By: Erika Nava

I am currently a graduate student working in Dr. Mark Steele’s Fish Ecology Lab at California State University, Northridge. My research is on unintended effects of Marine Protected Areas (MPAs), comparing fish foraging behavior within and outside MPAs in Southern California.

MPAs are usually established to allow organisms and habitats to recover from anthropogenic impacts such as overfishing. As populations rebuild within marine protected areas, the higher population densities may result in resource limitation. Such competition for resources may cause increased mortality, reduced growth rates, or reduced reproduction. While establishment of MPAs has clearly been shown to benefit targeted species in terms of their size and population biomass, it is not well known how these changes affect diet and feeding behavior, as would be expected if food resources become limited in MPAs. I am evaluating whether California sheephead, which is known to have higher biomass in MPAs, is prey limited within them and is shifting its foraging behavior as a result.

I am currently starting my second field season at Wrigley Institute with the support of their Wrigley Summer Fellowship. This summer I will focus on deploying a baited remote underwater video (BRUV) device at six MPAs and their paired non-MPA sites along the Southern California Bight. The BRUVs will allow me to observe fish foraging behavior, without the influence of divers. Since it can be difficult to observe diet with natural observations and impossible to control for prey availability, I use BRUVs to introduce a standardized prey item and observe sheephead’s attraction towards this bait. Since fish densities have increased within MPAs, competition for food might increase therefore I expect fish inside the MPAs to demonstrate higher attraction towards the BRUV.

Most studies on MPAs have focused on evaluating their performance in terms of recovery of targeted species, but few have evaluated how this protection can affect trophic interactions. Fish diet and behavior, for example, might change, and documenting such changes could improve our understanding of how MPAs affect protected species. My research intends to evaluate whether California sheephead is food limited within MPAs in southern California.