Coexistence of Pacific oyster Crassostrea gigas (Thunberg, 1793) and blue mussels Mytilus edulis Linnaeus, 1758 on a sheltered intertidal bivalve bed?

Bidragets oversatte titel: Koeksistens af Stillehavsøsters og Blåmuslinger på en beskyttet muslingebanke i tidevandszonen?

Mark Wejlemann Holm, Jens Davids, Esbern Holmes, Per Dolmer, Thomas Theis Nielsen, Bent Vismann, Benni Winding Hansen

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review


The invasive Pacific oyster, Crassostrea gigas Thunberg, 1793 was introduced in Denmark for aquaculture in the 1970s. Presently, feral
populations are found in many parts of the country, with the largest populations established on existing beds of blue mussel, Mytilus edulis
Linnaeus, 1758. This study was conducted in the Limfjord estuary, at Agger Tange, where C. gigas was introduced in 1972. The study site is a large
cluster of raised intertidal bivalve beds inhabited by C. gigas and M. edulis in a sheltered part of the estuary. The two bivalves have some of the
same living requirements, and as C. gigas have been present in the ecosystem for more than 40 years, we hypothesize that the presence of C. gigas
has altered the spatial and temporal distribution of M. edulis by inducing a niche separation. The spatiotemporal development of the bivalve bed was
determined using orthophotos. C. gigas and M. edulis were collected from the bivalve bed, shell lengths were converted into biomass, which were
interpolated to create biomass contours and combined with modelled topography of the bivalve bed to study niche separation. The bivalve bed
slowly extended northwards over a period of 11 years, where it also became more fragmented. The northern part of the bed was composed of
mussel mats on top of soft sediment. This area was dominated by M. edulis, while areas in the south were dominated by C. gigas. In the southern
part, the bivalve bed was composed of thick and compact sediment suggesting it represent the oldest part of the bivalve bed. There were no
differences in the conditions of C. gigas and M. edulis from old or newly established areas, and there were no difference in the vertical distributions
of the bivalve species. Thus, spatial and temporal separation of the two species is not pronounced at present, and thus unable to explain why they
seemingly coexist.
Bidragets oversatte titelKoeksistens af Stillehavsøsters og Blåmuslinger på en beskyttet muslingebanke i tidevandszonen?
TidsskriftAquatic Invasions
Udgave nummer2
Sider (fra-til)155-165
Antal sider11
StatusUdgivet - 8 maj 2016


  • Condition index
  • bioinvasion
  • bivalve bed dynamics
  • niche separation
  • succession

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