Contribution to the feeding ecology of the banded puffer fish Colomesus psittacus (Tetraodontidae) in north Brazilian mangrove creeks.

Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September, 1997 (early dry season) near Bragança (north Brazil). The study found that C. psittacus were specialized predators of Cirripedia (Balanus spp.) and Brachyuran crabs (Uca spp., Pachygrapsus gracilis) (mean: 58 and 38% by dry weight, respectively), emphasizing a short food chain in the mangrove system. Cirripedia and Brachyura dominated the diet in all size classes, however, the prey spectrum narrowed with fish size. The mean daily consumption of Cirripedia and Brachyura was 6.2% body weight of C. psittacus. On average C. psittacus consumed 100.3 g x ha(-1) x d(-1) of Cirripedia and 178.7 g x ha(-1) x d(-1) of Brachyura (wet weight). The predation on Brachyuran crabs--a significant driver of fluxes of organic matter and energy in the system--provides C. psittacus with an important ecological function in the mangrove food web. A plant-animal interaction is proposed where C. psittacus exerts a mutually beneficial cleaning function on the Aufwuchs (Cirripedia and associated epibiota) of Rhizophora mangle stilt roots. Our results and those of other studies suggest that C. psittacus encounter optimum foraging conditions in the mangrove at high inundations at daylight (spring tide-day) whereas darkness and low inundations are linked to poor foraging conditions (neap tide-night). The C. psittacus resource could be used as an alternative income in the region in terms of i) sustainable catch and filet processing for exports to East Asia, ii) developing certified aquaculture methods for breeding puffers for the aquarium trade.

Contribution to the feeding ecology of the banded puffer fish Colomesus psittacus (Tetraodontidae) in north Brazilian mangrove creeks

Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September, 1997 (early dry season) near Bragança (north Brazil). The study found that C. psittacus were specialized predators of Cirripedia (Balanus spp.) and Brachyuran crabs (Uca spp., Pachygrapsus gracilis) (mean: 58 and 38 percent by dry weight, respectively), emphasizing a short food chain in the mangrove system. Cirripedia and Brachyura dominated the diet in all size classes, however, the prey spectrum narrowed with fish size. The mean daily consumption of Cirripedia and Brachyura was 6.2 percent body weight of C. psittacus. On average C. psittacus consumed 100.3 g.ha-1.d-1 of Cirripedia and 178.7 g.ha-1.d-1 of Brachyura (wet weight). The predation on Brachyuran crabs - a significant driver of fluxes of organic matter and energy in the system - provides C. psittacus with an important ecological function in the mangrove food web. A plant-animal interaction is proposed where C. psittacus exerts a mutually beneficial cleaning function on the Aufwuchs (Cirripedia and associated epibiota) of Rhizophora mangle stilt roots. Our results and those of other studies suggest that C. psittacus encounter optimum foraging conditions in the mangrove at high inundations at daylight (spring tide-day) whereas darkness and low inundations are linked to poor foraging conditions (neap tide-night). The C. psittacus resource could be used as an alternative income in the region in terms of i) sustainable catch and filet processing for exports to East Asia, ii) developing certified aquaculture methods for breeding puffers for the aquarium trade.

Conteúdos estomacais de 102 baiacus Colomesus psittacus (Tetraodontidae) foram examinados. A amostragem foi realizada em canais de maré com vegetação de mangue, durante as marés de quadratura de dia, entre junho e setembro de 1997 (no início do período seco), nas proximidades de Bragança (norte do Brasil). O estudo constatou que C. psittacus era um predador especializado em Cirripedia (Balanus spp.) e Brachyura (Uca spp., Pachygrapsus gracilis), com médias de 58 e 38 por cento em peso seco, respectivamente, caracterizando uma curta cadeia alimentar no sistema de manguezal. Cirripedia e Brachyura dominaram a dieta em todos os tamanhos, entretanto, o espectro alimentar diminuiu de acordo com o tamanho do peixe. O consumo diário médio de Cirripedia e Brachyura foi de 6,2 por cento em peso corporal de C. psittacus. C. psittacus consumiu uma média de 100,3 g.ha-1.d-1 de Cirripedia e 178,7 g.ha-1.d-1 de Brachyura (peso úmido). A intensa predação de Brachyura por C. psittacus enfatiza a importante função ecológica desta espécie na cadeia alimentar do manguezal, contribuindo significativamente no fluxo de matéria orgânica. Uma interação planta-animal é indicada no fato que C. psittacus exerce uma função limpadora mutuamente beneficiável ao se alimentar do Aufwuchs (Cirripedia e epibiota asociada) que cresce nas raízes aéreas de Rhizophora mangle. Nossos resultados e os de outros estudos sugerem que C. psittacus encontra no manguezal as melhores condições para se alimentar no período diurno durante as maiores inundações (marés de sizigia - de dia), enquanto que períodos noturnos e de pequenas inundações determinam as piores condições para forragear (maré de quadratura - de noite). C. psittacus poderia ser usado como alternativa de renda na região com respeito a: i) pesca sustentável e processamento de filés para exportação ao leste da Ásia, ii) desenvolvimento de métodos de aqüicultura certificada para a criação de baiacu para o comércio de peixes...

Heterogeneity and subunit composition of the haemoglobins of five tilapiine species (Teleostei, Cichlidae) of the genera Oreochromis and Sarotherodon.

Haemoglobins of five tilapiine species of the genera Oreochromis and Sarotherodon were investigated. By gel filtration chromatography a molecular weight of 67-69 kDa was determined for the tetrameric molecules which remained stable between pH 5.0 and pH 9.1. When subjected to sodium dodecyl sulphate-Ureapolyacrylamide gel electrophoresis (PAGE), haemoglobins of all species each were split into monomers of three different molecular weights ranging between 16.3 kDA and 17.6 kDa. Subsequently, isoelectric focusing separated haemolysates into about 23 differently charged tetrameric haemoglobins that were arranged in species-specific patterns. This diversity was shown to result from the occurrence of different types of globin chains. By acidic urea PAGE a total of seven major alpha-globins and five major beta-globins were detected and species-characteristic chain variants were identified. To determine the globin chain composition of particular haemoglobin tetramers, 26 bands were isolated by isoelectric focusing and analysed by acidic urea PAGE. Tetramers consisted of doublets of identical alpha- and identical beta-chains (alpha 2 beta 2, symmetric tetramers), or combinations of three (alpha 2 beta beta *; alpha alpha * beta 2) or four (alpha alpha * beta beta *) distinct chains (asymmetric tetramers). Finally, globin chains of Oreochromis niloticus were subjected to partial N-terminal amino acid sequencing. Differences in the composition of the three major beta-chains could be shown, whereas the alpha-chains were N-terminally blocked.