Abstract

GIRALDO, Alan; VELASCO, Eliana  and  MARTINEZ, Tulia Isabel. Grazing Impact of Calanoid Copepods in the Colombian Pacific Ocean. rev. cienc. [online]. 2014, vol.18, n.2, pp.11-25. ISSN 0121-1935.

Grazing rate of copepods was evaluated in the oceanic province of the Colombian Pacific during September 2006. Gut pigment content was estimated by spectophotometry considering three size fraction: small (300-500 μm), medium (500-1000 μm) and big (> 1000 μm). In order to estimate the ingestion rate, an experimental gut evacuation rate of 0.702 h-1 was used. Feeding impact was calculated like a proportion of phytoplankton standing stock, projecting the total copepod consumption by size in relation to chlorophyll-a concentration in each station. Small copepods were most abundant than medium or big copepods (Kruskal-Wallis H=21.83; p=0.01). Although the ingestion rate of big copepods was higher than medium or small copepods (Kruskal-Wallis H=6.48; p= 0.04), no significant differences in the consumption rate were detected among sizes (Kruskal-Wallis H=3.07; p=0.21). The chlorophyll-a integrate (0-50m) in the study zone was between 4.4 and 9.5 mg Clo-a m-2, being estimated the grazing impact of the big copepod in 2.57 ± 0.80 %, medium 3.57 ± 1.89 % and small 12.06 ± 5.99%

Keywords : grazing; ingestion rate; chlorophyll; copepods; Pacific Ocean; Colombia.

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