BIOTIC

BIOTIC Species Information for Ostrea edulis

Researched by

Angus Jackson

Data supplied by

MarLIN

Refereed by

This information is not refereed.

Taxonomy

Scientific name

Ostrea edulis

Common name

Native oyster

MCS Code

W1758

Recent Synonyms

None

Phylum

Mollusca

Subphylum

Superclass

Class

Pelecypoda

Subclass

Order

Ostreoida

Suborder

Ostreina

Family

Ostreidae

Genus

Ostrea

Species

edulis

Subspecies

Additional Information

Also commonly known as the flat oyster and European oyster.

Taxonomy References

Howson & Picton, 1997, Hayward & Ryland, 1995b, Campbell, 1994, Christensen, 1980, Anonymous, 1999(b), Tebble, 1966, Yonge, 1960, Korringa, 1952,

General Biology

Growth form

Bivalved

Feeding method

Active suspension feeder

Mobility/Movement

Permanent attachment

Environmental position

Epifaunal

Typical food types

Suspended organic particles.

Habit

Attached

Bioturbator

Not relevant

Flexibility

None (< 10 degrees)

Fragility

Robust

Size

Small-medium(3-10cm)

Height

Insufficient information

Growth Rate

Insufficient information

Adult dispersal potential

None

Dependency

Independent

Sociability

Gregarious

Toxic/Poisonous?

General Biology Additional Information

There is some evidence that reduced growth, weight and poor conditions are a consequence of high population densities (300 per square yard). Size and shape can be extremely variable. Because the oyster cements itself to the substratum, growth of neighbouring individuals may result in competition or space and distort the usual shell shape. Feeding is carried out by pumping water through a filter in the gill chamber removing suspended organic particles. The native oyster starts life as male, becoming mature at around 3 years of age. After spawning the oyster becomes a functional female. Larvae are seldom produced by oysters under 50 mm. Growth is quite rapid for the first year and a half. It then remains constant at around 20 grams per year before slowing down after five years. In the British Isles, the main growing season is from April to October. The oyster faces serious competition from the introduced species Crepidula fornicata, the slipper limpet. Brought over from the United States this species can occur in very high densities competing for space and food. The slipper limpet deposits pseudo faeces which forms 'mussel mud' changing the substratum and hindering settlement. Native oysters are preyed on by a variety of species including starfish and Ocenebra erinacea, the sting winkle or rough tingle. Buccinum undatum, the common whelk also feeds on oysters but not as exclusively as the sting winkle. Urosalpinx cinerea, the American oyster drill was accidentally introduced to the British Isles with American oysters. This species lives on oyster beds and feeds almost entirely on oyster spat.

Biology References

Lilley, 2000, Dare, 1982, Sheldon, 1968, Richardson et al., 1993, Askew, 1972, Hutchinson & Hawkins, 1992, Yonge, 1960, Korringa, 1952,

Distribution and Habitat

Distribution in Britain & Ireland

Widely distributed around the British Isles but less so on the east and north-east coasts of Britain and Ireland. The main stocks are now in the west coast of Scotland, the south-east and Thames estuary, the Solent, the River Fal, and Lough Foyle.

Global distribution

Found naturally from the Norwegian Sea south through the North Sea down to the Iberian Peninsula and the Atlantic coast of Morocco. Found in the Mediterranean Sea and extends into the Black Sea.

Biogeographic range

Not researched

Depth range

0-80m

Migratory

Non-migratory / Resident

Distribution Additional Information

The native oyster has also been introduced and is cultivated in North America, Australia and Japan. Cultivated populations may be encouraged through the use of an artificial substratum (limed tiles) used preferentially for larval settlement. Oysters are found on a wide variety of substrata but typically where the seabed is hard. Can form into dense 'beds' of oyster shells.

Substratum preferences

Large to very large boulders
Small boulders
Cobbles
Pebbles
Gravel / shingle
Artificial (e.g. metal/wood/concrete)
Muddy gravel
Muddy sand
Mud
Bedrock

Physiographic preferences

Open coast
Sealoch
Ria / Voe
Estuary

Biological zone

Lower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Lower Infralittoral
Upper Circalittoral
Lower Circalittoral

Wave exposure

Exposed
Moderately Exposed
Sheltered
Very Sheltered
Extremely Sheltered

Tidal stream strength/Water flow

Insufficient information

Salinity

Full (30-40 psu)
Variable (18-40 psu)

Habitat Preferences Additional Information

Distribution References

Hayward & Ryland, 1995b, Campbell, 1994, Anonymous, 1999(b), Tebble, 1966, Lilley, 2000, Yonge, 1960, Korringa, 1952, Moore, 2002,

Reproduction/Life History

Reproductive type

Protandrous hermaphrodite

Developmental mechanism

Planktotrophic

Reproductive Season

June to September

Reproductive Location

As adult

Reproductive frequency

Annual protracted

Regeneration potential

Life span

6-10 years

Age at reproductive maturity

3-5 years

Generation time

Insufficient information

Fecundity

Up to 2,000,000 in large females

Egg/propagule size

ca 150 µm diameter

Fertilization type

Internal

Larvae/Juveniles
Larval/Juvenile dispersal potential	>10km	Larval settlement period	Insufficient information
Duration of larval stage	11-30 days

Reproduction Preferences Additional Information

A life span of 5-10 years is probably typical (majority of individuals in populations are 2-6 years old). However, they may reach in excess of 15 years old. Oysters are protandrous alternating hermaphrodites. This means that they start off as males producing sperm then switch to egg producing females, back to males and so on. Gamete maturation begins in March or April and is in part temperature dependent. Gametogenesis may be continuous in warmer conditions e.g. California. On the west coast of Ireland there is at least one spawning in each sexual phase during the summer. There may be some periodicity in spawning with peaks during full moon periods. Fecundity may be as high as 2,000,000 in large individuals. The eggs are around 150 microns in diameter. Eggs produced during the female stage are held in the gills and mantle cavity. The eggs are fertilized by sperm drawn in by the inhalant water flow used for feeding and respiration. The fertilized eggs are retained for 7-10 days for the early development until the veliger stage is reached. This is sometime called larviparous or incubatory development.

Reproduction References

Lilley, 2000, Dare, 1982, Orton, 1936, Wilson & Simons, 1985, Yonge, 1960, Korringa, 1952,