Ucides cordatus is the most commercially important mangrove crab in Brazil. In spite of its economic importance, there are few studies of its reproduction, in particular the female reproductive system. The present study describes the histology and histochemistry of the spermathecae of U. cordatus. Adult females were caught monthly from July 2004 through June 2005, at Iguape, State of São Paulo. The crabs were anaesthetized, and their spermathecae removed and fixed in Davidson's fluid, following the histological routine for paraffin. The slides were stained with HE, xylidine Ponceau, PAS, alcian blue (pH 1.0 and 2.5), Sudan black B and picrosirius-haematoxylin. Histologically, the spermathecae possesses a capsule of conjunctive tissue, rich in collagen fibres, which surrounds the secretory columnar epithelium. In the lumen, individual sperm packets are not observed; the spermatophores are intermixed with the seminal fluid and secretions of the spermathecae itself. A large proportion of the free spermatozoids and spermatophores are arranged in homogeneous masses in the proximal part of the spermathecae. The secretion produced by the columnar epithelium appears to promote the movement of the gametes to the fertilization chamber, in a ventral position, allowing fertilization of the oocytes. Histochemically, the secretion produced by the columnar epithelium was strongly positive for neutral polysaccharides, positive for acid polysaccharides, and weakly positive for proteins and lipids. This secretion forms a glycoprotein matrix which is associated with maintenance of the spermatophores, which can remain stored for long periods.

Invasive species are potential threats to biodiversity, especially if they become established and outnumber native species. In this study, a population of the non-indigenous crab Charybdis hellerii was analyzed in an estuary-bay complex on the southeastern Brazilian coast, with respect to its abundance relative to sympatric native brachyuran species, as well as the size structure, sexual maturity, sex ratio, frequency of mutilation, reproductive period, and development of the reproductive system. Crabs were sampled monthly both in the intertidal zone of rocky shores and on sublittoral soft-bottom. Nine species were recorded on the rocky shores, where C. hellerii was the second most abundant species; only three individuals of C. hellerii were collected in the sublittoral samples. This population of C. hellerii showed a unimodal size structure composed mainly of mature individuals; males were larger than females, and the sex ratio was skewed toward males (3.1:1). About 46.9% of the individuals (75 of 160 crabs) had mutilated or regenerating appendages, more frequent in males (56.8%) than in females (28.2%), which may reflect both inter- and intraspecific agonistic interactions. A continuous reproductive pattern is suggested for this population, although ovigerous females occurred unevenly during the year, with 58.82% of them being collected in winter. There was evidence of multiple spawning, since the ovigerous females with an initial egg mass showed mature ovaries as well as seminal receptacles filled with sperm. C. hellerii is well established in the estuary-bay complex, but is concentrated in intertidal and shallow subtidal rocky shores, where it may compete with and replace other species such as the portunid Cronius ruber. This study also highlights the importance of systematic monitoring studies to evaluate the effects of the introduction of non-indigenous species on ecologically similar natives.FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo) [JP Proc. 2005/04707-5, Biota Proc. 2010/50188-8]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)PROPe UNESP Programa Primeiros ProjetosPROPe UNESP - Programa Primeiros ProjetosCNPq [PQ Proc. 308215/2010-9, Proc. 138732/2011-6]CNP

Portunid crabs are an important resource in estuaries, and require appropriate management to guarantee their long-term availability. We investigated the population dynamics and reproduction of Callinectes danae in the Estuarine–Bay Complex of São Vicente, São Paulo, Brazil, to provide basic biological information for public policies for the management of this fishery. Monthly samples were obtained from March 2007 to February 2008 on eight transects, four in the estuary and four in the bay. A total of 2261 specimens (403 males, 1288 females, of which 570 were ovigerous) were collected. Males were significantly larger than females, and the size–frequency distribution was unimodal for males, females and ovigerous females. The sex ratio was nearly always skewed toward females (M:F - 1:4.6). C. danae showed seasonal-continuous reproduction, with high reproductive activity in the warmer season. C. danae breeds in the estuarine–bay complex, with males and juvenile females concentrated in the estuary. After copulation, fertilized females migrate to the estuary entrance and the bay, where ovigerous females are commonly found spawning in high-salinity areas. Therefore, to manage this important economic resource, both the estuary and the bay should be considered for protection, but special attention should be given to the estuary entrance during the summer months, when ovigerous females concentrate.

For many species the population structure varies along latitudinal gradients, especially at the extremes of their distributions. This may apply to invasive species, whose ability to grow, reproduce, feed and compete is hypothesized to be lower at higher latitudes. A population of Charybdis hellerii was investigated on a rocky shore at Armação do Itapocoroy (Santa Catarina, 26°40′–26°47′S and 48°36′–48°38′W), Brazil. The study was carried out over two periods to test the hypotheses that: (1) this population differs from other populations that presumably became established earlier and at lower latitudes; (2) the population parameters change over time (number and size of individuals and ovigerous females), progressively showing more indications of establishment; and (3) the diet overlaps with the native crabs. In total, 642 individuals were caught: 544 males, 55 females, and 43 ovigerous females. This population of C. hellerii is similar to others presumably established earlier and at lower latitudes on the Atlantic coast, with a predominance of larger males and a male-biased sex ratio. The population is reproducing, but the similarity in the population size and frequency of ovigerous females between periods may indicate that this population is encountering difficulty in increasing in size. The generalist diet was composed mainly of crustaceans, molluscs and algae, thus overlapping with other native crab species. Although the direct and indirect impacts of this invasive species were not assessed, the population parameters indicate that this population of C. hellerii is established and may act as a centre of dispersal to higher latitudes.