Oecologia

, Volume 87, Issue 3, pp 307–318 | Cite as

Modification of animal habitat by large plants: mechanisms by which seagrasses influence clam growth

  • E. A. Irlandi
  • C. H. Peterson
Original Papers

Summary

Field experiments withMercenaria mercenaria in a relatively high-energy environment demonstrated that clams on unvegetated sand flats failed to grow during autumn while those within seagrass beds grew substantially. Clam growth rates at the seagrass margin that first receives the faster-flowing, flood-tidal currents were about 25% less than at the opposite edge. In a second experiment, pruning, which reduced average blade length by 50–75%, was shown to enhance near-bottom current velocities and to reduce shell growth ofMercenaria during summer by about 50%. As in the first experiment, clams in the unvegetated sand flats exhibited no net growth. Clam mortality, caused mostly by predatory crabs and whelks, was much higher on sand flats than in seagrass beds and intermediate in clipped seagrass. Although consistent with some previous reports, these growth results are still surprising given that they contradict the generalization that suspension feeders grow faster under more rapid current regimes.

Three types of indirect interactions might explain the observed effect of seagrass on growth of buried clams: (1) altering food supply; (2) changing the intensity of biological disturbance on feeding clams; and/or (3) affecting the physical stability of the sediments. Previous research on this question has focused almost exclusively on processes that alter food supply rates. In this study, food concentrations, as indicated by suspended chla, were 30% higher inside than outside one seagrass bed, whereas chla concentrations in two other beds were not different from those on adjacent sand flats. This result is sufficient to show that more intense food depletion was not induced by the reduction in flow velocities under the seagrass canopy. Nevertheless, the possible small difference in food concentrations between vegetated and unvegetated bottom seems insufficient to explain the absence of growth of sand-flat clams, especially given the virtual lack of food limitation among suspension feeders in this system. Two data sets demonstrated that the effects of biological disturbance agents cannot be ignored. An outdoor laboratory experiment showed that even in the absence of physical contact between predator and prey the presence of a whelk reduces the amount of time spent feeding byMercenaria. This result suggests that sand flats, where predation rates are higher, may be sites of lower clam growth than seagrass beds because of greater consumer interference with clam feeding. Furthermore, clam siphons are proportionately larger inside seagrass than on sand flats, implying that siphon nipping may not be as intense inside seagrass. This process, too, would reduce net growth of sand-flat clams. Finally, no explicit test was conducted of the hypothesis that enhanced sediment transport in the absence of flow baffling and root binding by seagrass inhibits net growth of clams on high-energy sand flats. Nevertheless, this is a reasonable explanation for the pattern of enhanced growth of seagrass clams, and could serve to explain the otherwise unexplained pattern of lower clam growth at the edge of the seagrass bed that experiences the faster flood-tidal current velocities. Each broad process, changing fluid dynamics, altering consumer access, and varying sediment stability, represents a mechanism whereby habitat structure, provided by the dominant plant, has an important indirect influence on the functional value of the habitat for resident animals.

Key words

Biological disturbance Growth Habitat modification Mercenaria mercenaria Physical baffling 

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References

  1. Au S (1974) Vegetation and ecological processes on Shackleford Bank, North Carolina. US Natl Park Serv, Sci Monogr no. 6, Washington, DCGoogle Scholar
  2. Bayne BL, Newell RC (1983) Physiological energetics of marine molluscs. In: Saleuddin ASM, Wilbur KM (eds) The Mollusca, vol. 4. Academic Press, London, pp 409–515Google Scholar
  3. Blundon JA, Kennedy VS (1982) Refuges for infaunal bivalves from blue crab,Callinectes sapidus (Rathbun), predation in Chesapeake Bay. J Exp Mar Biol Ecol 65:67–81Google Scholar
  4. Coen LD, Heck KL Jr, Abele LG (1981) Experiments on competition and predation among shrimps of seagrass meadows. Ecology 62: 1484–1493Google Scholar
  5. Crawley MJ (1983) Herbivory. The dynamics of animal-plant interactions. Univ. of California Press, Berkeley, CaliforniaGoogle Scholar
  6. Denno RF, McClure MS (eds) (1983) Variable plants and herbivores in natural and managed systems. Academic Press, New YorkGoogle Scholar
  7. Eckman JE (1990) A model of passive settlement by planktonic larvae on to bottoms of differing roughness. Limnol Oceanogr 35:887–901Google Scholar
  8. Eckman JE, Peterson CH, Cahalan JA (1989) Effects of flow speed, turbulence, and orientation on growth of juvenile bay scallopsArgopecten irradians concentricus (Say). J Exp Mar Biol Ecol 132:123–140Google Scholar
  9. Folk RL (1980) Petrology of sedimentary rocks. Second edition. Hemphill, Austin, Texas, USAGoogle Scholar
  10. Fonseca MS, Fisher JS, Zieman JC, Thayer GW (1982) Influence of the seagrass,Zostera marina L., on current flow. Estuar Coast Shelf Sci 15:351–364Google Scholar
  11. Fonseca MS, Zieman JC, Thayer GW, Fisher JS (1983) The role of current velocity in structuring eelgrass (Zostera marina L.) meadows. Estuar Coast Shelf Sci 17:367–380Google Scholar
  12. Fréchette M, Bourget E (1985) Energy flow between the pelagic and benthic zones: Factors controlling particulate organic matter available to an intertidal mussel bed. Can J Fish Aquat Sci 42:1158–1165Google Scholar
  13. Fréchette M, Butman CA, Geyer WR (1989) The importance of boundary-layer flow in supplying phytoplankton to the benthic suspension feeder,Mytilus edulis L. Limnol Oceanogr 34:19–36Google Scholar
  14. Gambi MC, Nowell ARM, Jumars PA (1990) Flume observations on flow dynamics inZostera marina (eelgrass) beds. Mar Ecol Prog Ser 61:159–169Google Scholar
  15. Ginsburg RN, Lowenstam HA (1958) The influence of marine bottom communities on the depositional environment of sediments. J Geol 66:310–318Google Scholar
  16. Grizzle RE, Morin PJ (1989) Effect of tidal currents, seston, and bottom sediments on growth ofMercenaria mercenaria: results of a field experiment. Mar Biol 102:85–93Google Scholar
  17. Howe HF, Westley LC (1988) Ecological relationships of plants and animals. Oxford Univ Press, OxfordGoogle Scholar
  18. Irlandi EA (1988) The influence of seagrass cover on growth of a suspension-feeding bivalve,Mercenaria mercenaria. M.S. Thesis, Univ North Carolina, Chapel Hill, North Carolina, USA, 71 pGoogle Scholar
  19. Jackson GA, Winant CD (1983) Effects of a kelp forest on coastal currents. Cont Shelf Res 2:75–80Google Scholar
  20. Kerswill CJ (1949) Effects of water circulation on the growth of quahogs and oysters. J Fish Res Bd Can 7:545–551Google Scholar
  21. Leber KM (1985) The influence of predatory decapods, refuge, and microhabitat selection on seagrass communities. Ecology 66:1951–1964Google Scholar
  22. Lubchenco J, Gaines SD (1981) A unified approach to marine plant-herbivore interactions. I. Populations and communities. Ann Rev Ecol Syst 12:405–437Google Scholar
  23. Magalhaes H (1948) An ecological study of the snails of the genusBusycon at Beaufort, NC. Ecol Monogr 18:377–409Google Scholar
  24. Main KL (1987) Predator avoidance in seagrass meadows: prey behavior, microhabitat selection, and cryptic coloration. Ecology 68:170–180Google Scholar
  25. Monismith SG, Koseff JR, Thompson JK, O'Riordan CA, Nepf HM (1990) A study of model bivalve siphonal currents. Limnol Oceanogr 35:680–696Google Scholar
  26. Muschenheim DK (1987) The dynamics of near-bed seston flux and suspension-feeding benthos. J Mar Res 45:473–496Google Scholar
  27. Myers A (1977) Sediment processing in a marine subtidal sandy bottom community: II. Biological consequences. J Mar Res 35:633–647Google Scholar
  28. Okamura B (1984) The effects of ambient flow velocity, colony size, and upstream colonies on the feeding success of Bryozoa I.Bugula stolonifera Ryland, an arborescent species. J Exp Mar Biol Ecol 83:179–183Google Scholar
  29. Orth RJ (1977) The importance of sediment stability in seagrass communities. In: Coull B (ed) Ecology of Marine Benthos. Univ South Carolina Press, Columbia, South Carolina, pp 281–300Google Scholar
  30. Parsons TR, Maita Y, Lalli CM (1984) A manual of chemical and biological methods for seawater analysis. Pergamon Press, New YorkGoogle Scholar
  31. Peterson CH (1982) Clam predation by whelks (Busycon spp.): Experimental tests of the importance of prey size, prey density, and seagrass cover. Mar Biol 66:159–170Google Scholar
  32. Peterson CH, Beal BF (1989) Bivalve growth and higher order interactions: importance of density, site, and time. Ecology 70:1390–1404Google Scholar
  33. Peterson CH, Duncan PB, Summerson HC, Safrit GW (1983) A mark-recapture test of annual periodicity of internal growth band deposition in shells of hard clams,Mercenaria mercenaria, from a population along the southeastern United States. Fish Bull, US 81:765–779Google Scholar
  34. Peterson CH, Quammen ML (1982) Siphon nipping: its importance to small fishes and its impact on growth of the bivalveProtothaca staminea (Conrad). J Exp Mar Biol Ecol 63: 249–268Google Scholar
  35. Peterson CH, Summerson HC, Duncan PB (1984) The influence of seagrass cover on population structure and individual growth rate of a suspension-feeding bivalve,Mercenaria mercenaria. J Mar Res 42:123–138Google Scholar
  36. Rhoads DC, Young DK (1970) The influence of deposit-feeding organisms on sediment stability and community trophic structure. J Mar Res 28:150–178Google Scholar
  37. Schmitt RJ, Holbrook SJ (1990) Contrasting effects of giant kelp on dynamics of surfperch populations. Oecologia: 84:419–429Google Scholar
  38. Scoffin TP (1970) The trapping and binding of subtidal carbonate sediments by marine vegetation in Bimini Lagoon, Bahamas. J Sediment Petrol 40:249–273Google Scholar
  39. Strong DR, Lawton JH, Southwood R (1984) Insects on plants. Harvard Univ Press, CambridgeGoogle Scholar
  40. Summerson HC, Peterson CH (1984) Role of predation in organizing benthic communities of a temperate-zone seagrass bed. Mar Ecol Prog Ser 15:63–77Google Scholar
  41. Trevallion A, Edwards RRC, Steele JH (1970) Dynamics of a benthic bivalve. In: Steele JH (ed) Marine Food Chains. Univ California Press, Berkeley, pp 285–295Google Scholar
  42. Walne PR (1972) The influence of current speed, body size, and water temperature on the filtration rate of five species of bivalves. J Mar Biol Ass UK 52:345–374Google Scholar
  43. Wildish DJ (1977) Factors controlling marine and estuarine sublittoral macrofauna. Helgoländer Meeres 30:445–454Google Scholar
  44. Wildish DJ, Kristmanson DD (1979) Tidal energy and sublittoral macrobenthic animals in estuaries. J Fish Res Board Can 36: 1197–1206Google Scholar
  45. Wildish DJ, Kristmanson DD (1984) Importance to mussels of the benthic boundary layer. Can J Fish Aquat Sci 41:1618–1625Google Scholar
  46. Wildish DJ, Kristmanson DD (1985) Control of suspension-feeding bivalve production by current speed. Helgoländer Meeres 39:237–243Google Scholar
  47. Winter JE (1978) A review of the knowledge of suspension feeding in lamellibranchiate bivalves, with special reference to artificial aquaculture systems. Aquaculture 13:1–33Google Scholar
  48. Zieman JC (1982) The ecology of seagrasses of South Florida: a community profile. US Fish Wildl Serv Biol Serv Prog FWS/OBS-82/25Google Scholar

Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • E. A. Irlandi
    • 1
  • C. H. Peterson
    • 1
  1. 1.Institute of Marine SciencesUniversity of North Carolina at Chapel HillMorehead CityUSA

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