Influence of temperature on larval survival, development and respiration in Chasmagnathus granulata (Crustacea, Decapoda)

Larvae of an estuarine grapsid crab Chasmagnathus granulata Dana 1851, from temperate and subtropical regions of South America, were reared in seawater (32 ‰) at five different constant temperatures (12, 15, 18, 21, 24 °C). Complete larval development from hatching (Zoea I) to metamorphosis (Crab I) occurred in a range from 15 to 24 °C. Highest survival (60% to the first juvenile stage) was observed at 18°C, while all larvae reared at 12°C died before metamorphosis. The duration of development (D) decreased with increasing temperature (T). This relationship is described for all larval stages as a power function (linear regressions after logarithmic transformation of both D and T). The temperature-dependence of the instantaneous developmental rate (D-1) is compared among larval stages and temperatures using the Q10 coefficient (van't Hoff's equation). Through all four zoeal stages, this index tends to increase during development and to decrease with increasing T (comparing ranges 12-18, 15-21, 18-24 °C). In the Megalopa, low Q10 values were found in the range from 15 to 24 °C. In another series of experiments, larvae were reared at constant 18°C and their dry weight (W) and respiratory response to changes in T were measured in all successive stages during the intermoult period (stage C) of the moulting cycle. Both individual and weight-specific respiration (R, QO2) increased exponentially with increasing T. At each temperature, R increased significantly during growth and development through successive larval stages. No significantly different QO2 values were found in the first three zoeal stages, while a significant decrease with increasing W occurred in the Zoea IV and Megalopa. As in the temperature-dependence of D, the respiratory response to changes in temperature (Q10) depends on both the temperature range and the developmental stage, however, with different patterns. In the zoeal stages, the respiratory Q10 was minimum (1.7-2.2) at low temperatures (12-18 °C), but maximum (2.2-3.0) at 18-24 °C. The Megalopa, in contrast, showed a stronger metabolic response in the lower than in the upper temperature range (Q10 = 2.8 and 1.7, respectively). We interpret this pattern as an adaptation to a sequence of temperature conditions that should typically be encountered by C. granulata larvae during their ontogenetic migrations: hatching in and subsequent export from shallow estuarine lagoons, zoeal development in coastal marine waters, which are on average cooler, return in the Megalopa stage to warm lagoons. We thus propose that high metabolic sensitivity to changes in temperature may serve as a signal stimulating larval migration, so that the zoeae should tend to leave warm estuaries and lagoons, whereas the Megalopa should avoid remaining in the cooler marine waters and initiate its migration towards shallow coastal lagoons.

Reproductive patterns of Aratus pisonii (Decapoda: Grapsidae) from an estuarine area of São Paulo Northern Coast, Brazil

This paper describes the frequency of occurrence and reproductive patterns of the tree mangrove crab Aratus pisonii. Monthly samples were taken from January 1993 to June 1994 in an estuarine mangrove from Ubatuba region, Brazil. A total of 1 078 animals, 489 males and 589 females (131 ovigerous females) were collected. Carapace width ranged from 4.2 to 25.9 mm. A summer reproductive peak followed by a recruitment juvenile pulse was verified. Females were more abundant than males in the intermediate size classes. The sex-ratio in several months was biased towards females, suggesting a poligynous population and migration of females to mangrove fringes at the time of incubation and spawning.

Comparação do peso dos quelípodos e crescimento em duas espécies de sirís do gênero Callinectes (Brachyura, Portunidae)

A comparison of the cheliped's weight in two species of the genus Callinectes was accomplished. The species C. danae e C. ornatus were collected by two otter trawl in Ubatuba bay (23°26' S and 45°02' W). The allometric constants obtained from the regression adjusted to a power function (Y = aXb) were analyzed. These species presented different allometry degrees for each sex considered. The relation PQ x PC presented positive allometry for sex of both species, but male presented higher positive allometry than female. C. danae presented higher positive allometry for chelipeds than C. ornatus. We suggest here that C. danae could be indicated to be submitted to grow out in ponds since it reaches higher size and bigger chelipeds. © 1998, Paraná Institute of Technology Publication.

Population biology of Callinectes ornatus Ordway, 1863 (Decapoda, Portunidae) from Ubatuba (SP), Brazil

Population structure and reproductive season of the portunid crab Callinectes ornatus were studied in animals collected from the Ubatuba bays, Sao Paulo, Brazil (23°20' to 23°35' S and 44°50' to 45°14' W). The samples were taken in three trawls performed every other month from January 1991 to May 1993. A total of 3,829 specimens of C. ornatus were obtained. Their size ranged from 9.3 to 84.6 mm (carapace width). Their median size based on their cephalothoracic width and their size frequency were determined as well. Their reproduction was continuous, with variable proportions of ovigerous females. The highest incidence of ovigerous females occurred in January 1991, 1992 and 1993 and March and November 1992. The oscillations of the environmental factors between the seasons are not so intense in subtropical regions, therefore allowing the continuity of the physiological process of growth and reproduction throughout the year.

Larval development of Epialtus bituperculatus H. Milne Edwards, 1834 (Crustacea: Decapoda: Brachyura: Majidae) with comments on majid larvae from the southwestern Atlantic

The larval development of the spider crab Epialtus bituberculatus H. Milne Edwards which lives on rocky shores with algae such as Sargassum and Hypeneia, is described. Larvae were obtained from ovigerous females collected in Ubatuba, State of São Paulo, Brazil. Rearing was carried out at 24 ± 1°C, with an average salinity of 35%. Larval development consists of two zoeal stages and one megalopa. Zoeal development was completed in 9.5 days. Analysis indicated that zoeae of E. bituberculatus are very similar to those of E. brasiliensis Dana and Acanthonyx scutiformis (Dana). Differences noted between these species pertain to the setation of the carapace, maxillule and second maxilliped. The main morphological features useful for identification are presented together with a summary of features that characterize larvae of majid subfamilies in Brazil. A key for the identification of southwestern Atlantic majid zoeae to the family level is provided.

Feeding activity of Callinectes ornatus Ordway, 1863 and Callinectes danae Smith, 1869 (Crustacea, Brachyura, Portunidae) in Ubatuba, SP, Brazil

The feeding activity along the day cycle and the time consumed for extracellular digestion were evaluated in the portunids C. ornatus and C. danae. Swimming crabs were obtained from trawling in Ubatuba bay, São Paulo, Brazil, during both the rainy and dry seasons. In each season, daily scheduled samples were taken at dawn (±6 h), noon (±12 h), dusk (±18 h) and midnight (±24 h). All individuals were dissected and the degree of stomach replenishment was recorded. In order to estimate the time elapsed for extracellular digestion, crabs were fed, and groups were dissected at 30 min intervals to check the conditions of their stomachs. In general, both species show a higher feeding activity during periods of lower light intensity, as evidenced by an increased percentage of full stomachs in dusk and midnight samples. The obtained results support higher feeding activity at night in these species and indicate short time for extracellular digestion, not exceeding 8 h. Nevertheless, full stomachs were recorded in all sampling schedules. In this case, it should be considered that elimination of certain food items such as fish bones, mollusk shells and carapace fragments of crustaceans could take more time than other items. Additionally, some crab species could require a cycle of cell replacement in the midgut gland epithelium until they can take their next meal.

Vertical migration during tidal transport of megalopae of Necora puber in coastal shallow waters during daytime

For meroplanktonic larvae that must settle in coastal areas, their successful return to the shore is determined largely by physical transport processes; however, many organisms perform vertical movements to aid successful recruitment. In this study, daytime tidal vertical migration of megalopae of the velvet swimming crab Necora puber was investigated across two different exposures in the shallow waters of Plymouth Sound. Crabs were collected using a plankton net at the surface and near the bottom during flood and ebb tides. Distribution of the pelagic postlarvae was patchy and the abundance varied spatially in tens and thousands of metres. In temporal scales, the annual pattern was dominated by low occurrence of megalopae, punctuated by episodic peaks of high abundance. Most megalopae were collected at the surface irrespective of the tidal phase. The effect of wave exposure on the vertical migration of megalopae was not clear, although there was a general higher abundance of megalopae on exposed shores. Daytime abundance in the water column appears to be regulated by the tidal cycle, as megalopae were more abundant during flood than ebb tides. Although the megalopae do not appear to make large vertical migrations, this behaviour should produce a net shoreward transport. © 2005 Elsevier Ltd. All rights reserved.

Meat yield of Callinectes bocourti A. Milne Edwards, 1879 (Crustacea, Portunidae) in Iguape, São Paulo, Brazil

The objective of the present study was to analyze the meat yield for both sexes of the crab Callinectes bocourti in the region of Iguape, Brazil. The carapace width for males was 78.1-114.0 mm (96.7 ± 9.5 mm) and for females 76.0-106.3 mm (93.0 ± 7.8 mm). In males, the total wet weight ranged from 65.53 to 224.36 g (134.04 ± 40.77 g) and for females from 56.66 to 164.74 g (105.93 ± 26.88 g). A comparison of morphological structures revealed that the greatest meat yield was in the carapace (55.1%), followed by the right chela (16.9%), the left chela (15.9%), and the legs (12.1%). The total yield from the males (28.5%) was slightly higher than that from the females (22.1%). In general, portunids yield more meat than other crab species. The results of this study will allow the optimization of meat production for this crab species. Manual meat removal makes the process more expensive. This activity could offer an alternative to the fishing communities that live exclusively from this fishery resource. © 2007 Escuela de Ciencias del Mar Pontificia Universidad Católica de Valparaíso.

O impacto da pesca do camarão-rosa Farfantepenaeus paulensis (Perez-Farfante) (Decapoda, Penaeidae) nas assembléias de peixes e siris do Parque Nacional da Lagoa do Peixe, Rio Grande do Sul, Brasil

This work evaluates the impact of the pink shrimp Farfantepenaeus paulensis (Perez-Farfante, 1967) fishery on fish and crab assemblages of Lagoa do Peixe National Park, Brazil. We observed that composition of catches is similar to shrimp fisheries using fyke-net at others estuaries of Rio Grande do Sul State: pink shrimp (53%), accessory catches (24%) and bycatch (23%). However, fishery composition showed distinct differences along the saline gradient of the main park's lagoon. Regarding only fish species, the most impacted species in this fishery were Brevoortia pectinata (Jenyns, 1842), Micropogonias furnieri (Desmarest, 1823), and Jenynsia multidentata (Jenyns, 1842). In others estuaries from Rio Grande do Sul, in contrast, the most impacted species were M. furnieri, Genidens barbus (Lacepède, 1803) and Genidens genidens (Cuvier, 1829). The potential impact of the pink shrimp fishery at Lagoa do Peixe National Park seemed to be weaker when compared to shrimp fisheries elsewhere. We believe that the decision to prohibit this fishery at the Lagoa do Peixe National Park should not be based on its potential damage to the fish and crab assemblages but based on the simple fact that Brazilian laws do not allow fisheries inside National Parks.

Spatial distribution and shell utilization in three sympatric hermit crabs at non-consolidated sublittoral of estuarine-bay complex in São Vicente, São Paulo, Brazil

The objective of the present study was to characterize the spatial distribution and shell utilization of three hermit crab species in the estuarine-bay complex of São Vicente, São Paulo State, Brazil. Monthly samples were done throughout two years, in the non-consolidated sub-littoral at the estuarine-bay complex. The environmental factors, such as temperature, salinity and depth, were measured every month. The three hermit crab species, Clibanarius vittatus, Loxopagurus loxochelis and Isocheles sawayai, were captured utilizing shells from six gastropods species; 92.7% of the hermit crabs utilized Stramonita haemastoma. The results suggest a strong correlation between hermit crabs spatial distribution and salinity, which was considered the main environmental factor limiting their distribution in the estuary. I. sawayai was the only species present in all transects sampled; C. vittatus was captured only in regions with low salinity and L. loxochelis occurred only in high salinity waters.

Chromosomes of Crossopriza lyoni (Blackwall 1867), intraindividual numerical chromosome variation in Physocyclus globosus (Taczanowski 1874), and the distribution pattern of NORs (Araneomorphae, Haplogynae, Pholcidae)

Pholcidae (Haplogynae) encompasses 967 described species, of which only 14 have been cytogenetic analyzed. Several chromosomal features have already been described including presence of meta- and sub-metacentric chromosomes and sex determination chromosome system (SDCS) of the X, X1X2Y, and X1X2 types, which contrast with the telo- and acrocentric chromosomes and SDCS of the X1X2 type typical of entelegyne spiders. To obtain further cytogenetic information for the family, we examined two pholcid species, Crossopriza lyoni (Blackwall 1867) and Physocyclus globosus (Taczanowski 1874) using both conventional staining and silver staining techniques. Crossopriza lyoni exhibited 2n = 23 = 22 + X in males and 2n = 24 = 22 + XX in females, while P. globosus showed 2n = 15 = 14 + X and 4n = 30 = 28 + 2X, both in male adults, 2n = 16 = 14 + XX in female adults and embryos, and 2n = 15 = 14 + X in male embryos. Both species revealed predominately metacentric and submetacentric chromosomes and a SDCS of the X/XX type. The cytogenetic data obtained in this work and those already recorded for C. lyoni indicate interpopulational and intraspecific numerical chromosome variation, suggesting the presence of chromosomal races or cytotypes in this species. The intraindividual numerical chromosome variation observed in male adult specimens of P. globosus may be explained by the presence of cytoplasmatic bridges between germ cells. The use of the silver staining technique to reveal the nucleolar organizer region (NOR) showed that chromosome pairs 4 and 6 and the X chromosome in C. lyoni are telomeric NOR-bearers, and that the chromosome pair 2 in P. globosus possesses a proximal NOR in the long arm.

The megalopa stage of Portunus spinimanus Latreille, 1819 and Portunus gibbesii (Stimpson, 1859) (Decapoda, Brachyura, Portunidae) from the southeastern Atlantic coast of the United States

The identification of megalopae from plankton samples is difficult, because this larval stage is the least well known among crab larvae, unknown in some species and poorly described in others. Wild megalopa specimens of some swimming crabs (family Portunidae Rafinesque, 1815) were captured alive from neuston samples obtained during summer surveys near the coast of Charleston, South Carolina (U.S.A). For identification purposes, larvae were reared to the 8th juvenile instar. After reaching the 5th juvenile instar, the juvenile crabs exhibited morphological features suitable for identification to the species level. The specimens belonged to two species of Portunidae, Portunus spinimanus Latreille, 1819 and P. gibbesii (Stimpson, 1859). Their megalopae were described in detail and compared to other portunid megalopae known from the southeastern Atlantic coast of the U.S.A. Species-specific characters of portunid megalopae are the number of carpal spines on the chelipeds, the relative size of the sternal spines (7th sternite), the number of antennal flagellum segments, and the setation of mouthparts. Copyright © 2007 Magnolia Press.

Structure of a novel class II phospholipase D: Catalytic cleft is modified by a disulphide bridge

Phospholipases D (PLDs) are principally responsible for the local and systemic effects of Loxosceles envenomation including dermonecrosis and hemolysis. Despite their clinical relevance in loxoscelism, to date, only the SMase I from Loxosceles laeta, a class I member, has been structurally characterized. The crystal structure of a class II member from Loxosceles intermedia venom has been determined at 1.7. Å resolution. Structural comparison to the class I member showed that the presence of an additional disulphide bridge which links the catalytic loop to the flexible loop significantly changes the volume and shape of the catalytic cleft. An examination of the crystal structures of PLD homologues in the presence of low molecular weight compounds at their active sites suggests the existence of a ligand-dependent rotamer conformation of the highly conserved residue Trp230 (equivalent to Trp192 in the glycerophosphodiester phosphodiesterase from Thermus thermophofilus, PDB code: 1VD6) indicating its role in substrate binding in both enzymes. Sequence and structural analyses suggest that the reduced sphingomyelinase activity observed in some class IIb PLDs is probably due to point mutations which lead to a different substrate preference. © 2011 Elsevier Inc.

Ocorrência de anormalidades morfológicas externas em caranguejos marinhos (Decapoda, Brachyura) no litoral norte do estado de são paulo

Deformities and abnormalities in crustaceans have been associated to genetic problem, which occurred during molt process, damage caused by ectobionts, predators or environmental stress caused by chemical wastes. Some crab specimens collected in the São Paulo littoral were found having body abnormalities. They belong to the following crab species: Callinectes ornatus (Ordway, 1863), Arenaeus cribrarius (Lamarck, 1818) and Leurocyclus tuberculosus (H. Milne Edwards; Lucas, 1843). Samplings were performed by trawling during July 2008, August and October 2009 at the Ubatuba region, São Paulo State, Brazil. Body abnormalities were verified in the cheliped dactyl (C. ornatus an adult male), carapace deformities (A. cribrarius an adult male) and abdominal alterations (C. ornatus an adult female; L. tuberculosus an adult male and an ovigerous female). The record and analysis of such occurrences can help in the distinction of natural or human impact caused alterations. In this way, the occurrence study of this kind of body alterations could provide tools in order to control unprotected environmental areas, as well as bring subsides to understand the unusual variations during the ontogeny of important species in the benthic community.