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<title>UTas ePrints - Mortality and predation in ecosystem models: is it important how these are expressed?</title>
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<meta content="Fulton, Elizabeth A." name="eprints.creators_name" />
<meta content="Smith, Anthony D.M." name="eprints.creators_name" />
<meta content="Johnson, Craig R." name="eprints.creators_name" />
<meta content="beth.fulton@csiro.au" name="eprints.creators_id" />
<meta name="eprints.creators_id" />
<meta content="Craig.Johnson@utas.edu.au" name="eprints.creators_id" />
<meta content="article" name="eprints.type" />
<meta content="2007-05-31" name="eprints.datestamp" />
<meta content="2008-02-04T05:27:15Z" name="eprints.lastmod" />
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<meta content="Mortality and predation in ecosystem models: is it important how these are expressed?" name="eprints.title" />
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<meta content="270702" name="eprints.subjects" />
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<meta content="Functional response; Mortality; Model closure; Biogeochemical; Ecosystem; Model" name="eprints.keywords" />
<meta content="Definitive version available online at http://www.elsevier.com/locate/issn/03043800" name="eprints.note" />
<meta content="The effects of the form of the grazing and mortality terms used in plankton models are well known. The same cannot be said for
ecosystem models. As ecosystem models become more popular more needs to be known about the effects of model formulation
on model behaviour and performance. The impact of the form of the grazing response function and mortality terms used in
a biogeochemical ecosystem model are considered here. We show that in the large and inter-linked webs used in ecosystem
models, model behaviour is far more sensitive to the form of the grazing term than to that of the mortality terms that close the
modelled food web.
When using biogeochemical ecosystem models in shallow marine ecosystems, the most dynamic and sophisticated functional
responses describing grazing require more parameters and validation than the simpler Holling disk equation, but usually still
lead to the same general conclusions about the system state and the effects of changes in forcing functions. Thus, the use of
more complex functional responses is not necessarily warranted in many cases. Similarly, the extra effort and data required to
explicitly represent the top predators (sharks, mammals and birds) is not necessary if they are not the focus of the study. A
quadratic mortality term applied to intermediate predators (such as piscivores) is sufficient to achieve plausible model behaviour.
It should be noted, however, that some degree of sophistication is required in the grazing and mortality terms. Use of simple
linear functional responses and mortality terms is unsuitable for models used to consider a range of nutrient loading or harvesting
scenarios." name="eprints.abstract" />
<meta content="2003-11" name="eprints.date" />
<meta content="published" name="eprints.date_type" />
<meta content="Ecological Modelling" name="eprints.publication" />
<meta content="169" name="eprints.volume" />
<meta content="1" name="eprints.number" />
<meta content="157-178" name="eprints.pagerange" />
<meta content="10.1016/S0304-3800(03)00268-0" name="eprints.id_number" />
<meta content="UNSPECIFIED" name="eprints.thesis_type" />
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<meta content="0304-3800" name="eprints.issn" />
<meta content="http://dx.doi.org/10.1016/S0304-3800(03)00268-0" name="eprints.official_url" />
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Pyralidae). Environ. Entomol. 22, 849-858." name="eprints.referencetext" />
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<meta content="270702 Marine and Estuarine Ecology (incl. Marine Ichthyology)" name="DC.subject" />
<meta content="The effects of the form of the grazing and mortality terms used in plankton models are well known. The same cannot be said for
ecosystem models. As ecosystem models become more popular more needs to be known about the effects of model formulation
on model behaviour and performance. The impact of the form of the grazing response function and mortality terms used in
a biogeochemical ecosystem model are considered here. We show that in the large and inter-linked webs used in ecosystem
models, model behaviour is far more sensitive to the form of the grazing term than to that of the mortality terms that close the
modelled food web.
When using biogeochemical ecosystem models in shallow marine ecosystems, the most dynamic and sophisticated functional
responses describing grazing require more parameters and validation than the simpler Holling disk equation, but usually still
lead to the same general conclusions about the system state and the effects of changes in forcing functions. Thus, the use of
more complex functional responses is not necessarily warranted in many cases. Similarly, the extra effort and data required to
explicitly represent the top predators (sharks, mammals and birds) is not necessary if they are not the focus of the study. A
quadratic mortality term applied to intermediate predators (such as piscivores) is sufficient to achieve plausible model behaviour.
It should be noted, however, that some degree of sophistication is required in the grazing and mortality terms. Use of simple
linear functional responses and mortality terms is unsuitable for models used to consider a range of nutrient loading or harvesting
scenarios." name="DC.description" />
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<h1 class="ep_tm_pagetitle">Mortality and predation in ecosystem models: is it important how these are expressed?</h1>
<p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Fulton, Elizabeth A.</span> and <span class="person_name">Smith, Anthony D.M.</span> and <span class="person_name">Johnson, Craig R.</span> (2003) <xhtml:em>Mortality and predation in ecosystem models: is it important how these are expressed?</xhtml:em> Ecological Modelling, 169 (1). pp. 157-178. ISSN 0304-3800</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/1121/1/2003_Fulton%2C_Smith_%26_Johnson_Ecol_Mod.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/1121/1/2003_Fulton%2C_Smith_%26_Johnson_Ecol_Mod.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />383Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input value="1403" 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/10.1016/S0304-3800(03)00268-0">http://dx.doi.org/10.1016/S0304-3800(03)00268-0</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">The effects of the form of the grazing and mortality terms used in plankton models are well known. The same cannot be said for
ecosystem models. As ecosystem models become more popular more needs to be known about the effects of model formulation
on model behaviour and performance. The impact of the form of the grazing response function and mortality terms used in
a biogeochemical ecosystem model are considered here. We show that in the large and inter-linked webs used in ecosystem
models, model behaviour is far more sensitive to the form of the grazing term than to that of the mortality terms that close the
modelled food web.
When using biogeochemical ecosystem models in shallow marine ecosystems, the most dynamic and sophisticated functional
responses describing grazing require more parameters and validation than the simpler Holling disk equation, but usually still
lead to the same general conclusions about the system state and the effects of changes in forcing functions. Thus, the use of
more complex functional responses is not necessarily warranted in many cases. Similarly, the extra effort and data required to
explicitly represent the top predators (sharks, mammals and birds) is not necessary if they are not the focus of the study. A
quadratic mortality term applied to intermediate predators (such as piscivores) is sufficient to achieve plausible model behaviour.
It should be noted, however, that some degree of sophistication is required in the grazing and mortality terms. Use of simple
linear functional responses and mortality terms is unsuitable for models used to consider a range of nutrient loading or harvesting
scenarios.</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">Definitive version available online at http://www.elsevier.com/locate/issn/03043800</td></tr><tr><th valign="top" class="ep_row">Keywords:</th><td valign="top" class="ep_row">Functional response; Mortality; Model closure; Biogeochemical; Ecosystem; Model</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">1121</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">31 May 2007</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">04 Feb 2008 16:27</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=1121;">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=1121">item control page</a></p>
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