in a large number of shorelines features (Figure 15), CP, DL and TB did not significantly differ in terms of water temperature, pH or salinity. This may be due to the fact that the sites (especially CP and DL) are in close proximity and thus exposed to similar water conditions (Figure 4). It may also be result of limited sampling. The researchers suggest further studies are conducted to determine whether CP, DL and TB differ in terms of water conditions and how it could affect their intertidal biodiversity.     Figure 15. Photos of each intertidal collection site (CP: Creekside Park; DL: David Lam Park; TB: Third Beach). TB’s shoreline was more gradual, contained larger substrates, and had greater species diversity than the shorelines of CP and DL (Photos by Tamara Walton).  4.2. Features of Biodiverse Intertidal Zones   The results showed that species diversity had a strong, negative correlation with Acorn barnacle RA (r = -0.81). Acorn barnacles have high thermal and desiccation tolerances, allowing them to competitively exclude other intertidal species in stressful environments (Simon-Blecher et al., 2008). Thus, unfavourable abiotic condition may explain why Acorn barnacle dominated systems also have low biodiversity. Furthermore, Acorn barnacles have high fecundity and fast growth rates—meaning their populations can quickly recover from disturbances, such as frequent turn-over of substrate (Sousa, 1979). Thus, intertidal zones dominated by Acorn barnacles may CP DLTBhave low biodiversity due to high disturbance frequency, which prevents slow-growing, late-maturing species, such as brown macroalgae, from establishing populations.   In the PCA, species diversity was shown to have a strong, positive correlation with Rockweed RA (r = 0.57). This is consistent with the results of other studies, which show that species richness is typically high in sites with significant macroalgae cover due to its provision of thermal and desiccation refuges (Ape et al., 2018; Scrosati, 2011). In addition, the complex morphology of Rockweed is likely to help maintain intertidal biodiversity as it provides prey species, such as Rockweed isopods and limpets, with places to hide from predators (Bates, 2007). Lastly, the positive correlation between species diversity and Rockweed RA may be due to its effects on Acorn barnacles (Jenkins et al., 1999). When the fronds of Rockweed are washed against substrate, it dislodges settling Acorn barnacle larvae, opening up space for other intertidal species.  The results showed that species diversity increased with substrate size. This is consistent with the results of Gedan et al. (2011), which showed that large substrates enhance intertidal species survival through provision of thermal refuges. The authors explain that this is because larger substrates are more thermally stable than smaller substrates. Larger substrates also set up larger crevices and vertical surfaces than smaller substrates. These habitats are preferred by intertidal organisms as they are shaded, moist and provide shelter from predators (Denny et al., 2006; Strain et al., 2018). Lastly, larger substrates are less frequently turned over than smaller substrate, which help to prevent fast-growing colonizing species, such as Acorn barnacles, from dominating (Hughes, 2010). Overall, large substrates promote intertidal biodiversity through provision of favorable microhabitats and facilitation of species coexistence.    These findings suggest that if CP remains in its current state, it will not likely be able to support a biodiverse intertidal zone. CP’s current rip rap is relatively small and easily turned over by waves and humans. This means that slower growing species, like Rockweed, will not likely be able to establish large populations, and that Acorn barnacle populations will continue to dominate. Thus, development of CP will need to involve considerable changes in substrate.  4.3. Recommendations for Shoreline Design in Creekside Park  The results show that intertidal biodiversity is greatest in shorelines with large substrates, high Rockweed abundance, and low Acorn barnacle dominance. The authors therefore recommend that the future design of CP includes and/or promotes these features.    The authors recommend replacing CP’s current rip rap with large, rugged boulders (diameter > 63.0cm). This is likely to enhance biodiversity through provision of shaded, moist space and shelter from predators. To achieve this, the authors suggest flattening the slope of CP’s shoreline, as large boulders would not be stable on its current slope. A more gradual shoreline would also expand the width of site’s intertidal zone, which will likely promote biodiversity by relieving competition for space (Tomanek & Helmuth, 2002).  Incorporation of larger, rugged boulders in CP will also likely increase Rockweed abundance by providing greater amounts of suitable hold-fast attachment sites. Furthermore, using substrate with rough textures may enhance Rockweed cover through promotion of spore survival and recruitment (Fletcher & Callow, 1992).  With larger substrates and greater Rockweed abundance, the abundance of Acorn barnacles is likely to decrease. This is because large boulders are less frequently turned over by waves than smaller substrates, which helps prevent fast-growing colonizer species, such as Acorn barnacles, from dominating (Hughes, 2010). Meanwhile, the wave-induced movement of Rockweed fronds helps to limit Acorn barnacle abundance by dislodging their larvae from substrate (Jenkins et al., 1999).  In summary, the authors commend the CoV for making intertidal biodiversity a key goal in the development of NEFC. To achieve this, the authors recommend that the CoV reduces the slope of CP’s shoreline and replace its substrate with large, rugged boulders. This will in turn expand the width of the shoreline, create more, shaded moist space, promote Rockweed abundance, and limit Acorn barnacle abundance—all of which are features of biodiverse intertidal zones.   4.4. Recommendations for Future Research  Before finalizing shoreline designs for CP, the authors recommend further research on the effects of natural and human disturbances on rocky intertidal biodiversity. Examples of natural disturbances include movement of loose and smaller rocks by waves, while examples of human disturbances include trampling, overturning of substrate and collection of organisms. The authors suspect there is currently a high degree of both natural and human disturbances in CP as it has small substrate and significantly more litter than DL and TB. Whether natural or human, these disturbances create patches of bare rock, opening up room for species to colonize. However, when these disturbances become too frequent, they prevent slow-growing, late-maturing species from establishing populations and lower overall macroinvertebrate and macroalgae diversity (Sousa, 1979; Mendez et al., 2018, Stevčić et al., 2018).    The authors also recommend further research that studies the effects of shade and tide pools on species abundance and diversity (Chapman & Blockley 2009). These features provide refuges for intertidal organisms during low tide and are significantly impacted by shoreline slope and substrate size (Jackson & McIlvenny, 2011). The authors found few tidal pools at CP and suspect the site has limited shade, as most species were under substrates.    Lastly, the authors recommend future research on the effects of water quality on intertidal biodiversity. This encompasses factors such as heavy metals, pollution, pH, temperature and levels of dissolved CO2, which have been shown to have significant effects on the development of intertidal organisms (Helmuth et al., 2006; Gusmao et al., 2016; Portugal et al., 2017). Furthermore, recent studies have shown that water quality is significantly worse in waters adjacent to CP than in mid-channel waters, (Cummings, 2016).     The authors believe that the research outlined above will help inform shoreline design and ultimately increase the likelihood that intertidal biodiversity returns to CP. Beyond design, this research may also influence signage regarding human activity in intertidal zones as well as sewage and effluent regulations.  5. Conclusion  RIZs are some of the most biodiverse and productive ecosystems found in coastal areas. The majority of species permanently inhabiting this ecosystem fall into one of two groups: algae and marine invertebrates. However, RIZs serve as important feeding and nursing grounds for a variety of fishes, cephalopods, birds, and mammals. In addition, RIZs has long been an important food source for humans living in the coastal areas and have more recently come to serve an important role in education and scientific research.   In Vancouver, relatively natural RIZs can be found along the Stanley Park Seawall; however, other less natural RIZs exist within Vancouver’s downtown neighbourhoods. In False Creek, human-manufactured RIZs, which have been significantly affected by pollution and recreational use, can be found in CP and DL. Compared to TB’s RIZ, False Creek’s RIZs are less biodiverse and have lower cover of macroalgae (especially Rockweed). Furthermore, RIZs in False Creek have smaller substrates and steeper slopes than the RIZ at TB.   This study suggests that the difference in intertidal biodiversity between False Creek’s RIZs and TB is largely due to their differences in Acorn barnacle abundance, Rockweed abundance, and substrate size. Specifically, intertidal biodiversity tends to be greatest in sites with high Rockweed abundance and large boulders (such as TB), and lowest in sites dominated by Acorn barnacles (such as CP and DL). Fortunately, the CoV has plan to redevelop the shoreline of CP under the NEFC Plan, providing an opportunity incorporate the features of biodiverse intertidal zone into the new design.  To enhance CP’s intertidal biodiversity, the researchers recommend that the CoV flattens the site’s shoreline and replaces its substrate with large, rugged boulders. This will promote biodiversity through provision of shaded, moist space and shelter from predators. Furthermore, rugged boulders will likely enhance Rockweed abundance through promotion of spore survival and recruitment. With larger substrates and greater Rockweed abundance, the abundance of Acorn barnacles is likely to decrease. This is because larger substrates are turned over less frequently, preventing fast-growing colonizer species, such as Acorn barnacles, from dominating. Furthermore, the brushing of Rockweed’s frond against substrate helps prevent recruitment of Acorn barnacle larvae.  Acknowledgements  We would like to acknowledge Michael Lipsen and Tara Ivanochko for their endless support and guidance through-out the duration of this project. We are extremely grateful for the scientific knowledge, communication advice, and constructive feedback you have provided us over the past school year. We would also like to acknowledge Angela Danyluk and Ileana Costrut for their continual encouragement and for providing us with the information and equipment needed to achieve our objectives. 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Type Scientific Name Common Name Annelids (Annelida) Eudistylia vancouveri  Northern feather-duster   Nereis vexillosa  Banner sea-nymph Arthropods (Arthropoda) Balanus glandula  Common Acorn barnacle   Pedunculata Goose barnacle   Pentidotea wosnesenskii  Rockweed Isopod    Semibalanus cariosus  Thatched Acorn Barnacle  Cnidarians (Cnidaria) Anthopleura artemisia Burrowing anemone   Anthopleura elegantissima  Aggregating Anemone   Anthopleura xanthogrammica  Giant green anemone    Metridium farcimen  Giant plumose anemone   Metridium senile  Short plumose anemone   Urticina felina Painted anemone Echinoderms (Echinoddermata) Dermasterias imbricata  Leather sea-star   Evasterias troschelii  Mottled star   Ophiuroidea Brittle star    Pisaster ochraceus  Ochre star    Pycnopodia helianthoides Sunflower star    Strongylocentrotus droebachiensis  Green sea urchin          Table A1. List of benthic, marine invertebrate species considered in this study continued.  Type Scientific Name Common Name Mollusc (Mollusca) Calliostoma ligatum Blue topsnail    Clinocardium nuttallii  Nuttall's cockle   Crassostrea gigas Pacific oyster   Cryptochiton stelleri  Giant pacific chiton   Cryptomya californica Californa soft-shell clam   Diodora aspera Rough key-hole limpet   Katharina tunicata  Black lather chiton   Littorina scutulata  Checkered periwinkle   Lottia digitalis Ribbed limpet   Lottia pelta Shield limpet   Macoma nasuta  Bent nose macoma   Mopalia muscosa Mossy chiton   Mytilus trossulus  Pacific blue mussel   Nucella lamellosa  Wrinkled dogwinkle   Nutallia obscurata  Varnish clams   Polinices lewisii Lewis's moonsnail   Protothaca staminea  Pacific little neck   Tectura persona  Masked limpet   Tonicella lineata  Lined chiton   Tonicella undocaerulea Blue-lined chiton   Tresus capax Fat gaper Ribbonworms (Nemertean) Paranemertes peregrina  Mud nemertean              Table A2. List of macroalgae species considered in this study. Type Scientific Name Common Name Green macroalgae Acrosiphonia coalita Witches hair (Chlorophyta) Cladophora spp.  Sea moss   Ulva intestinalis  Corn-row sea lettuce   Ulva lactuca Sea lettuce   Ulva linza  N/A Brown macroalgae Alaria marginata  Broad-winged kelp (Phaeophyta) Costaria costata  Seersucker kelp   Fucus gardneri  Rockweed   Nereocystis luetkeana  Bull-kelp   Saccharina latissima  Sugar wrack kelp   Saccharina sessile  Sea cabbage   Sargassum muticum  Wireweed Red macroalgae Chondrachanthus exasperatus  Turkish towel (Rhodophyta) Mastocarpus papillatus  Turkish washcloth   Mazzaella splendens  Iridescent seaweed   Polysiphonia spp. Filamentous red seaweed   Poryphyra spp. N/A   Sparlingia pertusa  Red eyelet silk        

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