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Effects of enrichment on simple aquatic food webs

Persson, Anders LU ; Hansson, Lars-Anders LU ; Brönmark, Christer LU ; Lundberg, Per LU ; Pettersson, Lars LU ; Greenberg, L; Nilsson, Anders LU ; Nyström, Per LU ; Romare, Pia LU and Tranvik, L (2001) In American Naturalist 157(6). p.654-669
Abstract
Simple models, based on Lotka-Volterra types of interactions between predator and prey, predict that enrichment will have a destabilizing effect on populations and that equilibrium population densities will change at the top trophic level and every second level below. We experimentally tested these predictions in three aquatic food web configurations subjected to either high or low nutrient additions. The results were structured by viewing the systems as either food chains or webs and showed that trophic level biomass increased with enrichment, which contradicts food chain theory. However, within each trophic level, food web configuration affected the extent to which different functional groups responded to enrichment. By dividing trophic... (More)
Simple models, based on Lotka-Volterra types of interactions between predator and prey, predict that enrichment will have a destabilizing effect on populations and that equilibrium population densities will change at the top trophic level and every second level below. We experimentally tested these predictions in three aquatic food web configurations subjected to either high or low nutrient additions. The results were structured by viewing the systems as either food chains or webs and showed that trophic level biomass increased with enrichment, which contradicts food chain theory. However, within each trophic level, food web configuration affected the extent to which different functional groups responded to enrichment. By dividing trophic levels into functional groups, based on vulnerability to consumption, we were able to identify significant effects that were obscured when systems were viewed as food chains. The results support the prediction that invulnerable prey may stabilize trophic-level dynamics by replacing other, more vulnerable prey. Furthermore, the vulnerable prey, such as Daphnia and edible algae, responded as predicted by the paradox of enrichment hypothesis; that is, variability in population density increased with enrichment. Hence, by describing ecosystems as a matrix of food web interactions, and by recognizing the interplay between interspecific competition and predation, a more complete description of the ecosystem function was obtained compared to when species were placed into distinct trophic levels. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
predation, paradox of enrichment., variability, stability, food chain
in
American Naturalist
volume
157
issue
6
pages
654 - 669
publisher
University of Chicago Press
external identifiers
  • scopus:0034972735
ISSN
0003-0147
DOI
10.1086/320620
language
English
LU publication?
yes
id
7ec3a646-6c35-47d6-814e-d535e96e5f11 (old id 146651)
alternative location
http://www.journals.uchicago.edu/doi/pdf/10.1086/320620
date added to LUP
2007-06-26 11:21:57
date last changed
2018-10-03 10:12:24
@article{7ec3a646-6c35-47d6-814e-d535e96e5f11,
  abstract     = {Simple models, based on Lotka-Volterra types of interactions between predator and prey, predict that enrichment will have a destabilizing effect on populations and that equilibrium population densities will change at the top trophic level and every second level below. We experimentally tested these predictions in three aquatic food web configurations subjected to either high or low nutrient additions. The results were structured by viewing the systems as either food chains or webs and showed that trophic level biomass increased with enrichment, which contradicts food chain theory. However, within each trophic level, food web configuration affected the extent to which different functional groups responded to enrichment. By dividing trophic levels into functional groups, based on vulnerability to consumption, we were able to identify significant effects that were obscured when systems were viewed as food chains. The results support the prediction that invulnerable prey may stabilize trophic-level dynamics by replacing other, more vulnerable prey. Furthermore, the vulnerable prey, such as Daphnia and edible algae, responded as predicted by the paradox of enrichment hypothesis; that is, variability in population density increased with enrichment. Hence, by describing ecosystems as a matrix of food web interactions, and by recognizing the interplay between interspecific competition and predation, a more complete description of the ecosystem function was obtained compared to when species were placed into distinct trophic levels.},
  author       = {Persson, Anders and Hansson, Lars-Anders and Brönmark, Christer and Lundberg, Per and Pettersson, Lars and Greenberg, L and Nilsson, Anders and Nyström, Per and Romare, Pia and Tranvik, L},
  issn         = {0003-0147},
  keyword      = {predation,paradox of
enrichment.,variability,stability,food chain},
  language     = {eng},
  number       = {6},
  pages        = {654--669},
  publisher    = {University of Chicago Press},
  series       = {American Naturalist},
  title        = {Effects of enrichment on simple aquatic food webs},
  url          = {http://dx.doi.org/10.1086/320620},
  volume       = {157},
  year         = {2001},
}