Trophic responses to nutrient enrichment in a temperate seagrass food chain

York, PH; Kelaher, BP; Booth, DJ; Bishop, MJ

Trophic responses to nutrient enrichment in a temperate seagrass food chain

York, PH

Kelaher, BP

Booth, DJ

Bishop, MJ

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Publication Type:: Journal Article
Citation:: Marine Ecology Progress Series, 2012, 449 pp. 291 - 296
Issue Date:: 2012-03-08

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Field	Value	Language
dc.contributor.author	York, PH https://orcid.org/0000-0003-3530-4146	en_US
dc.contributor.author	Kelaher, BP https://orcid.org/0000-0002-7505-4412	en_US
dc.contributor.author	Booth, DJ https://orcid.org/0000-0002-8256-1412	en_US
dc.contributor.author	Bishop, MJ https://orcid.org/0000-0001-8210-6500	en_US
dc.date.issued	2012-03-08	en_US
dc.identifier.citation	Marine Ecology Progress Series, 2012, 449 pp. 291 - 296	en_US
dc.identifier.issn	0171-8630	en_US
dc.identifier.uri	http://hdl.handle.net/10453/22130
dc.description.abstract	Simple ecological models that predict trophic responses to bottom-up forcing are valuable tools for ecosystem managers. Traditionally, theoretical ecologists have used resource-dependent functional responses to explain the modification of food chains exposed to bottom-up perturbations. These models predict alternating positive, negative and zero responses at each trophic level. More recently, ratio-dependent functional response models that predict proportional increases at each level have challenged this paradigm. The present study tested the predictions of the 2 hypotheses empirically by comparing the relative biomasses of 4 trophic levels of an estuarine seagrass food chain in relatively undisturbed, low-nutrient catchments and 'developed' catchments subjected to a prolonged period of nutrient enrichment. We found that nutrient-enriched sites had significantly greater biomass of both epiphytic algae and grazing invertebrates; however, the bottom- up forcing of nutrients was attenuated at higher trophic levels (occupied by juvenile and piscivorous fish), with no significant effect of catchment development. This disconnect in the upward cascade of energy may be due to a number of possible reasons including high levels of diversity and omnivory, trophic subsidy within the system or the strength or nature of perturbations. Although the predictions of both hypotheses failed to hold across all trophic groups, ratio dependence was prevalent at the lower levels of the food chain, which has implications for catchment management. © 2012 Inter-Research.	en_US
dc.relation.ispartof	Marine Ecology Progress Series	en_US
dc.relation.isbasedon	10.3354/meps09541	en_US
dc.subject.classification	Marine Biology & Hydrobiology	en_US
dc.title	Trophic responses to nutrient enrichment in a temperate seagrass food chain	en_US
dc.type	Journal Article
utslib.citation.volume	449	en_US
utslib.for	0602 Ecology	en_US
utslib.for	0405 Oceanography	en_US
utslib.for	0608 Zoology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of the Environment
utslib.copyright.status	closed_access
pubs.publication-status	Published	en_US
pubs.volume	449	en_US

Abstract:

Simple ecological models that predict trophic responses to bottom-up forcing are valuable tools for ecosystem managers. Traditionally, theoretical ecologists have used resource-dependent functional responses to explain the modification of food chains exposed to bottom-up perturbations. These models predict alternating positive, negative and zero responses at each trophic level. More recently, ratio-dependent functional response models that predict proportional increases at each level have challenged this paradigm. The present study tested the predictions of the 2 hypotheses empirically by comparing the relative biomasses of 4 trophic levels of an estuarine seagrass food chain in relatively undisturbed, low-nutrient catchments and 'developed' catchments subjected to a prolonged period of nutrient enrichment. We found that nutrient-enriched sites had significantly greater biomass of both epiphytic algae and grazing invertebrates; however, the bottom- up forcing of nutrients was attenuated at higher trophic levels (occupied by juvenile and piscivorous fish), with no significant effect of catchment development. This disconnect in the upward cascade of energy may be due to a number of possible reasons including high levels of diversity and omnivory, trophic subsidy within the system or the strength or nature of perturbations. Although the predictions of both hypotheses failed to hold across all trophic groups, ratio dependence was prevalent at the lower levels of the food chain, which has implications for catchment management. © 2012 Inter-Research.

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http://hdl.handle.net/10453/22130