Maternal investment in egg production: environmental and population-specific effects on offspring performance in the snapping shrimp Alpheus nuttingi (Schmitt, 1924) (Decapoda, Alpheidae)

Among marine invertebrates, the overall biomass invested in egg production varies widely within populations, which can result from the interaction of endogenous and exogenous factors. Species that have constant reproduction throughout the year can be good models to study the influence of environmental factors on reproductive processes. We conducted a seasonal comparison of egg production in the intertidal snapping shrimp Alpheus nuttingi, which shows a continuous reproductive pattern, to examine the hypothesis that differences in egg production are driven by environmental conditions and population features. This population showed an uncommon strategy, characterized by females that produce eggs of varying sizes within their clutches, with reduced egg volume when the number of eggs is higher (Spring-Summer). In these seasons, higher temperatures and greater food availability may allow the production of more eggs compared to the Autumn-Winter seasons. Compared to other alpheid shrimps, this population produces small eggs, but in larger numbers. Despite the higher fecundity, the reproductive output is relatively low, this production being supported by the large size of females from the southern Atlantic region. Our findings showed that the egg production of A. nuttingi was greatly influenced by environmental factors. Therefore, this shrimp, and probably other decapods that possess continuous reproduction, adopt different reproductive strategies during the year. (C) Koninklijke Brill NV, Leiden, 2010.PIBIC/CNPqCAPES[563934/2005-0]CNPq[PQ 301261/04-0]CNPq[301359/07-5]Universidade de São Paulo - FFCLRP/USPUniversidade de São Paulo - Centro de Biologia Marinha (CEBIMar/USP

Populational and reproductive aspects of Southern Macrobrachium acanthurus (Wiegmann, 1836) (Crustacea: Palaemonidae), Brazil

Macrobrachium acanthurus has a wide geographic distribution in America, mainly in rivers that flow into the Atlantic Ocean. Considering the economic interest in the Brazilian freshwater shrimp culture and its potential as a living resource, this study addresses the population and reproductive information of M. acanthurus that inhabit the north coast of São Paulo State. Individuals (N: 466,164 males and 302 females, with size ranging from 3.96 to 35.14 mm of carapace length) were captured with sieves (two people during 30 minutes) and traps (four hours after the nightfall) in April and October/2008 and in March/2009. Females were predominant in all sampled months; their ovaries showed changes in color and their size increased according to the developmental stage. The presence and percentage of ovigerous females in all sampled months indicated the possibility that the reproductive activity was continuous. The average fecundity (2299 ± 1653 eggs) found was directly related to the female’s size. The ovarian development occurred concomitantly with the eggs’ development, indicating successive spawning. It was observed that the eggs changed color and increased their volume independently of the female size. The absence of embryo loss during the incubation process may be speculated to be an efficient strategy developed by the ovigerous females, as a mechanism of parental care against the most common causes of egg loss

Reproductive strategy of the snapping shrimp Alpheus armillatus H. Milne-Edwards, 1837 in the South Atlantic: fecundity, egg features, and reproductive output

The family Alpheidae, composed by shrimps of relatively small size, popularly known as snapping shrimps, is the one of the most diverse decapod groups. These shrimps are found worldwide and Occur in tropical and subtropical waters, from the intertidal zone to great depths. We investigated reproductive aspects of Alpheus armillatus, in order to gather information on egg production, aiming to enhance knowledge of its reproductive strategies in a population in an intertidal area of the South Atlantic. Ovigerous females were collected under rocks, in May and July 2006 (dry season) and in November 2006 and March 2007 (rainy season). Egg production and reproductive output were analyzed and compared seasonally and during the period of embryonic development. Females measured on average 11.28 mm CL with a mean of 763 eggs and 0.11 mm(3) egg volume. The egg volume of this population was smaller than previous estimates for other species of snapping shrimps, but the mean egg number was higher. The volume of eggs doubled during the incubation period, but despite this increase, no significant loss of eggs was observed. Alpheus armillatus invests oil average about 12% of body weight in reproduction. The proportional investment in egg production IS Significantly higher in the rainy season when compared with the dry season (17.9% vs 4.8%), correlated with higher temperatures and increased food availability at this time. Our results corroborated the hypothesis of a pattern of egg production influenced by environmental conditions and intraspecific variability among the family Alpheidae, as a function of the biogeographic region.PIBIC/CNPqCAPES[563934/2005-0]CNPq[PQ 301261/04-0]CNPq[301359/07-5]Universidade de São Paulo - FFCLRP/USPUniversidade de São Paulo - Centro de Biologia Marinha (CEBIMar/USP

Reproductive aspects of the caridean shrimp Atya scabra (Leach, 1815) (Decapoda: Atyidae) in S\ue3o Sebasti\ue3o Island, southwestern Atlantic, Brazil

The caridean freshwater shrimp Atya scabra is a common resident of stream systems of tropical rainforests in America, including Brazilian drainages. This shrimp has an amphidromous life cycle, which increases its vulnerability when facing habitat fragmentation. Since information on the reproduction of this species is still limited, we present here data on egg production, egg loss, and energy investment, to achieve a better understanding of reproductive features of A. scabra. Specimens were collected between 2006 and 2007 in São Sebastião Island, southeastern Brazil, in 13 locations. The fecundity of 21 ovigerous females analyzed ranged between 414 and 19,250 eggs, which were higher than previously reported. However, the larger size of females analyzed may explain the observed intraspecific difference in egg production. During embryogenesis, egg volume and water content increased by 103 and 22.6%, respectively. The initial egg volume of A. scabra in the present study (0.027 mm³) was slightly lower, but comparable to the values reported previously from the same study area. During incubation, females of A. scabra lost 15% of their initially produced eggs. The reproductive output (average RO of 3.6%) is the first report for any atyid species. Its value is fairly low compared to other freshwater shrimps, and it is hypothesized that this might be related to a high energy investment in morphological adaptations, which allows the shrimp to cling on to the substrate in the fast flowing environment they inhabit. Additionally, the long life span, a well-known phenomenon in atyid shrimp, may allow the species to invest a relatively low amount of energy per brood in egg production, but over a longer time span

Exotic species of freshwater decapod crustaceans in the state of São Paulo, Brazil: Records and possible causes of their introduction

Based on recent surveys of the freshwater decapod fauna, distributional data of five exotic species of freshwater decapod crustaceans for the hydrographic basins of the state of São Paulo are presented, as part of a large initiative for a comprehensive survey of the state's biodiversity (BIOTA-FAPESP Program). These species are the North American crayfish Procambarus clarkii (Girard) (Cambaridae), the crab Dilocarcinus pagei Stimpson (Trichodactylidae) from the Amazon and Paraguay/lower Paraná River Basins, and the palaemonid shrimps Macrobrachium rosenbergii (De Man), from the Indo-Pacific region, Macrobrachium amazonicum (Heller) and Macrobrachium jelskii (Miers), both from the Orinoco, Amazon and the Paraguay/lower Paraná River Basins. Possible modes by which their introduction might have occurred are commented upon and potential consequences are discussed. © Springer 2005