FLAMMINGGOS

Wetlands are globally important biogeochemical hotspots. Their roles as either sinks or sources of greenhouse gases (GHG) are strongly controlled by environmental drivers such as nutrient availability, especially carbon (C), nitrogen (N), and phosphorus (P), which stimulate emission of three main GHGs: nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2).

Beyond nutrient availability, we know that biotic communities in wetlands play an important - but not yet well understood - role in GHG fluxes. For example, mounting evidence suggests that aquatic invertebrate activity can enhance GHG emissions (e.g. the burrows of midge larvae emit high concentrations of nitrous oxide). Considering that in wetland sediments, invertebrates can reach high densities (over 100,000 per square meter), they may be substantial drivers of wetland biogeochemical processes.

So how do higher trophic levels play a role? Waterbirds, for instance, have been shown to reduce densities of aquatic invertebrates, which could potentially moderate GHG flux. But on the other hand, C, N, and P subsidies in waterbird guano may stimulate microbial activity. These bottom-up forces could then enhance GHG flux and dampen the top-down effects of predation.

Our FLAMMINGGOS (Functional Links in Avian, Microbial, Macrophyte, and INvertebrate Greenhouse Gas Output Stimulation) project was created in order to test the relative strength of top-down and bottom-up effects of predatory waterbirds on wetland GHG flux by examining these and other interactions through controlled field and laboratory experiments. This represents a new and potentially transformative line of inquiry into the roles of multiple trophic levels in regulating global wetland GHG flux.