RUI: Collaborative Research: Larval behavior and supply-side ecology: Consequences of dissolved versus adsorbed chemical cues

California State L A University Auxiliary Services Inc., Los Angeles CA

Investigators

Abstract

Supply-side ecology has punctuated the role of large-scale physical-oceanographic processes in determining recruitment success. Although large-scale flows, such as upwelling, thermal fronts, tidal bores, and storms, could episodically bathe the shoreline with larvae, they are not entirely responsible for localized variations in larval supply and settlement. These smaller-scale distributions are due, in part, to interactions between planktonic larval behaviors and the flow regime. No longer considered a novelty associated strictly with laboratory still-water conditions, waterborne chemical cues have growing visibility as causative factors in larval settlement over a range of hydrodynamic regimes and taxa. Because of technology limitations, however, previous studies have demonstrated only the potential capacities of dissolved signal molecules on behavior or settlement. They have neither provided a mechanistic basis for broader-scale ecological effects nor achieved dynamic similarity between dissolved chemical environments of experimental and natural field settings. A synthetic theory is therefore yet to emerge on interactions between the transport of waterborne compounds, behavioral responses of the larvae, and dynamics of the flow regime. This research project explores the ecological relevance of chemical signal molecules in a remarkable biological system, where alternative cue types and larval developmental morphs occur within a single species and habitat. Moreover, novel research methods are applied to overcome many classic stumbling blocks in larval-settlement research. Use of reliable chemical markers for the natural cue, non-invasive methods for computer/video imaging larvae in moving water, and controlled cue release from a polymer gel will facilitate flume and field research that is dynamically scaled for both the chemical and physical regimes. The research involves, first, field measurements of the naturally occurring ranges in dissolved cue concentrations and flow variables. Second, flume studies quantify behavioral responses of larvae to the waterborne cue, and test experimentally effects of the two cue types (waterborne and surface-adsorbed), separately and together, on settlement. These studies build toward the third, most ecologically meaningful research component, field experimental manipulations aimed at resolving how dissolved versus adsorbed cues determine juvenile distributions in nature. This research links mechanisms acting at small scales in the water column with settlement on the bed, passive transport with active behavior, and chemical ecology with hydrodynamics. The work will help fill the gap between relatively large-scale supply-side processes and individual-scale exploration of the bed. Given the highly interdisciplinary nature of this research, graduate and undergraduate students will be stimulated to cross disciplinary lines and embrace new technology as they develop into young scientists. Students from underrepresented groups will be employed through the CARE and LEADS Programs at UCLA and the CEA-CREST center at CSULA, and they will be encouraged to participate in both flume and field work. Further, this project will foster collaboration among two professors at a Ph.D.-granting institution (UCLA) and a new faculty member at a principally undergraduate university (CSULA), having 84% minority enrollment.