Marine Conservation Ecology Lab

Department of Biology

San Diego State University

• Effects of kelp forest habitat structure on spiny lobster abundance and survival
• Movement rates of spiny lobsters in kelp forest and surfgrass habitat
• Spiny lobster survival and behavior inside and outside of the La Jolla Ecological Reserve

Effects of kelp forest habitat structure on spiny lobster abundance and survival

Personnel: Mai, Thien (MS student in Hovel lab, graduated in 2006); Loflen, Chad (former BS student in Hovel lab, now MS student in Hovel lab)

Summary: Thien's master's thesis project examined how habitat structure at fine scales (the scale of individual shelters) and at landscape scales (the dispersion and abundance of shelter in broader areas) influence the abundance of juvenile and adult spiny lobsters in the Pt. Loma kelp forest. Working in twelve 50 m x 50 m landscapes, Thien, with help from Chad Loflen, mapped out all available lobster shelters, and then characterized each shelter in terms of size and composition. Thien then surveyed each landscape several times and recorded lobster shelter use and size distribution. Thien found that the best predictor of lobster abundance was not shelter type or shelter dispersion, but rather the amount and type of understory algae in the kelp forest. Lobster tethering revealed that relative survival was higher under algae than when no algal cover was present. His research indicates the large role of understory algae plays in lobster ecology, which corresponds to recent findings from our California Sea Grant funded project on lobster movement.

Funding for this project was provided by the San Diego Foundation and California Sea Grant.

Publications:

Mai, T.T. and K.A. Hovel. Influence of local-scale and landscape-scale habitat characteristics on California spiny lobster (Panulirus interruptus) abundance and survival. Submitted to Journal of Marine and Freshwater Research.

Movement rates of spiny lobsters in kelp forest and surfgrass habitat

Personnel: Hovel, K.A.; Lowe, Chris (faculty at CSU Long Beach); Loflen, Chad (former BS student in Hovel lab, now MS student in Hovel lab); Palaoro, Kristian (former SDSU undergraduate and field technician in Hovel lab).

Summary: I am collaborating with Dr. Chris Lowe of CSU Long Beach on a project to determine the effect of habitat structure in the Pt. Loma kelp forest on spiny lobster nocturnal movements. Spiny lobsters remain in shelter during the day, but leave shelters at dusk to forage. We are testing hypotheses about the effects of shelter location, type, and size on the propensity of lobters to home to shelters and the distances that they travel to forage at night. In 2005 and 2006 we tagged lobsters with sound emitting (sonic) tags, and used hydrophones to track lobsters from dusk to dawn. We have found that lobsters travel average distances of ca. 600 m each night, and readily move between kelp forest and surfgrass habitats. They also appear to follow corridors of algae (kelp) as they move, avoiding open areas devoid of kelp cover. Many lobsters settled into patterns of short-distance movements and established new home ranges after long-distance initial movements. This project will be continuing in 2007-2009 with continued funding from California Sea Grant.

Presentations:

2006. Center for Environmental Analysis-Centers for Research Excellence in Science and Technology, 7th Annual Conference, CSU Los Angeles. Shelter use and movement of California spiny lobsters in a southern California kelp forest.

Loflen, C.L. and K.A. Hovel. 2006. Does the La Jolla ecological reserve protect California spiny lobsters? Western Society of Naturalists 87th annual meeting, Redmond, WA.

Hovel, K.A. and C.G. Lowe. 2005. Shelter use and movement of spiny lobsters in a southern California kelp forest. Western Society of Naturalists 86th annual meeting, Monterey, CA.

Spiny lobster survival and behavior inside and outside of the La Jolla Ecological Reserve

Personnel: Loflen, Chad (former BS student in Hovel lab, now MS student in Hovel lab); Palaoro, Kristian (former SDSU undergraduate and field technician in Hovel lab).

Summary: For his master's thesis project, Chad is investigating how variable predation pressure influences the survival and behavior of California spiny lobsters. The La Jolla Ecological Reserve differs from surrounding kelp forest habitat, such as the Pt. Loma kelp forest, in that large predatory fishes are more abundant within the reserve. Chad has found that relative survival rates of spiny lobsters are far higher outside of the reserve than inside the reserve. Moreover, lobster behavior appears to differ between the two locations; lobsters appear to form larger aggregations and use larger shelters that permit larger aggregations inside the reserve.

Presentations:

Loflen, C.L. and K.A. Hovel. 2006. Does the La Jolla ecological reserve protect California spiny lobsters? Western Society of Naturalists 87th annual meeting, Redmond, WA.

KAH January 4, 2007

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