A recent study led by Kelton McMahon, a researcher at the University of Rhode Island’s Graduate School of Oceanography, reveals that food webs on tropical coral reefs are more fragile and siloed than previously understood. This important research sheds light on the challenges faced by nutrient flow in these ecosystems and consequences on marine biodiversity.
McMahon’s Ocean Ecogeochemistry Lab used stable isotopes to learn more about the life histories of different reef-dwelling species. The study focused on three common snapper species: Lutjanus kasmira, L. ehrenbergii, and L. fulviflamma. Every species had unique feeding activities associated with various functional groups of the reef community. Lutjanus kasmira primarily feeds on phytoplankton residing in the water column. L. ehrenbergii flourishes in a food web based on macroalgae at the benthic interface. L. fulviflamma is mostly connected to a coral-rich food web.
The research team developed a unique technique called compound-specific stable isotope analysis of amino acids (CSIA-AA). This powerful new approach enables scientists to track nutrient pathways through ecosystems over time, uncovering complex patterns that had previously remained hidden. McMahon explained that the ability to trace where energy comes from really takes understanding the coral reef food web to the next level.
We took the samples from corals and fishes during our expedition in the Red Sea. They have remained buried for more than a decade prior to this analysis. Advances in analytical tools allowed the team to conduct their analysis at the Graduate School of Oceanography and partner institutions, including the Woods Hole Oceanographic Institution.
Aside from these dramatic overarching trends, the study reveals much more targeted and nuanced findings regarding reef food webs. It addresses a perennial ecological conundrum: why is high species diversity able to prosper in reef ecosystems that are famously nutrient-poor? Beyond bridging the creative and scientific disciplines, McMahon’s work deepens our ecological understanding by focusing our attention on complex relationships at the individual, cultural, and evolutionary levels.
McMahon’s lab really had the opportunity to dive deeply into some really cool projects. They’ve done research on penguins in Antarctica, researched ancient human diets in Mesoamerica, and studied the local fisheries such as the jonah crab fishery. His varied research portfolio speaks to this deep-seated desire to study and comprehend these complicated, intertwined ecological systems.
