Zooplankton biomass of reservoirs in different trophic conditions in the State of São Paulo, Brazil

Abstract

This paper reports on a study involving an estimate of the biomass of rotifers, cladocerans, and cyclopoid and calanoid copepods found in reservoirs in different trophic conditions, comparing and relating numerical density data and pointing out differences between the dry and rainy seasons. In terms of numerical densities, both reservoirs were dominated by rotifers, although cladocerans represented a higher biomass in the oligotrophic environment in both seasons. In the eutrophic environment, higher biomass values were found for cyclopoids during the dry season and for cladocerans during the rainy one. Different biomass patterns were observed relating to both the trophic conditions and the rainy and dry seasons.Keywords: biomass, zooplankton, trophic state, Alto Tietê Basin. RESUMO Biomassa de organismos zooplanctônicos em represas de diferentes condições tróficas do Estado de São Paulo, BrasilEste trabalho descreve um estudo sobre a determinação dos valores de biomassa de rotíferos, cladóceros, copépodos calanóides e ciclopóides em represas de diferentes estados tróficos, com o objetivo de comparar e relacionar com dados de densidades numéricas, considerando os períodos chuvoso quente e estiagem frio. Verificou-se que, embora rotíferos tenham dominado numericamente em ambas as represas, em termos de biomassa os cladóceros predominaram no ambiente oligotrófico, em ambos os períodos considerados. No ambiente eutrófico, copépodos ciclopóides predominaram no período estiagem frio, e cladóceros, no chuvoso quente, evidenciando padrões diferenciados de biomassa tanto em relação às condições tróficas quanto aos períodos chuvoso e seco.Palavras-chave: biomassa, zooplâncton, estado trófico, Bacia do Alto Tietê.

Zooplankton communities as eutrophication bioindicators in tropical reservoirs

“…Relative numbers and biomass of Calanoids decreased and those of Cyclopoids increased at sites under more eutrophic conditions, thus resulting in lower values of Calanoida-Cyclopoida ratios. This pattern has been reported before for other Brazilian reservoirs (Tundisi 1988, Santos-Wisniewski & Rocha 2007, Sendacz et al 2006) and elsewhere for both, tropical, and subtropical water bodies (Pace 1986, Caramujo & Boavida 2000, namely that the presence of calanoid copepods relates to a low trophic level in the habitat, while cyclopoid copepods are favored in the more productive areas of higher trophic state. The higher proportion of calanoids in oligotrophic waters is due to the herbivorous-filter feeding habit of most species belonging to this group, especially in adulthood; and such feeding is based on nano-phytoplankton, which is replaced by micro-phytoplankton in environments of higher trophic state.…”

“…The only site at which a high density of zooplankton was found was near the entrance of the Jaguari river, probably reflecting the higher trophic conditions suggested by the high phosphorus and chlorophyll concentrations (TSI value = 69). The fall in zooplankton at the end of the rainy season has also been observed in other reservoirs, as in the Guarapiranga reservoir, by Sendacz et al (2006), and the Barra Bonita reservoir, by Tundisi et al (2008).…”

“…In contrast, in the meso-eutrophic Guarapiranga Reservoir Sendacz et al (2006) reported that the Cyclopoida were the main contributors to the biomass in the reservoir during the dry period, a fact commonly observed in other eutrophic Brazilian reservoirs, like Barra Bonita, SP (Santos-Wisniewski & Rocha 2007).…”

“…Besides recording biomass as a quantitative parameter, another community property used to indicate the trophic condition of the water body is the set of ratios between component populations of the zooplankton (rotifers, copepods and cladocerans) given that these ratios are also affected by eutrophication (Sampaio et al 2002, Sendacz et al 2006, Bini et al 2007.…”

The influence of environmental factors on the seasonal dynamics and composition of Rotifera in the Sapucaí River arm of Furnas Reservoir, MG, Brazil

“…They are generally present in great numbers and with high species richness in tropical zooplankton, being opportunistic organisms capable of colonizing a wide variety of habitats, from temporarily flooded areas (Koste & Robertson 1990, Lima et al 1996, Garcia et al 1998, Martínez et al 2000, LansacTôha et al 2009) to large rivers, lakes and reservoirs (Oliveira Neto & Moreno 1999, Aoyagui & Bonecker. 2004, Sendacz et al 2006, Corgosinho & Pinto-Coelho, 2006, Almeida et al 2009, Borges & Pedrozo, 2009.…”