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Diatom cultures exhibit differential effects on larval metamorphosis in the marine gastropod Ilyanassa obsoleta (Say)

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Esther M. Leise, Professor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: Adult Ilyanassa obsoleta recruit from the plankton to surface sediments of intertidal mudflats along the U.S. East Coast as a result of metamorphic induction of planktonic larvae by environmental cues. A previous researcher discovered that seawater extracts of mud from juvenile habitats could induce metamorphosis and provided evidence that the inductive agent was of biological origin. Because juvenile I. obsoleta are herbivorous and grow when fed diets of benthic diatoms, we hypothesized that benthic diatoms or their associated microflora might be responsible for producing a metamorphic stimulus. We tested extracts of a culture of mixed diatoms and extracts of cultures of 6 diatom species isolated from mudflat sediments along the coast of North Carolina in which sexually mature and immature adult (juvenile) I. obsoleta commonly co-occur. We also tested extracts of one diatom culture isolated at the Friday Harbor Laboratories (Friday Harbor, WA). We found differential effects among the diatom species tested. One centric diatom, Coscino-discus sp., induced metamorphosis at levels close to those triggered by a known neuroactive compound, serotonin. Several species of benthic diatoms displayed neutral effects, showing little or no inductive capability. In one experiment, an unidentified pennate diatom species appeared to inhibit spontaneous metamorphosis that occurred in some competent larvae. We hypothesize that Coscinodiscus sp. or its associated microflora, is part of a suite of benthic species that is either indicative of a favorable juvenile environment or is itself part of the post-metamorphic diet. Our results also indicate that larval Ilyanassa demonstrated positive, neutral, and perhaps even negative responses to potential metamorphic cues.

Additional Information

Publication
Journal of Experimental Marine Biology and Ecology 379(1-2):51-59.
Language: English
Date: 2009
Keywords
Caenogastropod, Coscinodiscus, Mollusc, Prosobranch, Snail, Tychopelagic