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Title: Whole-lake invasive crayfish removal and qualitative modeling reveal habitat-specific food web topology

Patterning of the presence/absence of food web linkages (hereafter topology) is a fundamental characteristic of ecosystems that can influence species responses to perturbations. However, the insight from food web topology into dynamic effects of perturbations on species is potentially hindered because most described topologies represent data integrated across spatial and temporal scales. We conducted a 10-year, whole-lake experiment in which we removed invasive rusty crayfish ( Orconectes rusticus) from a 64-ha north-temperate lake and monitored responses of multiple trophic levels. We compared species responses observed in two sub-habitats to the responses predicted from all topologies of an integrated, literature-informed base food web model of 32 potential links. Out of 4.3 billion possible topologies, only 308,833 (0.0072%) predicted responses that qualitatively matched observed species responses in cobble habitat, and only 12,673 (0.0003%) matched observed responses in sand habitat. Furthermore, when constrained to predictions that both matched observed responses and were highly reliable (i.e., predictions were robust to link strength values), only 5040 (0.0001%) and 140 (0.000003%) topologies were identified for cobble and sand habitats, respectively. A small number of linkages were nearly always present in these valid, reliable networks in sand, while a greater variety of possible network configurations were possiblemore » in cobble. Direct links involving invasive rusty crayfish were more important in cobble, while indirect effects involving Lepomis spp. were more important in sand. Importantly, the importance of individual species linkages differed dramatically among cobble and sand sub-habitats within a single lake, even though species composition was identical. Furthermore the true topology of food webs is difficult to determine, constraining topologies to include spatial resolution that matches observed experimental outcomes may reduce possibilities to a small number of plausible alternatives.« less
 [1] ;  [2] ;  [3] ;  [2]
  1. Univ. of Wisconsin, Madison, WI (United States); Minnesota Dept. of Natural Resources, St. Paul, MN (United States)
  2. Univ. of Wisconsin, Madison, WI (United States)
  3. Univ. of Wisconsin, Madison, WI (United States); Rensselaer Polytechnic Inst., Troy, NY (United States)
Publication Date:
Grant/Contract Number:
SC0009988; DEB-0083545; DEB-9632853
Published Article
Journal Name:
Additional Journal Information:
Journal Volume: 8; Journal Issue: 2; Journal ID: ISSN 2150-8925
Ecological Society of America
Research Org:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; food web; indirect effects; invasive species; qualitative modeling; rusty crayfish; topology
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1343322; OSTI ID: 1358442