Diel and seasonal changes in the macrozooplankton community of a tropical estuary in Northeastern Brazil

Abstract

ABSTRACT. Studies were carried out to assess the macrozooplankton small-scale temporal and spatial variability at three stations in three hours intervals, during 24 hours in July 1996 (rainy season) and December 1996 (dry season). A plankton net 300µm mesh size was hauled at surface during three minutes. Water samples for salinity, temperature, dissolved oxygen and pH were taken simultaneously with the zooplankton samples. Sixty-five macrozooplankton taxa were registered. Copepoda constituted the most common taxon and comprised 58% of the total zooplankton counts. Brachyuran zoeae, cirripedian larvae, Larvacea (Oikopleura dioica Fol, 1872), and Gastropoda veligers were abundant at some tidal cycles, mainly during the night. Species diversity average was 2.0 bits . ind -1 . The mean density ranged from 23 ind . m -3 to 5,201 ind . m -3 . The rainy season presented greater numerical abundance. A regular temporal zooplankton cycle was not observed. Instead, there was a large stochastic variation between samples.

Zooplankton community dynamics in relation to the seasonal cycle and nutrient inputs in an urban tropical estuary in Brazil

“…Most of the problems observed in this estuary are related to domestic sewage, thus closely linked to human population density. This is a feature common to most estuaries in northeastern Brazil, mainly those close to cities (Sankarankuty et al, 1979;Neumann-Leitão et al, 1992;Neumann-Leitão and Matsumura-Tundisi, 1998;Silva et al, 2003). Relatively high loads of nutrients in both months caused by anthropogenic inputs could favor phytoplankton growth, but the turbidity of the water (transparency < 0.20 m) probably limited the primary production.…”

Response of estuarine meiofauna assemblage to effects of fertilizer enrichment used in the sugar cane monoculture. Pernambuco, Brazil

“…Such results may be related either to the high nutrient input from each application, possibly associated with the already eutrophicated natural conditions in mangrove swamps that may magnify the nutrient input, or to the time scale used. Meiofauna organisms are known to have generation times on scales of from several days to a few weeks (HEIP et al, 1982;HICKS;COULL, 1983;SANTOS et al 1995;SOUZA-SANTOS et al, 1999), even in temperate areas. The interval between the initial nutrient input and the first sampling was long enough for two or more generations to have developed and thus for the sampling to have missed the initial density increase.…”

“…The Santa Cruz Channel estuarine complex is characterized by extensive highly productive mangrove areas with great biodiversity. As with most estuaries, the Itamaracá ecosystem is exposed to multiple pressures from industrial pollution, domestic sewage discharge, urban expansion, land reclamation and fisheries (SILVA et al 2003), the sugar-cane monoculture constituting the basis of various municipalities' economies (CPRH, 2001). 2 ) was also sampled in each area for sediment composition (percentage of silt+clay) but this parameter was analyzed only for the initial (Day 0) and final (Day 118) samplings.…”

Variação sazonal do macrozooplâncton do estuário do rio Siriji, litoral norte de Pernambuco – Brasilexclusiva do nordeste do Brasil

“…Silva et al (2003) realizaram um estudo nos estuários dos rios Botafogo, Igarassú e no Canal de Santa Cruz, próximos à região de estudo, e observaram que vários táxons, principalmente Decapoda, foram abundantes na estação seca, enquanto Copepoda Calanoida dominou na estação chuvosa.…”

“…No estuário do rio Timbó, foi observado também a predominância de Copepoda por Nascimento-Vieira; Santana (1987Santana ( /1989. Nascimento-Vieira; Feitosa; Passavante (1988) e Eskinazi-Sant'anna; Tundisi (1996) Assim como o presente estudo, que constatou diferenças significativas quanto à variação sazonal e quanto ao fotoperíodo, o trabalho de Silva et al (2003) realizado na região estuarina de Itamaracá, apresentou diferenças significativas entre dia e noite nos estuários dos rios Botafogo (p=0,04) e Igarassú (p=0,01) e entre as estações chuvosa e seca (p=0,04).…”