A hurricane alters the relationship between mangrove cover and marine subsidies

Abstract

As global change alters the composition and productivity of ecosystems, the importance of subsidies from one habitat to another may change. We experimentally manipulated black mangrove (Avicennia germinans) cover in 10 large plots and over a 5-year period (2014-2019) quantifying the effects of mangrove cover on subsidies of floating organic material (wrack) into coastal wetlands. As mangrove cover increased from 0% to 100%, wrack cover and thickness decreased by ~60%, the distance that wrack penetrated into the plots decreased by ~70%, and the percentage of the wrack trapped in the first 6 m of the plot tripled. These patterns observed during 4 "normal" years disappeared in a fifth year following Hurricane Harvey (2017), when large quantities of wrack were pushed far into the interior of all the plots, regardless of mangrove cover. Prior to the storm, the

The Dynamic Nature of Wrack: An Investigation into Wrack Movement and Impacts on Coastal Marshes Using sUAS

“…The high-water levels, storm surge, and strong winds from Hurricane Isaias caused wrack mats to enter into regions of the study area where wrack was not found before the storm passed, nor after for the rest of the study. As Peng et al (2022) [40] observed from Hurricane Harvey, a strong storm can move wrack deeper into a wetland than otherwise found during other normal conditions. The largest clusters of wrack were found on the western edge of the study area, close to largest nearby water body-the Harbor River.…”

“…In each of those respective studies, they established the opportunity for wrack to benefit the overall system, despite the time required for these to be had. Even simple identification of wrack falling beneath the canopy in our study suggests a positive impact because the matted down wrack can now serve as a home to several species of aquatic creatures [40,45]. It has even been suggested by one researcher that the warm climate found on the South Carolina coast can enhance the decomposition of wrack detritus to benefit the entire salt marsh [25].…”