Secondary production and biomass of Cladocera in marginal lakes after the recovery of their hydrologic connectivity in a river–reservoir transition zone

Abstract

Secondary production and biomass of Cladoceran populations were studied in two marginal lakes whose connections to a tropical river were re-established after a prolonged drought period. This study investigates the process of the recovery of the cladoceran populations after the hydrologic reconnection with the river was established. It also compares the energetic dynamic of Cladoceran populations in two lakes, one with a wide and another with a narrow connection to the river. Samples were collected every 48 h for 1 month, immediately after the river water inflow to the lakes, and 7 months after the reconnection with the river during a period of hydrologic stability of the lakes. Secondary production and biomass were compared between lakes and periods, to identify the main controlling factors for the observed variations in Cladoceran productivity. Cladocerans were more productive during the rainy period, immediately after the increased water volume, when high water temperatures were recorded in the two lacustrine systems. Secondary production and biomass values were higher in the more eutrophic lake, wherein the water chemical and physical characteristics presented slow alterations during the rainy period. Although the lake with large spatial heterogeneity and linkages with the river exhibited high Cladoceran richness, the secondary production and biomass were low. Variations in water volumes and temperatures and changes in trophic status affected the secondary production and biomass of the main Cladoceran species in the two studied lakes.

How does the Taquari River influence in the cladoceran assemblages in three oxbow lakes?

“…The relationship of a larger river-lake connection to high cladoceran richness was observed by Panarelli et al (2010) in lakes adjacent to the Paranapanema River (São Paulo), in contrast to our observations for Taquari oxbow lakes. Nevertheless, these authors observed the highest richness and diversity associated with low organism density and extensive macrophyte colonisation, similar to the situation observed for Taquari oxbow lakes.…”

Secondary productivity of main microcrustacean species of two tropical reservoirs in Brazil and its relationship with trophic state

“…The impacted station of Lake Batata showed intermediate values, because this station is mesotrophic due to bauxite tailings. A similar pattern was observed by Panarelli et al (2010), comparing two marginal lakes of the Paranapanema River in São Paulo (Brazil). Conversely, Rietzler et al (2004) found much higher values in the eutrophic Salto Grande Reservoir in São Paulo (Brazil).…”

“…This relationship between the increasing of microcrustacean productivity with the increasing of trophic state (Tab. 5) recurs in other Brazilian aquatic ecosystems.All studies in Brazilian lakes and reservoirs used the biomass increment method of Winberg et al (1965) and the present study applied the method of Hart (1987), and both direct (Maia-Barbosa, 2000;Melão et al, 2004 and2006;Rietzler et al, 2004;Santos-Wisniewski and Rocha, 2007) and indirect (Panarelli et al, 2010;Santos et al, 2010) methods were employed to estimate the zooplankton biomass. In spite of these methodological differences, the values of secondary productivity were compatible with each other.…”

“…Several estimates of secondary productivity of tropical zooplankton have been made for large African lakes (Burgis, 1974;Hart and Allanson, 1975;Mavuti, 1994). Despite the scarcity of similar studies in Brazilian aquatic ecosystems in past decades (Rocha and Matsumura-Tundisi, 1984), the number of studies has been growing (Maia-Barbosa, 2000;Peláez-Rodríguez, and Matsumura-Tundisi, 2002;2006;Rietzler et al, 2004;Santos-Wisniewski and Rocha, 2007;Panarelli et al, 2010;Santos et al, 2010). The aim of this study was to estimate the secondary productivity rates of the main microcrustacean species of two tropical reservoirs, Três Marias and Furnas in the state of Minas Gerais (Brazil), during the dry and rainy periods.…”

Cladocera (Crustacea, Branchiopoda) of a temporary shallow pond in the Caatinga of Pernambuco, Brazil

“…On the other hand, reduced water volume causes instability of aquatic populations and influences diversity of Cladocera (Panarelli et al, 2010). This may be in agreement with the theory proposed by Naselli-Flores et al (2003), who suggest a tendency of nonequilibrium of the steady-state conditions in the phytoplanktonic community when one or more environmental factors are at the extreme of the range in which organisms can grow and when the change is either too abrupt or too complete and exceeds the homeostatic plateau of the assemblage.…”