Abundância e ecologia reprodutiva de Abudefduf saxatilis (Linnaues, 1758) (Osteichthyes:Pomacentridae) no arquipélago de São Pedro e São Paulo, Brasil.
| Ano de defesa: | 2013 |
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| Autor(a) principal: | |
| Orientador(a): | |
| Banca de defesa: | |
| Tipo de documento: | Dissertação |
| Tipo de acesso: | Acesso aberto |
| Idioma: | por |
| Instituição de defesa: |
Universidade Federal da Paraíba
Brasil Zoologia Programa de Pós-Graduação em Ciências Biológicas UFPB |
| Programa de Pós-Graduação: |
Não Informado pela instituição
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| Departamento: |
Não Informado pela instituição
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| País: |
Não Informado pela instituição
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| Palavras-chave em Português: | |
| Link de acesso: | https://repositorio.ufpb.br/jspui/handle/tede/4141 |
Resumo: | The abundance and ecological attributes, as behavior and reproduction, of reef fishes are usually influenced by variations in habitat structure, e.g. benthic cover and structural complexity. The preference for different habitats generally varies according to the ontogenetic stage, with juveniles generally concentrated in shallow waters and adults in deeper and away from the coast areas. Abudefduf saxatilis, the sergeant-major (Pomacentridae) is a reef fish widely distributed in coastal and oceanic reef habitats in the West Atlantic. In the small and remote St. Peter and St. Paul s Archipelago (SPSPA), located on the Mid Atlantic Ridge, the sergeant-major is one of the most abundant reef fish species. The sergeant-major population of the SPSPA is morphologically and genetically distinct from other populations in West Atlantic, suggesting low genetic connectivity and self-maintenance by local reproduction. The main objectives of this study are: 1) to describe the abundance and spatial distribution of the sergeant-majors from SPSPA (tidal pools and the islands inlet) and 2) to quantitatively characterize the reproductive ecology aspects of the species on site. Data on fish and nest abundance were collected using a stationary visual census methodology. Benthic complexity was measured using a rolling stick, at the inlet and the chain link method on tide pools. Benthic cover was estimated using photo-quadrats. Data on the reproductive behavior of male guardians and the nests individual monitoring were collected by the focal animal method and photographs, respectively. The smaller sergeant-majors representatives (<2 cm in total length, TL) were recorded exclusively in the tidal pools, predator-free environments that have been identified as potential nurseries for this species in the SPSPA. No significant influences were recorded on the complexity of the substrate in the abundance and distribution of sergeant-majors in tidal pools and little or no influence of benthic coverage. In the inlet, there was a positive relationship between A. saxatilis body size and depth, with individuals sized between 2-10 cm CT concentrated on shallower strata (0-10 m depth). Individuals among 10-20 cm CT switch to occupy depths below 10 m and suffered significant influence of complexity, suggesting greater need of refuge from predators. The density of A. saxatilis nests was lower in areas with higher abundance of Stegastes sanctipauli, a territorial Pomacentridae, abundant in the archipelago, suggesting possible negative interactions as competition for territory and optimal nesting sites. Places with higher densities of nests of A. saxatilis also had higher densities of the eggs' predator Halichoeres radiatus, suggesting aggregation of this predator in areas with a greater supply of eggs. The agonistic interactions between male guardian and nests invaders were more frequent in less accessible nests, probably due to greater difficulty on detecting intruders in these nests. Factors that negatively influenced the spawning success, i.e. proportion of eggs remaining over time, were the total agonistic interactions between males and invaders, total bites by male guardian in their own nest and guardian male's size. Depth was the only factor that positively influenced the spawning success. These last results suggest that larger males probably defend spawning that is more attractive to egg's predators and egg predation significantly influences the spawning success of A. saxatilis in SPSPA. Furthermore, if the male spends more time in nest defense, the chances of foraging in areas distant from the nest are smaller, being one of the most plausible explanations for the significant influence of filial cannibalism in spawning success. The higher reproductive success at greater depths may be related to the absence of competition with other abundant territorial damsels species that spawn in shallow areas from SPSPA, specially Stegastes sanctipauli and Chromis multilineata. |