Trophic responses to nutrient enrichment in a temperate seagrass food chain

Paul H. York, Brendan P. Kelaher, David J. Booth, Melanie J. Bishop

Research output: Contribution to journalArticleResearchpeer-review

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.

LanguageEnglish
Pages291-296
Number of pages6
JournalMarine Ecology Progress Series
Volume449
DOIs
Publication statusPublished - 8 Mar 2012

Fingerprint

nutrient enrichment
seagrass
food chain
eutrophication
catchment
trophic level
functional response
algae
nutrient
nutrients
perturbation
omnivory
prediction
biomass
omnivores
functional response models
subsidies
ecologists
managers
grazing

Bibliographical note

Copyright Inter-Research 2012. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Cite this

York, Paul H. ; Kelaher, Brendan P. ; Booth, David J. ; Bishop, Melanie J. / Trophic responses to nutrient enrichment in a temperate seagrass food chain. In: Marine Ecology Progress Series. 2012 ; Vol. 449. pp. 291-296.
@article{98503080336847c6ad3262a6838dfd37,
title = "Trophic responses to nutrient enrichment in a temperate seagrass food chain",
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.",
author = "York, {Paul H.} and Kelaher, {Brendan P.} and Booth, {David J.} and Bishop, {Melanie J.}",
note = "Copyright Inter-Research 2012. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",
year = "2012",
month = "3",
day = "8",
doi = "10.3354/meps09541",
language = "English",
volume = "449",
pages = "291--296",
journal = "Marine Ecology Progress Series",
issn = "0171-8630",
publisher = "Inter-Research",

}

Trophic responses to nutrient enrichment in a temperate seagrass food chain. / York, Paul H.; Kelaher, Brendan P.; Booth, David J.; Bishop, Melanie J.

In: Marine Ecology Progress Series, Vol. 449, 08.03.2012, p. 291-296.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Trophic responses to nutrient enrichment in a temperate seagrass food chain

AU - York, Paul H.

AU - Kelaher, Brendan P.

AU - Booth, David J.

AU - Bishop, Melanie J.

N1 - Copyright Inter-Research 2012. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2012/3/8

Y1 - 2012/3/8

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=84858136465&partnerID=8YFLogxK

U2 - 10.3354/meps09541

DO - 10.3354/meps09541

M3 - Article

VL - 449

SP - 291

EP - 296

JO - Marine Ecology Progress Series

T2 - Marine Ecology Progress Series

JF - Marine Ecology Progress Series

SN - 0171-8630

ER -