Comparison of the population structure of the fiddler crab Uca vocator (Herbst, 1804) from three subtropical mangrove forests

The population structure of U. vocator was investigated during a one-year period in three mangrove forests in southeast Brazil. The study specifically addressed comparisons on individual size juvenile recruitment and sex-ratio. The structure of the mangrove forests, i.e. density, basal area, and diameter, and the physical properties of sediments. i.e. texture and organic matter contents, were also examined. A catch-per-unit-effort (CPUE) technique was used to sample the crab populations using 15-min sampling periods by two people. Males always outnumbered females, probably due to ecological and behavioural attributes of these crabs. The median size of fiddler crabs differed among the sampled populations. The mangroves at Indaiá and Itamambuca showed higher productivity than those at Itapanhaú, where oil spills impacting the shore were reported. Marked differences were found regarding individual size, either their size at the onset of sexual maturity or their asymptotic size, suggesting that food availability may be favouring growth in the studied populations.

Population structure of the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) (Crustacea: Penaeoidea) in the littoral of São Paulo, Brazil

The population structure of the penaeidean shrimp Xyphopenacus kroyeri was studied in Ubatuba Bay, Ubatuba, Sd̃ao Paulo, Brazil. The period and site of juvenile recruitment were monitored using a monthly sampling design with eight fixed areas (transects) from September 1995 to August 1996. The population structure was assessed using size frequency distributions (based on carapace length) for each month and sampling area. Females were significantly larger than males, suggesting a differential growth between sexes. The very low occurrence of large adults in the Bay can be related to offshore migration for reproduction. Recruitment occurred throughout the year, with a peak during the summer, when the highest recruitment rates were obtained along inshore transects. The present investigation revealed valuable information on the biology of the species mainly in the study region, which is considered a nursery ground for juveniles of X. kroyeri. The species showed an important variation from the typical life cycle that it is assumed to hold over its entire range and X. kroyeri should be classified as having a life cycle different from that proposed previously in the literature, i.e. the juveniles prefer inshore areas instead of estuaries. Some suggestions for the seabob fishery management are proposed as an alternative for minimising the impact during the harvest period and adjusting the protection schedule.

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.

Utilization of shells of the snail Achatina fúlica Bowdich, 1822 (Mollusca, Gastropoda) by the hermit crab Clibanarius vittatus (Bosc, 1802) (Decapoda, Anomura) in the São Vicente Estuary, São Paulo, Brazil

Hermit crabs depend on mollusc shells for housing. In this study, an unusual resource is reported for a hermit crab that usually inhabits marine gastropod shells. During a field study conducted from May 2001 to April 2003 in an estuarine area in São Vicente, state of São Paulo, Brazil, 21 individuals of Clibanarius vittatus (Bosc, 1802) were found inhabiting the shells of the terrestrial gastropod Achatina fullea Bowdich, 1822. A. fúlica occurs in nearshore grass patches, where occasional contact with sea water kills them, and their shells then become available to the hermit crabs.

Relative growth of the mangrove crab Ucides cordatus (Linnaeus, 1763) (Crustacea, Brachyura, Ocypodidae) at Iguape, São Paulo, Brazil

A total of 2,130 individuals of Ucides cordatus (1,255 males and 875 females) were captured in a mangrove forest at Iguape, São Paulo, Brazil. For each crab, the following body structures were measured: carapace (width = CW; length = CL; depth = CD), 5th abdominal somite (AW), major chelar propodus (length = PL; width = PW; depth = PD), and 1st and 2 nd gonopod pairs (length = GL1 and GL2). The Student t and Snedecor F tests were used to verify any changes in growth allometric rates during ontogeny. The relationships CLxCW, PLxCW (for both sexes), GL1xCW and GL2xCW (males) and AWxCW (females), showed a better fit by two equations for the juvenile and adult phases (p<0.01). The inflexion point size between regression lines, indicated by each morphometric relationship, allowed to propose four morphotypes for U. cordatus. Males were classified in juvenile (CW le; 32 mm), pre-puberty (32 ≤ CW ≤ 51 mm), sub-adult (51 ≤ CW ≤ 59 mm) and adult (CW > 59 mm). Females showed a similar size interval: (juvenile CW ≤ 39 mm, pre-puberty 39 ≤ CW ≤ 53 mm, sub-adult 53 ≤ CW ≤ 58 mm, adult CW > 58 mm).

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.

Escape of the fiddler crab Uca rapax (Smith, 1870) (Crustacea: Ocypodidae) in the state of Minas Gerais, Brazil

A escape of the fiddler crab Uca rapax (Smith, 1870), in the state of Minas Gerais is reported for the first time. This record was made more than 200 km away from its original habitat, a mangrove area in the state of Rio de Janeiro. The species has been introduced in ponds in the study area, located in the largest ornamental pisciculture/aquaculture center of Brazil. Male individuals of U. rapax were observed engaged in territorial and courtship displays around their burrows. Despite this, there is no well-established population of the species in the area, due to the physiological dependence of the larvae on brackish water. © 2007 Instituto de Ciências Biológicas - UFMG.

Changes in blood parameters of hybrid tambacu fish parasitized by Dolops carvalhoi (Crustacea, Branchiura), a fish louse

Measurement of blood parameters has been used for many years as a tool for monitoring the health offish. The present study investigated the effects of a natural infestation of Dolops carvalhoi Lemos de Castro, 1949, on red blood cells, thrombocytes and white blood cell counts, as well as plasma glucose and serum electrolyte levels in hybrid tambacu (Piaractus mesopotamicus × Colossoma macropomum). Parasitized fish showed low haematocrit and magnesium levels and increases in MCHC, plasma glucose levels, serum protein, sodium and chloride levels, number of monocytes and PAS-positive granular leukocytes (PAS-GL), when compared with values in control fish. This study is the first to report changes in fish physiology caused by D. carvalhoi infestation, and the results obtained indicate that a mild infection can lead to important osmoregulatory disturbances in hosts.

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.

Gonad development in females of fiddler crab Uca rapax (Crustacea, Brachyura, Ocypodidae) using macro and microscopic techniques

The morphology of the ovaries in Uca rapax (Smith, 1870) was described based on macroscopic and microscopic analysis. Females were collected in Itamambuca mangrove, Ubatuba, state of São Paulo, Brazil. In the laboratory, 18 females had their ovaries removed and prepared for histology. Each gonad developmental stage was previously determined based on external and macroscopic morphology and afterwards each stage was microscopically described. The ovaries of U. rapax showed a pronounced macroscopic differentiation in size and coloration with the maturation of the gonad, with six ovarian developmental stages: immature, rudimentary, developing, developed, advanced and spent. During the vitellogenesis, the amount of oocytes in secondary stage increases in the ovary, resulting in a change in coloration of the gonad. Oogonias, primary oocytes, secondary oocytes and follicular cells were histologically described and measured. In female's ovaries of U. rapax the modifications observed in the oocytes during the process of gonad maturation are similar to descriptions of gonads of other females of brachyuran crustaceans. The similarities are specially found in the morphological changes in the reproductive cells, and also in the presence and arrange of follicle cells during the process of ovary maturation. When external morphological characteristics of the gonads were compared to histological descriptions, it was possible to observe modifications that characterize the process in different developmental stages throughout the ovarian cycle and, consequently, the macroscopic classification of gonad stages agree with the modifications of the reproductive cells.

Distribuição de cladóceros planctônicos (Crustacea: Branchiopoda) em um reservatório eutrófico raso (Paraná, Brasil)

This study focused the spatial and temporal distribution of the composition, abundance, and diversity of planktonic cladocerans from eutrophic, Iraí Reservoir, as well as their relationships with some biotic and abiotic variables. The tested hypothesis was that cladocerans present higher variation in a temporal than in a spatial scale. The samples were taken monthly in 6 stations, from March/02 to July/03. Twenty-four taxa were identified, distributed in 7 families, the richest families being Daphniidae (6 spp.), Chydoridae (6 spp.), and Bosminidae (5 spp.). The most frequent and abundant species were Bosmina hagmanni, Moina minuta, and Ceriodaphnia cornuta. The highest abundances were found in September/2002. Temporally, rainfall influenced organism's distribution, while spatially cladocerans were more affected by reservoir hydrodynamics and wind action. The low species richness could be a reflection of the trophic state of the reservoir, in which a dominance of Cyanobacteria was observed during that study period. Both scales showed high variation, but only the temporal scale showed significant difference to richness and abundance. Nearby the end of this study, higher stable values of species richness were recorded, which could suggest an increase in the water quality due to des-pollutions actions.

Multi-dimensional effects on Cladoceran (Crustacea, Anomopoda) assemblages in two cascade reservoirs in Southeast Brazil

The Cladocera assemblages in two cascade reservoirs located in the Paranapanema River in Brazil were studied during two consecutive years. Upstream Chavantes Reservoir is an accumulation system, with a long water retention time, high depth and oligo-mesotrophic status. The downstream Salto Grande Reservoir is a small, run-of-river reservoir, with a short water retention time, shallow depth and meso-eutrophic status. The goal of this study was to determine the inter- and intra-reservoir limnological differences with emphasis on the Cladocerans assemblages. The following questions were posed: (i) what are the seasonal dynamics of the reservoir spatial structures; (ii) how dynamics, seasonally, is the reservoirs spatial structure; and (iii) are the reservoir independent systems? A total of 43 Cladoceran species were identified in this study. Ceriodaphnia silvestrii was the most abundant and frequent species found in Chavantes Reservoir, while C. cornuta was most abundant and frequent in Salto Grande Reservoir. The Cladoceran species richness differed significantly among sampling sites for both reservoirs. In terms of abundance, there was a significant variation among sampling sites and periods for both reservoirs. A cluster analysis indicated a higher similarity among the deeper compartments, and the intermediate river-reservoir zones was grouped with the riverine sampling sites. For the smaller Salto Grande Reservoir, the entrance of a middle size tributary causes major changes in the system. A distinct environment was observed in the river mouth zone of another small tributary, representing a shallow environment with aquatic macrophyte stands. A canonical correlation analysis between environmental variables and Cladoceran abundance explained 75% of the data variability, and a complementary factorial analysis explained 65% of the variability. The spatial compartmentalization of the reservoirs, as well as the particular characteristics of the two study reservoirs, directly influenced the structure of the Cladoceran assemblages. The conditions of the lacustrine (dam) zone of the larger Chavantes Reservoir were reflected in the upstream zone of the smaller downstream Salto Grande Reservoir, highlighting the importance of plankton exportation in reservoir cascade systems. The comparative spatial-temporal analysis indicated conspicuous differences between the two reservoirs, reinforcing the necessity of considering tropical/subtropical reservoirs as complex, multi-compartmental water systems. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Asia Pty Ltd.

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.

Food selection by a mangrove crab: Temporal changes in fasted animals

The feeding choices of the mangrove crab Ucides cordatus for various mangrove plant leaves (Avicennia schaueriana, Laguncularia racemosa, and Rhizophora mangle) at different ages (mature, senescent pre-abscission, and decomposing leaves) were examined. In a controlled experiment set in a mangrove area, we evaluated crab selection for different plant leaves by analyzing foraging rate (number of leaves with predation marks) and leaf consumption. Crabs were housed individually in plastic containers and after a 3-day fast supplied with leaf fragments every 24 h for 72 h. Uneaten leaves were removed before each new food offering. No food selection was observed in the first day, but after this period, senescent leaves, which have a high polyphenol content, were rejected. On the third day, an interactive effect between plant species and leaf age was shown to affect leaf selection, with mature leaves of A. schaueriana and L. racemosa being more selected than the other treatments. This observation was consistent across crab sexes and ages. Our results show that food selection by this mangrove crab changes through time in fasted animals, suggesting that this variable must be controlled in food preference studies. © 2012 Springer Science+Business Media B.V.

Tafonomia dos Pygocephalomorpha (Crustacea, Peracarida, Malacostraca), Permiano, Bacia do Paraná, Brasil, e seu significado paleoambiental

Taphonomy of the pygocephalomorpha (Crustacea, Peracarida, Malacostraca), Permian, Paraná Basin, Brazil, and its paleoenvironmental meaning. Crustaceans (Pygocephalomorpha, Peracarida) are the main fossil invertebrates recorded in the Early Permian Assistência Formation, Irati Subgroup, State of São Paulo, Paraná Basin. For this study, samples taken from the base of the Ipeúna Member, Bairrinho Bed, State of São Paulo, were analyzed and complemented by fossils from the Irati Formation, State of Rio Grande do Sul. The taphonomic spectrum of the pygocephalomorphs includes three main preservational modes: Type 1. Complete pygocephalomorphs (with outstretched or flexed abdomen), which are associated to cream-colored mudstones and more commonly to black shales. In rare cases, molds of soft parts are preserved. They suffered rapid burial (hours to days) by mud blankets associated to storm events in anoxic bottoms, below storm wave base with minimum bottom disruption, followed by low rates of background sedimentation; Type 2. Partly articulated (carapace and abdomen, with or without caudal fan and without appendages) pygocephalomorphs, with extended or flexed abdomen, which are present in cream-colored pelites, associated with hummocky cross-stratifications, intercalated with black shales. These may represent individuals or remains lying in the sediment-water interface preserved by rapid burial associated to episodic sedimentation events; Type 3. Disarticulated pygocephalomorphs, with isolated carapaces, abdomen, or abdominal segments. This is the predominant preservational mode in our samples. The skeletal remains can be found isolated or in dense, bioclast-supported concentrations (micro-coquines), representing proximal to distal tempestites. Finally, the extreme preservational quality seen in crustaceans of the Type 1 recorded in black shales, occasionally with molds of soft parts, indicates that the host rocks may represent Konservat-Lagerstätten deposits, as already suggested to coeval occurrences of the Irati Formation in Uruguay. © 2013 by the Sociedade Brasileira de Paleontologia.