• Biodiversity and ecosystem functioning in marine ecosystems

A major focus of the Bruno lab is to understand the role of species diversity in controlling a variety of marine ecosystem properties. The lab recently completed a series of experiments in North Carolina and Jamaica testing the hypothesis that algal species richness is directly related to primary productivity. Unlike work in terrestrial grasslands, they have not detected a significant effect of algal richness. Instead, species’ identity appears paramount in controlling production. The lab is currently focusing on the role of diversity at higher trophic levels. For example, field and mesocosm experiments performed in 2004 indicate that predator diversity has striking effects on prey and plant biomass and composition. This project is funded by NSF and is being performed in collaboration with J. Emmett Duffy (VIMS).

• Coral reef ecology and conservation

The Bruno lab is also focused on untangling the many factors causing the global decline in reef-building corals. For example, they are using mesocosm and field experiments to test the hypothesis that nutrient pollution and increasing sea surface temperatures have increased the severity of coral disease by making coral hosts more susceptible and/or by making bacterial and fungal pathogens more virulent. They have recently begun to compliment this experimental approach with correlative analysis of regional data on coral disease dynamics, water shed model, and Pathfinder satellite SST data. Preliminary analysis indicates that coral disease outbreaks are highly correlated with the recent thermal history of a reef (e.g., the frequency of temperature stress anomalies). This research (funded by NSF) is being performed in collaboration with C.D. Harvell, S. Ellner, and G. Smith at field sites in Akumal, Mexico, the Florida Keys, Jamaica and Moorea.

• Seed dispersal in an estuarine plant metacommunity

The Bruno lab has been working on dispersal in a New England cobble beach plant metacommunity since 1996. The main goal is to quantify the dispersal functions of all 12 constituent species, including annuals and perennial and both common and rare species. The role of current direction, habitat patch orientation and isolation, and patch size in controlling seed export and dispersal are all being quantified through yearly direct dispersal measurements. Dispersal functions of each species are then used in spatially explicit metacommuity models to test the effects of habitat patch quality, isolation, and density on metacommunity dynamics (Figure 3.24). This NSF-funded project will continue through August 2005 and is being carried out in the Narragansett Bay National Estuarine Research Reserve.



• Dispersal and recruitment limitation in invertebrate metacommunities

Members of the Bruno lab are also working on the effects of dispersal and connectivity on community structure in a variety of invertebrate metacommunities. For example, recent work at IMS has tested the effect of recruitment limitation and propagule flux on community composition and richness. If mobile invertebrate communities are saturated, then increasing the number and richness of immigrants should not affect resident richness, but could alter composition. They are also working in Moorea (Figure 3.25) and Mexico, using obligate inhabitants of branching corals (e.g, shrimp and crabs) as a model system to test several metacommunity models.


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