PARENT SESSION
Poster Session 4: Marine Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Hints of a link: Coupling of benthic adult production and larval recruitment in the blue mussel, Mytilus edulis.
Smith, Geneviève1, Graf, Matthew1, Petrovic, Filip1, Guichard, Frédéric1, McKindsey, Christopher2, 1 McGill University, Montréal, Québec, Canada2 Maurice Lamontagne Institute, Mont-Joli, QC, Canada
ABSTRACT- An increasing number of studies are challenging the view of coastal populations as open systems. However, these efforts are constrained by our limited ability to measure larval dispersal. While some indirect measures are available, we still ignore the dispersal distance of marine invertebrates. Here we present results from a large-scale survey of blue mussel (Mytilus edulis) onshore populations and recruitment along a 150km stretch of the southern shore of the St. Lawrence Estuary, Quebec. We used the residual downstream current of our study system to test the hypothesis of demographic coupling between onshore populations and recruitment. More precisely, onshore post-recruitment processes (biotic and abiotic) or "supply-side" forces (fluctuation in larval transport) were predicted to result in a positive relationship between local adult abundance and recruitment. The hypothesis of demographic coupling was predicted to result in a covariance between adult abundance and recruitment at downstream sites corresponding to the dispersal distance. Within-site covariance analysis failed to show any correlation between adults and recruits. However, using cross-covariance analysis between the abundance of adults upstream with the number of recruits at sites downstream, we observed maximal cross-covariance between sites separated by approximately 14-35km, suggesting that mussel larvae are transported downstream by the residual current of the St. Lawrence before finally recruiting into adult populations. These results provide the first quantification of demographic coupling between adult production and larval recruitment of Mytilus at the scale of tens-of-kilometers in the Estuary, challenging traditional assumptions of "supply-side" ecology and theories of open populations as they apply to marine benthic organisms.
Key words: Mytilus edulis, recruitment, dispersal scale, open vs. closed systems