667 resultados para Hermit crabs
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Acanthonyx scutiformis, an endemic species in the Brazilian coast, is commonly found in intertidal rocky-shore algal communities. This study analyzes the population biology of A. scutiformis from Ubatuba region. A total of 371 specimens were collected over one year. Size range was 4.2[long dash]12.7 mm CW (carapace width) for females and 3.7[long dash]15.8 mm CW for males. Females predominated in intermediate size classes, whereas males prevailed in the largest ones. The estimated size when 50% crabs were mature was 10.7 mm CW for males and 8.9 mm CW for females. Sex ratio varied among the demographic groups. The processes that influence A. scutiformis population structure can be related to the different times males and females reach sexual maturity and probably to the distinct predation pressures on each sex during the adult phase.
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Marine biological invasions have been regarded as one of the major causes of native biodiversity loss, with shipping and aquaculture being the leading contributors for the introductions of alien species in aquatic ecosystems. In the present study, five aquatic alien species (one mollusk, three crustaceans and one fish species) were detected during dives, shore searches and from the fisheries on the coast of the Delta do Parnaiba Environmental Protection Area, in the States of Piaui and Maranhao, Northeastern Brazil. The species were the bicolor purse-oyster Isognomon bicolor, the whiteleg shrimp Litopenaeus vannamei, the giant river prawn Macrobrachium rosenbergii, the Indo-Pacific swimming crab Charybdis hellerii and, the muzzled blenny Omobranchus punctatus. Ballast water (I. bicolor, C. hellerii, and O. punctatus) and aquaculture activities (L. vannamei and M. rosenbergii) in adjacent areas are the most likely vectors of introduction. All exotic species found have potential impact risks to the environment because they are able to compete against native species for resources (food and habitat). Isognomon bicolor share the same habitat and food items with the native bivalve species of mussels and barnacles. Litopenaeus vannamei share the same habitat and food items with the native penaeids such as the pinkspot shrimp Farfantepenaeus brasiliensis, the Southern brown shrimp Farfantepenaeus subtilis, and the Southern white shrimp Litopenaeus schmitti, and in the past few years L. vannamei was responsible for a viral epidemics in the cultivation tanks that could be transmitted to native penaeid shrimps. Charybdis hellerii is also able to cause impacts on the local fisheries as the species can decrease the populations of native portunid crabs which are commercialized in the studied region. Macrobrachium rosenbergii may be sharing natural resources with the Amazon River prawn Macrobrachium amazonicum. Omobranchus punctatus shares habit with the native redlip blenny Ophioblennius atlanticus and other fishes, such as the frillfin goby Bathigobius soporator. Some immediate remedial measures to prevent further introductions from ballast water and shrimp farm ponds should be: (i) to prevent the release of ballast water by ship/vessels in the region; (ii) to reroute all effluent waters from shrimp rearing facilities through an underground or above-ground dry well; (iii) to install adequate sand and gravel filter which will allow passage of water but not livestock; (iv) outdoor shrimp pounds located on floodable land should be diked, and; (v) to promote environmental awareness of those directly involved with ballast water (crews of ship/vessels) and shrimp farms in the region. Rev. Biol. Trop. 58 (3): 909-923. Epub 2010 September 01.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Determinations of Al and Mn concentrations in the tissues (gills, hepatopancreas and muscle) of the freshwater crab Trichodactylus fluviatilis and water samples, both collected from sites on tributaries of the Corumbatai River (São Paulo, Brazil) were performed. The Bioaccumulation Factor (BAF), calculated for different sites with respect to the water concentration, ranged from 173-555 for Al and from 636 - 921 for Mn. Dissolved concentrations of Al and Mn in water samples (collected in different sites) were related to the accumulation of these metals in crabs, suggesting that T. fluviatilis is good biomonitor for Al and Mn pollution in aquatic ecosystem.
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A biologia de Ucides cordatus na Baía de Vitória (ES) foi avaliada como subsídio ao manejo populacional. As amostragens ocorreram mensalmente durante um ano (outubro/1998 a setembro/1999), com análise biométrica (LC = largura da carapaça; PE = peso total úmido) e de fatores abióticos em quatro transectos, com quatro faixas cada (margem à região supratidal). A densidade foi de 3,7±1,5 caranguejos.m-2, com incremento em direção à região supratidal, sendo a profundidade das galerias de 1,1±0,3 m. A salinidade da água intersticial diferiu entre as faixas, sendo mais elevada na região supratidal. Houve correlação significativa entre a abundância de exemplares e alguns fatores ambientais, o mesmo ocorrendo quanto as tocas abertas e fechadas. A razão sexual evidenciou um predomínio de fêmeas (1,0M:1,6F), particularmente entre 50 e 75 mm LC. A maior incidência de tocas fechadas ocorreu em agosto e setembro, enquanto as fêmeas ovígeras foram registradas de janeiro a abril. A relação PE/LC mostrou isometria para os machos (PE=0,425.10-3 LC3,0014; R²=0,99) e fêmeas (P=0,439.10-3 LC2,97; R²=0,99). Para o total da população a média de tamanho (LC) e peso (PE) foi de 54,6±11,8 mm e de 77,5±42,4 g, respectivamente. Os dados evidenciam que a população encontra-se sobrexplotada, requerendo manejo adequado para a viabilidade da atividade extrativa na área estudada.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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All the larval stages of the hermit crab Pagurus brevidactylus were studied in the laboratory, with special emphasis on external morphology and on the duration of each stage. The larvae were kept in individual containers, with water of 35 salinity and fed on nauplii of Artemia salina; room temperature was maintained at 24±1ºC. The post-embryonic development includes four stages of zoea and one of megalopa. All the larval stages are drawn and described in detail.
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The developmental stages of Dardanus insignis (Saussure, 1858) from first through eighth zoea and megalopa are described and illuslraled. The experiments were carried out involving 100 larvae, obtained from ovigerous females collected on the north littoral of the state of São Paulo, Brazil. The larvae were kept in individual containers, with water of 34 salinity and fed with freshly hatched nauplii of Artemia; room temperature was maintained at 25±1ºC. The larval characters of this species are compared with Dardanus arrosor (Herbst, 1796). the only species of the genus that has also heen reared in laboratory.
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Some individuals of the species Arenaeus cribrarius (Lamarck, 1818) bear a characteristic pink abdomen, which is notably different from the usual white coloration. The incidence of this chromatic alteration was determined for a single population and its relation with other individual variables were examined. The individuals were monthly collected from May, 1991 to April, 1993, in Ubatuba, São Paulo, with the aid of a shrimp fishery boat provided with double-rig trawling nets. All specimens were sexed, measured (CW = carapace width), distributed in 10-mm size classes and classified according to growth phase (juvenile and adult), molting condition and development stage of gonads. The occurrence of pink-colored morphs was also recorded. From a total of 2,096 collected individuals, only 60 females (nine of those ovigerous) presented a pink-colored abdomen, which represents 2.9% of the whole sample and 5.2% of the females. Almost all of them were intermolt individuals (96.6%) and 63.3% showed mature gonads. According to published data, size at the onset of functional maturity in A. cribrarius females is around 60 mm CW, from which the incidence of pink morphs and ovigerous crabs were recorded. The obtained results suggest that such a chromatic alteration is associated to sexual maturity in these females. This characteristic may enhance the attraction potential for mating, shortly after the puberty molt.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)