Habitat fragmentation is the breaking up of contiguous regions into smaller patches. Seagrass fragmentation can occur from disturbances such as storms, nutrient loading, or coastal development, often negatively impacting vital nursery habitat. The transition to increased patches creates more habitat edge and less interior habitat. Shifts between ratios of interior habitat to edge may lead to shifts in community diversity and abundance as edges have altered physio-chemical properties and species interactions. However, edge effects are not uniform across habitats and space. The lack of clear consensus on the definition of an edge limits synthesis and comparison across studies. There is a need to determine specific distances from the habitat edges at which organisms are affected and how that may vary by mobility or life history traits. Our goal is to use seagrass ecosystems to understand edge effects driving organismal response to habitat fragmentation. In order to quantify organismal responses, we collected twelve variables from the edge of turtle grass (Thalassia testudinum) to the bed interior along ten meter transects on the Texas coast. These variables ranged from seagrass morphometrics to community diversity.
Results/Conclusions
Preliminary results indicate there is no statistical difference in rates of predation events based on distance from the edge. Seagrass had increased biomass, longer blade width and height with increasing distance from the edge. Species evenness was constant throughout; however, we found higher species richness along the seagrass edge as well as a higher abundance of bivalves and polycheates. These results show a denser seagrass bed with lower flow rates with increased distance from the edge. This supports the concept that larger, more mobile organisms are likely responding at a larger scale to the edge than less mobile organisms. Understanding the scales at which organisms respond to habitat edge is critical for future seagrass studies to choose the correct distances for edge effects based on the study objective.