Discipline: Ecology Environmental and Earth Sciences
Room: Exhibit Hall
Alyssa Fritz - University of Missouri
Co-Author(s): Paul Barber, University of California Los Angeles. Derrick Richardson, Hampton University. Jada Alexander, University of California Santa Barbara. Yadi Galindo-Salazar, University of California Santa Barbara.
Coral reefs are highly productive and diverse marine ecosystems that provide humans with important goods and services, including protection from storms and costal erosion, food security and pharmaceuticals. Globally, coral reefs are shifting from coral dominated to macroalgal dominated, a shift caused by increases in anthropogenic stressors, including sedimentation, nutrient runoff, and overfishing. Managing coral reefs for sustainability requires understanding how these anthropogenic stressors are affecting local reefs, but assessing each of these stressors on local reefs can be time consuming and costly. As such, new approaches are needed. Here we test the hypothesis that algal community traits can reveal differences in anthropogenic stressors, using a trait-based ecology approach. We examined macroalgae from 5 sites in Cooks Bay, Mo’orea, that vary in distance from known sources of anthropogenic stress. We then used the alga Padina boryana as a bioassay for nutrient, sedimentation, and herbivory levels. Specifically, more algal growth infers more nutrients; sediment collects on the algal surface in high sedimentation environments; and the amount of algae consumed reflects herbivory rate. Results showed variation in all three stressors across all five sites. Next, we used trait-based ecology to measure 8 traits from 20-25 random macroalgae samples at each site regardless of species, focusing on traits and how they link to ecosystem function. We then conducted a principal component analysis (PCA) to test whether these algal community traits varied across sites and anthropogenic stressors. At sites with high herbivory, algal communities had high tensile strength, high penetration weight and a large volume, whereas algal communities with low herbivory had high surface area to wet weight ratio and large surface areas, suggesting that these traits could be used as predictors of overfishing of herbivorous fish. Similarly, sites with high sedimentation, algae had a large height to wet weight ratio, large surface area to dry weight ratio and large surface area, whereas sites with low sedimentation, algae had smaller height to wet weight ratios and surface areas, suggesting that height to wet weight ratio could be used as a predictor of sedimentation. Lastly, at high nutrient sites, algae had smaller height to wet weight ratios and smaller surface areas, whereas algae from low nutrient sites had larger surface areas and height to wet weight ratios, suggesting that height to wet weight ratio and surface area could be used to predict nutrient levels. Combined, these results suggest that algal community traits can provide insights into local anthropogenic stressors. Future research should include field experiments to demonstrate causal links between these anthropogenic stressors and macroalgal trait variation.
Funder Acknowledgement(s): This research was funded by the NSF through the Gateway program
Faculty Advisor: Paul Barber, email@example.com
Role: I took part in project development including generating an idea, developing methods and project execution. I also performed data analysis and writing the abstract.