Marcelo Dias de Mattos Burns

Checklist comparison and dominance patterns of the fish fauna at Taim Wetland, South Brazil

Taim Hydrological System is a unique subtropical wetland in southern Brazil harboring an exceptional biological diversity. In 1978, an ecological reserve was established to protect part of this area from increasing anthropogenic impacts in its surroundings. Fishes have been poorly investigated in this system. Based on a multi-gear sampling study encompassing several years (2001-2005), and on comparisons with previous fish inventories, we provide an up-to-date species list of fishes occurring in the Taim Wetland. In addition, we made the first preliminary description of fish dominance patterns found in the main lakes of the system (Flores, Nicola, Jacare and Mangueira). Checklist comparison resulted in 62 fish species distributed in 24 families, with Characidae (19 species) and Cichlidae (7) showing the highest species richness. Six species are cited for the first time in the reserve: Trachelyopterus lucenai (Auchenipteridae), Hoplosternum littorale (Callichthyidae), Rineloricaria cadeae (Loricariidae), Eigenmannia trilineata (Sternopygidae), Odontesthes mirinensis and O. perugiae (Atherinopsidae). Apparently, the black catfish T. lucenai invaded the system in the last decade and became one of the dominant species in the pelagic waters. Although differences in gears hindered direct comparisons, differences in species composition and dominance patterns between shallow margins and pelagic waters of lakes seem to occur in the lakes. A more diverse assemblage dominated by small fishes ( 15 cm) seemed to dominate in pelagic waters. O Sistema Hidrologico do Taim e um banhando subtropical localizado no sul do Brasil que abriga uma diversidade biologica excepcional. Em 1978, uma reserva ecologica foi estabelecida para proteger parte dessa area do crescente impacto de acoes antropicas nos seus arredores. Os peixes tem sido muito pouco investigados nessa regiao. Baseado em coletas com varios amostradores durante varios anos (2001-2005), e em comparacoes com estudos previos, esse trabalho fornece uma lista de especies atualizada dos peixes ocorrendo no Taim. Tambem e apresentada a primeira descricao preliminar dos padroes de dominância nos principais lagos que compoem o sistema (Flores, Nicola, Jacare e Mangueira). A analise comparada indicou a presenca de 62 especies de peixes distribuidas em 24 familias, sendo Characidae (19 especies) e Cichlidae (7) as familias com o maior numero de especies. Seis especies sao registradas pela primeira vez na reserva: Trachelyopterus lucenai (Auchenipteridae), Hoplosternum littorale (Callichthyidae), Rineloricaria cadeae (Loricariidae), Eigenmannia trilineata (Sternopygidae), Odontesthes mirinensis e O. perugiae (Atherinopsidae). Aparentemente, o penharol T. lucenai invadiu o sistema na ultima decada e tornou-se uma das especies dominantes nas zonas pelagicas das lagoas. Embora diferencas nos amostradores nao permitam comparacoes diretas, parecem ocorrer diferencas na composicao de especies e padroes de dominância entre as margens rasas e as zonas pelagicas dos lagos. Uma assembleia de peixes mais diversa, dominada por peixes pequenos ( 15cm) parece dominar as zonas pelagicas.

Evidence of habitat fragmentation affecting fish movement between the Patos and Mirim coastal lagoons in southern Brazil

The communication between the Patos and Mirim lagoon systems occurs via a natural channel called Sao Goncalo. In 1977, a dam was built in this channel to prevent entrance of saline waters from Patos Lagoon estuary into the Mirim Lagoon. Our results showed an abrupt discontinuity in salinity and fish species distribution along the study sites. Sites below the dam showed salinity values higher than zero, whereas sites above had zero salinity values across all sampling periods. Marine and estuarine fishes (e.g., mullets Mugil platanus, M. curema, silversides Odontesthes argentinensis, Atherinella brasiliensis, sardine Brevoortia pectinata, and white croaker Micropogonias furnieri) were not captured above the dam. If these juvenile fishes could enter the Mirim lagoon in greater numbers, they probably would enhance catches in the artisanal fishery. We hypothesized that the Sao Goncalo dam acts as a barrier hindering the entrance of salinity water and fishes inside the Mirim Lagoon. A comunicacao entre o sistema lagunar Patos-Mirim ocorre atraves de um canal natural denominado Sao Goncalo. Em 1977, foi construida uma eclusa com o objetivo de evitar a entrada de agua salgada, proveniente do estuario da Lagoa dos Patos, para o interior da Lagoa Mirim. Os resultados mostraram uma descontinuidade abrupta na distribuicao da salinidade e dos peixes ao longo da area de estudo. Estacoes de coleta abaixo da barragem tiveram valores de salinidade acima de zero, enquanto os valores foram iguais a zero nas estacoes acima da barragem durante o periodo amostrado. Peixes marinhos e estuarinos (p.ex., tainhas Mugil platanus, M. curema, peixes-rei Odontesthes argentinensis, Atherinella brasiliensis, sardinha Brevoortia pectinata) nao foram capturados acima da barragem. Caso entrassem em abundância na Mirim tais especies poderiam contribuir positivamente para os desembarques da pesca artesanal nessa regiao. Dessa forma, e sugerida a hipotese de que a barragem do Sao Goncalo atua como uma barreira impedindo a entrada de aguas salobras e peixes marinhos e estuarinos para o interior da Lagoa Mirim.

Pisces, Perciformes, Gobiidae, Ctenogobius stigmaticus (Poey, 1860): new species record at Patos Lagoon estuary, state of Rio Grande do Sul, Brazil

The present note records for the first time the gobiid fish Ctenogobius stigmaticus (Poey, 1860) at Patos Lagoon stuary, state of Rio Grande do Sul, southern Brazil. The known distribution of this species is therefore extended 600 km southwards.

Plasma ion levels of freshwater and marine/estuarine teleosts from Southern Brazil

levels in the plasma of freshwater and marine/estuarine teleosts collected at different salinities (0 to 34) from the estuarine and freshwater portions of the Sao Goncalochannel in Southern Brazil. Any relationship between plasma ion levels and salinity and the capacity of ionic regulation ofteleosts found at three or more different salinities (

Pisces, Perciformes, Eleotridae, Dormitator maculatus (Bloch, 1792): distribution extension for Patos-Mirim lagoon system, state of Rio Grande do Sul, Brazil

We present here the record of Dormitator maculatus (Bloch, 1792) to the Patos-Mirim lagoon system, Rio Grande do Sul, Brazil. This is also the southernmost occurrence in South America, extending species range ca. 150 km from the previously known localities.

Pisces, Perciformes, Gobiidae, Evorthodus lyricus (Girard, 1858): new record from Patos-Mirim Lagoon System, state of Rio Grande do Sul, southern Brazil

The present note records for the first time the tropical gobiid fish Evorthodus lyricus (Girard, 1858) from Patos- Mirim Lagoon System, state of Rio Grande do Sul, southern Brazil. Considering the known distribution of the species, and unpublished data obtained from fish collections, the present record widens the distribution of E. lyricus in 300 km southwards, and is the first occurrence of the species for freshwater conditions in southern Brazil.