Crassostrea gigas in Denmark

Species name:	Crassostrea gigas
Family:	Ostreidae
Group:	Molluscs
Common names:	Stillehavsøsters, Japansk østers
Synonymes:	Crassostrea angulata
Habitats:	Marine habitats
Time of introduction:
Year of first report:	1980
Type of introduction:	Intentional
Distribution details:	Japan
Donor area:
Status:	Established
Frequency:	Local
Invasiveness:	Invasive
Impact:	Not known
Comments:
Last updated	10-01-2016 (day-month-year)
Resources:	Fact sheet Google image search
References:	Erik Rasmussen, Zool.Mus., København. 1987, Pers. comm Jensen, K.R. and Knudsen, J. 2005. A summary of alien marine benthic invertebrates in Danish waters. Oceanological and Hydrobiological Studies 34, Supplement 1: 137-162. Lindner,G., 1976. Konkylier. Snegle og muslinger i havet. Gads Naturbøger. Rasmussen,E., 1985. Østersbanken i Isefjorden. Naturligvis. Naturvidenskab ved Københavns Universitet. Informationsudvalget, Det Naturvidenskabelige Fakultet, Panuminstituttet.

Habitat	Explanation
Agricultural areas	Under cultivation
Arctic/alpine	Arctic/alpine vegetation types (latitude and altitude aspects involved)
Boreal forest	Conifer forest (Neddleleaf)
Coastland	Along and influenced by the sea
Continental ice	e.g. the glaciers on Greenland
Disturbed areas	Under human influence, but not under cultivation
Estuaries and brackish areas	Where freshwater meets the sea, and where salinity varies between 35 ppm and <5 ppm (such as the Baltic Sea)
Grass and heathlands	Dry grassland incl. steppe/prarie and heathland
Greenhouses or compost heaps	Here the climate is regulated to natural situation (temperature and humidity)
Host	Organism were the IAS gets protection or nourishment
Lakes	Freshwater bodies (stagnant, lentic waters)
Marine habitats	All saltwater habitats, benthic and pelagic (e.g. Atlantic, North Sea, Barents Sea)
Mixed conifer/broadleaf forest	Conifers (Neddleleaf) mixed with decidous trees
Not known
Riparian zones	Along rivers
Rocks and lavafields	Rocky areas without natural vegetation or with very sparse vegetation
Shrublands	Shrubs and dwarfed trees
Temperate broadleaf forest	Decidous forests
Under human management	Inside houses and warehouses, inside furfarms, in closed aquacultural sites, in closed aquaria
Urban areas	Near human dvellings
Watercourses	Running water (lotic waters)
Vector	The bearer or carrier of pathogenic IAS
Wetlands	Bogs, mires and wet grasslands, lakeshores

Group	Explanation
Angiosperms	The other flowering plants - Angiospermophyta, classes Dicotyledoneae and Monocotyledoneae (Dicots and monocots)
Annelids	Lophotrochozoans: Annelida (Segmented Worms), Phoronida (horseshoe worms), Pogonophora (bearded tube worms), Sipuncula (peanut worms), Nemertini (ribbon worms), Echiura (Spoon worms),
Arthropods	Phylum Arthropoda (Spiders, Insects, Crabs, Crayfish etc.)
Birds	Not a big group in numbers, but one of the charismatic groups of vertebrates, Phylum Chordata
Bryophytes	Mosses and allies, such as liverworts
Cnidarians	Phylum Cnidaria (jellyfishes, corals, hydra, anemones)
Comb jellies	Phylum Ctenophora (comb jellies)
Coniferous plants	Gymnosperms - Coniferophyta/Pinophyta
Ferns	Pteridophyta (Ferns and allies)
Fish	An aquatic charismatic group, Phylum Chordata
Flatworms	Phylum Platyhelminthes (Flatworms)
Fungi	Macrofungi (incl. Lichens)
Macroalgae	Multicellular plants living in water (also called seaweeds)
Mammals	Not a big group in numbers, but one of the charismatic groups of vertebrates, Phylum Chordata
Microorganisms	Bacteria, vira, microfungi, diseases
Molluscs	Phylum Mollusca (Snails, Clams, Squid & Octopus)
Nematodes	The Ecdysozoan worms: Nematoda, Nematomorpha, Cephaloryncha, Onychophora
Other chordates	Urochordata (tunicates, sea squirts), Myxini (hagfish), Cephalochordata (lancelets)
Other invertebrates	Phylum Brachiopoda (Lamp Shells), Phylum Porifera (Sponges), Phylum Bryozoa ("Moss animals"), Phylum Rotifera (Rotifers)
Phytoplankton	Microscopic plants that live in water
Protozoans	Single-celled eukaryotic organisms
Reptilia & amphibia	Not big groups in numbers, but charismatic groups of vertebrates, Phylum Chordata
Sea urchins & starfish	Phylum Echinodermata (sea urchins & starfish, sea cucumbers)

Type of introduction	Explanation
Intentional	On purpose
Intentional & unintentional	Both the above ways
Not known	No information available
Unintentional	Unknowingly - as a by-product of human activities

Invasiveness	Explanation
Invasive	Threatens native biological diversity
Not invasive	Does not threaten native biological diversity
Not known
Potentially invasive	Has a potential to threaten native biological diversity

Distribution	Explanation
Africa
Antarctica	This is a continent where we will probably not see too many aliens species from
Arctic Ocean	Surrounding the north pole
Asia	Divides to Europa along Ural/Kazakstan, Black Sea
Europe	Divides to Asia along the Ural/Kazakstan (check maps for details)
Indian Ocean	South of India to the southern tips of Africa and Australia respectively
N. America	Canada, USA, Mexico
N. Atlantic Ocean	The upper part of the Atlantic, equator divides from the southern part
N. Pacific Ocean	Pacific Ocean the upper part, equator divides from the southern part.
Not known
Oceania	Australia, New Zealand and small islands
S. America	All countries south of Mexico
S. Atlantic Ocean	The southern part of the Atlantic Ocean
S. Pacific Ocean	The lower part of the Pacific ocean
Southern Ocean	Ocean surrounding Antarctica and extends to 60 degrees latitude

Frequency	Explanation
Absent	Not found(primarily intended for phase II where we compare lists)
Common	Many sites in the country
Eradicated	Has been succesfully eradicated
Extinct	Has been successfully eradicated
Local	Locally abundant, many individuals in some areas of the country
Not known
Rare	Few sites where it is found in the country
Very common	Many sites and many individuals

Pathway	Explanation
Agriculture	Plants for production of food for human and animal consumption, incl. crops and contaminants of hay, grain, fodder
Angling/sport	Live bait or dispersal via fishing gear or/and boats or as a consequence of aquasports
Animal husbandry	Animals for production of food for human, including the pest species introduced via the animal hosts
Aquaculture	Fish/crayfish/algae/seafood farming, or a consequences of stocking of species (pest species) - includes mariculture
Aquaria	Ponds and aquariums
Ballast water & sediments	Ballast water and sediments in tanks, as well as solid ballast, incl also the dispersal via shipping in general (eg. Brown rat)
Biological control	Introduced as a putative biocontrol agent/pest of another species
Escapes	Fur farming, pet-animals escaping from cativity, laboratory animals, animal escapes, pet trade
Fisheries	Commercial fishing
Forestry	Timber and tree production, including the pest species introduced via tree hosts or product thereof
Horticulture	Plants used for ornamental purposes, gardening
Hull fouling	Fouling of ships hulls
Hunting	Released as hunting quarry or prey
Landscaping	The use of plants in the landscape (such as hegde plantings, binding of silt, erosion control)
Medicinal	Typically plants (maybe a few animals) for this purpose
Not known
Ornamental	Animals used for ornamental purposes auch as colourful slugs and birds in parks etc.
Reintroduction	Re-introduction of species that have died out in the country previously
Secondary introduction	Introduced species where populations have been introduced from a nearby country/sea area - not the natural distribution area
Transport	Infrastructure, translocation of machinery, transportation along roads and rails, planes, package material etc.

Status	Explanation
Established	The species has formed self-reproducing populations in semi-natural or natural areas.
In captivity/culture	Greenhouses, houses and otherwise confined by humans
Not established	The species has not formed self-reproducing populations (also called casual or incidental)
Not known
Suspected	The species is suspected to be found in the country, but no scientific proof published
Within country transfer	The species occurs naturally (is indigenous) within one part of the country but has been introduced by humans into another region where it has not previously occurred.

Impact	Explanation
Abiotic changes	Modification of fire regime, succession, hydrology, nutrient availability,
Competition	Competing with other organisms filling the same niche in the food chain (horizontal effect), physical disturbance
Decomposition	Entering the local food web by being a new decomposer (vertical effects)
Disease transmission	Being a reservoir for parasites or a vector for pathogen or being a parasite/pathogen
Extinction	Extinction of native species - such a grave effect is rarely seen in our parts of the world (let's hope we se no records here)
Genetic	hybridising with a related species or varieties, may lead to extinction by gene flow or dilution of locally adapted genepool
Herbivory	Entering the local food web by being a new herbivore (vertical effects)
Human health	Human health effects by being toxic, causing diseases or allergies
None	Preferably (!) based on some kind of scientific knowledge
Not known	no information available
Predation	Entering the local food web by being a new predator (vertical effects)
Resource allocation	Being a new ressource for native or introduced species (for herbivores, predators or decomposers) (vertical effects)
Socio-economic	Fouling, clogging of waterways, leading to increased pesticide/herbicide use, control and management costs etc.
Toxic	Being toxic for local species, thereby displacing these.

Crassostrea gigas in Denmark

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