aqua International Journal 6(4)
Volume 6, Issue 4 – March 2003
Volume 6, Issue 4 – March 2003
Leonardo Francisco Machado, Áthila Bertoncini Andrade, Maurício Hostim–Silva and João Pedro Barreiros: Habitat use by the juvenile dusky grouper Epinephelus marginatus and its relative abundance, in Santa Catarina, Brazil, pp. 133-138
The dusky grouper (Epinephelus marginatus) is a species whose stock management deserves special attention. It has an important role in hard-bottom ecosystems and, as a protogynous hermaphrodite; it is especially susceptible to overfishing. Data on the species’ use of habitat, and on the way environmental and behaviour parameters influence its abundance can help to improve management and conservation strategies. The aim of this study was to evaluate the influence of bottom type, temperature and species behaviour on the abundance of E. marginatus, using a quadrat for visual census. An area of 80 mq., divided between rocky shore, rocky outcrop and sandy habitats was surveyed monthly. Densities of juveniles were: 1.16 groupers m-2 over the rocky shore and 1.47 groupers m-2 over the rocky outcrop, while no groupers were found over sand. Analysis of the yearly variation in abundance revealed a migratory pattern of dispersal and gathering. All size groups observed in this study were below the first maturation length.
Wilson J. E. M. Costa, Cristiano R. Moreira and Flávio C. T. Lima: Simpsonichthys cholopteryx n. sp. (Cyprinodontiformes: Rivulidae: Cynolebiatinae): a new dwarf annual fish from the upper Rio Araguaia basin, central Brazil, pp. 139-144
Simpsonichthys cholopteryx n. sp., collected in the upper Rio Araguaia basin, central Brazil, is described. It belongs to a clade that includes S. boitonei and S. parallelus, diagnosed by the absence of pelvic fin and girdle. The new species is considered to be a sister group to S. parallelus, both sharing apomorphic colour patterns of the caudal fin and iris in males, small adult size and absence of teeth on the second pharyngobranchial. It differs from S. boitonei and S. parallelus in the colour patterns of the flank and unpaired fins in males, and by having more anal fin rays in females.
Jeffrey T. Williams and Julie H. Mounts: Descriptions of six new Caribbean fish species in the genus Starksia (Labrisomidae), pp. 145-164
Extensive collecting efforts using rotenone sampling throughout the Caribbean over the past four decades have vastly increased the numbers of specimens of cryptic fishes in museum collections. Among these specimens, we discovered representatives of six new cryptic fish species belonging in the Starksia fasciata and S. sluiteri species complexes. Descriptions are provided herein for the following new species: S. leucovitta from Navassa Island; S. melasma from Mona Island, Puerto Rico, and Buck Island Reef National Monument, St. Croix; S. multilepis from Fernando de Noronha Island and Atol das Rocas, Brazil; S. rava from Tobago, Trinidad and Tobago; S. sella from Tobago, Trinidad and Tobago, all in the S. sluiteri complex; and in the S. fasciata complex, S. smithvanizi from Buck Island Reef National Monument (St. Croix), Navassa Island, St. Barthelemy, and Dominica. Starksia fasciata is restricted in distribution to the Bahamas and northern Cuba. We provide an identification key and diagnostic characters for the 21 western Atlantic species (those species in the S. ocellata complex are diagnosed only in the key). The descriptions herein bring the total number of recognized western Atlantic species of Starksia to 21.
Thelma L. P. Dias and Ierecê L. Rosa: Habitat preferences of a seahorse species, Hippocampus reidi (Teleostei: Syngnathidae) in Brazil, pp. 165-176
The habitat preferences of Hippocampus reidi are reported, based on the first field study of a seahorse population in the western south Atlantic. Data on holdfasts used by juveniles and adults were obtained in north-east Brazil between October 2000 and December 2001, during four-hour daily underwater observation sessions over a period of 45 days. The random visual census method was used while snorkelling or scuba diving. Occurrences of seahorses on each holdfast were recorded on an underwater slate, filmed and photographed. H. reidi used a total of 18 different holdfasts, of which the green algae Caulerpa racemosa and C. kempfi, the tunicate Ascidia nigra, and the roots of the mangrove plants Avicennia schaueriana and Rhizophora mangle were the most frequent. H. reidi was also found in crevices or leaning against the muddy bottom. While using the holdfasts, H. reidi were seen feeding (mostly young individuals) or engaging in courtship behaviour. During tidal shifts, they were seen moving with the tide, apparently not engaged in any particular activity. The results of the present study suggest that strategies to conserve seahorse populations in Brazil should emphasize habitat conservation. The algae of the genus Caulerpa constitute one of the most important holdfasts for H. reidi in the study area, both for juveniles and adults.
|Dimensions||26.6 × 20.3 × 0.3 cm|
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