RUI: Scale-Dependence of Flow Effects on Coral Reef Community Primary Production

The University Corporation, Northridge, Northridge CA

Investigators

Abstract

Understanding the control of material fluxes in marine environments is a major goal of oceanography. In coastal marine environments, there is a growing appreciation for the role of hydrodynamics in modulating these fluxes. Coral reefs are among the most productive ecosystems in the ocean and water flow is central to maintaining high rates of photosynthesis in reef primary producers. On many reefs the major primary producing component is comprised of free-living algae that form a thin veneer over dead coral. Rates of photosynthesis by reef algal turfs on spatial scales of tens of centimeters are enhanced significantly by water motion, and similar patterns have been demonstrated for rates of nitrogen fixation. Metabolic and nutrient uptake processes of other reef organisms are also positively related to flow speed on similar spatial scales. This project will develop a more complete understanding of the role of water flow in modulating coral reef primary production by: 1) examining the generality of how flow effects reef community primary production at larger spatial scales and how surface roughness affects this relationship, and, 2) investigating in more detail the small-scale interactions between algal turf physical structure, flow, and boundary layer dynamics, as this will allow a coupling between the ecological process of disturbance and the physical processes of hydrodynamics and mass transfer. Using both correlational and experimental methods, explicit hypotheses about the effects of flow, shear stress, and roughness on net community primary production at several spatial scales will be tested. Broader impacts include a significant contribution to the development of human resources in marine science via training of both undergraduate and graduate students and a postdoctoral researcher, and better understanding of flow effects on a critical marine ecosystem.