176 research outputs found

    Decapod crab zoeae as food for rearing cephalopod paralarvae

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    A simple method of providing a regular supply of live food for the experimental culture of paralarval cephalopods is described. The primary food source utilized was hatched zoeae of large laboratory populations of the hermit crab, Pagurus prideaux. Zoeal size, swimming behaviour, and distribution in the water column make these zoeae a suitable live prey for rearing early post-hatching planktonic stages of cephalopods and probably other marine zooplanktivores. Ovigerous P. prideaux females were collected from the sea throughout the year at depths between 10 and 90 m in the NW Mediterranean and maintained at densities of up to 500 specimens ¬∑ m‚ąí2. One month after spawning in aquaria, 38% of the females of P. prideaux started to incubate a second clutch of eggs. Other decapod crustacean species, such as Liocarcinus depurator and Dardanus arrosor, were maintained to use their zoeae as a food source for cephalopod paralarvae. P. prideaux zoeae were used as the sole or main food resource for rearing Loligo vulgaris and Octopus vulgaris, during the first 2 months of life. First feeding and initial growth in L. vulgaris and O. vulgaris paralarvae can be successfully stimulated using decapod zoeae with a total length equivalent to 50‚Äď100% of the cephalopod's mantle length

    Efectos sobre la composición faunística y características poblacionales de crustáceos decápodos posteriormente a la implementación de una zona cerrada a la pesca en el Mediterráneo noroccidental

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    The establishment of fisheries no-take areas is considered an effective method for the recovery of populations of exploited species and their habitats. Here we study the faunistic composition of decapod crustaceans after the implementation of a no-take area in the Gulf of Roses (NW Mediterranean) in 2014. We studied the occurrence (presence/absence) and density of all decapod crustaceans sampled by trawling inside and outside a no-take area from March 2015 to July 2018. Sizes were assessed for all common species. A total of 33 species of decapod crustaceans were recorded. Four species showed significantly higher occurrences in the no-take area and three in the open area, while significantly higher densities were found for four species in the no-take area and three in the open area. Multivariate analysis showed marked differences between the no-take area and the open area, while also showing that the two areas were undergoing a divergence. The comparison of sizes between the two zones showed species-specific patterns that in many cases showed that both the smallest and the largest individuals were present in the no-take area, suggesting that the closing of this area would be important for recruitment and juvenile development, as well as for protection of large-sized individuals. All evidence indicates that the establishment of the no-take area has led to an improvement in biodiversity and species population descriptors.La creación de áreas restringidas a la pesca se considera un método efectivo para la recuperación de las poblaciones de especies comerciales y sus hábitats. En el presente trabajo se estudia la composición faunística referente a los crustáceos decápodos después de la implementación de un área cerrada a la pesca en el golfo de Roses en 2014. Se han estudiado las pautas de presencia y abundancia de los crustáceos decápodos muestreados con arte de arrastre comercial en el interior y exterior del área cerrada a la pesca entre marzo 2015 y julio 2018. Se detectó un total de 33 especies de crustáceos decápodos. Tanto en las presencias como en las abundancias se detectaron diferencias significativas entre las dos zonas. Se determinó la talla individual de los individuos capturados o de una submuestra. Cuatro especies mostraron una presencia significativamente mayor en el área cerrada a la pesca, mientras que tres lo hicieron en el área abierta. Respecto a las densidades, cuatro especies mostraron valores significativamente mayores en el área protegida, mientras que tres lo hicieron en la abierta. Un análisis multivariante mostró claramente la existencia de diferencias significativas entre las dos zonas, mostrando también que las dos áreas se encuentran en proceso de divergencia. La comparación de tallas entre las dos zonas presentó pautas específicas para cada especie que mayoritariamente indicaron que tanto los individuos de menor talla como los de mayor talla se presentaban en el área cerrada a la pesca, sugiriendo que el cierre de esta zona sería relevante para el reclutamiento y desarrollo juvenil, así como para la protección de los ejemplares de mayor talla. Las evidencias indican que el establecimiento del área cerrada a la pesca está implicando un proceso de conservación de la biodiversidad y mejora del estado de las poblaciones presentes

    Las comunidades de crust√°ceos dec√°podos de fondos litorales del mar de Albor√°n (Espa√Īa, Mediterr√°neo occidental): variabilidad espacial y temporal

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    The structure of decapod crustacean assemblages living in shallow waters (5 to 25 m depth) in an area of the Alborán Sea (Mediterranean Sea) neighbouring the Strait of Gibraltar was studied. The relatively high richness found in this area is probably due to the diversity of substrata and the confluence of Atlantic and Mediterranean waters. The most abundant species was the hermit crab Diogenes pugilator due to the prevalence of sandy substrate, the shallow depth-range, and the species‚Äô life history. The coralligenous bottom showed the highest species richness and diversity values due to the complexity of microhabitats in this type of bottom and probably due to the food flux associated with currents. Conversely, shallow, well calibrated, fine to medium sandy bottoms of 5 m had the lowest values and the maximum densities due to the high abundance of a few well adapted species. The analysis of the different stations showed significant spatial differences according to depth and sedimentary characteristics. Depth is the environmental variable that correlates best with the decapod assemblages, with a particularly significant boundary between 5 m and 15 m. Nevertheless, there was a continuous transition between the assemblages. These results evidence the importance of quantitative studies in differentiating decapod assemblages. Relationships between these assemblages should also be taken into account in coastal management, since altering a substrate could have repercussions for the structure of the communities of neighbouring substrates. No seasonal significant differences were found in the overall analysis of the area, but there were differences between spring and autumn and spring and summer in relation to depth and substrate (crossed analysis). Finally, we present the species which allow us to discriminate the different assemblages according to sediment and depth, as well as the species‚Äô contributions.Se ha analizado la estructura de las comunidades de dec√°podos de fondos poco profundos (5 a 25 m) de una zona del Mar de Albor√°n (Mediterr√°neo) pr√≥xima al Estrecho de Gibraltar. La relativamente alta riqueza espec√≠fica hallada se debe probablemente a la variedad de sustratos y a la confluencia de aguas atl√°nticas y mediterr√°neas. La especie m√°s abundante fue Diogenes pugilator, debido a la naturaleza del sustrato dominante, el rango batim√©trico analizado y la biolog√≠a de la especie. Los valores m√°s altos de riqueza espec√≠fica y diversidad se encontraron en fondos coral√≠genos, como consecuencia de la mayor complejidad de microh√°bitats y probablemente por el flujo de alimento asociado a corrientes. Contrariamente, los valores m√°s bajos y las mayores densidades se hallaron en los fondos superficiales de arenas finas-medias bien calibradas de 5 m. Esto √ļltimo es debido a las fuertes dominancias de unas pocas especies bien adaptadas. El an√°lisis de las muestras indic√≥ diferencias espaciales significativas seg√ļn el tipo de sedimento y profundidad (√©sta fue la variable mejor correlacionada con los agrupamientos faun√≠sticos), con una frontera m√°s marcada entre los 5 - 15 metros. En cualquier caso resulta obvia la existencia de una continuidad ‚Äď relaci√≥n entre las diferentes comunidades. Estos datos apoyan la importancia de los estudios cuantitativos a la hora de la caracterizaci√≥n de las comunidades de dec√°podos, pues una actuaci√≥n sobre un sustrato puede repercutir sobre la estructura de las comunidades de otros fondos colindantes. Por otro lado, no se encontraron diferencias temporales significativas en el conjunto de la comunidad de dec√°podos de la zona, pero los an√°lisis por profundidades y substratos mostraron diferencias entre primavera y oto√Īo y primavera y verano. Finalmente, se indican las especies que mejor contribuyen a discriminar los distintos tipos de fondos con sus grados de contribuci√≥n

    Taxonomic study of the Pagurus forbesii "complex" (Crustacea: Decapoda: Paguridae). Description of pagurus pseudosculptimanus sp. nov. from albor√°n sea (Southern Spain, Western Mediterranean Sea)

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    Study of hermit crabs from Alboran Sea has allowed recognition of two different morphological forms under what had been understood as Pagurus forbesii. Based on morphological observations with various species of Pagurus, and molecular studies, a new species is described as P. pseudosculptimanus. An overview of species of Pagurus from the eastern Atlantic and Mediterranean Sea is provided. © Copyright 2014 Magnolia Press.This work was supported by the Junta de Andalucía RNM-0141 Research Group.Peer Reviewe

    Agregaciones de pennatul√°ceos en la plataforma del norte de Espa√Īa: distribuci√≥n y agrupaciones faun√≠sticas

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    The sea pens Funiculina quadrangularis, Pennatula aculeata, Pennatula phosphorea, Pteroeides spinosum and Veretillum cynomorium are known to be characteristic species of the habitat ‚Äėpennatulacean communities on circalittoral and upper bathyal soft bottoms‚Äô, described recently on the northern Atlantic Spanish shelf under the terms of the EU directives. Distribution, abundance and environmental data collected from 1995 to 2010 in the Northern Spanish Shelf Groundfish Surveys in the Cantabrian Sea and off Galicia (SPNGFS) were analysed. Although low densities of sea pens were commonly found over the years, some aggregations were shown. Multivariate analysis separated the aggregations of F. quadrangularis and of Pennatula spp. found on circalittoral soft bottoms. In addition, evidence of aggregations of F. quadrangularis on upper bathyal sites was also found. Depth and longitude, which were closely related to organic matter and sediment particle size, were key factors in determining the distribution and abundance of these aggregations. However, very little information on distribution and density of the species P. spinosum and V. cynomorium was obtained. Details of community composition of F. quadrangularis and Pennatula spp. were studied and compared with those of the OSPAR habitat ‚Äúsea pen and burrowing megafauna communities‚ÄĚ in other areas. The results improve our knowledge concerning sea pen communities in the southern Bay of Biscay and contribute to a global assessment of the status of these communities in the northeast Atlantic.Los pennatul√°ceos Funiculina quadrangularis, Pennatula aculeata, Pennatula phosphorea, Pteroeides spinosum y Veretillum cynomorium son especies caracter√≠sticas del h√°bitat ‚Äúcomunidades de pennatul√°ceos sobre fondos blandos profundos y circalitorales‚ÄĚ descrito recientemente en la plataforma noratl√°ntica espa√Īola bajo directrices europeas. Datos de distribuci√≥n, abundancia y ambientales recogidos desde 1995 hasta 2010 en las campa√Īas demersales de la plataforma del norte de Espa√Īa y Galicia (SPNGFS) han sido analizados. Aunque predominan las bajas densidades de pennatul√°ceos a lo largo de los a√Īos, se han encontrado agregaciones. El an√°lisis multivariante ha separado las agregaciones encontradas de F. quadrangularis y Pennatula spp. en los fondos blandos circalitorales. Adem√°s, se han encontrado agregaciones de F. quadrangularis en los fondos blandos profundos. La profundidad y la longitud, estrechamente relacionadas con el contenido de materia org√°nica y el tama√Īo de part√≠cula del sedimento, han sido los factores clave en la distribuci√≥n y abundancia de estas agregaciones. Sin embargo, se ha obtenido poca informaci√≥n de la distribuci√≥n y densidad de las especies P. spinosum y V. cynomorium. Se ha estudiado la composici√≥n de las comunidades de F. quadrangularis y Pennatula spp. y se ha comparado con el h√°bitat definido por OSPAR ‚Äúsea pen and burrowing megafauna communities‚ÄĚ en otras √°reas. Los resultados mejoran el conocimiento de las comunidades de pennatul√°ceos en el sur del Golfo de Vizcaya y ayudan en la evaluaci√≥n global del estatus de estas comunidades en el noreste Atl√°ntico

    Composizione dello "sporco" (macrobenthos non commerciale) della pesca a strascico Campagna MEDITS 2013 - Stretto di Sicilia

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    E’ riportata la lista tassonomica del macrobenthos campionato nel corso del trawl-surveys MEDITS 2013 svolto nello Stretto di Sicilia
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