The latitudinal gradient of species diversity is a widely recognized but poorly understood phenomenon. In marine systems, differences in dispersal abilities among species may pose an additional problem in identifying the processes that affect diversity. We compared latitudinal diversity gradients along two parallel continental coasts, the east and west coasts of South America, of two groups of Crustacea (Brachyura and Anomura), which exclusively exhibit planktonic development. We also evaluated the species-area and the energy-input hypotheses. Diversity decreased with increasing latitude for both groups in both oceans. Results suggest that the spatial structure of sea surface temperature (SST) explains diversity of both groups at large, but not small (< 5°), scales. Range size and latitude were not correlated. We hypothesize that SST differentially affects taxa with contrasting modes of development, influencing patterns of diversity. We suggest that developmental modes of marine organisms should be considered in future diversity analyses.
RESUMEN. Se analiza y se resume toda la información disponible sobre las pesquerías de crustáceos Decápodos comerciales del Mar Epicontinental Argentino y del talud contiguo. En la actualidad son cinco las especies que tienen valor comercial. Dos anomuros: Lithodes santolla (centolla) y Paralomis granulosa (centollón), dos peneidos: Pleoticus muelleri (langostino) y Artemesia longinaris (camarón) y un braquiuro: Ovalipes trimaculatus (cangrejo nadador). Mediante campañas y viajes a distintas regiones donde se hallan y explotan estos crustáceos se dispone de una importante información biológico-pesquera, relativa a las épocas y zonas de reproducción, crecimiento, reclutamiento, áreas de concentraciones pescables, fluctuaciones, etc, lo que ha permitido recomendar un ordenamiento adecuado en la pesquería de alguna de ellas. Se destaca las poblaciones de langostino del litoral patagónico, por ser el recurso de mayor importancia. Desde 1980 ha crecido la extracción de langostino en forma significativa, con fluctuaciones anuales, llegando en algunos años a volúmenes de desembarques de más de 25.000 tm lo que sobrepasa los 100 millones de dólares americanos en valor de exportación.
Sexual maturity, temporal reproductive pattern, and recruitment of juveniles were examined for the penaeoid shrimp Artemesia longinaris sampled for five and a half years in a tropical locality off the coast of São Paulo (23º S), Brazil. Monthly samples were taken from January 1998 to June 2003 at depths between 5 and 45 m. Ovarian maturity was used to examine breeding in adult females. Recruitment was defined as the percentage of juveniles of the total number of individuals in each month and season. A total of 10 288 females and 5 551 males were collected. Estimated sizes (carapace length) at the onset of sexual maturity were 11.0 mm and 13.4 mm for males and females, respectively. Over the five and a half years, females with ripe gonads were found in every season, with the highest percentages in summer (January-March). Juvenile shrimps occurred year-round. These results suggest a continuous reproduction of A. longinaris with temperature acting as an environmental stimulus for the duration of the ovary development cycle. These data and the hypothesis of the intrusion of the South Atlantic Central Water mass, which lowered water temperature and raised plankton production, suggest that the end of spring and the beginning of summer were the principal reproductive months. The classical paradigm of continuous reproduction at lower latitudes, with increased seasonality of breeding period at higher latitudes seems to apply to this species. Rev. Biol. Trop. 55 (Suppl. 1): 39-48. Epub 2007 June, 29.
RESUMEN. El trabajo se refiere a los aspectos biológicos del crecimiento y a los métodos empleados para estudiar el aumento de tamaño en los crustáceos Decápodos del mar epicontinental argentino. Primeramente se reseñan los mecanismos endócrinos que controlan y desencadenan la muda. Luego se describen las características distintivas del crecimiento en los crustáceos, que se produce en forma discontinua y sujeto a las sucesivas mudas (cambio del exoesqueleto). Se mencionan los métodos usados por distintos autores, especialmente los referidos a especies argentinas, incluyendo algunos de los métodos cuantitativos empleados en Argentina para analizar el crecimiento. Se presentan ejemplos sobre el dimorfismo sexual y caracteres sexuales secundarios permanentes o transitorios relacionados con el ciclo reproductivo de algunas especies. Finalmente, se destaca la influencia de las condiciones ambientales (temperatura, salinidad, contaminación) y de otros factores tales como la nutrición, la pérdida de apéndices y el parasitismo sobre el crecimiento.
Adults of the palaemonid prawn Palaemon macrodactylus Rathbun, 1902 were reported for the first time from the southwestern Atlantic waters. Males and ovigerous females were collected in Mar del Plata harbor (38°03¢ S; 57°31¢ W), Argentina; larvae obtained from one of the collected females were reared in the laboratory until the juvenile stage. The geographical range of P. macrodactylus was previously restricted to the Pacific Ocean: it was originally described in Japan and has been reported as an invasive species in the western coast of USA in the 1950's and in Australia in the 1970's. Recently, this prawn has been also reported from European waters.
SUMMARY: The distribution of decapod crustaceans in the southernmost areas of South America and the Antarctic is assessed considering the Magellan Biogeographic Province instead of the antiboreal region. Possible associations between decapod crustaceans from the Magellan Biogeographic Province and those from the Antarctic region are analysed. Species records were assigned to seven geographic regions that were clustered using multivariate analyses based on species presence/absence and Bray-Curtis similarity. The results showed two well-established clusters, one of which included the Pacific and Atlantic areas of the Magellan Province, the southern tip of South America and the Kerguelen Arc islands, with the highest similarity between the southern tip and the Atlantic area. Another cluster was well separated and included the Antarctic and South Georgia with the highest similarity index. Earlier studies and results obtained here suggest that the faunas of southern Chile and southern Argentina are biogeographically related. There is a low level of association among decapod species from the circum-Antarctic region and the Magellan Province.Keywords: decapod crustaceans, Magellan Biogeographic Province, circum-Antarctic distribution.RESUMEN: SOBRE LA DISTRIBUCIÓN DE LOS CRUSTÁCEOS DECÁPODOS DE LA PROVINCIA BIOGEOGRÁFICA MAGALLÁNICA Y LA REGIÓN ANTÁRTICA. -Se estudió la distribución de los crustáceos decápodos en las áreas más australes de Sudamérica, considerando la Provincia Biogeográfica Magallánica en lugar de la región antiboreal. Se analizó la posible asociación entre los crustáceos de la Provincia Magallánica y los de la región antártica. Las especies registradas fueron asignadas a siete regiones geográficas, las que fueron agrupadas utilizando análisis de agrupamientos basado en presencia/ausencia de especies. Se utilizó el índice de similitud de Bray-Curtis. Los resultados mostraron dos grupos bien definidos de los cuales uno incluyó las áreas pacífica y atlántica de la Provincia Magallánica, la del extremo más austral de Sudamérica y las islas del Arco de Kerguelen. El otro grupo estuvo separado del anterior e incluyó la Antártida y las Islas Georgias con el índice de similitud más alto. Estudios anteriores y los resultados obtenidos en éste, sugieren que las faunas del sur de Chile y sur de Argentina se encuentran relacionadas. Existe baja asociación entre las especies actuales de crustáceos decápodos con distribución circumantártica y las de la Provincia Magallánica.Palabras clave: crustáceos decápodos, Provincia Biogeográfica Magallánica, distribución circumantártica.
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