BIOTIC

BIOTIC Species Information for Amphiura chiajei

Researched by

Lizzie Tyler

Data supplied by

University of Sheffield

Refereed by

This information is not refereed.

Taxonomy

Scientific name

Amphiura chiajei

Common name

A brittlestar

MCS Code

ZB152

Recent Synonyms

None

Phylum

Echinodermata

Subphylum

Superclass

Class

Ophiuroidea

Subclass

Order

Ophiurida

Suborder

Family

Amphiuridae

Genus

Amphiura

Species

chiajei

Subspecies

Additional Information

Other Amphiura species are similar. Mixed populations of Amphiura chiajei and Amphiura filiformis are common.

Taxonomy References

Mortensen, 1927, Hayward et al., 1996, Picton, 1993, Hayward & Ryland, 1995b,

General Biology

Growth form

Stellate
Radial

Feeding method

Surface deposit feeder
Sub-surface deposit feeder

Mobility/Movement

Crawler
Burrower

Environmental position

Infaunal

Typical food types

Organic detritus.

Habit

Free living

Bioturbator

Flexibility

High (>45 degrees)

Fragility

Fragile

Size

Small-medium(3-10cm)

Height

Insufficient information

Growth Rate

0.5 mm/year

Adult dispersal potential

1km-10km

Dependency

Independent

Sociability

Gregarious

Toxic/Poisonous?

General Biology Additional Information

Feeding method
Amphiura chiajei buries in the sediment with its disc at 4-6 cm depth. One or two arms are stretched up above the sediment to collect food at the surface. Food particles are then transported along the arms to its mouth and ingested (Buchanan, 1964).
Population densities
The species is mostly found in low numbers throughout its range, although a number of high density populations are reported. Survey work by Keegan & Mercer (1986) revealed Amphiura chiajei to be a dominant member of the bottom community in Killary Harbour (a fjord-like inlet on the west coast of Ireland). The highly dense population of about 700 individuals per m², occurred in sediments with a silt/clay content of 80-90% and organic carbon levels of 5-7%. In contrast, Buchanan (1964) reported the mean population density of Amphiura chiajei to be 13 individuals per m² off the Northumbrian coast.
Interactions with other species
The heart urchin, Brissopsis lyrifera, which typically co-occurs with Amphiura chiajei, can negatively affect the growth of body and gonads of Amphiura chiajei, whilst Amphiura chiajei seemingly has no effect on the growth of Brissopsis lyrifera. Hollertz et al. (1998) suggested that this was attributable to the extensive bioturbation of the sediment caused by Brissopsis lyrifera.

Biology References

Buchanan, 1964, Keegan & Mercer,1986, Hollertz et al., 1998, Aizenberg et al., 2001, Hayward & Ryland, 1990,

Distribution and Habitat

Distribution in Britain & Ireland

Recorded off the west, north and east coasts of the British Isles, mostly below 10 m in depth. There is some doubt over records from the south coast.

Global distribution

Distributed from western Norway (Trondhjemfjord), southwards along European coasts to the Mediterranean, the west coast of North Africa, and the Azores.

Biogeographic range

Not researched

Depth range

9 - 1000 m

Migratory

Non-migratory / Resident

Distribution Additional Information

Substratum preferences

Mud
Muddy sand

Physiographic preferences

Open coast
Offshore seabed
Sealoch
Enclosed coast / Embayment

Biological zone

Upper Circalittoral
Lower Circalittoral
Circalittoral Offshore
Bathybenthic (Bathyal)

Wave exposure

Sheltered
Very Sheltered
Extremely Sheltered

Tidal stream strength/Water flow

Weak (<1 kn)
Very Weak (negligible)

Salinity

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

Habitat Preferences Additional Information

Distribution References

Mortensen, 1927, Picton, 1993, Crothers, 1966, Bruce et al., 1963, Foster-Smith, 2000, Mortensen, 1927,

Reproduction/Life History

Reproductive type

Gonochoristic

Developmental mechanism

Planktotrophic

Reproductive Season

End of summer until middle of autumn

Reproductive Location

As adult

Reproductive frequency

Annual episodic

Regeneration potential

Life span

6-10 years

Age at reproductive maturity

3-5 years

Generation time

See additional information

Fecundity

Egg/propagule size

Fertilization type

External

Larvae/Juveniles
Larval/Juvenile dispersal potential	See additional information	Larval settlement period	Insufficient information
Duration of larval stage

Reproduction Preferences Additional Information

Life span
Munday (1992) suggested from his observations in Killary Harbour, Ireland that individuals of Amphiura chiajei attained an age of 10 years, an estimate that was consistent with that reported for populations of Amphiura chiajei living off the Northumbrian coast (Buchanan, 1964).
Reproduction
In most species of ophiuroids the sexes are separate and fertilization external, leading to the development of a pelagic larva, the ophiopluteus (Fish & Fish, 1996). Individuals reach reproductive maturity after four years and in Amphiura chiajei there is a seasonal cycle in gonad development. A period of rest occurs at the end of autumn followed by growth over winter. Gonads reach maturity towards the end of spring and summer. Spawning occurs over the period from the end of summer until the middle of autumn (Fenaux, 1970).
Larval settling time and recruitment
In the laboratory, Fenaux (1970) observed a complete larval metamorphosis through to the formation of a young ophiuroid within 8 days at temperature 18-20 °C. Fenaux (1970) suggested that for eggs laid at the end of summer and at the beginning of autumn in which the water temperature exceeds 20°C, the pelagic life is probably shorter. With such a short life in the plankton the dispersal potential is likely to be rather limited in comparison to other echinoderms.
Amphiura chiajei is a species with sporadic recruitment, which, in combination with its slow growth rate, later maturity and longevity make it a striking contrast to Amphiura filiformis (see Buchanan, 1964).
Cohort dominance
A heavy and successful settlement of Amphiura chiajei can dominate an area for over 10 years. Buchanan (1964), sampled Amphiura chiajei off the Northumbrian coast between 1958 and 1965, and found the entire population to consist of large individuals (disc diameter > 7.5 mm). Between 1958 and 1964, there was no evidence of any new recruitment to the population, but at the end of 1965 a heavy and successful recruitment occurred. Prior to this settlement it was apparent that the same single ageing population had been measured for over 8 years. Spawning had occurred but without successful recruitment. This pattern of longevity and of episodic recruitment is consistent with that if the population of Amphiura chiajei in Killary Harbour, west coast of Ireland (Munday & Keegan, 1992). The mortality rate was measured between 1961-1963 and shown to be small.

Reproduction References

Buchanan, 1964, Munday, 1993, Fish & Fish, 1996, Munday & Keegan, 1992, Fenaux, 1970, Eckert, 2003,