Abstract
The main purpose of this study was to investigate the seasonal variation of copepod community structure during the months of July, September and November 2003 (dry season) and January, March and May 2004 (rainy season) in the Curuçá estuary, northern Brazil. Samples were collected during neap tides via gentle 200microm mesh net tows from a small powerboat. Measurements of surface water conductivity were accomplished in situ using an electronic conductivimeter and salinity was later obtained through the transformation of the conductivity values. Salinity varied seasonally from 7.2 +/- 0.1 to 39.2 +/- 1.8 (mean +/- standard deviation) and was influenced mainly by differences in the amount of rainfall between the studied sampling seasons. In total, 30 Copepoda taxa were identified and Acartia tonsa comprised the most representative species throughout the entire studied period followed by Acartia lilljeborgii, Subeucalanus pileatus and Paracalanus quasimodo. In the present study, the density values, ecological indexes and copepod species dominance presented a clear seasonal pattern, showing that the studied area may be considered seasonally heterogeneous in relation to the investigated parameters.
Highlights
Mangrove estuaries are located in tropical and subtropical regions and in these ecosystems phytoplankton and zooplankton productivity are sustained by the input of organic and inorganic nutrients originated from adjacent mangrove forests (Yáñez Arancibia et al 1993, Schwamborn et al 1999)
The cluster and multidimensional scaling (MDS) analyses performed on monthly density of taxa registered during the present study clearly showed the temporal differences in the copepod community at the Curuçá estuary
Sub-surface water salinity was characterized by pronounced seasonality, with the largest values found in the dry season
Summary
Mangrove estuaries are located in tropical and subtropical regions and in these ecosystems phytoplankton and zooplankton productivity are sustained by the input of organic and inorganic nutrients originated from adjacent mangrove forests (Yáñez Arancibia et al 1993, Schwamborn et al 1999). In these environments copepods are usually the dominant zooplanktonic component comprising 60 to 80% of the total biomass (López-Ibarra and Palomares-García 2006) and playing an important role as prey for many juvenile and adult zooplanktophage fish (Schipp et al 1999, Sommer et al 2002) becoming a. The purpose of the present study was to assess the copepod composition and characterize seasonal density and dominance patterns as well as ecological indexes of their populations related to salinity variations in the Curuçá estuary, northern Brazil
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