LACK OF POST-HURRICANE IMPACTS ON ALGAL BIOFILMS IN TWO TROPICAL HEADWATER STREAMS IN PUERTO RICO
In tropical streams, large-scale disturbances such as hurricanes can increase light availability through defoliation, influencing the response of algal primary producers. After Puerto Rico was struck by two successive Category 4 hurricanes (Irma and Maria) in September 2017, we examined the response of algae to canopy defoliation in two headwater streams draining the El Yunque National Forest. We predicted increases in algal standing crop in response to greater light availability. Building on our 15-year dataset of algal standing crop at the reach scale, we quantitatively sampled algae along a 100 m reach of each stream. Contrary to our initial prediction, algal standing crop did not increase post-hurricane, as was observed in 1989 in response to large-scale defoliation by Hurricane Hugo. We attribute the lack of increase in chlorophyll a to repeated high discharge events (increased “flashiness” with storm events) following Hurricanes Irma and Maria. In contrast, Hurricane Hugo was followed by drought and the lack of scouring events resulted in visibly high algal standing crop. Our study highlights the importance of the interacting effects of disturbance events such as hurricanes with droughts and high discharge events.
Amber Faulkner (Co-Presenter/Co-Author), University of Georgia, firstname.lastname@example.org;
Pablo Gutierrez (Co-Presenter/Co-Author), University of Puerto Rico,
Pedro J Torres (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, email@example.com;
Alonso Ramirez (Co-Presenter/Co-Author), North Carolina State University, firstname.lastname@example.org;
Catherine Pringle (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, email@example.com;
Kelsey Morton (Primary Presenter/Author), University of Georgia, firstname.lastname@example.org;