Dam, H.G. & W.T. Peterson. (1993). Seasonal contrasts in the diel vertical distribution, feeding behavior, and grazing impact of the copepod Temora longicornis in Long Island Sound. Journal of Marine Research 51:561-594.

83413

Dam, H.G. & W.T. Peterson

1993

51:561-594.

Publication

Available in Wilson Copepod Library (non-digital)

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We studied die1variability in vertical distribution, feeding behavior and grazing impact of female Temora longicomis in Long Island Sound on seven cruisesfrom March to July. T. longicomis usually performed die1vertical migration characterized by deep residenceduring the day and ascentto near-surfacewaters at night for variable periods. The pattern of die1 migration was independent of either the vertical distribution or relative abundance of chlorophyll in the water column. There wasno clear evidencelinking the amplitude of vertical migration to food concentration. Rather, the amplitude of migration decreasedtoward the end of the seasonprobably due to animalsavoiding warm waters (> 17°C) near the surface. Gut pigment content showeddie1 variation characterized by maximum values during the nighttime. However, the estimated mean ingestion rate from the nighttime period was significantlygreater than that of the daytime period in only 2 of 11comparisonsindicating that this copepod usually fed throughout the day at about the samerate. The shapeof the die1 curve wasusually similar for femalesat 5 and 20 m. Usually there was no difference in gut content of femaleswith depth even when differences in chlorophyll with depth were pronounced.Therefore, the die1variability in gut content wasunlikely to result from continuous feeding in a vertically stratified food environment. Short-term (hourly) changesin chlorophyll concentration could not entirely account for changesin gut content over a die1cycle. We estimatethat female T. longicomis removed daily < l-34% of the phytoplankton stock and < l-49% of the primary production in Long Island Sound. Estimatesof daily carbon rations indicate that a herbivorous diet can satisfy the metabolic requirements and support egg production of T. longicomis throughout mostof its season.

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