Higher ingestion rates and importance of ciliates in the diet of a large, subarctic copepod revealed by larger volume incubations

Despite ecological importance, the feeding ecology of the large calanoid copepod, Neocalanus cristatus is little known, as its ingestion rate under experimental conditions consistently falls short of its metabolic demand. The conventional incubation bottle size (~ 2 liters) used in previous studies may have affected its feeding behavior. Here, we examined the effect of bottle size (2.4 vs. 13liters) and copepod density on the feeding of N. cristatus Stage C5. Under similar copepod density (0.4 ind. L−1) ingestion rates decreased significantly for tests conducted in small bottles and thus, small bottles inhibited copepod feeding. In experiments with large bottles, ingestion rates were highest in the single‐individual treatments (1 ind. 13 L−1), decreasing exponentially to