Volumen 43 - Número 2: 399-411 | 2008
Article

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Patterns of distribution of the hermit crab Loxopagurus loxochelis (Moreira, 1901)(Decapoda, Diogenidae) in two coastal areas of southern Brazil

Luciane Ayres-Peres¹ and Fernando L. Mantelatto^1* 

¹Laboratory of Bioecology and Crustacean Systematics, Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto (FFCLRP), University of São Paulo (USP), Av. Bandeirantes 3900, CEP 14040-901, Ribeirão Preto, São Paulo, Brazil

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The present study determined the distribution pattern of the hermit crab Loxopagurus loxochelis by a comparison of catch, depth and environmental factors at two separate bays (Caraguatatuba and Ubatuba) of São Paulo State, Brazil. The influence of these parameters on the distribution of males, non-ovigerous females and ovigerous females was also evaluated. Crabs were collected monthly, over a period of one year (from July/2002 to June/2003), in seven depths, from 5 to 35 m. Abiotic factors were monitored as follows: superficial and bottom salinity (psu), superficial and bottom temperature (°C), organic matter content (%) and sediment composition (%). In total, 366 hermit crabs were sampled in Caraguatatuba and 126 in Ubatuba. The highest frequency of occurrence was verified at 20 m during winter (July) in Caraguatatuba and 25 m during summer (January) in Ubatuba. The highest occurrences were recorded in the regions with bottom salinities ranging from 34 to 36 psu, bottom temperatures from 18 to 24°C and, low percentages of organic matter, gravel and mud; and large proportion of sand in the substrate. There was no significant correlation between the total frequency of organisms and the environmental factors analyzed in both regions. This evidence suggests that other variables as biotic interactions can influence the pattern of distribution of L. loxochelis in the analyzed region, which is considered the limit of the northern distribution of this species.

Key words: Crustacea, environmental factors, clustering analysis, abundance