Fate and legacy of an invasion: extinct and extant populations of the soft-shell clam (Mya arenaria) in Grays Harbor (Washington)

Mollusks as ecosystem engineers: the role of shell production in aquatic habitats

“…assemblages of dead organisms and parts of dead organisms; Powell et al 1989), and these death assemblages are widespread (Kidwell 1985, Powell et al 1989). The durability of shells and their occurrence at locally high densities in reefs and beds are characteristics that increase the likelihood of important engineering effects over large temporal and spatial scales (Kidwell and Jablonski 1983, Kidwell 1985, 1986, Gutiérrez and Iribarne 1999, Palacios et al 2000).…”

“…(5) Humans have caused large changes in mollusk density and biomass in aquatic habitats through exploitation of shellfish populations, cultivation of species, species introductions and habitat modification (Roadhouse and Roden 1987, Rothschild et al 1994, Beukema and Cadée 1996, Carlton 1999, Strayer et al 1999, Palacios et al 2000). Shell extraction is also important in certain locales (La Salle and de la Cruz 1985, Beukema and Cadée 1999).…”

“…All these activities alter rates of shell production. However, with a few exceptions (Ricciardi et al 1997, Lenihan and Peterson 1998, Stewart et al 1998, Lenihan 1999, Palacios et al 2000), most studies dealing with community or ecosystem impacts of changes in mollusk density and biomass have not considered the engineering‐mediated consequences of altered shell production.…”

“…Predator‐mediated negative feedbacks are also plausible explanations for shell habitats that are mostly full of empty shells. Low recruitment of the soft‐shell clam, Mya arenaria , in shell deposits of the Grays Harbor estuary (Washington, USA), is attributed to predation by juvenile Dungeness crab, Cancer magister , whose densities are orders of magnitude higher in shell beds than in adjacent flats (Palacios et al 2000).…”

Rare self-facilitation in terrestrial plants as compared to aquatic sessile organisms: empirical evidences and causal mechanisms

“…(Appendix S3 in Supplementary material) can induce negative plant-substrate interactions by the accumulation of hydrogen sulfide in their root zone. Among sessile animals, no such evidences have been reported in the literature, but one example has been described for the mobile clam Mya arenaria (Palacios et al 2000). Here, the accumulation of the shells provides refuge for the predator crab that, in turn, negatively affects the clam recruitment.…”