Densidade e distribuição espacial de lagostas espinhosas (Decapoda: Palinuridae) nas piscinas do Atol das Rocas

Abstract

The loss of natural habitat due to increased human activity on ecosystems causes the degradation of the same, cause upsets and affects the balance of populations of organisms and thus is considered the main cause of the decline rate of species extinctions and population. Lobster populations have suffered a noticeable decline in recent decades due to overexploitation of its stocks offshore Brazil. A tool that is gaining more strength to preserve and restore degraded environments is the creation of protected areas. The Rocas Atoll was the first Marine Conservation Unit created in Brazil in 1979 with the aim to preserve and prevent further damage to biodiversity and scenic beauty within this environment. The data collections were held in april and october 2013 in the pools formed during low tide in the Rocas Atoll at daytime. Sampling was carried out through free diving (apnea) in which the researcher actively sought by lobsters in their refuges covering a total internal area of each sampled pool, measuring the time required for this procedure. Three species of lobsters Panulirus argus (Latreille, 1804), Panulirus echinatus Smith, 1869 e Parribacus antarticus (Lund, 1793) were found. P. echinatus was dominant on the other species and the abundance of this species was 0.02 lobsters/m². It is estimated that the maximum potential of lobsters that can occur in the pools sampled in Rocas Atoll is 6,603 lobsters of this species. Panulirus argus specie was found in low abundances and varied between 0,00035 and 0,001 lobsters/m² in the Rocas Atoll waters.The ecological data collected in situ in april adjust to the proposed model to evaluate lobsters populations, however, the data for october showed an undefined pattern and that does not fit the proposed model. More samples are needed to verify if some factor not measured may influence the application of the model. The Atol das Rocas acts as a concentrator of puerulus postlarvae, juveniles and adults lobsters due to the restriction imposed by the local bathymetry with near 4000 m depth and to the local current system. It is suggested that studies have to being conducted regarding the patterns of larval recruitment, patterns of locally ocean current and populations connectivity in Brazilian lobsters populations to assess whether Atol das Rocas is acting as exporter of lobster larvae, or just providing larvae to self-recruitment of these populations.