Navegando por Autor "Schwamborn, Ralf"
Agora exibindo 1 - 3 de 3
Resultados por página
Opções de Ordenação
Item Diversity and distribution of the mesozooplankton in the tropical Southwestern Atlantic.(2008) Leitão, Sigrid Neumann; Sant'Anna, Eneida Maria Eskinazi; Gusmão, Lúcia Maria de Oliveira; Vieira, Dilma Aguiar do Nascimento; Paranaguá, Maryse Nogueira; Schwamborn, RalfMesozooplankton species distribution and abundance were studied in the tropical Southwestern Atlantic, in neritic and oceanic regions off the state of Rio Grande do Norte, northeastern Brazil (38 to 68 S and 32830’ to 35830’ W). Samples were collected with a 120 mm mesh net towed horizontally at 40 stations along five transects in June 1986. A total of 151 taxa were identified. Copepoda (93 species) numerically dominated (78%) the community. The highest zooplankton abundance was recorded at a coastal station (1098 ind m23), and the lowest at the station farthest offshore (82 ind m23). The low abundance of zooplankton corresponded to oligotrophic water masses, and differences in abundance were locally affected by topographic upwelling. Three groups were distinguished: (i) oceanic with very low total abundance (,15 ind m23), (ii) a mix of neritic and oceanic species and (iii) coastal neritic group. Species diversity was high (mean 3.14+0.42 bits ind21) and increased with the ecological stability of the area. The local oceanographic conditions, with a strong connection between the oligotrophic oceanic water masses and the enriched coastal water, are of paramount importance to the local food chain and patterns of zooplankton diversity.Item Plankton community as an indicator of water quality in tropical shrimp culture ponds.(2008) Cunha, Maristela Casé Costa; Leça, Enide Eskinazi; Leitão, Sigrid Neumann; Sant'Anna, Eneida Maria Eskinazi; Schwamborn, Ralf; Moraes Junior, Antônio Travassos deThe plankton was examined as an indicator of water quality in 14 shrimp Litopenaeus vannamei farms in Brazil in 2003. The ponds were categorized by high stocking density (>30 PL m_2) of phytoplankton, consisting of 51 species with concentrations ranging from 365,218 ± 416,615 cells mL_1 to 1,961,675 ± 3,160,172 cells mL_1. Diatoms contributed to almost 70% of the species number and high densities resulted from Cyanophyta blooms, mainly Pseudanabaena cf limnetica. Forty zooplankton taxa were registered and were essentially composed of typical marine euryhaline species and suspension-feeders. Copepoda dominated (45%) the make-up, followed by Protozoa (18%), Rotifera (12%), and Mollusca (12%) larvae. Zooplankton varied from 972 ± 209 ind m_3 to 4235 ± 2877 ind m_3. Enhanced nutrient input affected plankton density and composition. Diatom and Copepoda dominance was replaced by cyanobacteria, protozoan, and rotifers as nutrient concentrations increased with the cultured period, indicating that plankton structure is affected by eutrophic conditions.Item Zooplankton from shrimp culture ponds in Northeastern Brazil.(2009) Porto Neto, Fernando de Figueiredo; Leitão, Sigrid Neumann; Cunha, Maristela Casé Costa; Sant'Anna, Eneida Maria Eskinazi; Cavalcanti, Eliane Aparecida Holanda; Schwamborn, Ralf; Gusmão, Lúcia Maria de Oliveira; Melo, Pedro Augusto Mendes de CastroZooplankton was examined in 14 commercial shrimp Litopenaeus vannamei ponds in tropical Brazil to assess their composition, determine their density, and indicate environmental quality. In each farm, two ponds and the water intake point were monitored in 2003. Sampling was made with a standard plankton net 50 micrometers mesh size. The zooplankton presented 40 taxa and was essentially composed of typical marine euryhaline species and suspensionfeeding forms. In all farms the dominant group was Copepoda with a total of 45%, followed by Protozoa (18%). The most abundant meroplankton were Polychaeta larvae, Gastropoda larvae, nauplii of Cirripedia and zoeae of Brachyura with large distribution in the region, sometimes dominating the community. Zooplankton abundance varied from 972+209 ind m-3 to 4,235 + 2,877 ind m-3. In the studied marine shrimp culture ponds, copepods dominance were replaced by protozoan and rotifers as nutrient concentrations increased with the culture period, indicating that zooplankton trophic structure can be strongly affected by the occurrence of eutrophic conditions in shrimp ponds. The tendency of low species diversity is indicative of an unbalanced hypereuthrophic system decreasing the water quality and the cultured species. These results can be an important appointment to understand the effects of eutrophication in coastal plankton structure and its effects to marine aquatic food web.