Marine Biology

, Volume 143, Issue 2, pp 393–403

Mechanical clam dredging in Venice lagoon: ecosystem effects evaluated with a trophic mass-balance model

  • F. Pranovi
  • S. Libralato
  • S. Raicevich
  • A. Granzotto
  • R. Pastres
  • O. Giovanardi


Harvesting of the invasive Manila clam, Tapes philippinarum, is the main exploitative activity in the Venice lagoon, but the mechanical dredges used in this free-access regime produce a considerable disturbance of the lagoon ecosystem. An ecosystem approach to study the complex effects of clam harvesting was implemented using a trophic mass-balance model. The trophic relations in the ecosystem were quantified with a mixed trophic impact analysis and further evaluated by considering different explanations for the "Tapes paradox", which consists of the apparent population enhancement of Manila clams by dredging and the apparent nutritional advantages that this species receives from re-suspended organic matter. The key-role played by this introduced species is highlighted by a network analysis that indicates a "wasp-waist control" of the system by Manila clams. The model constructed to characterise the present state of the Venice lagoon ecosystem is compared with models produced for a reconstructed past lagoon and a projected future lagoon. The future model was obtained by simulating the elimination of clam dredging in 10 years. The three different models were compared using thermodynamic and informational indices. Simulating the elimination of clam dredging produced a 33% increase in artisanal fishery catches, carried out by means of static gears, even with no change in fishing effort. These simulations also forecast an increase in the mean trophic level of the artisanal fishery catches as a positive effect of eliminating mechanical clam harvesting.


  1. Arias A (1980) Crecimiento, regimen alimentarioy reproduccion de la dorada (Sparus aurata L.) y del robalo (Dicentrarchus labrax L.) en los esteros de Cadiz. Investig Pesq 44:59–83Google Scholar
  2. ASAP (Azienza Speciale Acquacoltura e Pesca) (1999) Studio per la razionalizzazione delle attività di pesca e di molluschicoltura nel bacino di Chioggia, laguna di Venezia. ASAP, VeniceGoogle Scholar
  3. Auteri R, Abella A, Baino R, Righini P, Serena F, Silvestri R, Voliani A (1993) Interazioni trofiche e attività di pesca nella laguna di Orbetello. Cons Reg Idrobiol Pesca 6:1–222Google Scholar
  4. Baird D, McGlade JM, Ulanowicz RE (1991) The comparative ecology of six marine ecosystems. Philos Trans R Soc Lond B Biol Sci 333:15–29Google Scholar
  5. Barbaro A, Francescon A, Guidastri R (1983) Allevamento in una valle da pesca della laguna veneta di Sparus aurata L. ottenuta per riproduzione artificiale. Nova Thalassia 6:281–286Google Scholar
  6. Botsford W, Castilla JC, Peterson CH (1997) The management of fisheries and marine ecosystems. Science 277:509–515Google Scholar
  7. Brey T (1990) Estimating productivity of macrobenthic invertebrates from biomass and mean individual weight. Meeresforschung 32:329–343Google Scholar
  8. Buia MC, Gambi MC, Zupo V (2000) Structure and functioning of Mediterranean seagrass ecosystems: an overview. Biol Mar Mediterr 7:167–190Google Scholar
  9. Caddy JF, Cochrane KL (2001) A review of fisheries management past and present and some future prospectives for the third millennium. Ocean Coast Manag 44:653–682CrossRefGoogle Scholar
  10. Carrer S, Opitz S (1999) Trophic network model of a shallow water area in the northern part of the lagoon of Venice. Ecol Model 124:193–219CrossRefGoogle Scholar
  11. Casale M, Giovanardi O, Grimm F, Orel G, Pessa G (2001) Distribuzione ed abbondanza delle principali specie di molluschi bivalvi nella Laguna di Venezia nell'estate 1999, con particolare riguardo per Tapes philippinarum (Adams and Reeve, 1850). Biol Mar Mediterr 8:413–423Google Scholar
  12. Ceretti G, Ferraresi U, Francescon A, Barbaro A (1987) Chironomids (Diptera: Chironomidae) in the natural diet of gilthead seabream (Sparus aurata L.) farmed in the Venice lagoon. Entomol Scand Suppl 29:289–292Google Scholar
  13. Cesari P, Pellizzato M (1985) Molluschi pervenuti in laguna di Venezia per apporti antropici volontari o casuali. Acclimazione di Saccostrea commercialis (Iredale e Rougley, 1933) e di Tapes philippinarum (Adams e Reeve, 1850). Boll Malacol 21:237–274Google Scholar
  14. Christensen V (1995) Ecosystem maturity, towards quantification. Ecol Model 77:3–32CrossRefGoogle Scholar
  15. Christensen V, Pauly D (1993) Trophic models of aquatic ecosystems. ICLARM (Int Cent Living Aquat Resour Manag) Conf Proc 26:390Google Scholar
  16. Christensen V, Pauly D (1998) Changes in models of aquatic ecosystem approaching carrying capacity. Ecol Appl 8[Suppl]:104–109Google Scholar
  17. Christensen V, Walters CJ (2000) Ecopath and Ecosim: methods, capabilities and limitations. In: Pauly D, Pitcher TJ (eds) Methods for assessing the impact of fisheries on marine ecosystems of the North Atlantic. Fish Cent Res Rep 8:79–105Google Scholar
  18. Christensen V, Walters CJ, Pauly D (2000) Ecopath  4 user manual. UBC and ICLARM, VancouverGoogle Scholar
  19. Christian RR, Fores E, Comin F, Viaroli P, Ferrari I (1993) Comparative network analysis of the nitrogen cycling in several eutrophic coastal ecosystems. In: Guerrero R, Pedros-Alio C (eds) Trends in microbial ecology. Spanish Society for Microbiology, Madrid, pp 449–452Google Scholar
  20. Cloern JE (2001) Our evolving conceptual model of the coastal eutrophication problem. Mar Ecol Prog Ser 210:223–253Google Scholar
  21. Da Ponte (2001) La pesca a strascico come fattore di disturbo ecologico in Laguna di Venezia e in alto Adriatico. MSc thesis, University of Venice, VeniceGoogle Scholar
  22. Dayton PK, Tegner MJ, Edwards PB, Riser KL (1998) Sliding baselines, ghosts, and reduced expectations in kelp forest communities. Ecol Appl 8:309–322Google Scholar
  23. Duffy JE (2002) Biodiversity and ecosystem function: the consumer connection. Oikos 99:201–219CrossRefGoogle Scholar
  24. Duplisea DE, Jennings S, Malcom SJ, Parker R, Sivyer B (2001) Modelling potential impacts of bottom trawl fisheries on soft sediment biogeochemistry in the North Sea. Goechem Trans 14:1–6Google Scholar
  25. Finn JT (1976) Measures of ecosystem structure and function derived from analysis. J Theor Biol 56:363–380PubMedGoogle Scholar
  26. Flindt M, Salomonsen J, Carrer M, Bocci M, Kamp-Nielsen L (1997) Loss, growth and transport dynamics of Caetomorpha aerea and Ulva rigida in the lagoon of Venice during an early summer field campaign. Ecol Model 102:133–141Google Scholar
  27. Fox JW, Olsen E (2000) Food web structure and the strength of transient indirect effects. Oikos 90:219–226Google Scholar
  28. Francescon A, Barbaro A, Antonini G (1986) Alimentazione ed acrescimento dell'orata (Sparus aurata L.) in valli da pesca del nord Adriatico. Agric Ital (Pisa) 60:7–12Google Scholar
  29. Froese R, Pauly D (2003). FishBase. Available via World Wid Web Version Nov 2001Google Scholar
  30. Goulletquer P, Heral M, Deslous-Paoli JM, Prou J, Garnier J, Razet D, Boromthanarat W (1989) Ecophysiologie et bilan energetique de la palourde japonaise d'elevage Ruditapes philippinarum. J Exp Mar Biol Ecol 132:85–108Google Scholar
  31. Granzotto A, Franzoi A, Longo A, Pranovi F, Torricelli P (2000) La pesca nella laguna di Venezia: un percorso di sostenibilità nel recupero delle tradizioni—lo stato dell'arte. Repporto sullo Sviluppo Sostenibile 2.2001, Fondazione ENI Enrico MatteiGoogle Scholar
  32. Herman PMJ, Scholten H (1990) Can suspension-feeders stabilize estuarine ecosystems? In: Barnes M, Gibson R (eds) Trophic relationships in the marine environment. Aberdeen University Press, Aberdeen, pp 104–116Google Scholar
  33. Holling CS (1973) Resilience and stability of ecological systems. Annu Rev Ecol Syst 4:1–23Google Scholar
  34. Jackson J (2001) What was natural in the coastal oceans? Proc Natl Acad Sci USA 98:5411–5418Google Scholar
  35. Jackson J, Kirby MX, Berger WH, Bjorndal A, Botsford LW, Bourque BJ, Bradbury RH, Cooke R, Erlandson J, Estes J, Hughes TP, Kidwell S, Lange C, Lenihan HS, Pandolfi JM, Peterson CH, Steneck RS, Tegner MJ, Warner RR (2001) Historical overfishing and the recent collapse of coastal ecosystems. Science 293:629–638PubMedGoogle Scholar
  36. Jennings S, Pinnegar JK, Polunin NVC, Warr KJ (2001) Impacts of trawling disturbance on the trophic structure of benthic invertebrate communities. Mar Ecol Prog Ser 213:127–142Google Scholar
  37. Jørgensen SE (1992) Integration of ecosystem theories: a pattern. Kluwer, DordrechtGoogle Scholar
  38. Kinzing AP, Pacala SW, Tilmann D (eds) (2002) The functional consequences of biodiversity. Empirical progress and theoretical expectations. Princeton University Press, Princeton, N.J.Google Scholar
  39. Krantzenberg G (1985) The influence of bioturbation on physical, chemical and biological parameters in aquatic environments: a review. Environ Pollut Ser A Ecol Biol 39:99–122Google Scholar
  40. Laureau M, Naeem S, Inchausti P (2001) Biodiversity and ecosystem functioning: current knowledge and future challenges. Science 294:804–808PubMedGoogle Scholar
  41. Libralato S, Pastres R, Pranovi F, Raicevich S, Granzotto A, Giovanardi O, Torricelli P (2002) Comparison between the energy flow networks of two habitats in the Venice lagoon. Mar Ecol 23:228–236Google Scholar
  42. Menge BA (1995) Indirect effects in marine rocky intertidal interaction webs: patterns and importance. Ecol Monogr 65:21–74Google Scholar
  43. Monaco ME, Ulanowicz RE (1997) Comparative ecosystem trophic structure of three U.S. mid-Atlantic estuaries. Mar Ecol Prog Ser 161:239–254Google Scholar
  44. Müller F (1997) State-of-the-art in ecosystem theory. Ecol Model 100:135–161CrossRefGoogle Scholar
  45. Naeem S (2002) Autotrophic–heterotrophic interactions and their impacts on biodiversity and ecosystem functioning. In: Kinzing AP, Pacala SW, Tilmann D (eds) The functional consequences of biodiversity. Empirical progress and theoretical expectations. Princeton University Press, Princeton, N.J., pp 96–119Google Scholar
  46. NRC (National Research Council) (1995) Understanding marine biodiversity: a research agenda for the nation. National Academy Press, Washington, DCGoogle Scholar
  47. Odum EP (1969) The strategy of ecosystem development. Science 164:262–270PubMedGoogle Scholar
  48. Pauly D, Christensen V, Dalsgaard J, Froese R, Torres F Jr (1998) Fishing down marine food webs. Science 279:860–863PubMedGoogle Scholar
  49. Pinnegar JK, Polunin NVC (1999) Contributions of stable-isotope data to elucidating food webs of Mediterranean rocky littoral fishes. Oecologia 122:399–409CrossRefGoogle Scholar
  50. Pinnegar JK, Polunin NVC, Francour P, Badalamenti F, Chemello R, Harmelin-Vivien M-L, Hereu B, Milazzo M, Zabala M (2000) Trophic cascades in fisheries and protected-area management of benthic marine ecosystems. Environ Conserv 27:179–200CrossRefGoogle Scholar
  51. Pitcher TJ (2001) Fisheries managed to rebuild ecosystems? Reconstructing the past to salvage the future. Ecol Appl 11:601–617Google Scholar
  52. Pranovi F, Giovanardi O (1994) The impact of hydraulic dredging for short-necked clams, Tapes spp., on an infaunal community in the lagoon of Venice. Sci Mar 58:345–353Google Scholar
  53. Pranovi F, Raicevich S, Da Ponte F, Boscolo R, Franceschini G, Torricelli P, Giovanardi O (2001) Effects of mechanical clam harvesting on bottom sediment in the Venice lagoon. In: 36th CIESM Congress Proceedings. Multiprint, Monaco, p 410Google Scholar
  54. Prins TC, Smaal AC, Dame RF (1998) A review of the feedbacks between bivalve grazing and ecosystem processes. Aquat Ecol 31:349–359CrossRefGoogle Scholar
  55. Provincia di Venezia (2000) Piano per la gestione delle risorse alieutiche delle lagune della provincia di Venezia. Provincia di Venezia, VeniceGoogle Scholar
  56. Raffaelli DG, Van der Putten W, Persson L, Wardle DA, Petchey O, Koricheva J, Van der heijden M, Mikola J, Kennedy E (2002) Multi-trophic processes and ecosystem functions. In: Loreau M, Naeem S, Inchausti P (eds) Biodiversity and ecosystem functioning. Oxford University Press, Oxford, pp 147–154Google Scholar
  57. Sfriso A, Ghetti PF (1998) Seasonal variation in biomass, morphometric parameters and production of seagrasses in the lagoon of Venice. Aquat Bot 61:207–223CrossRefGoogle Scholar
  58. Sfriso A, Marcomini A (1996) Decline of Ulva growth in the lagoon of Venice. Bioresour Technol 58:299–307CrossRefGoogle Scholar
  59. Sfriso A, Pavoni B, Marcomini A (1989) Macroalgae and phytoplankton standing crops in the central Venice lagoon: primary production and nutrient balance. Sci Total Environ 80:139–159Google Scholar
  60. Shannon LJ, Cury PM, Jarre A (2000) Modelling effects of fishing in the southern Benguela ecosystem. ICES J Mar Sci 57:720–722CrossRefGoogle Scholar
  61. Solidoro C, Pastres R, Melaku Canu D, Pellizzato M, Rossi R (2000) Modelling the growth of Tapes philippinarum in the northern Adriatic lagoons. Mar Ecol Prog Ser 199:137–148Google Scholar
  62. Sorokin YI, Giovanardi O (1995) Trophic characteristics of the Manila clam (T. philippinarum Adams & Reeve, 1850). ICES J Mar Sci 52:853–862CrossRefGoogle Scholar
  63. Sorokin YuI, Sorokin PYu, Giovanardi O, Dalla Venezia L (1996) Study of the ecosystem of the lagoon of Venice, with emphasis on anthropogenic impact. Mar Ecol Prog Ser 141:247–261Google Scholar
  64. Sorokin YuI, Giovanardi O, Pranovi F, Sorokin PYu (1999) Need for restricting bivalve culture in the southern basin of the lagoon of Venice. Hydrobiologia 400:141–148CrossRefGoogle Scholar
  65. Ulanowicz RE (1986) Growth and development: ecosystems phenomenology. Springer, New York Heidelberg BerlinGoogle Scholar
  66. Ulanowicz RE, Puccia CJ (1990) Mixed trophic impacts in ecosystems. Coenoses 5:7–16Google Scholar
  67. Ulanowicz RE, Wulff F (1991) Comparing ecosystem structures: the Chesapeake Bay and the Baltic Sea. In: Cole J, Lovett G, Findlay S (eds) Comparative analysis of ecosystems: patterns, mechanisms and theories. Springer, Berlin Heidelberg New York, pp 140–166Google Scholar
  68. Vasconcellos M, Mackinson S, Sloman K, Pauly D (1997) The stability of trophic mass-balance models of marine ecosystems a comparative analysis. Ecol Model 100:125–134CrossRefGoogle Scholar
  69. Walters CJ, Christensen V, Pauly D (1997) Structuring dynamic models of exploited ecosystems from trophic mass-balance assessments. Rev Fish Biol Fish 7:139–172CrossRefGoogle Scholar
  70. Watson R, Pauly D (2001) Systematic distortion in world fisheries catch trends. Nature 414:534–536CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  • F. Pranovi
    • 1
  • S. Libralato
    • 1
  • S. Raicevich
    • 1
  • A. Granzotto
    • 1
  • R. Pastres
    • 2
  • O. Giovanardi
    • 3
  1. 1.Dipartimento Scienze AmbientaliUniv. Ca' FoscariVeniceItaly
  2. 2.Dipartimento Chimica FisicaUniv. Ca' FoscariVeniceItaly
  3. 3.Istituto Centrale per la Ricerca Applicata al MareICRAMChioggia (VE)Italy

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