A survey on diversity and distribution of crabs in inter tidal and sub tidal shore of the Sistan and Baloochestan Province (Oman sea)

This project was done for identifying and survey on distribution and diversity of true crabs in inter tidal and sub tidal zones of the Gulf of Oman (Sistan and Baluchistan province) during two year from 2009 to 2010. Specimens of inter tidal zones were carried out at 10 stations and 8 stations from sub tidal. The specimens were collected by hand and dip-net from inter tidal and by trawl net from sub tidal regions, preserved in 70% alcohol and carried to the laboratory. A total of 37 species belonged to 17 families from inter tidal and 23 species belonged to 9 families from sub tidal were identified. Of which 54 species were identified up to species level. 2 species from Matutidae, 1 species from Eriphiidae, Menippidae, Pseudoziidae, Plagusidae, Varunidae, Camptandriidae, Dromiidae and Dorippidae, 2 species from Oziidae, 3 species from Epialtidae, 2 species from Majidae, 4 species from Pilumnidae, 12 species from Portunidae, 6 species from Xanthidae, 2 species from Grapsidae, 3 species from Dotillidae, 3 species from Macrophthalmidae, 3 species from Ocypodidae, 3 species from Calappidae, 2 species from Parthenopidae and 1 species from Galenidae were identified. All specimens are deposited in the Zoological Museum, University of Tehran (ZUTC). The results of the present study revealed that family Portunidae with 6 species from inter tidal and 9 species from sub tidal regions have the highest species richness among the 22 families. Maximum similarity (Sorenson's Index) was obtained among the stations Breis, Lipar, Pozm and Gordim, and minimum was obtained among the stations Chazire-Kharchang with Pasabandar, Beris, Lipar, Daria-Bozorg, Pozm and Gordim in intertidal regions. In sub tidal regions maximum similarity (Sorenson's Index) was obtained among the stations Pasa bandar with Berisand minimum was obtained among the stations Govatr with Ramin and Gordim, Ramin with Pozm. Also maximum species richness was observed at Tiss in inter tidal and Chabahar in sub tidal stations, whereas minimum was obtained at Beris, Pozm, Gordim and Lipar in inter tidal and Govatr and Pozm in sub tidal stations. Family Ocypodidae in inter tidal and Portunidae in sub tidal regions have the highest distribution. In all of the species length and Breadth of carapace showed significant relation.

Crabbing into an uncertain future: the blue swimming crab fisher in coastal town of Eastern Philippines

This research project sought to find out the socio-economic status of the small-scale fishers of the blue swimming crab (Portunuspelagicus) in Samar, considering the diminishing volume of catch of the species in the recent years. Using a blend of quantitative and qualitative methods, the study employed an interview schedule, focus group discussion (FGD) and observation in collecting data not only from the fishers but also from other sectors directly involved in the blue swimming crab industry.

The importance of novelty: Male–female interactions among blue-black grassquits in captivity

Mate choice is a primary mechanism driving the evolution of sexually selected traits such as elabo-rate displays and ornaments. In a majority of taxa studied to date, females are seen to actively sampleand evaluate multiple males, presumably to optimize mating opportunities. During this process femalesmay encounter males both familiar and novel, a distinction that might influence how mate choice pro-ceeds. Using a socially monogamous passerine, the blue-black grassquit (Volatinia jacarina), we studiedhow females respond to novel versus familiar (“paired”) males, and how encounters with novel malesinfluence subsequent interactions with their paired males. Additionally, we measured the hormonalresponse of males after visualizing their paired females interacting with novel males. We found thatfemales were attentive to novel males irrespective of these males’ phenotypic attributes, suggesting thatin these interactions novelty is highly relevant. After exposure to novel males, females tended to respondaggressively towards their paired males; by contrast, the behaviour of males towards their paired femalesdid not change. Moreover, we did not detect any hormonal responses of males to viewing their pairedfemales interacting with novel males. Together these results suggest that the distinction between famil-iarity and novelty may hold special relevance for females in mate choice, a finding that bears upon ourunderstanding of the evolution of extra-pair paternity and reproductive behaviour.

Spermathecae of the mangrove crab Ucides cordatus: a histological and histochemical view

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 can lit 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 collalgen 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. Tills secretion forms a glycoprotein matrix which is associated with maintenance of the spermatophores, which can remain stored for long periods.

A field study to describe diel, tidal and semilunar rhythms of larval release in an assemblage of tropical rocky shore crabs

Available information on the larval release rhythms of brachyurans is biased to temperate estuarine species and outcomes resulting from some sort of artificial manipulation of ovigerous females. In this study we applied field methods to describe the larval release rhythms of an assemblage of tropical rocky shore crabs. Sampling the broods of ovigerous females of Pachygrapsus transversus at two different shores indicated a spatially consistent semilunar pattern, with larval release maxima around the full and new moon. Yet, synchronism between populations varied considerably, with the pattern obtained at the site exposed to a lower wave action far more apparent. Breeding cohorts at one of the sampled shores apparently belonged to actual age groups composing the ovigerous population. The data suggest that these breeding groups release their larvae in alternate syzygy periods, responding to a lunar cycle instead of the semilunar pattern observed for the whole population. For the description of shorter-term rhythms, temporal series at hour intervals were obtained by sampling the plankton and confinement boxes where ovigerous females were held. Unexpectedly, diurnal release activity prevailed over nocturnal hatching. Yet, only grapsids living higher on the shore exhibited strong preferences over the diel cycle, with P. transversus releasing their larvae during the day and Geograpsus lividus during the night. The pea crab Dissodactylus crinitichelis, the spider crab Epialtus brasiliensis and a suite of xanthoids undertook considerable releasing activity in both periods. Apart from the commensal pea crab D. crinitichelis, all other taxa revealed tide-related rhythms of larval release, with average estimates of the time of maximum hatching always around the time of high tides; usually during the flooding and slack, rather than the ebbing tide. Data obtained for P. transversus females held in confinement boxes indicated that early larval release is mostly due to nocturnal hatching, while zoeal release in diurnal groups took place at the time of high tide. Since nocturnal high tides at the study area occurred late, sometimes close to dusk, early release would allow more time for offshore transport of larvae when the action of potential predators is reduced.

Developing European operational oceanography for Blue Growth, climate change adaptation and mitigation, and ecosystem-based management

Operational approaches have been more and more widely developed and used for providing marine data and information services for different socio-economic sectors of the Blue Growth and to advance knowledge about the marine environment. The objective of operational oceanographic research is to develop and improve the efficiency, timeliness, robustness and product quality of this approach. This white paper aims to address key scientific challenges and research priorities for the development of operational oceanography in Europe for the next 5-10 years. Knowledge gaps and deficiencies are identified in relation to common scientific challenges in four EuroGOOS knowledge areas: European Ocean Observations, Modelling and Forecasting Technology, Coastal Operational Oceanography and Operational Ecology. The areas "European Ocean Observations" and "Modelling and Forecasting Technology" focus on the further advancement of the basic instruments and capacities for European operational oceanography, while "Coastal Operational Oceanography" and "Operational Ecology" aim at developing new operational approaches for the corresponding knowledge areas.

Feeding habits of the blue shark (Prionace glauca) off the coast of Brazil

Estômagos de 222 tubarões-azuis coletados ao longo da costa brasileira foram analisados, sendo 116 da região nordeste e 106 da região sul. Um total de 51 táxons de presas foram identificados. Os itens mais importantes na região sul foram baleias Mysticeti, teleósteos, o peixe gempilídeo Ruvettus pretiosus e o nomeídeo Arioma bondi. Cefalópodes foram mais diversos, com preferência pelas espécies migradoras verticais Histioteuthis spp., Cranchiidae e o polvo epipelágico Ocythoe tuberculata. Na região nordeste, o tubarão-azul consumiu principalmente teleósteos, incluindo o peixe alepisaurídeo Alepisaurus ferox e o gempilídeo Gempylus serpens. Entre os cefalópodes, Histioteuthis spp. e o polvo epipelágico Tremoctopus violaceus foram os itens principais. Predação sobre cardumes foi ocasional, como observada para Arioma bondi. Aves também foram consumidas em ambas as regiões. Puffinus gravis foi o quinto item mais freqüente na região nordeste. Durante o ciclo migratório reprodutivo, o tubarão-azul costuma predar nas adjacências da termoclina, que é mais profunda na região nordeste e mais perto da superfície na região sul.

Study seeks candidates for blue shrimp polyculture in New Caledonia

Seasonal pathologies reduce the profitability and sustainability of the shrimp-farming industry in New Caledonia. A study was therefore conducted to estimate the effects of polyculture of blue shrimp with goldline rabbitfish or mullet on production performance and environmental quality. The fish did not affect shrimp production, and the combined shrimp/fish yields were significantly greater than the yield from shrimp monoculture. Changes in environmental quality in all treatments were few and minor throughout the culture period.

Are the preference and selection patterns of hermit crabs for gastropod shells species- or site-specific?

Experimental analyses of hermit crabs and their preferences for shells are essential to understand the intrinsic relationship of the crabs' dependence on shells, and may be useful to explain their shell use pattern in nature. The aim of this study was to evaluate the effect of crab species and site on the pattern of shell use, selection, and preference in the south-western Atlantic hermit crabs Pagurus brevidactylus and Pagurus criniticornis, comparing sympatric and allopatric populations. Differently from the traditional approach to evaluate shell preference by simply determining the shell selection pattern (i.e., the number of shells of each type selected), preference was defined (according to [Liszka, D., Underwood, AJ., 1990. An experimental design to determine preferences for gastropod shells by a hermit-crab. J. Exp. Mar. Biol. Ecol., 137(1), 47-62]) by the comparison of the number of crabs changing for a particular shell type when three options were given (Cerithium atratum, Morula nodulosa, and Tegula viridula) with the number of crabs changing for this same type when only this type was offered. The effect of crab species was tested at Cabelo Gordo Beach, where P. brevidacrylus was found occupying shells of C. atratum, M. nodulosa, and T viridula in similar frequencies, whereas P. criniticornis occupied predominantly shells of C atratum. In laboratory experiments the selection patterns of the two hermit-crab species for these three gastropods were different, with P criniticornis selecting mainly shells of C atratum, and R brevidactylus selecting more shells of M. nodulosa. The shell preference was also dependent on crab species, with P. criniticornis showing a clear preference for shells of C atratum, whereas P. brevidactylus did not show a preference for any of the tested shells. The effect of site was tested for the two species comparing data from Cabelo Gordo to Preta (P brevidactylus) and Araca beaches (P. criniticornis). The pattern of shell use, selection, and preference was demonstrated to be dependent on site only for P. brevidactylus. The results also showed that the shell use pattern of P criniticornis can be explained by its preference at both sites, whereas for P. brevidactylus it occurred only at Cabelo Gordo, where the absence of preference was correlated with the similar use of the three gastropod species studied. Finally, the results showed that the shell selection pattern cannot be considered as a measure of shell preference, since it overestimates crab selectivity. (C) 2009 Elsevier B.V. All rights reserved.

Source populations in coastal crabs: parameters affecting egg production

Benthic marine invertebrates may form metapopulations connected via propagule dispersal. Conservation efforts often target potential source coastlines to indirectly benefit areas depending on allochthonous offspring production. Besides population density, adult size structure, sex ratio, brooding frequency and the proportion of breeding individuals may significantly influence the reproductive output of benthic populations, but these effects have seldom been tested. We used rocky shore crabs to assess the spatial variability of such parameters at relevant scales for conservation purposes and to test their consistency over 2 consecutive years; we then used the data to address whether bottom-up processes or biological interactions might explain the patterns observed. We decomposed egg production rates into their components for the 2 most abundant brachyuran species inhabiting the intertidal rocky habitat. Adult density and brooding frequency varied consistently among shores for both species and largely explained the overall spatial trends of egg production. Temporally consistent patterns also included among-shore differences in the size of ovigerous females of the grapsid Pachygrapsus transversus and between-bay differences in the fecundity of the spider crab Epialtus brasiliensis. Sex ratio was remarkably constant in both. We found no positive or negative correlations between adult density and brooding frequency to support either the existence of a component Allee effect (lack of mate encounters) or an effect of intra-specific competition. Likewise, shore-specific potential growth in P. transversus does not negatively correlate with frequency of ovigerous individuals, as would be expected under a critical balance between these 2 processes. The patterns observed suggest that bottom-up drivers may best explain spatial trends in the reproductive output of these species.