Marine Conservation Ecology Lab

Department of Biology

San Diego State University

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American lobster projects:

Effects of cobble habitat structure on juvenile American lobster abundance, survival, and movement

Personnel: Hovel, K.A.; Wahle, R.A. (researcher at the Bigelow Laboratory for Ocean Sciences in Boothbay Harbor, Maine); Selgrath, Jennifer (former MS student in Hovel lab); Brown, Curt (MS student at University of Maine); numerous interns including Tom Langley, Caitlin Luderer, Anthony Bellantuono, Adam Frantz, Jeff Mercer, George Sharrard, Richard Crowley, and Jackie Bowie.

Summary: This project is a collaboration between Dr. Hovel and Dr. Rick Wahle, and has been funded by the National Science Foundation and the NOAA National Undersea Research Foundation. The main goal of the project is to determine whether a demographic bottleneck exists for American lobsters in New England. A bottleneck may exist for lobsters if there is a limitation of shelter during the juvenile phase, a point in the life history in which lobsters are vulnerable to a variety of predators, particularly fishes. We are using manipulative experiments and surveys located throughout New England to determine the degree of shelter limitation for lobsters, and the consequences of being without shelter (using tethering). We also have been determining the effects of cobble habitat fragmentation on lobster movement and survival. The experiments and surveys took place during the summers of 2003 - 2005. One of the innovations of the project is that our experiments and surveys were conducted within four major regions of New England, from eastern Maine to Rhode Island. In this way, we are able to take advantage of major environmental gradients that exist throughout coastal New England waters, including a gradient in predator abundance (our initial surveys confirmed that predatory fish abundance and diversity are higher in southern New England than in northern New England). Some of the major findings include: (i) lobsters relative survival varied more among sites within regions than among regions; (ii) across all regions of New England, cobble habitat fragmentation reduces the propensity of lobsters to move from shelter; and (iii) lobsters are most shelter limited where their densities are highest, in mid-coast Maine.

Selected presentations:

Hovel, K.A. and R.A. Wahle. 2006. Scripps Institution of Oceanography, La Jolla, CA. Linking lobsters with benthic landscapes: controls on American lobster population dynamics in New England waters

Selgrath, J.C., K.A. Hovel and R.A Wahle. 2006. Cobble habitat configuration influences American lobster abundance in New England. 21st annual symposium of the US Regional Chapter of the International Association for Landscape Ecology, San Diego, CA.

Selgrath, J.C., K.A. Hovel, and R.A. Wahle. 2005. Edge effects on American lobster (Homarus americanus) survival and abundance. Western Society of Naturalists 86th annual meeting, Monterey, CA.

Hovel, K.A. and R.A. Wahle. 2005. Regional patterns of juvenile American lobster shelter use, mortality, and movement. Benthic Ecology Meeting, Williamsburg, VA

Brown, C., R.A. Wahle, K.A. Hovel, and J. Selgrath. 2005. Predators of the American lobster in New England. Benthic Ecology Meeting, Williamsburg, VA

Hovel, K.A. and R.A. Wahle. 2004. Regional patterns of juvenile American lobster shelter use, mortality, and movement. Western Society of Naturalists 85th annual meeting, Rohnert Park, CA

A juvenile American lobster with t-bar tag (lower right corner) about to be deployed within an experimental cobble array.
A lobster within an artificial shelter deployed as part of our shelter supplementation experiment to determine if lobsters are shelter limited.

Effects of cobble patch edges on American lobster abundance and survival

Personnel: Selgrath, Jennifer C. (former MS student in Hovel lab, now PhD student at the University of British Columbia, Vancouver, Canada).

Summary: Jennifer was involved in two studies for her master's thesis, this project and the one listed below. In this project, Jennifer designed and conducted a study to determine the effect that cobble patch edges have on American lobster abundance and survival. Cobble habitat in shallow water is patchy, and may be bordered by seagrass or unvegetated sediment. Working in Rhode Island with funding from NSF, Jennifer performed surveys for lobsters to determine how proximity to cobble patch edges and the type of edge (seagrass vs. unvegetated) inflluenced lobster abundance, and she performed tethering experiments to determine how promixity to edge and type of edge influenced lobster survival. She found that the effect of edges on lobsters depended on lobster size; larger lobsters were more likely to be near patch edges, and smaller lobsters were more likely to be found away from edges. Habitat type had strong influences on lobster survival, with high lobster survival in cobble and seagrass, and lower survival in unvegetated sediment, but proximity to edge did not influence lobster survival.

Publications:

Selgrath, J.C, K.A. Hovel, and R.A. Wahle. In prep. Effects of habitat edges on American lobster abundance and survival.

Selected presentations:

Selgrath, J.C., K.A. Hovel, and R.A. Wahle. 2005. Edge effects on American lobster (Homarus americanus) survival and abundance. Western Society of Naturalists 86th annual meeting, Monterey, CA.

 

A tethered juvenile lobster. This lobster has lost part of its right claw to a predator.

Regional variability in American lobster abundance in deep water habitat

Personnel: Selgrath, Jennifer C (former MS student in Hovel lab, now PhD student at the University of British Columbia, Vancouver, Canada); Wahle, R.A. (researcher at the Bigelow Laboratory for Ocean Sciences in Boothbay Harbor, Maine); Hovel, K.A.; Belknap, Dan (professor of geology, University of Maine) Gontz, Allen (former PhD student at the University of Maine, now an assistant professor at the University of Massachusetts).

Summary: Little is known about the effects of habitat on American lobsters in general, let alone in waters that are too deep for SCUBA-based surveys and experiments. In this NOAA National Undersea Research Foundation-funded project, we teamed up with geologists from the University of Maine to map rocky habitat in deep coastal waters (ca. 20 - 60 m deep) and then survey these habitats for lobsters using a remotely operated vehicle (ROV) owned by NURP. Our mapping and lobster surveys took place in eight separate regions of New England, from Rhode Island to Mt. Desert, Maine, and occurred in summer 2003 and 2004. Jennifer Selgrath based a portion of her masters thesis on this project, and she used GIS to quantify cobble habitat structure for lobsters among the eight regions, and then to determine the relationship between lobster sightings and cobble habitat structure. We found that lobsters primarily inhabited cobble patch edges, and that lobster abundance was correlated with increasing fragmentation of cobble habitat.

Publications:

Selgrath, J.C., K.A. Hovel, and R.A. Wahle. In prep. Benthic habitat configuration influences the abundance of American lobsters.

Selected presentations:

Selgrath, JC, K.A. Hovel, and RA Wahle. 2006. Hot lobster destinations: American lobster distribution in coastal New England. Western Society of Naturalists 87th annual meeting, Redmond, WA.

The RV Connecticut was our research ship in 2003 and 2004
The ROV is lowered into the wate in preparation for a dive to survey for lobsters.

KAH January 3, 2007

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The statements found on this page/site are for informational purposes only. While every effort is made to ensure that this information is up to date and accurate, official information can be found in the university publications. Comments can be addressed to Kevin Hovel at: hovel@sciences.sdsu.edu