Marine Conservation Ecology Lab

Department of Biology

San Diego State University

• Seagrass patch edges and predator-prey relationships
• Seagrass fragmentation and blue crabs in Chesapeake Bay
• Effects of seagrass loss on epifaunal communities in San Diego Bay
• Effects of seagrass structural complexity on community composition in San Diego Bay
• Effects of seagrass bed patchiness on scallop behavior and faunal community composition in San Diego Bay

Seagrass patch edges and predator-prey relationships

Personnel: Moore, Eliza (MS student in Hovel lab); Hovel, K.A.; Regan, H.M. (faculty in the Ecology Program Area, SDSU)

Summary: This new project is initially being funded by the San Diego Foundation, a local non-profit organization that provides funds to "help public-spirited citizens find ways to address community problems". In this project, Moore, Hovel, and Regan are investigating how the structrure of eelgrass (Zostera marina) at fine scales and landscape scales influences the behavior of predators and the survival of prey in San Diego Bay. Eliza's thesis, which seeks to distinguish the relative effects of seagrass complexity, edge, and predator pressure on colonization of eelgrass patches, forms part of this project. Additional field work is planned for 2007 in San Diego Bay, and we also will be conducting lab experiments on predator and prey behavior in SDSU's new Coastal Waters Laboratory. Finally, Hovel and Regan have together written an individual-based model in NetLogo that predicts how various behaviors of predators and prey in a patchy environment will influence prey survival. Results from field and laboratory work will allow us to improve upon this initial model.

Publications:

Hovel, K.A. and H. M. Regan. In press. Using an individual-based model to examine the roles of habitat fragmentation and behavior on predator-prey relationships in seagrass landscapes. Landscape Ecology.

Effects of seagrass habitat fragmentation and structural complexity on juvenile blue crab abundance and survival.

Personnel: Hovel, K.A. (with his PhD advisor, Dr. Rom Lipcius, and postdoc advisor Dr. Mark Fonseca).

Location: Chesapeake Bay, Virginia (dissertation work at the Virginia Institute of Marine Science); Beaufort, North Carolina (postdoctoral work at the NOAA/NOS Center for Coastal Fisheries and Habitat Research).

Summary: This project examined how seagrass landscape structure (patchiness, patch size, connectivity) and within-patch structural complexity influence the survival and abundance of juvenile blue crabs (Callinectes sapidus). The primary findings were that seagrass patchiness promotes juvenile blue crab survival, though it is likely that a mixture of patchy and continuous seagrass habitat is necessary to promote blue crab persistence.

Funding for this project was provided by the Willard A. Van Engel scholarship for crustacean research, the Chesapeake Bay Restoration Fund, Sigma Xi, Lerner Gray, and the VIMS Graduate Student Association.

Publications:

Hovel, K.A. and M.S. Fonseca. 2005. Influence of seagrass landscape structure on the juvenile blue crab habitat-survival function. Marine Ecology Progress Series 300: 179-191.

Hovel, K.A. 2003. Habitat fragmentation in marine landscapes: relative effects of seagrass cover and configuration on juvenile crab survival in California and North Carolina seagrass beds. Biological Conservation 110: 401-412

Hovel, K.A., M.S. Fonseca, D.L. Meyer, W.J. Kenworthy, and P.G. Whitfield. 2002. Effects of seagrass landscape structure, structural complexity and hydrodynamic regime on macrofaunal densities in North Carolina seagrass beds. Marine Ecology Progress Series 243: 11-24.

Hovel, K.A. and R.N. Lipcius. 2002. Effects of seagrass habitat fragmentation on juvenile blue crab survival and abundance. Journal of Experimental Marine Biology and Ecology 271: 75-98.

Hovel, K.A. and R.N. Lipcius. 2001. Habitat fragmentation in a seagrass landscape: patch size and complexity control blue crab survival. Ecology 82: 1814-1829.

Effects of seagrass disturbance and loss on epifaunal diversity and community composition in San Diego Bay

Personnel: Reed, Brendan (MS student in Hovel lab, graduated in 2005)

Summary: Brendan's project examined how the loss of seagrass from donor beds used in seagrass restoration influences the diversity and composition of the community of fauna in those beds. The major findings were that, in isolated areas within a large Zostera marina bed, a loss of over 50% of the habitat was necessary to reduce diversity and alter community composition of epifauna. However, the effects of even moderate levels of seagrass loss on epifaunal communities may be great in small seagrass beds.

Funding for this project was provided by the Port of San Diego and the San Diego State University Research Foundation.

Publications:

Reed, B.J. and K.A. Hovel. 2006. Seagrass habitat disturbance: how loss and fragmentation of eelgrass (Zostera marina) influences epifaunal abundance and diversity in San Diego Bay, California, USA. Marine Ecology Progress Series 326:133-143.

Effects of seagrass structural complexity on epifaunal diversity and community composition in San Diego Bay

Personnel: Sirota, Lindsay (MS student in Hovel lab, graduated in 2005)

Summary: Lindsay's project examined the effects of eelgrass shoot density, shoot length, and surface area on the diversity and composition of epifaunal communities. Her major innovation was to design simulated eelgrass patches in which she factorially varied the density and length of artificial eelgrass shoots, such that she could determine whether the quality of the habitat (shoot density and length) or the quantity of the habitat (shoot surface area) had a larger influence on the epifaunal community. Her major findings were that most species responded strongly to the quantity of the habitat available (e.g., plots with the most habitat were most heavily colonized by epifauna such as shrimps, crabs, isopods, amphipods and fishes), but that habitat quality played a role in dictating the abundance of selected species, particulary at the time of recruitment.

Funding for this project was provided by the Port of San Diego and the San Diego State University Research Foundation.

Publications:

Sirota, L. and K.A. Hovel. 2006. Eelgrass (Zostera marina) structural complexity: relative effects of shoot length, shoot density, and surface area on epifaunal community composition in San Diego Bay, California, USA. Marine Ecology Progress Series 326: 115-131.

Seagrass patchiness: effects on epifaunal communities and the movement and survival of speckled scallops in San Diego Bay

Personnel: Healey, Danielle (MS student in Hovel lab, graduated in 2005)

Summary: For her project, Danielle investigated how the "breaking apart" of seagrass patches influenced the diversity and abundance of common epifaunal species in south San Diego Bay. She found that increasing fragmentation of seagrass patches promoted, or did not reduce the diversity of seagrass epifauna. In the second part of her theses, Danielle investigated how the amount of habitat (manipulated through patch size) and configuration independently influenced mortality and emigration of speckled scallops (Aequipecten aequisculatus). She found that patch size and configuration both influenced emigration and mortality of scallops, although variability was high both within and among treatments and through time. Overall, decreases in patch size strongly increased mortality while effects on emigration were less consistent.

Publications:

Healey, D. and K.A. Hovel. 2004. Seagrass patchiness influences epifaunal abundance and diversity in San Diego Bay, USA. Journal of Experimental Marine Biology and Ecology 313: 155-174.

KAH January 3, 2007

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