Hopcroft, R. R.; Rolf, J. C.; Webber, Dale F.; Witt, J. D. S.
Author Affiliation, Ana.
Department of Life Sciences
Zooplankton growth rates: The influence of size and resources in tropical marine copepodites
Date of Publication
Growth rates were determined for copepodites of the genera: Acartia, Centropages, Coryeaeus, Oithona, Paracalamus, Parvocalamus and Temora in nearshore waters of Jamaica from in situ microcosm incubations. At these high local temperatures (~28 °C), total copepodite development time was as short as 4 to 5 d. Mean instantaneous growth rates (g) ranged from as high as 1.2 d-1 to as low as 0.1 d-1. In general, cyclopoid copepods appeared to grow more slowly than calanoids of the same size. Enhancement of resources by nutrient addition caused a 32% increase in growth rates in experiments from a mesotropic site, but only a 17% increase at a more eutrophic site. Additionally, copepodites at both sites show faster development and generally larger size at stage in response to nutrient addition. Growth rates were positively related to chlorophyll concentration in the >2 mm size-fraction. A significant relationship of growth rate to body size (r2 = 0.45) emerged across a wide range of trophic status, but it was confounded with resource availability. It appears that growth in tropical copepod copepodites may be frequently limited by resources in a size-dependent manner.....