The Impacts of Coastal Headlands on Larval Supply and Habitat Quality: Implications for Marine Reserves

EPA Grant Number: F6E21119
Title: The Impacts of Coastal Headlands on Larval Supply and Habitat Quality: Implications for Marine Reserves
Investigators: Wood, Megan Elisha
Institution: Sonoma State University
EPA Project Officer: Jones, Brandon
Project Period: September 1, 2006 through September 1, 2008
Project Amount: $73,542


The objective of this research is to understand the regional population dynamics of an intertidal species with a pelagic larval phase by incorporating the contributions from all of the habitat types utilized by the species and determine whether small-scale coastal features impact larval supply and habitat quality. Due to differences in landscape features or anthropogenic impacts, local populations experience different recruitment rates, individual growth rates, predation pressure, and competition. I will measure the demographic effects of these coastal features and predict the relative contribution of exposed and protected populations to the regional population. Understanding the relative contributions of populations in different habitat types to regional dynamics can help managers spatially allocate habitat conservation priorities.


I will investigate the relationship between local demographics and regional population dynamics using a species that is found in both exposed and protected habitats. Because it uses both habitat types created by headlands, this organism can provide a “common currency” to compare differences in larval supply, habitat quality, and post-settlement processes between protected and exposed habitats. I plan to investigate how exposed and protected habitats contribute to the Petrolisthes cinctipes regional population by examining habitat quality and larval supply. At each research site, I will measure larval supply and settlement, phytoplankton abundance and suspended sediments, individual P. cinctipes growth and reproductive output, predator abundance and predation rate on P. cinctipes. Examining these factors will provide information on whether small-scale coastal features create habitat differences, how these habitat differences influence local P. cinctipes populations, and how these differences in local populations contribute to regional-scale dynamics.

Expected Results:

I expect to find that the exposed sites are higher quality habitat having higher food supply, lower sedimentation and fewer predators (or lower rates of predation). However, the high flow environment may also reduce larval supply, and interspecific competition could reduce individual P. cinctipes growth. I expect that the protected sites may be poorer quality habitat having lower food supply, higher sedimentation and more predators. However, oceanographic processes may accumulate large amounts of larvae in protected areas and the lack of interspecific competition could increase individual growth. Therefore, protected habitat may provide a low quality/low variance habitat, while exposed habitat provides a high quality/high variance habitat. How these factors impact reproductive output is key to understanding the relationship between local and regional scale population dynamics. Headlands may create a natural landmark for reserve placement, incorporating multiple habitat types that are important not only for exporting larvae but also for receiving larvaeconsistently enough to maintain the regional population.

Supplemental Keywords:

Ecology, marine conservation, invertebrates, population dynamics, regional population, marine protected areas, marine reserves, rocky intertidal, multiple habitats, pelagic larvae, larval supply, habitat quality, reproductive output, recruitment, population management,, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Habitat, Environmental Monitoring, Ecology and Ecosystems, marine ecosystem, habitat dynamics, community composition, anthropogenic stressors, coastal species, habitat preservation, habitat population structure