Abstract

RIOS JARA, Eduardo. Seasonal abundance of the demersal copepod Pseudodiaptomus cokeri (Calanoidea: Pseudodiaptomidae) in a Caribbean estuarine environment. Rev. biol. trop [online]. 1998, vol.46, n.3, pp.661-672. ISSN 0034-7744.

Seasonal abundance variations of the demersal copepod Pseudodiaptomus cokeriwere examinated at three locations (center, north shore and south shore) in Phosphorescent Bay, Puerto Rico, throughout an annual cycle. Nocturnal oblique tows (21:00-23:00 hr) were taken biweekly (three replicates) at each location with a conical net (mouth diameter = 0.5 m; mesh size = 135 µm) and a standard calibrated flowmeter. Water temperature and salinity measurements were taken at the surface and near the bottom in each location before towing activities using a SCT meter. Chlorophyll-a concentrations were fluorometrically determined. The adult and copepodite stages of this species accounted for approximately 1.6% of the annual mean total zooplankton abundance of the bay. Higher abundance of P. cokeri (mean +1 SD = 4 191 + 1 444 individuals m^-3) was associated with cool water temperatures and dry conditions (cool/dry season) which prevailed between December and March relative to the period between April and November (warm/wet season) with lower abundance. Fluctuations of this population followed progressive increments in chlorophyll-a concentrations at the three sampling stations (One-way ANOVA, p<0.05). However, abundance was generally higher on the north shore of the bay (Tukey’s test, p<0.05). Differences in abundance of P. cokeri between sampling stations could be related to the different types of substratum found in the bay. Apparently, this species prefers areas with heterogeneous substrata. Its demersal behavior may contribute to the observed distribution inside the bay.

Keywords : Demersal; copepod; population variations; zooplankton; Caribbean estuary.