Benthic community modification and recovery following intensive grazing byStrongylocentrotus droebachiensis

Foreman, R. E.

doi:10.1007/bf02207855

Cited by 92 publications

(55 citation statements)

References 14 publications

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“…They are often aggregated (see Lawrence 1975, Warner 1979, Sloan 1980, Lawrence & Sammarco 1982 for reviews) and populations may fluctuate in density with time (Lang & Mann 1976, Foreman 1977, Andrew & Choat 1982see Lawrence 1975, Lawrence & Sammarco 1982, Ebert 1983 for reviews). Because of these general features of their ecology sea urchins have been conspicuous in studies that seek to isolate and explain the processes that structure marine communities.…”

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confidence: 99%

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Contrasting ecological implications of food limitation in sea urchins and herbivorous gastropods

Andrew¹

1989

Mar. Ecol. Prog. Ser.

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Populations of sea urchins often fluctuate greatly in density. The density of sea urchins is usually inversely correlated with the abundance of macrolagae. It is argued that fluctuations in density are a predictable consequence of the unique morphology and physiology of sea urchins. An extraordinary ability to accomodate food Limitation through variations in growth rate means that surv~vorship and food abundance are largely decoupled. These features of sea urchins differ from those of the herbivorous gastropods. The ecological implications of these differences are discussed. A different perspective is required for the interpretation of the population dynamics of sea urchins.

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confidence: 99%

“…Variable recruitment has been documented in both echinoids and gastropods (Ebert 1968, Foreman 1977; see Underwood 1979, Ebert 1983 for reviews); however, the consequences will differ considerably between groups. The morphology and physiology of the echinoids would, all else being equal, allow a greater survivorship than would occur in gastropods.…”

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confidence: 99%

Contrasting ecological implications of food limitation in sea urchins and herbivorous gastropods

Andrew¹

1989

Mar. Ecol. Prog. Ser.

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“…The importance of large kelps in influencing seaweed community development and characteristics has been noted by Paine & Vadas (1969), Kain (1975) and Foreman (1977). Their studies addressed secondary succession on substrate cleared by divers or intensive sea urchin grazing, but conceivably, harvesting of a Lamlnaria canopy could alter the diversity and stability of the understory community and resilience of the Laminaria population.…”

Section: Discussionmentioning

confidence: 99%

Recovery following experimental harvesting ofLaminaria longicruris andL. digitata in southwestern Nova Scotia

Smith

1985

Helgolander Meeresunters

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Laminaria population variables and understory community composition were monitored just prior to, and for two summers following, a September 1980 experimental total harvest of L. longicruris De la Pylaie and L. digitata (L.) Lamouroux within two plots in Lobster Bay, Nova Scotia. Both plots, distinguished mainly by depth, were characterized by high Laminaria standing crop and no recent history of extensive sea urchin grazing. Within the shallower plot (2-3 m below MSL), recovery could not be assessed thoroughly due to ice damage, but within the deeper plot (3--4m below MSL), L. longicruris regrew cropped biomass and attained maximum observed abundance within one year. Both Laminaria species required two years to mature to pre-harvest population characteristics. Survivorship of 0-1 year old and mature populations of both species was generally low (0--67 % per year); however, the higher maximum life expectancy of L. digitata (> 4 years vs 2 years) can result in that species persisting to the disadvantage of L. longicruris. Analysis of understory community composition for both harvested plots and their adjacent controls weakly distinguished the harvested plots one summer after harvesting from all others. It is doubtful the distinction is attributable to harvesting and in neither site was there evidence of a critical change in the understory community. Management implications for the commercial harvest of the brown alga Laminaria are discussed.

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“…This generalization is based, in part, on evidence indicating that outbreak populations of sea urchins can decimate large kelp forests (Leighton et al 1966, Leighton 1971, Breen & Mann 1976, Foreman 1977, Hagen 1983 and maintain a barren community configuration dominated by crustose coralline algae (Chapman 1981); and, in part, on evidence indicating that reduced grazing pressure in such barren grounds invariably triggers rapid recolonization of kelp (Breen & Mann 1976, Pearse & Hines 1979, Duggins 1980, Andrew & Choat 1982, Breen et al 1982, Hirnrnelman et al 1983, Dayton et al 1984, Miller 1985b, Novaczek & McLachlan 1986, Scheibling 1986, Hughes et al 1987, Keats et al 1990). How-ever, at the next level of causality there exists a multitude of l~ttle known factors which, depending on the initial community configuration, may either control the onset of destructive grazing or allow a reduction in grazing pressure to a level which permits macroalgal recovery.…”

Section: Introductionmentioning

confidence: 99%

“…the amoeba Paramoeba invadens Jones (Jones 1985, Jones & Scheibling 1985, Jones et al 1985a. Other suggested mechanisms which may reduce the grazing pressure of sea urchins sufficiently to permit macroalgal recovery include a lack of recruitment of juvenile sea urchins (Foreman 1977, Watanabe & Harrold 1991, storm disturbance (Harris et al 1984, Ebeling et al 1985, Andrew 1991, or a temporarily increased influx of unattached food items (Duggins 1981, Harrold & Reed 1985.…”

Section: Introductionmentioning

confidence: 99%

Recurrent destructive grazing of successionally immature kelp forests by green sea urchins in Vestfjorden, Northern Norway

Hagen¹

1995

Mar. Ecol. Prog. Ser.

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Outbreak populations of the green sea urchin Strongylocentrotus droebachiensis Miiller caused widespread decimation of the original Laminaria hyperborea (Gunn.) Fosl. kelp forest in Vestflorden, Northern Norway, during the early 1980s. In the follow~ng decade, some of the resulting urch~n-dominated barren grounds reverted to kelp forest, which, after persisting for more than 5 yr, began to be eliminated yet again. Age analysis of annual growth rings in kelp stipes from field sites at V~r a y Island i n l c a t e that the time of initial kelp recovery varied from site to site but took place between 1984 and 1987. The earliest independent observations of localized macrophyte recovery were made in 1984 at the Harbour Pier site, where, by August 1992, the new kelp forest had already been eliminated by recurrent destructive grazing. Sea urchin density inside re-established kelp forests at 3 other sites on Vaer~y Island was 45 to 75 ind. m-2 in 1992. These urchin populations had significantly aggregated spatial patterns, and recurrent destructive grazing appeared to be mrmnent. This prediction was verified in 1993 when barren grounds reappeared at all study sltes. The threshold conditions for initiation of destructive grazing have been approximated by a curve in the aggregation-density plane. Sea urchins in the Vestfjorden area are infected by the recently discovered epizootic endoparasitic nematode Echinornermella matsi. In 1992, the prevalence of E. matsiat Varay Island ranged from 8.8% in the barren ground at the Harbour Pier site, to between 13.6 and 21.6% in the successionally immature kelp forest at the 3 other sites. The observed kelp forest recovery at Vceray Island was predicted by the macroparasite hypothesis which states that E. matsi may function as a terminator of sea urchin outbreaks in Northern Norway. However, the succession towards an ecologically mature kelp forest community has been interrupted by the unexpected recurrence of destructive grazing, and the macroparasite hypothesis must therefore be rejected in its present form. Furthermore, these local events may, on the larger time and spatial scales of the current outbreak phenomenon, indicate that the euphotic hard bottom component of the coastal ecosystem in Northern Norway has entered a cyclical domain.

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Benthic community modification and recovery following intensive grazing byStrongylocentrotus droebachiensis

Cited by 92 publications

References 14 publications

Contrasting ecological implications of food limitation in sea urchins and herbivorous gastropods

Contrasting ecological implications of food limitation in sea urchins and herbivorous gastropods

Recovery following experimental harvesting ofLaminaria longicruris andL. digitata in southwestern Nova Scotia

Recurrent destructive grazing of successionally immature kelp forests by green sea urchins in Vestfjorden, Northern Norway

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