Bertini G.,Sao Paulo State University |
Bertini G.,Ecology and Culture Study Group |
Baeza J.A.,Clemson University |
Baeza J.A.,Catolica del Norte University
Invertebrate Reproduction and Development | Year: 2014
The neotropical amphidromous shrimp Macrobrachium acanthurus is one of various freshwater crustaceans heavily exploited in the southwestern Atlantic. Fecundity (no early embryos female-1) was examined during 2007 at four different localities (Iguape, Registro, Sete Barras, and Eldorado) along a stretch of river extending over 85 km (Ribeira de Iguape, São Paulo State, Brazil). Also, fertility (no hatched larvae female-1) was examined at one locality (Registro) during 2009-2010. Fecundity (mean ± SD: 5191 ± 2635; range: 1086-13,014 embryos female-1) did not vary throughout the segment of river studied. Fecundity increased with female body size (carapace length, CL). However, fecundity scaled negatively with shrimp body size; females produce disproportionably fewer eggs with a unit increase in CL. The conditions explaining the negative allometric relationship between fecundity and female body size in M. acanthurus remain to be addressed. Nevertheless, natural food constraints limiting the ability of large but not small females to acquire enough resources to produce and fill their gonads with oocytes represents a plausible explanation for the negative scaling of fecundity with body size. Fertility varied between 545 and 12,465 hatched larvae female-1 with an average (±SD) of 3981 (± 2693) and increased isometrically with a unit increase in female body size. M. acanthurus has an average fecundity and fertility that represents one of the extremes regarding the trade-off between fecundity/fertility and egg-size reported for caridean shrimps. All of this information needs to be considered in assessing shrimp stocks and establishing a sustainable management plan for this exploited species in the southwestern Atlantic. © 2014 Taylor & Francis.
Almeida A.C.,Ecology and Culture Study Group |
Almeida A.C.,Federal University of Uberlandia |
Hiyodo C.M.,Ecology and Culture Study Group |
Cobo V.J.,Ecology and Culture Study Group |
And 7 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2013
The relative growths of Persephona lichtensteinii, P. mediterranea, and P. punctata were investigated on the south-eastern Brazilian coast, focusing on differences in the growth rates between immature and mature phases, the onset of morphological sexual maturity, and the breeding seasons of these species. Crabs were collected every two months from January 1991 through to November 1992, from a shrimp fishing boat equipped with two otter-trawl nets. Significant differences in the patterns of body growth were observed between immature and mature phases of all three species. Changes in the growth rates of the chelipeds (males) and abdomen (females) observed for P. lichtensteinii, P. mediterranea, and P. punctata, seem to be related to the puberty moult for both sexes. Males of P. mediterranea and P. punctata reached larger mean sizes of carapace width than females, whereas no difference was recorded for P. lichtensteinii. The body size at which 50% of males attained sexual maturity was also larger in P. mediterranea and P. punctata, and smaller in P. lichtensteinii. The absence of a pronounced sexual dimorphism and the size at the onset of sexual maturity observed only for P. lichtensteinii might be explained by distinct reproductive strategies of males. The presence of ovigerous females during the entire sampling period suggests that all three species have a continuous reproduction pattern at the Ubatuba region. Future studies on the population structure, functional maturity, and mating system should improve the understanding of factors driving the biology and ecology of these species at a subtropical region. © Marine Biological Association of the United Kingdom 2013.
de Andrade L.S.,Ecology and Culture Study Group |
de Andrade L.S.,Sao Paulo State University |
Frameschi I.F.,Ecology and Culture Study Group |
Frameschi I.F.,Sao Paulo State University |
And 6 more authors.
Marine Ecology | Year: 2015
This study evaluated the effect of environmental stimuli and selective pressures in different geographical areas along a latitudinal gradient, on the juvenile recruitment, population structure, and sex ratio of the speckled swimming crab Arenaeus cribrarius. Samples were collected monthly during 1 year in three locations along the Brazilian coast: Macaé, state of Rio de Janeiro (MAC, 22°47′ S, 41°45′ W); Ubatuba, São Paulo (UBA, 23°27′ S, 44°58′ W); and São Francisco do Sul, Santa Catarina (SFS, 26°08′ S, 48°34′ W). The specimens of A. cribrarius were identified, counted, sexed, and measured for maximum carapace width (CW). The largest juvenile found was in UBA (47.7 ± 1.36 mm); and the largest adult females and males in MAC (74.26 ± 0.93 and 77.04 ± 0.79 mm, respectively). Recruitment in MAC was continuous, whereas in UBA and SFS, recruitment showed seasonal characteristics. The sex ratio was skewed toward females only in UBA; in MAC and SFS, males and females were present in equal proportions. These results indicate that geographical variations can cause differences in the recruitment and population structure of A. cribrarius. These regional differences call attention to the necessity for improved management plans and control of shrimp fishing, which can affect population patterns such as juvenile recruitment, population structure and life history of the target species and species that are caught in bycatch from shrimping, such as the swimming crab A. cribrarius. © 2015 Blackwell Verlag GmbH.