Behavioral Responses of Invertebrate Larvae to Water Column Cues

Jeanette Wheeler, Ph.D., 2016
Lauren Mullineaux, Advisor

Many benthic marine invertebrates have two-phase life histories, relying on planktonic larval stages for dispersal and exchange between adult populations.  Historically, larvae were considered passive drifters in ocean currents, but recently the paradigm has shifted toward active larval behavior mediating transport.  Larvae in the plankton encounter physical, chemical, and biological cues, and their behavioral responses to these cues impact transport, survival, settlement, and recruitment.  I investigated effects of turbulence, light, and conspecific adult exudates on larval swimming behavior.  I focused on two species of distinct morphologies: the purple urchin Arbacia punctulatain pre-settlement planktonic stages, and the eastern oyster Crassostrea virginica in the competent-to-settle larval stage.  I developed a conceptual framework within which larval behavior is driven simultaneously by environmental cues and larval age.  As no theory for larval behavior is derivable from first principles, it is only through experimental work that we can access behaviors and link them to specific environmental triggers.  In this work, I studied larval responses at the individual level, but these dynamics play out at larger scales in the ocean, impacting population connectivity, and community structure.  My work represents progress in understanding how the ocean environment and larval behavior couple to influence marine ecological processes.