Habitat preferences of a seahorse species, Hippocampus reidi (Teleostei: Syngnathidae) in Brazil
Thelma L. P. Dias and Ierecê L. Rosa
aqua, International Journal of Ichthyology, pp. 165-176, Volume 6, Issue 4 – March 2003
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.
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