Historical background of the population biology of the swimming crab Arenaeus cribrarius (Crustacea: Portunidae) in the Ubatuba Coast, Southeast Brazil / Antecedentes históricos da biologia populacional do siri Arenaeus cribrarius (Crustacea: Portunidae) na costa de Ubatuba, Sudeste do Brasil

ABSTRACT

This study presents results obtained 25 years ago on the population structure, sex ratio, and handedness of Arenaeus cribrarius in Ubatuba, North coast of São Paulo State, Brazil. Sampling studies were conducted during two different periods (from November 1988 to October 1989, and from May 1991 to April 1993), one of them performed for pooled data, and other exclusively for Fortaleza Bay (monthly samples from November 1988 to October 1989). Males were larger (CW, average ± SD 73.38 ± 15.78 mm) than females (68.45 ± 12.20 mm). The size between juvenile and adult stages has an overlap, for males (40-70mm CW) e fêmeas (45-75 mm CW). A prevalence of females was registered for pooled data (11.42; P 0.05). The sex ratio was close to 11 in the smaller size classes, with females dominating in the intermediate classes, and males in larger ones. In Fortaleza Bay, a female biased sex ratio was only noted in transect I (13.88; P < 0.05) and in the autumn (11.67; P < 0.05), with 73% of the specimens measured were right-handed.

RESUMO

Este estudo apresenta resultados obtidos há 25 anos sobre a estrutura populacional, razão sexual e heteroquelia de Arenaeus cribrarius, em Ubatuba, Litoral Norte do Estado de São Paulo, Brasil. As amostragens foram realizadas em dois períodos diferentes (novembro/1988 a outubro/1989, e maio/1991 a abril/1993), um delas realizada para os dois períodos agrupados, como também exclusivamente para a Enseada da Fortaleza. Os machos (LC, média ± DP 73,38 ± 15,78 mm) apresentaram maior tamanho do que as fêmeas (68,45 ± 12,20 mm). O tamanho nos estágios juvenil e adulto se sobrepuseram, para machos (40-70mm LC) e fêmeas (45-75 mm LC). Houve prevalência de fêmeas para os dados agrupados (11,42; P 0,05). A razão sexual foi de 11 nas classes inicias de tamanho, com predomínio das fêmeas nas classes intermediárias, e dos machos naquelas maiores. Na Enseada da Fortaleza a razão sexual foi desbalanceada apenas no transecto I (13,88; P < 0,05) e no outono (11,67; P < 0,05), sendo 73% dos espécimes destros.