Dr. Matthieu Leray


Project Title:  The role of competition during succession across a latitudinal gradient

Advisors:  Nancy Knowlton, Rick Osman, Co-Advisor: Chris Meyer

Introduction. Numerous hypotheses have been proposed to explain the latitudinal gradients in species diversity on Earth. One of them suggests that these patterns are the result of an increased gradient in the strength of biotic interactions from the poles to the tropics. Yet there is still limited support for a gradient in the strength of competitive interactions at the community level. This is partly due to the difficulty of quantifying diffuse competitive interactions. Furthermore, the relative influence of intensity of competition and productivity on the rate of ecological succession across latitude is currently unknown despite significant implications for management and conservation strategies.

Objectives. Here, I propose to use a large-scale experimental approach to investigate latitudinal patterns in the role of competition at structuring local assemblages of marine invertebrates in these reef communities during the course of ecological succession.

Methods. I will employ Autonomous Reef Monitoring Structures (ARMS) as a standardized sampling method. ARMS will be deployed on oyster reefs in Maryland and Florida, and on coral reefs in Belize and Panama [total of 4 sites x 4 settlement durations (see below) x 6 replicates or 96 ARMS in total]. Sampling will be conducted after 3 months (November 2012), 6 months (February 2013), 12 months (September 2013), and 18 months (February 2014). I will use novel metrics of phylogenetic composition to determine the relative influence of competition at structuring assemblages across locations and through time.

Significance/relevance. The proposed work would address major goals of the Smithsonian Marine Science Network program by (1) investigating macroecological patterns that can be explored across all MSN sites, (2) developing standardized sampling approaches that could be used in future MarineGEO studies, (3) using novel community phylogenetic tools, and (4) complementing previous research conducted as part of the MSN network by Amy L. Freestone on local interactions and predation across the same spatial scale. Moreover, I will be able to provide the first experimental data on the dynamics of community recovery across a large spatial scale. This is particularly important as human-induced perturbations increase in intensity and frequency worldwide.