Award: OCE-2126729

Human actions impact marine ecosystems in a variety of ways, including shifting wave and current dynamics through global warming and altering the composition of the ocean floor. These changes, in turn, affect the location and distribution of marine communities. For soft-sediment communities, such as sandy beaches, the interaction between fluid forces and sediment disturbance is well understood. This allows scientists to measure sediment mobility and to create detailed predictions of the impact of human activities on these ecosystems. Prior to this research, there were measurements analogous to sediment mobility available for marine hard rock ecosystems. This research investigated a potential measurement system which connects the forces of waves and currents to the resulting erosion of hard rock substrates and tested and evaluated how these disturbance patterns govern the distribution of communities themselves. By developing and testing this substrate mobility metric, this research opened new avenues of investigation for core ecological hypotheses. In addition, this work will allow managers, conservationists, and engineers to better predict the impact of human-generated change on hard rock marine communities. This project supported the training and education of groups underrepresented in the geosciences for three undergraduates and two graduate students through (1) field and data analysis via Research Experiences for Undergraduates summer programs and graduate level field data collection and management, (2) professional development via mentoring relationships between the fellow and graduate and undergraduate trainees, and (3) the expansion of their professional network via cross-institutional coordination.

Disturbance, including fluid forces via waves on rocky shores, is well understood as a community organizing and structuring force. Foundational concepts within ecology, such as Connell’s Intermediate Disturbance Hypothesis and Menge and Sutherland’s Competition/Predation/Disturbance model, recognize that communities exist within a complex mosaic of physical and biological disturbance. This mosaic presents challenges when measuring disturbance regimes since the scales, causes, and consequences of disturbance vary between systems. However, in the marine environment, substrate mobility represents an explicit measure of disturbance impact present across marine ecosystems. This project determined how to measure substrate mobility on hard substrates through collaboration with USGS geologists. In addition, this research investigated a mechanism for disturbance via substrate mobility on benthic organisms through lab experiments and used field surveys to compare patterns of substrate mobility with the distribution of benthic communities and species functional groups. Explicitly quantifying the realized movement of hard substrate in response to fluid-forcing integrates hard substrates into the already well understood sediment disturbance paradigm. This results in a universal framework of marine disturbance that is potentially revolutionary as it allows for comparative questions spanning a huge diversity of marine ecosystems, from coral reefs to the abyssal plain. This mechanistic framework provides a new connection between the disciplines of geomorphology and marine ecology.

Last Modified: 12/10/2024
Modified by: Allison N Cramer