Kelp beds as habitat for American lobster Homarus americanus

Abstract

The American lobster Homarus americanus and kelp Laminaria longicruris and L. saccharina are prominent and often intimately associated members of the subtidal community in the western North Atlantic Ocean. However, no one has identified the nature of this relationship or specifically investigated whether kelp beds are a superior habitat for lobsters. We conducted field studies in 1990 and 1991 at a coastal site centrally located along the Gulf of Maine. USA, to determine how lobsters use kelp beds as habitat. Identically sized and spaced plots of live and artificial (plastic) kelp were established and monitored for lobster population densities. Adjacent featureless sediment plots of identical size served as controls. Lobster population density and biomass were significantly higher in both real and artificial kelp treatments than in non-kelp control plots (p < 0 0001). The change in lobster density was apparent the day following placement of the expenment, so a secondary trophic effect such as attracting prey into treatments is unlikely to have occurred. Thus, kelp beds can affect local lobster population dens~ties by providing shelter for lobsters, thereby concentrating individuals and increasing the local carrying capacity of potential lobster habitats The effect of kelp beds on the local carrying capacity of lobster habitats was further explored by test~ng how lobsters respond to differing patch sizes. A graded size series of circular patches of artificial kelp was established, in which kelp blade density and total area were held constant for each treatment. Treatments were subdivided into four 1 m', two 2 m*, or one 4 m2 patches. Experiments were surveyed for lobster population density and size structure to determine if statistical differences existed among treatments. Lobster density was significantly greater in the smallest patches (p c 0.001). Moreover, lobsters typically occupied the edges of kelp beds, and their abundance within kelp patches corresponded to the patch's perimeter-to-area relationship. This suggests that 'edge effects' influence the local carrying capacity for lobsters by influencing the lobsters' choice of kelp beds as habitat.

Community-Wide Effects of Nonindigenous Species on Temperate Rocky Reefs

“…Kelp and associated ma- croalgae are important nursery grounds for fish (Levin 1991, 1994b, Carr 1994, Tupper and Boutilier 1995a, Steneck 1997) and decapods (Bologna and Steneck 1993), and also provide important recruitment habitat for numerous other invertebrate species (Duggins et al 1990). Kelp and associated ma- croalgae are important nursery grounds for fish (Levin 1991, 1994b, Carr 1994, Tupper and Boutilier 1995a, Steneck 1997) and decapods (Bologna and Steneck 1993), and also provide important recruitment habitat for numerous other invertebrate species (Duggins et al 1990).…”

“…We selected these species and functional groups because previous work has demonstrated their importance to other species in kelp bed communities (Levin 1991, 1994b, Bologna and Steneck 1993, Tupper and Boutilier 1995b. Using the same transect procedure described above, we sampled percent cover of L. saccharina, Codium, Ulva lactuca, Chondrus crispus, crustose coralline algae, and filamentous red algae (mostly Ceramium spp.…”

Revealing stock–recruitment relationships in lobsters and crabs: is experimental ecology the key?

“…In these experiments, the challenge is to design the exclosure in such a way as to minimize these artifacts and run parallel control treatments that mimic the experimental treatment in all ways except the predator treatment. Marx and Herrnkind (1985), Eggleston et al (1990, , Mintz et al (1994), , Herrnkind et al (1997), Sosa-Cordero et al (1998) Eggleston and Lipcius (1992) Herrnkind and Butler (1986), Smith and Herrnkind (1992), , Mintz et al (1994), Acosta and Butler (1997), Lipcius et al (1998), Acosta andButler (1999) Forcucci et al (1994), , , Acosta (1999) P. marginatus Hawaii DeMartini et al Bologna and Steneck (1993), Wahle and Incze (1997), Palma et al (1998), Lavalli and Barshaw (1985), Barshaw and Lavalli (1988), Wahle et al (2001) Wahle and Steneck (1992), Barshaw and Able (1990) Krouse (1981), Robichaud and Cambell (1995), Wahle and Incze (1997), Cowan (1999), Comeau et al (1999) H. gammarus Northern Europe Bannister et al (1994), Bannister and Addison (1998), Van der Meeren (2000) Robinson and Tully (2000), Linnane et al…”

Dynamic and spatial models of kelp forest of Macrocystis integrifolia and Lessonia trabeculata (SE Pacific) for assessment harvest scenarios: short‐term responses

“…In turn, the presence of predatory fish such as C. variegatus and P. chilensis, in spite of the fishing pressure exerted on them, could be explained by the fact that kelp offers them a better habitat, more refuges, and more food (Bologna and Steneck, 1993;Anderson et al, 1997). The magnitude of throughput (T) estimated for this ecological system (84 200 g wet weight m À2 year À1 ) (Table 3) is much higher than that calculated for the benthic system in Tongoy Bay (central-northern Chile) (Wolff, 1994;Ortiz and Wolff, 2002b), due to, at least: (1) the inclusion of flows to the pelagic system in the models constructed in the present study; (2) the greater heterogeneity of habitats of the rocky bottoms dominated by brown macroalgae and calcareous algae, allowing more abundant invertebrates and vertebrates; and (3) highly productive marine macroalgae.…”