Larvae of the shrimps Crangon crangon L. and C. alImanni Kinahan were reared in the laboratory from hatching through metamorphosis. Effects of rearing methods (larval density, application of streptomycin, food) and of salinity on larval development were tested only in C.crangon, influence of temperature was studied in both species. Best results were obtained when larvae were reared individually, with a mixture of Artemia sp. and the rotifer Brachionus plicatilis as food. Streptomycin had partly negative effects and was thus not adopted for standard rearing techniques. All factors tested in this study influenced not only the rates of larval survival and moulting, but also morphogenesis. In both species, in particular in C. crangon, a high degree of variability in larval morphology and in developmental pathways was observed. Unsuitable conditions, e.g. crowding in mass culture, application of antibiotics, unsuitable food (rotifers, phytoplankton), extreme temperatures and salinities, tend to increase the number of larval instars and of morphological forms. The frequency of moulting is controlled mainly by temperature. Regression equations describing the relations between the durations of larval instars and temperature are given for both Crangon species. The number of moults is a linear function of larval age and a power function of temperature. There is high variation in growth (measured as carapace length), moulting frequency, morphogenesis, and survival among hatches originating from different females. The interrelations between these different measures of larval development in shrimps and prawns are discussed.
Los ecosistemas de corales mesofóticos (MCEs) albergan comunidades únicas que no han sido suficientemente estudiadas debido al alto costo de las tecnologías disponibles. Estos arrecifes pueden encontrarse entre 30 y 150 m de profundidad, donde la cantidad de luz incidente es < 10 % de la que llega a la superficie. Las zooxantelas asociadas a estos arrecifes tienen una tasa fotosintética reducida debido a la baja disponibilidad de luz, por lo que el zooplancton se convierte en la principal fuente de alimento para las colonias de coral. Para el estudio de la composición de las comunidades zooplanctónicas asociadas a estos ecosistemas, se diseñó y probó un dispositivo que permitió la recolección de zoopláncteres presentes sobre el andamio arrecifal de Bajo Fríjol, en el Parque Nacional Natural Corales de Profundidad. El dispositivo consistió en una manguera lastrada que llegaba a la profundidad deseada, conectada al dispositivo recolector, mediante el cual se filtraba el agua gracias a una bomba de succión. La cantidad de agua filtrada, las especies recolectadas y su abundancia permitieron concluir que el dispositivo es una herramienta útil, versátil y económica para la caracterización y el monitoreo de la comunidad zooplanctónica en el Parque Corales de Profundidad, por lo que podría extenderse a otros ecosistemas de arrecifes someros y mesofóticos.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.