Spatial and temporal distribution in density and biomass of two Pseudodiaptomus species (Copepoda: Calanoida) in the Caeté river estuary (Amazon region - North of Brazil)

Abstract

Spatial and temporal density and biomass distribution of the planktonic copepods Pseudodiaptomus richardi and P. acutus along a salinity gradient were investigated in the Caeté River Estuary (North-Brazil) in June and December, 1998 (dry season) and in February and May, 1999 (rainy season). Copepod biomass was estimated using regression parameters based on the relation of dry weight and body length (prosome) of adult organisms. The Caeté River Estuary was characterized by high spatial and temporal variations in salinity (0.8-37.2‰). Exponential length-weight relationships were observed for both Pseudodiaptomus The results showed that the contribution of P. richardi for the secondary production in the Caeté River Estuary is more important in the limnetic zone than in other zones where euhaline-polyhaline regimes were predominant. However, it was not possible to observe a clear pattern of spatial and temporal distribution for P. acutus.Keywords: Pseudodiaptomus, Caeté River Estuary, biomass, spatial and temporal distribution, Brazil. RESUMOVariação espacial e temporal da densidade e biomassa de duas espécies de Pseudodiaptomus (Copepoda, Calanoida) no estuário do rio Caeté (Região Amazônica -Norte do Brasil)A distribuição espacial e temporal da densidade e biomassa dos copépodos planctônicos Pseudodiaptomus richardi e P. acutus, ao longo de um gradiente de salinidade, foi estudada no Estuário do Rio Caeté (Norte do Brasil) durante os meses de junho e dezembro de 1998 (estação seca) e fevereiro e maio de 1999 (estação chuvosa). A biomassa dos copépodos foi estimada a partir de parâmetros da regressão baseada na relação entre o peso seco e o comprimento do corpo (prossoma) de organismos adultos. O Estuário do Rio Caeté caracterizou-se por uma grande variação espacial e sazonal na salinidade (0,8-37,2‰

Salinity and freshwater discharge determine rotifer distribution at the Mossoró River Estuary (Semiarid Region of Brazil)

“…Typical estuaries tend to show the opposite pattern with downstream salinity gradients frequently observed (Barletta-Bergan et al, 2002;Magalhães et al, 2006). Due to the well-known negative influence of salinity on many zooplankton species (e.g.…”

“…Medeiros, 1983;Neumann-Leitão, 1994;Magalhães et al, 2006;Silva et al, 2009). These authors attributed these findings to opposing patterns of salt concentration and zooplankton distribution, with freshwater being a highly important determinant.…”

Microfitoplâncton de águas costeiras amazônicas: Ilha Canela (Bragança, PA, Brasil)

“…Este padrão sazonal da salinidade é característico de ambientes costeiros do Nordeste paraense (Magalhães et al 2006).…”

Relationships between copepod community structure, rainfall regimes, and hydrological variables in a tropical mangrove estuary (Amazon coast, Brazil)

“…In recent years, research into the region's zooplankton (Krumme and Liang 2004;Costa et al 2008) and especially its copepods Magalhães et al (2006Magalhães et al ( , 2009aMagalhães et al ( , b, 2011Leite et al 2010) has increased considerably. In temperate waters, the seasonal relationship of phytoand mesozooplankton populations often shows what resembles coupled oscillations which might suggest a classical Lotka-Volterra predator-prey relationship (Kiør-boe 1997), i.e., the phytoplankton populations are limited by predation, while the zooplankton (predator) populations are limited by the availability of feeding resources.…”