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- <meta content="Johnson, Craig R." name="eprints.creators_name" />
- <meta content="Mann, Kenneth H." name="eprints.creators_name" />
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- <meta content="community structure; competition; disturbance; diversity; kelp; Laminaria; multiple
- adaptations; Nova Scotia; sea urchins; stability; stress; succession.
- " name="eprints.keywords" />
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- <meta content="There are two alternate community states in the rocky subtidal of the Atlantic
- coast of Nova Scotia, an unproductive sea urchin/coralline alga community, and highly
- productive kelp beds dominated by Laminaria longicruris. Disease-induced mortality of
- the sea urchins (Strongylocentrotus droebachiensis) triggered a switch from the first state
- to the second and provided a unique opportunity to study (1) the ability of L. longicruris
- to recover its former dominant status, and (2) its stability when competing with other
- seaweeds and when perturbed by storms and grazers other than urchins. Rates of recolo-
- nization of L. longicruris depended on the proximity of a refugial source of spores. When
- reproductive plants were nearby, a closed canopy developed within 18 mo of urchin mortality. When a reproductive population was several kilometres away, there was sparse
- recolonization for 3 yr, then a massive recruitment occurred with closure of the canopy in
- the 4th yr.
- Laminaria is clearly the competitive dominant in the seaweed community. Manipulative experiments showed that the kelp limits the abundance of several understory species,
- but there was no evidence that the abundant annual seaweeds limited kelp recruitment.
- When sea urchins were rare, the density and growth rates of Laminaria were influenced
- mostly by intraspecific competition. When the canopy of adult plants was removed there
- was a dramatic increase in kelp recruitment, but the recruits that grew in dense patches in
- the clearings were significantly smaller than those of a similar age that grew more sparsely
- beneath the canopy. Once the kelp recovered from destructive grazing and formed a mature
- forest, it was able to maintain its dominance, even in habitats subject to severe nutrient
- stress for 8 mo of the year. For most ofthe year mortality and erosion of laminae outweighed
- the effects of recruitment and growth, and the canopy declined, especially during winter
- when storms were frequent. Erosion was exacerbated by grazing of the gastropod Lacuna
- vincta. However, in late winter and early spring, recruitment and rapid growth restored
- the canopy. When severe storm damage was simulated by completely removing Laminaria
- in patches, the kelp rapidly recolonized and soon outgrew other seaweeds.
- Unlike the competitive dominants in kelp bed systems in the northeast Pacific, L .
- longicruris in Nova Scotia manifests multiple patterns of adaptation that enable it to
- dominate early and late stages of succession in a range of habitats of different levels of
- nutrient stress and of disturbance from storms and grazers. The principal threat to the
- stability of the kelp beds is destructive grazing by sea urchins. We suggest that the consid-
- erable differences between the dynamios of kelp beds in Nova Scotia and those of the
- northeast Pacific, and the high degree of stability of L . longicruris stands in Nova Scotia,
- is attributable to the low diversity of kelps and therefore low levels of competition in Nova
- Scotia, and to the multiple adaptations of L . longicruris that enable it to tolerate several
- stresses and disturbances.
- We argue that the dynamics of community organization, and therefore the stability
- properties of this system are determined primarily by biological interactions and not by
- physical variables. This differs from the kelp communities in the northeast Pacific, in which
- both biological and physical factors influence dynamics significantly at a primary level.
- We offer a qualitative model of the dynamics of community structure in Nova Scotia that may be viewed as a set of deterministic "subroutines," in which each subroutine describes
- the outcome of a particular biological interaction. The subroutine(s) that predominate at
- one point in time and space are probably determined mostly by physical hydrographic
- variables that have a large stochastic component.
- " name="eprints.abstract" />
- <meta content="1988-06" name="eprints.date" />
- <meta content="published" name="eprints.date_type" />
- <meta content="Ecological Monographs" name="eprints.publication" />
- <meta content="58" name="eprints.volume" />
- <meta content="2" name="eprints.number" />
- <meta content="129-154" name="eprints.pagerange" />
- <meta content="10.2307/1942464" name="eprints.id_number" />
- <meta content="UNSPECIFIED" name="eprints.thesis_type" />
- <meta content="TRUE" name="eprints.refereed" />
- <meta content="http://dx.doi.org/10.2307/1942464" name="eprints.official_url" />
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- 2891674-676." name="eprints.referencetext" />
- <meta content="Johnson, Craig R. and Mann, Kenneth H. (1988) Diversity, patterns of adaptation, and stability of Nova Scotian kelp beds. Ecological Monographs, 58 (2). pp. 129-154." name="eprints.citation" />
- <meta content="http://eprints.utas.edu.au/1237/1/Johnson_and_Mann_1988.pdf" name="eprints.document_url" />
- <link rel="schema.DC" href="http://purl.org/DC/elements/1.0/" />
- <meta content="Diversity, patterns of adaptation, and stability of Nova Scotian kelp beds" name="DC.title" />
- <meta content="Johnson, Craig R." name="DC.creator" />
- <meta content="Mann, Kenneth H." name="DC.creator" />
- <meta content="270702 Marine and Estuarine Ecology (incl. Marine Ichthyology)" name="DC.subject" />
- <meta content="There are two alternate community states in the rocky subtidal of the Atlantic
- coast of Nova Scotia, an unproductive sea urchin/coralline alga community, and highly
- productive kelp beds dominated by Laminaria longicruris. Disease-induced mortality of
- the sea urchins (Strongylocentrotus droebachiensis) triggered a switch from the first state
- to the second and provided a unique opportunity to study (1) the ability of L. longicruris
- to recover its former dominant status, and (2) its stability when competing with other
- seaweeds and when perturbed by storms and grazers other than urchins. Rates of recolo-
- nization of L. longicruris depended on the proximity of a refugial source of spores. When
- reproductive plants were nearby, a closed canopy developed within 18 mo of urchin mortality. When a reproductive population was several kilometres away, there was sparse
- recolonization for 3 yr, then a massive recruitment occurred with closure of the canopy in
- the 4th yr.
- Laminaria is clearly the competitive dominant in the seaweed community. Manipulative experiments showed that the kelp limits the abundance of several understory species,
- but there was no evidence that the abundant annual seaweeds limited kelp recruitment.
- When sea urchins were rare, the density and growth rates of Laminaria were influenced
- mostly by intraspecific competition. When the canopy of adult plants was removed there
- was a dramatic increase in kelp recruitment, but the recruits that grew in dense patches in
- the clearings were significantly smaller than those of a similar age that grew more sparsely
- beneath the canopy. Once the kelp recovered from destructive grazing and formed a mature
- forest, it was able to maintain its dominance, even in habitats subject to severe nutrient
- stress for 8 mo of the year. For most ofthe year mortality and erosion of laminae outweighed
- the effects of recruitment and growth, and the canopy declined, especially during winter
- when storms were frequent. Erosion was exacerbated by grazing of the gastropod Lacuna
- vincta. However, in late winter and early spring, recruitment and rapid growth restored
- the canopy. When severe storm damage was simulated by completely removing Laminaria
- in patches, the kelp rapidly recolonized and soon outgrew other seaweeds.
- Unlike the competitive dominants in kelp bed systems in the northeast Pacific, L .
- longicruris in Nova Scotia manifests multiple patterns of adaptation that enable it to
- dominate early and late stages of succession in a range of habitats of different levels of
- nutrient stress and of disturbance from storms and grazers. The principal threat to the
- stability of the kelp beds is destructive grazing by sea urchins. We suggest that the consid-
- erable differences between the dynamios of kelp beds in Nova Scotia and those of the
- northeast Pacific, and the high degree of stability of L . longicruris stands in Nova Scotia,
- is attributable to the low diversity of kelps and therefore low levels of competition in Nova
- Scotia, and to the multiple adaptations of L . longicruris that enable it to tolerate several
- stresses and disturbances.
- We argue that the dynamics of community organization, and therefore the stability
- properties of this system are determined primarily by biological interactions and not by
- physical variables. This differs from the kelp communities in the northeast Pacific, in which
- both biological and physical factors influence dynamics significantly at a primary level.
- We offer a qualitative model of the dynamics of community structure in Nova Scotia that may be viewed as a set of deterministic "subroutines," in which each subroutine describes
- the outcome of a particular biological interaction. The subroutine(s) that predominate at
- one point in time and space are probably determined mostly by physical hydrographic
- variables that have a large stochastic component.
- " name="DC.description" />
- <meta content="1988-06" name="DC.date" />
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- <h1 class="ep_tm_pagetitle">Diversity, patterns of adaptation, and stability of Nova Scotian kelp beds</h1>
- <p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Johnson, Craig R.</span> and <span class="person_name">Mann, Kenneth H.</span> (1988) <xhtml:em>Diversity, patterns of adaptation, and stability of Nova Scotian kelp beds.</xhtml:em> Ecological Monographs, 58 (2). pp. 129-154.</p><p style="margin-bottom: 1em" class="not_ep_block"></p><table style="margin-bottom: 1em" class="not_ep_block"><tr><td valign="top" style="text-align:center"><a href="http://eprints.utas.edu.au/1237/1/Johnson_and_Mann_1988.pdf"><img alt="[img]" src="http://eprints.utas.edu.au/style/images/fileicons/application_pdf.png" border="0" class="ep_doc_icon" /></a></td><td valign="top"><a href="http://eprints.utas.edu.au/1237/1/Johnson_and_Mann_1988.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />5Mb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input value="1605" name="docid" accept-charset="utf-8" type="hidden" /><div class=""><input value="Request a copy" name="_action_null" class="ep_form_action_button" onclick="return EPJS_button_pushed( '_action_null' )" type="submit" /> </div></form></td></tr></table><p style="margin-bottom: 1em" class="not_ep_block">Official URL: <a href="http://dx.doi.org/10.2307/1942464">http://dx.doi.org/10.2307/1942464</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">There are two alternate community states in the rocky subtidal of the Atlantic
- coast of Nova Scotia, an unproductive sea urchin/coralline alga community, and highly
- productive kelp beds dominated by Laminaria longicruris. Disease-induced mortality of
- the sea urchins (Strongylocentrotus droebachiensis) triggered a switch from the first state
- to the second and provided a unique opportunity to study (1) the ability of L. longicruris
- to recover its former dominant status, and (2) its stability when competing with other
- seaweeds and when perturbed by storms and grazers other than urchins. Rates of recolo-
- nization of L. longicruris depended on the proximity of a refugial source of spores. When
- reproductive plants were nearby, a closed canopy developed within 18 mo of urchin mortality. When a reproductive population was several kilometres away, there was sparse
- recolonization for 3 yr, then a massive recruitment occurred with closure of the canopy in
- the 4th yr.
- Laminaria is clearly the competitive dominant in the seaweed community. Manipulative experiments showed that the kelp limits the abundance of several understory species,
- but there was no evidence that the abundant annual seaweeds limited kelp recruitment.
- When sea urchins were rare, the density and growth rates of Laminaria were influenced
- mostly by intraspecific competition. When the canopy of adult plants was removed there
- was a dramatic increase in kelp recruitment, but the recruits that grew in dense patches in
- the clearings were significantly smaller than those of a similar age that grew more sparsely
- beneath the canopy. Once the kelp recovered from destructive grazing and formed a mature
- forest, it was able to maintain its dominance, even in habitats subject to severe nutrient
- stress for 8 mo of the year. For most ofthe year mortality and erosion of laminae outweighed
- the effects of recruitment and growth, and the canopy declined, especially during winter
- when storms were frequent. Erosion was exacerbated by grazing of the gastropod Lacuna
- vincta. However, in late winter and early spring, recruitment and rapid growth restored
- the canopy. When severe storm damage was simulated by completely removing Laminaria
- in patches, the kelp rapidly recolonized and soon outgrew other seaweeds.
- Unlike the competitive dominants in kelp bed systems in the northeast Pacific, L .
- longicruris in Nova Scotia manifests multiple patterns of adaptation that enable it to
- dominate early and late stages of succession in a range of habitats of different levels of
- nutrient stress and of disturbance from storms and grazers. The principal threat to the
- stability of the kelp beds is destructive grazing by sea urchins. We suggest that the consid-
- erable differences between the dynamios of kelp beds in Nova Scotia and those of the
- northeast Pacific, and the high degree of stability of L . longicruris stands in Nova Scotia,
- is attributable to the low diversity of kelps and therefore low levels of competition in Nova
- Scotia, and to the multiple adaptations of L . longicruris that enable it to tolerate several
- stresses and disturbances.
- We argue that the dynamics of community organization, and therefore the stability
- properties of this system are determined primarily by biological interactions and not by
- physical variables. This differs from the kelp communities in the northeast Pacific, in which
- both biological and physical factors influence dynamics significantly at a primary level.
- We offer a qualitative model of the dynamics of community structure in Nova Scotia that may be viewed as a set of deterministic "subroutines," in which each subroutine describes
- the outcome of a particular biological interaction. The subroutine(s) that predominate at
- one point in time and space are probably determined mostly by physical hydrographic
- variables that have a large stochastic component.
- </p></div><table style="margin-bottom: 1em" border="0" cellpadding="3" class="not_ep_block"><tr><th valign="top" class="ep_row">Item Type:</th><td valign="top" class="ep_row">Article</td></tr><tr><th valign="top" class="ep_row">Additional Information:</th><td valign="top" class="ep_row">Copyright by the Ecological Society of America.</td></tr><tr><th valign="top" class="ep_row">Keywords:</th><td valign="top" class="ep_row">community structure; competition; disturbance; diversity; kelp; Laminaria; multiple
- adaptations; Nova Scotia; sea urchins; stability; stress; succession.
- </td></tr><tr><th valign="top" class="ep_row">Subjects:</th><td valign="top" class="ep_row"><a href="http://eprints.utas.edu.au/view/subjects/270702.html">270000 Biological Sciences > 270700 Ecology and Evolution > 270702 Marine and Estuarine Ecology (incl. Marine Ichthyology)</a></td></tr><tr><th valign="top" class="ep_row">Collections:</th><td valign="top" class="ep_row">UNSPECIFIED</td></tr><tr><th valign="top" class="ep_row">ID Code:</th><td valign="top" class="ep_row">1237</td></tr><tr><th valign="top" class="ep_row">Deposited By:</th><td valign="top" class="ep_row"><span class="ep_name_citation"><span class="person_name">Professor Craig R. Johnson</span></span></td></tr><tr><th valign="top" class="ep_row">Deposited On:</th><td valign="top" class="ep_row">25 Jun 2007</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">04 Feb 2008 17:28</td></tr><tr><th valign="top" class="ep_row">ePrint Statistics:</th><td valign="top" class="ep_row"><a target="ePrintStats" href="/es/index.php?action=show_detail_eprint;id=1237;">View statistics for this ePrint</a></td></tr></table><p align="right">Repository Staff Only: <a href="http://eprints.utas.edu.au/cgi/users/home?screen=EPrint::View&eprintid=1237">item control page</a></p>
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