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UBC Theses and Dissertations

The feeding ecology of Neomysis mercedis Holmes in the Fraser River estuary Johnston, N. Thomas


N. mercedis in the Fraser River estuary is a predator on the meiobenthos, especially harpacticoid copepods. There are no clear seasonal differences in its utilization of food resources. The consumption rate of N. mercedis feeding from natural sediments varies with body size and temperature as C = 3.81*(W**0.782)*(T**0.515), where C is the consumption rate of meiofauna in ug dry weight/animal/h, W is the mysid size in mg dry weight, and T is the temperature in degrees C. The weight dependence of the ingestion rate is identical to that of the metabolic rate but the temperature dependence is significantly lower. The mysid selectively feeds on the animal fraction of the sediments but only one-half of the ingested material (by weight) is of biological origin. In mid-April, mysid predation may result in a 12% per day mortality rate on harpacticoid copepods. Thus, mysid predation may strongly influence meiofaunal densities. The availability of food resources may contribute to the observed cessation of mysid population growth in late summer.

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