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Volume 45 - Number 3 - 2010


Effects of substratum and conspecific adults on the development and metamorphosis of Acanthocyclus hassleri (Brachyura: Bellidae) megalopae under laboratory conditions

Erwin M. Barría1, Mauricio A. Pradenas1 and Carlos G. Jara1


1Instituto de Zoología, Universidad Austral de Chile, Casilla 567, Valdivia, Chile




Success in the pelagic-benthic transition of the meroplankton depends to a great extent on the environmental signals that induce the settlement and metamorphosis. Acanthocyclus hassleri interacts with sessile colonies of Perumytilus purpuratus and Phragmatopoma virgini from its early ontogenetic stages onwards. Thus, we propose that megalopal development and metamorphosis of A. hassleri are influenced by the presence of such species and/or conspecific adults. We evaluated the development time, frequency of metamorphosis, and survival of megalopae in culture, using as substrates P. purpuratus, P. virgini, empty shells and dwellings of both species, a treatment with water exposed to conespecific adults, and a control experiment without stimulus. Megalopal development was significantly shorter in treatments with a substrate. The average delay in metamorphosis was four days. Mortality was slightly lower in treatments without a substrate, but this was not statistically significant. Megalopal development was influenced by the physical conditions of the substrate, but not the survival because the larvae metamorphosed spontaneously in the absence of stimulation. Delay in metamorphosis was lower than in other species; furthermore, the temperature of the culture was lower than the thermal optimum, thus it is likely that this threshold would be even narrower under conditions closer to the optimum. Comparing our results with studies in estuarine and gregarious species, we suggested that the nature of stimulus and larval response could depend on the population density of the adults and the energy involved in the hydrodynamics of habitat


Key words: Decapoda, larvae, induction, environmental cue, pelagic-benthic transition



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