The role of behavioral responses to predators in modifying urchins' (Strongylocentrotus droebachiensis) destructive grazing and seasonal foraging patterns

Bernstein, Brock B.; Williams, B.; Mann, K. H.

doi:10.1007/bf00394661

Cited by 153 publications

(82 citation statements)

References 19 publications

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“…Massive urchin aggregations of the genus Strongylocentrotus have been widely reported to overgraze giant kelp forests (e.g. Bernstein et al 1981, Hart & Scheibling 1988, Tegner et al 1995, Scheibling et al 1999. Heavy grazing by the sea urchin Paracentrotus lividus can mediate the transition of assemblages from erect algae to coralline barrens in the Mediterranean Sea (Sala et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Effects of sea urchin grazing on seagrass (Thalassodendron ciliatum) beds of a Kenyan lagoon

Alcoverro

Mariani²

2002

Mar. Ecol. Prog. Ser.

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Section: Introductionmentioning

confidence: 99%

Effects of sea urchin grazing on seagrass (Thalassodendron ciliatum) beds of a Kenyan lagoon

Alcoverro

Mariani²

2002

Mar. Ecol. Prog. Ser.

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“…Large-scale, destructive grazing, or overgrazing, by sea urchins does not appear to occur with either the frequency or magnitude in seagrass communities as in kelp forests (e.g. Breen & Mann 1976, Bernstein et al 1981), though the role of sea urchins on overfished coral reefs can become increasingly important in lirniting the distribution and abundance of algae and sea-grasses adjacent to the reef when densities increase due to the absence of predatory fishes (Hay 1984). Few small-scale, seagrass overgrazing events have been reported (e.g.…”

Section: Introductionmentioning

confidence: 99%

Overgrazing of a large seagrass bed by the sea urchin Lytechinus variegatus in Outer Florida Bay

Rose¹,

Sharp²,

Kenworthy³

et al. 1999

Mar. Ecol. Prog. Ser.

123

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Unusually dense aggregations of the sea urchin Lytechinus variegatus overgrazed at least 0.81 kmz of seagrass habitat in Outer Florida Bay (USA) between August 1997 and I\,Iay 1998. Initially, sea-urchin densities were as high as 364 sea urchins m-', but they steadily declined to within a range of 20 to 50 sea urchins m-2 by December 1998. Prior to this event, sea-urchin densities were <1 sea urchin m-2 in this area of Outer Florida Bay. Seagrasses in Outer Florida Bay consist primarily of manatee grass Syringodium filiforme. of which 82% or 390 g dry weight rn-2 of total seagrass biornass and >95% of the short-shoot apical menstems were removed by sea-urchin grazing in our study area. Such extensive loss may severely limit recovery of this seagrass comrnunity by vegetative reproduction. Effects of the removal of seagrass biomass have already resulted in the depletion of epifaunal-infaunal mollusk assemblages and resuspension of fine-grained (<64 pm) surface sediments-which have caused significant changes in cornrnunity structure and in the physical properties of the Sediments. These changes, coupled with the loss of essential fishery habitat, reductions in primary and secondary production, and degradation of water quality, may lead to additional, longer-term, indirect effects that may extend beyond the boundaries of the grazed areas and into adjacent coastal ecosystems.

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“…Running responses are very common in motile benthic invertebrates (Feder 1963, Ansell 1969, Schmitt 1981, McKillup 1982. Motility also allows prey to use temporary refuges, thereby reducing exposure to predation (Hall et al 1970, Nelson & Vance 1979, Wells 1980, Bernstein et al 1981, Menge & Lubchenco 1981, Hines & Pearse 1982. These responses may have important consequences for prey distributions and the organization of the prey assemblage (Vance 1979, Markowitz 1980, Menge & Lubchenco 1981, Schmitt 1982, Fawcett 1984.…”

Section: Introductionmentioning

confidence: 99%

“…In spite of motility-related defenses, predation on motile species has been reported to be important in some communities. In temperate subtidal habitats, sea otters, fish, and crabs may drastically reduce the abundance of urchins (Muntz et al 1965, Duggins 1980, Bernstein et al 1981) a n d abalone (Hines & Pearse 1982). Slower-moving predators such as seastars may affect gastropod (Paine 1969, Schmitt 1982 and urchin (Bernstein et al 1981) distnbutions and abundances.…”

Section: Introductionmentioning

confidence: 99%

Effects of octopus predation on motile invertebrates in a rocky subtidal community

Ambrose¹

1986

Mar. Ecol. Prog. Ser.

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Octopus birnaculatus, a common member of intertidal and subtidal communities in southern California, consumes many motile benthic invertebrate species, including snails, chitons, h p e t s , bivalves, and crustaceans. An analysis of octopus d d holes in empty snail shells indicates that 0. bimaculatus is a major s n d predator in the community. The addition of marked snails to a natural reef with unmanipulated octopus densities demonstrated that octopuses can quickly reduce s n d abundances, consuming 24 % of the available snails within 24 d. During 5 yr at 1 site, octopus abundance declined from 40 to 8 octopuses, while total prey abundance increased from 16 to 80 ind m-'. A second site experienced a similar drop in octopus density and increase in prey density over 3 yr. At both sites, snails and hermit crabs showed the greatest increases. Sedentary grazers, bivalves, and crabs and shrimps occurred at low densities throughout, possibly because the abundances of these preferred prey were depressed by octopus predation even during years of low octopus density. In splte of the strong negative association at the 2 sltes between octopus and prey over time, for a single time penod at 15 different s~t e s prey densities were not negatively correlated w t h the densities of their predators. However, octopus densities were much higher when they appeared to reduce the abundances of their prey than when the 15 different sites were sampled. I conclude that octopus predation can dramatically reduce prey densities when octopuses are unusually common, but that in most years the abundance of octopuses 1s too low to disrupt the basic patterns of prey abundance that result from other processes. The hghest prey species richness and diversity at the 2 study sites occurred during years of lowest octopus densities. Species richness, chversity and evenness of the prey assemblage were not correlated with octopus, lobster or predatory gastropod abundances at the 15 different locations; when the effects of habitat structure were held constant by partial correlation, seastar abundance was negatively correlated with species nchness and diversity. The relation between predation and species chversity suggests that, when predation is effective in this assemblage, it decreases diversity.

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The role of behavioral responses to predators in modifying urchins' (Strongylocentrotus droebachiensis) destructive grazing and seasonal foraging patterns

Cited by 153 publications

References 19 publications

Effects of sea urchin grazing on seagrass (Thalassodendron ciliatum) beds of a Kenyan lagoon

Effects of sea urchin grazing on seagrass (Thalassodendron ciliatum) beds of a Kenyan lagoon

Overgrazing of a large seagrass bed by the sea urchin Lytechinus variegatus in Outer Florida Bay

Effects of octopus predation on motile invertebrates in a rocky subtidal community

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