Community Ecology

, Volume 13, Issue 2, pp 230–237 | Cite as

Dynamical effects of weak trophic interactions in a stochastic food web simulation

  • M. Scotti
  • N. Gjata
  • C. M. Livi
  • F. JordánEmail author


Network models are traditional in community ecology. For example, they provide a rich analytical toolkit to put higher predators into a multispecies context. Better understanding their top-down effects and the potential bottom-up control on them would be of key importance for predictive ecosystem management. Food web architecture may be used to predict community dynamics, but it is an old question how reliable are the studies considering only static information. A general and intuitive assumption is that stronger links (with larger weights) mediate stronger effects. We study this statement and use an illustrative case study. We investigate the trophic structure of the Prince William Sound food web in terms of biomass flows, and study its simulated dynamics in a stochastic modelling framework. We aim to understand bottom-up effects of preys on consumers: we focus on the fluctuations of top predator populations, following disturbance on their prey. Several disturbance regimes are studied and compared. Food web structure and link weight generally predict well the average impacts of preys on top-predators, with larger flows mediating stronger effects. Most exceptions appear for weak links: these are less predictable, some of them can be surprisingly important.


Food web Simulation Network analysis 


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  1. Berlow, E. 1999. Strong effects of weak interactions in ecological communities. Nature 398: 330–334.CrossRefGoogle Scholar
  2. Berlow, E.L., A.M. Neutel, J.E. Cohen, P.C. de Ruiter, B. Ebenman, M. Emmerson, J.W. Fox, V.A.A. Jansen, J.I. Jones, G.D. Kokkoris, D.O. Logofet, A.J. McKane, J.M. Montoya and O. Petchey. 2004. Interaction strengths in food webs: issues and opportunities. J. Anim. Ecol. 73: 585–598.CrossRefGoogle Scholar
  3. Christensen, V. and C.J. Walters. 2004. Ecopath with Ecosim: methods, capabilities and limitations. Ecol. Model. 172: 109–139.CrossRefGoogle Scholar
  4. Cury, P., A. Bakun, R.J.M. Crawford, A. Jarre, R.A. Quiñones, L.J. Shannon and H.M. Verheye. 2000. Small pelagics in upwelling systems: patterns of interaction and structural changes in “wasp-waist” ecosystems. J. Mar. Sci. 57: 603–618.Google Scholar
  5. Dematté, L., C. Priami and A. Romanel. 2007. BetaWB: modelling and simulating biological processes. In: Wainer, G.A. and Vakilzadian, H. (Eds.), Proceedings of Summer Computer Simulation Conference (SCSC 2007). San Diego, CA, USA, 777–784.Google Scholar
  6. Dematté, L., C. Priami and A. Romanel. 2008. The Beta Workbench: a computational tool to study the dynamics of biological systems. Brief. Bioinform. 9: 437–449.CrossRefPubMedPubMedCentralGoogle Scholar
  7. de Ruiter, P.C., A. Neutel and J.C. Moore. 1995. Energetics, patterns of interaction strengths, and stability in real ecosystems. Science 269: 1257–1260.CrossRefPubMedPubMedCentralGoogle Scholar
  8. Emmerson, M. and J.M. Yearsley. 2004. Weak interactions, om-nivory and emergent food-web properties. Proc. Roy. Soc. London B 271: 397–405.CrossRefGoogle Scholar
  9. Estes, J.A. and J.F. Palmisano. 1974. Sea otters: their role in structuring nearshore communities. Science 185: 1058–1060.CrossRefPubMedPubMedCentralGoogle Scholar
  10. Feest, A., T.D. Aldred and K. Jedamzik. 2010. Biodiversity quality: a paradigm for biodiversity. Ecol. Indic. 10: 1077–1082.CrossRefGoogle Scholar
  11. Gillespie, D.T. 1977. Exact stochastic simulation of coupled chemical reactions. J. Phys. Chem. 81: 2340–2361.CrossRefGoogle Scholar
  12. Hannon, B. 1973. The structure of ecosystems. J. Theor. Biol. 41: 535–546.CrossRefPubMedPubMedCentralGoogle Scholar
  13. Hollowed, A.B., N. Bax, R. Beamish, J. Collie, M. Fogarty, P. Livingston, J. Pope and J.C. Rice. 2000. Are multispecies models an improvement on single-species models for measuring fishing impacts on marine ecosystems?. J. Mar. Sci. 57: 707–719.Google Scholar
  14. Hollowed, A.B., K.Y. Aydin, T.E. Essington, J.N. Ianelli, B.A. Me-grey, A.E. Punt and A.D.M. Smith. 2011. Experience with quantitative ecosystem assessment tools in the northeast Pacific. Fish and Fisheries 12: 189–208.CrossRefGoogle Scholar
  15. Hurlbert, S.H. 1997. Functional importance vs keystoneness: reformulating some questions in theoretical biocenology. Austral. J. Ecol. 22: 369–382.CrossRefGoogle Scholar
  16. Jordán, F. 2009. Keystone species in food webs. Philos. Trans. Roy. Soc., London, B 364: 1733–1741.CrossRefGoogle Scholar
  17. Jordán, F., I. Scheuring and G. Vida. 2002. Species positions and extinction dynamics in simple food webs. J. Theor. Biol. 215: 441–448.CrossRefPubMedPubMedCentralGoogle Scholar
  18. Jordán, F., W.C. Liu and F.J.F. van Veen. 2003. Quantifying the importance of species and their interactions in a host-parasitoid community. Community Ecol. 4: 79–88.CrossRefGoogle Scholar
  19. Jordán, F., T.A. Okey, B. Bauer and S. Libralato. 2008. Identifying important species: a comparison of structural and functional indices. Ecol. Model. 216: 75–80.CrossRefGoogle Scholar
  20. Livi, C.M., F. Jordán, P. Lecca and T.A. Okey. 2011. Identifying key species in ecosystems with stochastic sensitivity analysis. Ecol. Model. 222: 2542–2551.CrossRefGoogle Scholar
  21. Luczkovich, J.J., S.P. Borgatti, J.C. Johnson and M.G. Everett. 2003. Defining and measuring trophic role similarity in food webs using regular equivalence. J. Theor. Biol. 220: 303–321.CrossRefGoogle Scholar
  22. MacArthur, R.H. 1955. Fluctuations of animal populations and a measure of community stability. Ecology 36: 533–536.CrossRefGoogle Scholar
  23. May, R.M., J.R. Beddington, C.W. Clark, S.J. Holt and R.M. Laws. 1979. Management of multispecies fisheries. Science 205: 267–277.CrossRefPubMedPubMedCentralGoogle Scholar
  24. McCann, K., A. Hastings and G.R. Huxel. 1998. Weak trophic interactions and the balance of nature. Nature 395: 794–798.CrossRefGoogle Scholar
  25. McCann, K. 2000. The diversity-stability debate. Nature 405: 228–233.CrossRefPubMedPubMedCentralGoogle Scholar
  26. Montoya, J.M. and R.V. Solé. 2002. Small world patterns in food webs. J. Theor. Biol. 214: 405–412.CrossRefGoogle Scholar
  27. Navia, A.F., E. Cortés and P.A. Mejía-Falla. 2010. Topological analysis of the ecological importance of elasmobranch fishes: A food web study on the Gulf of Tortugas, Colombia. Ecol. Model. 221: 2918–2926.CrossRefGoogle Scholar
  28. Okey, T.A. and D. Pauly. (Eds) 1999. A trophic mass-balance model of Alaska’s Prince William Sound ecosystem, for the post-spill period 1994–1996, 2nd edition, Vol. Fisheries Centre Research Report 7(4), University of British Columbia, Vancouver.Google Scholar
  29. Okey, T.A. 2004. Shifted community states in four marine ecosystems: some potential mechanisms. PhD thesis, University of British Columbia, Vancouver.Google Scholar
  30. Okey, T.A. and B.A. Wright. 2004. Toward ecosystem-based extraction policies for Prince William Sound, Alaska: Integrating conflicting objectives and rebuilding pinnipeds. Bull. Mar. Sci. 74: 727–747.Google Scholar
  31. Okuyama, T. 2009. Local interactions between predators and prey call into question commonly used functional responses. Ecol. Model. 220: 1182–1188.CrossRefGoogle Scholar
  32. Ortiz, M., M. Avendano, M. Cantillanez, F. Berrios and L. Campos. 2009. Trophic mass balanced models and dynamic simulations of benthic communities from La Rinconada Marine Reserve off northern Chile: network properties and multispecies harvest scenario assessments. Aquat. Conserv.: Mar. Freshw. Ecosyst. 20: 58–73.Google Scholar
  33. Paine, R.T. 1980. Food webs: linkage, interaction strength and community infrastructure. J. Anim. Ecol. 49: 667–685.CrossRefGoogle Scholar
  34. Paine, R.T. 1992. Food-web analysis through field measurement of per capita interaction strength. Nature 355: 73–75.CrossRefGoogle Scholar
  35. Patten, B.C. 1959. An introduction to the cybernetics of the ecosystem: the trophic-dynamic aspect. Ecology 40: 221–231.CrossRefGoogle Scholar
  36. Perry, R.I., P. Cury, K. Brander, S. Jennings, C. Möllmann and B. Planque. 2010. Sensitivity of marine systems to climate and fishing: Concepts, issues and management responses. J. Mar. Syst. 79: 427–435.CrossRefGoogle Scholar
  37. Powell, C.R. and R.P. Boland. 2009. The effects of stochastic population dynamics on food web structure. J. Theor. Biol. 257: 170–180.CrossRefPubMedPubMedCentralGoogle Scholar
  38. Scotti, M., J. Podani and F. Jordán. 2007. Weighting, scale dependence and indirect effects in ecological networks: a comparative study. Ecol. Compl. 4: 148–59.CrossRefGoogle Scholar
  39. Scotti, M., C. Bondavalli and A. Bodini. 2009. Linking trophic positions and flow structure constraints in ecological networks: Energy transfer efficiency or topology effect?. Ecol. Model. 220: 3070–180.CrossRefGoogle Scholar
  40. Scotti, M. and F. Jordán. 2010. Relationships between centrality indices nd trophic positions in food webs. Community Ecol. 11: 59–67.CrossRefGoogle Scholar
  41. Stevens, J.D., R. Bonfil, N.K. Dulvy and P.A. Walker. 2000. The effects of fishing on sharks, rays, and chimaeras (chondrichthy-ans), and the implications for marine ecosystems. J. Mar. Sci. 57: 476–494.Google Scholar
  42. Ulanowicz, R.E. 2004. Quantitative methods for ecological network analysis. Comp. Biol. Chem. 28: 321–339.CrossRefGoogle Scholar
  43. Ulanowicz, R.E. and C.J. Puccia. 1990. Mixed trophic impacts in ecosystems. Coenoses 5: 7–16.Google Scholar
  44. Valentini, R. and F. Jordán. 2010. CoSBiLab Graph: the network analysis module of CoSBiLab. Env. Model. Softw. 25: 886–888.CrossRefGoogle Scholar
  45. Whipple, S.J. 1998. Path-based network unfolding: A solution for the problem of mixed trophic and non-trophic processes in trophic dynamic analysis. J. Theor. Biol. 190: 263–276.CrossRefPubMedPubMedCentralGoogle Scholar
  46. Yen, P.P.W., W.J. Sydeman and K.D. Hyrenbach. 2004. Marine bird and cetacean associations with bathymetric habitats and shallow -water topographies: implications for trophic transfer and conservation. J. Mar. Syst. 50: 79–99.CrossRefGoogle Scholar

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© Akadémiai Kiadó, Budapest 2012

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Authors and Affiliations

  1. 1.The Microsoft ResearchUniversity of Trento Centre for Computational and Systems BiologyRoveretoItaly
  2. 2.Department of Information Engineering and Computer ScienceUniversity of TrentoTrentoItaly
  3. 3.The Microsoft ResearchUniversity of Trento Centre for Computational and Systems BiologyTrentoItaly

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