Reproductive biology of the South American endemic hermit crabIsocheles sawayai(Crustacea, Anomura) from the Southern coast of Brazil

Abstract

The goal of this study was to investigate the sex ratio, structure and reproductive biology of Isocheles sawayai, a hermit crab captured as bycatch in a non-selective shrimp fishery. The animals were collected from July 2010 to June 2011. Out of the 575 individuals found, the majority were concentrated near the coast with a predominance of silt and clay in the sediment and warmer water. The mean length of males was 7.5 mm, which was larger than that of females (5.5 mm). The sex ratios were male-biased, except in November. The reproductive period was seasonal, with a peak during the spring, mainly in November, when 95% of the total ovigerous females were recorded. Our results suggest different habitat preferences exist according to sex; males prefer coastal regions and females prefer intertidal zones. However, the data demonstrated that both sexes utilised the same coastal regions in the reproductive period, mainly in November. A higher intensity of rainfall was observed in the spring (October, November and December), and early summer, which probably promotes the transport of coastal organic materials, and creates an excellent environment for the reproduction and subsequent larval development of benthic animals such as I. sawayai.

Geographical variation and local environment effects in the reproductive output and fecundity of the shrimpExhippolysmata oplophoroides(Decapoda: Caridea) in southeastern Brazil

“…Species with planctotrophic larval stages, such as E. oplophoroides, allocate greater reproductive energy in periods of the highest oceanic productivity, since these periods are characterized by greater food availability (phytoplankton) for larval offspring. Stanski and Castilho (2016) recorded similar seasonal reproduction in another species of decapod crustacean, Isocheles sawayai Forest and de Saint Laurent 1968, in the north littoral region of Santa Catarina (26º06′S, 48º34′W) during months of higher temperatures (late spring and summer). The larger body size (CL) of the female E. oplophoroides population in Cananéia is also in accordance with Bauer (1992), who proposed that longevity with growth to larger size tend to increase at higher latitudes.…”

Population dynamics of the crabHepatus pudibundus(Herbst, 1785) (Decapoda, Aethridae) on the southern coast of São Paulo state, Brazil

“…Individuals were considered juvenile or immature when their abdomens were adhered to the thoracic sternite, and females were considered ovigerous when they carried embryos in their pleopods (Mantelatto & Fransozo, 1992; Stanski & Castilho, 2016). Furthermore, all individuals were dissected to conduct macroscopic analysis of the gonads and were classified into four categories as a function of the shape, colour and volume of the gonads in the cephalothorax cavity: immature (IM), rudimentary (RU), developing (ED) and developed (DE) (for more details see Reigada & Negreiros-Fransozo, 2000).…”