A brittlestar (Amphiura chiajei)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help

Summary

Description

A small brittle star with very long arms which lives buried in muddy sand. Disc may be up to 11 mm in diameter with upper and underside surfaces covered in small smooth scales. Each arm segment has between 4-6 short spines on each side, none flattened or widened at the tip and two large tentacle scales. Colour in life reddish or greyish-brown, often somewhat mottled.

Recorded distribution in Britain and 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.

Habitat

Amphiura chiajei lives partially buried in mud and muddy sand.

Depth range

10 - > 100 m

Identifying features

  • Small disc and long coiled arms, up to 8 times the diameter of the disc.
  • Dorsal and ventral surfaces of disc covered with fine scales, those of the dorsal side diminishing gradually in size towards the edge of the disc.
  • Primary plates of disc generally distinct.
  • Two conspicuous tentacle scales.
  • 4-6 conical arm spines.
  • Lives buried in mud or fine sand.

Additional information

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

Listed by

- none -

Biology review

Taxonomy

LevelScientific nameCommon name
PhylumEchinodermata
ClassOphiuroidea
OrderAmphilepidida
FamilyAmphiuridae
GenusAmphiura
AuthorityForbes, 1843
Recent Synonyms

Biology

ParameterData
Typical abundance
Male size rangedisc diameter < 11mm
Male size at maturity
Female size rangeSmall-medium(3-10cm)
Female size at maturity
Growth formStellate
Growth rate0.5mm/year
Body flexibilityHigh (greater than 45 degrees)
Mobility
Characteristic feeding methodSurface deposit feeder
Diet/food source
Typically feeds onOrganic detritus.
Sociability
Environmental positionInfaunal
DependencyNo text entered.
SupportsNo information
Is the species harmful?No

Biology 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 the 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.

Habitat preferences

ParameterData
Physiographic preferencesOpen coast, Offshore seabed, Sea loch or Sea lough, Enclosed coast or Embayment
Biological zone preferencesBathybenthic (Bathyal), Circalittoral offshore, Lower circalittoral, Upper circalittoral
Substratum / habitat preferencesMud, Muddy sand
Tidal strength preferencesVery weak (negligible), Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferencesExtremely sheltered, Sheltered, Very sheltered
Salinity preferencesFull (30-40 psu), Variable (18-40 psu)
Depth range10 - > 100 m
Other preferencesNo text entered
Migration PatternNon-migratory or resident

Habitat Information

-

Life history

Adult characteristics

ParameterData
Reproductive typeGonochoristic (dioecious)
Reproductive frequency Annual episodic
Fecundity (number of eggs)No information
Generation timeSee additional information
Age at maturity4 years
SeasonSummer - Autumn
Life span5-10 years

Larval characteristics

ParameterData
Larval/propagule type-
Larval/juvenile development Planktotrophic
Duration of larval stageSee additional information
Larval dispersal potential See additional information
Larval settlement periodInsufficient information

Life history information

Lifespan. 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 eight days at a temperature of 18 to 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, 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 of the population of Amphiura chiajei in Killary Harbour, west coast of Ireland (Munday & Keegan, 1992). The mortality rate was measured between 1961-1963 and was shown to be small.

Sensitivity reviewHow is sensitivity assessed?

Physical pressures

Use / to open/close text displayed

 IntoleranceRecoverabilitySensitivityEvidence / Confidence
Substratum loss [Show more]

Substratum loss

Benchmark. All of the substratum occupied by the species or biotope under consideration is removed. A single event is assumed for sensitivity assessment. Once the activity or event has stopped (or between regular events) suitable substratum remains or is deposited. Species or community recovery assumes that the substratum within the habitat preferences of the original species or community is present. Further details

Evidence

Amphiura chiajei is an infaunal species that lives partially buried in sediment with its disc at a depth of 6 cm. It is not sufficiently mobile to avoid substratum removal. Thus removal of the substratum would also remove the resident population of Amphiura chiajeiand intolerance has been assessed to be high.
In the absence of a resident population, recovery is likely to be achieved through a heavy settlement of juveniles from the plankton which is likely to be more successful in the absence of competition from established adults (Künitzer, 1989; O'Connor et al., 1983), see additional information below.

High Moderate Moderate High
Smothering [Show more]

Smothering

Benchmark. All of the population of a species or an area of a biotope is smothered by sediment to a depth of 5 cm above the substratum for one month. Impermeable materials, such as concrete, oil, or tar, are likely to have a greater effect. Further details.

Evidence

Amphiura chiajei lives partially buried in sediment with its disc at a depth of 6 cm. As a brittlestar adapted for burrowing it is probably tolerant of additional sediment at the benchmark level and intolerance has been assessed to be low. However smothering by impermeable or viscous materials would probably have an adverse effect upon the brittlestar and intolerance reported to be higher.

Low Immediate Not sensitive Low
Increase in suspended sediment [Show more]

Increase in suspended sediment

Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details

Evidence

Amphiura chiajei is a non-selective surface deposit feeder and does not therefore rely on suspended food. However, for most benthic deposit feeders, food is suggested to be a limiting factor for body and gonad growth, at least between events of sedimentation of fresh organic matter (Hargrave, 1980; Tenore, 1988). Consequently, an increase in the suspended matter settling out from the water column to the substratum will be utilisable by Amphiura chiajei as a food resource. This suggests that an increase in siltation may be beneficial to the population and the species has been considered to be tolerant*.

Tolerant* Not relevant Not sensitive* High
Decrease in suspended sediment [Show more]

Decrease in suspended sediment

Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details

Evidence

Amphiura chiajei is a non-selective surface deposit feeder and therefore does not rely on suspended food. However, for most benthic deposit feeders, food is suggested to be a limiting factor for body and gonad growth, at least between events of sedimentation of fresh organic matter (Hargrave, 1980; Tenore, 1988). Amphiura chiajei is likely to be intolerant of a decrease in siltation as a reduced food supply will increase competition and depress growth. Recovery is likely to be rapid once food availability increases.

Low Very high Very Low Moderate
Desiccation [Show more]

Desiccation

  1. A normally subtidal, demersal or pelagic species including intertidal migratory or under-boulder species is continuously exposed to air and sunshine for one hour.
  2. A normally intertidal species or community is exposed to a change in desiccation equivalent to a change in position of one vertical biological zone on the shore, e.g., from upper eulittoral to the mid eulittoral or from sublittoral fringe to lower eulittoral for a period of one year. Further details.

Evidence

Populations of Amphiura chiajei occur subtidally and are not likely to be affected by desiccation. However, Amphiura chiajei is likely to be intolerant of continuous exposure to air and sunshine for one hour e.g. on the deck of a ship as by-catch. As a mobile, infaunal burrower and crawler it is likely to make efforts to avoid the factor by seeking shade, but the viability of individuals is likely to be affected and some may dry up and die, therefore intolerance has been assessed to be intermediate. Recoverability has been assessed to be high as a proportion of the breeding population is likely to remain.

Intermediate High Low Moderate
Increase in emergence regime [Show more]

Increase in emergence regime

Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details

Evidence

Emergence is very unlikely to occur in the circalittoral and an assessment of an increase in the emergence regime is not considered relevant for Amphiura chiajei.

Not relevant Not relevant Not relevant Low
Decrease in emergence regime [Show more]

Decrease in emergence regime

Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details

Evidence

Emergence is very unlikely to occur in the circalittoral and an assessment of a decrease in the emergence regime is not considered relevant for Amphiura chiajei.

Not relevant Not relevant Not relevant Low
Increase in water flow rate [Show more]

Increase in water flow rate

A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details

Evidence

Unlike Amphiura filiformis, Amphiura chiajei shows no clear response to directional bottom currents or an increase in water current rate (Buchanan, 1964). In laboratory conditions, Amphiura chiajei maintained a position within the sediment with its arms stretched out across the sediment until 30 cm/s (0.6 knots), when the arms streamed out in the direction of the water current (Buchanan, 1964). If the water current were to increase to moderately strong (1-3 knots), individuals would be unlikely to maintain this position and possibly retract their arms into the burrow, if not loose them. This would prevent the animal from feeding. A long term increase in water flow rate is also likely to change the nature of the sediment removing finer particles. High density aggregations of Amphiura chiajei seem to be characteristic of sediments with a silt/clay content of 80-90% and organic carbon levels of 5-7% (Keegan & Mercer,1986), so removal of particular matter is likely to reduce abundance and over a year many individuals may die, so intolerance has been assessed to be high.
With a reduced population, recovery is likely to be achieved through migration and a heavy settlement of juveniles from the plankton, which is likely to be more successful in the absence of competition from established adults (Künitzer, 1989; O'Connor et al., 1983). However, as recruitment tends to be sporadic recovery has been assessed to be moderate.

High Moderate Moderate Moderate
Decrease in water flow rate [Show more]

Decrease in water flow rate

A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details

Evidence

Amphiura chiajei is characteristic of offshore and shallower, stable muddy habitats exposed to only weak or very weak currents. Sediments may become muddier due to increased settlement of silt if current strength declines. However, at the level of the benchmark it is not expected that populations will be affected and Amphiura chiajei has been assessed to tolerate a decrease in water flow rate.

Tolerant Not relevant Not sensitive Low
Increase in temperature [Show more]

Increase in temperature

  1. A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges.
  2. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges.

For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details

Evidence

The species is distributed in waters to the south of the British Isles and so is probably able to tolerate a long term change in temperature of 2 °C.
Increases in temperature may enhance growth and fecundity. Muus (1981) showed that juvenile Amphiura filiformis are capable of much higher growth rates in experiments with temperatures between 12 and 17 °C (unlimited food supply). Juvenile disc diameter increased from 0.5 to 3.0 mm in 28 weeks under these conditions compared to over two years in the North Sea. Mean summer temperatures of 14 °C and an apparent abundant food supply may also account for the early rapid growth of Amphiura chiajei in Killary Harbour (Munday & Keegan, 1992). As the species appears to be killed only by extreme increases in temperature, intolerance has been assessed to be low.

Low Moderate Low High
Decrease in temperature [Show more]

Decrease in temperature

  1. A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges.
  2. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges.

For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details

Evidence

The species is distributed in waters to the north of the British Isles and so is probably able to tolerate a long term change in temperature of 2 °C.
Populations of Amphiura chiajei seem periodically affected by winter cold. Mean densities of Amphiura chiajei in Killary Harbour, west coast of Ireland, decreased following months with the lowest recorded bottom temperatures, 4 °C and 6 °C, for February 1986 and January 1987 respectively. Intolerance of the acute change and depressed temperatures on the part of some of the older individuals probably led to their demise (Munday & Keegan, 1992). Low temperatures are also a limiting factor for breeding which occurs in the warmest months in the British Isles. Intolerance has been assessed to be intermediate. Recolonization is likely but assessed to be moderate, see additional information below.

Intermediate Moderate Moderate High
Increase in turbidity [Show more]

Increase in turbidity

  1. A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity.
  2. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details

Evidence

Amphiura chiajeimay be able to perceive changes in irradiance but is probably tolerant of increased turbidity.

Not relevant Not relevant Not relevant Low
Decrease in turbidity [Show more]

Decrease in turbidity

  1. A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity.
  2. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details

Evidence

Amphiura chiajei may be able to perceive changes in irradiance but is probably tolerant of changes to a decrease in turbidity.

Not relevant Not relevant Not relevant Low
Increase in wave exposure [Show more]

Increase in wave exposure

A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details

Evidence

Amphiura chiajei is found offshore and in sheltered coastal habitats characterised by fine muddy sediments and low/negligible wave exposure. Populations of Amphiura chiajei occurring offshore at depths greater than 60 m are not subject to exposure from wave action, as the effects are attenuated with depth. However, for populations occurring at depths less than 60 m and nearer the coast, wave action resulting from storms may cause disturbance to the sediment surface and may periodically displace specimens form the sediment (McIntosh, 1875). Amphiura chiajei is a burrower and may withdrawal its arms inside the burrow for additional protection, but because wave action may cause displacement and stranding, it is likely to cause some mortality in shallower locations at the benchmark level and intolerance has been assessed to be intermediate.

Intermediate Moderate Moderate Moderate
Decrease in wave exposure [Show more]

Decrease in wave exposure

A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details

Evidence

Amphiura chiajei is found offshore and in shallower, sheltered nearshore habitats characterised by fine muddy sediments and low/negligible wave exposure. Thus an assessment for a decrease in wave exposure was not considered relevant.

Not relevant Not relevant Not relevant Moderate
Noise [Show more]

Noise

  1. Underwater noise levels e.g., the regular passing of a 30-metre trawler at 100 metres or a working cutter-suction transfer dredge at 100 metres for one month during important feeding or breeding periods.
  2. Atmospheric noise levels e.g., the regular passing of a Boeing 737 passenger jet 300 metres overhead for one month during important feeding or breeding periods. Further details

Evidence

No information concerning sound or vibration reception in echinoids was found.

No information Not relevant No information Not relevant
Visual presence [Show more]

Visual presence

Benchmark. The continuous presence for one month of moving objects not naturally found in the marine environment (e.g., boats, machinery, and humans) within the visual envelope of the species or community under consideration. Further details

Evidence

Brittlestars exhibit a wide range of responses to light intensity, from a largely indifferent behaviour to pronounced colour changes and rapid escape behaviour. Aizenberg et al. (2001) reported that certain calcite crystals used by brittlestars for skeletal construction are also a component of a specialised photosensory organ. However, these structures are absent in light indifferent species. Thus Amphiura chiajei may have visual perception but is likely to have poor visual acuity and consequently probably not sensitive to visual disturbance at the benchmark level.

Tolerant Not relevant Not sensitive Not relevant
Abrasion & physical disturbance [Show more]

Abrasion & physical disturbance

Benchmark. Force equivalent to a standard scallop dredge landing on or being dragged across the organism. A single event is assumed for assessment. This factor includes mechanical interference, crushing, physical blows against, or rubbing and erosion of the organism or habitat of interest. Where trampling is relevant, the evidence and trampling intensity will be reported in the rationale. Further details.

Evidence

Brittlestars have fragile arms which are likely to be damaged by abrasion or physical disturbance. Amphiura chiajei burrows in the sediment and extends its arms across the sediment surface to feed. Ramsay et al. (1998) suggested that Amphiura species may be less susceptible to beam trawl damage than other species of echinoid or tube dwelling amphipods and polychaetes. For example, Bergman & Hup (1992) found that beam trawling in the North Sea had no significant direct effect on small brittlestars. Brittlestars can tolerate considerable damage to arms and even the disc without suffering mortality and are capable of disc and arm regeneration. Intolerance to physical disturbance has been assessed to be low. Individuals can still function whilst an arm is regenerating so recovery would probably be rapid.

Low Very high Very Low High
Displacement [Show more]

Displacement

Benchmark. Removal of the organism from the substratum and displacement from its original position onto a suitable substratum. A single event is assumed for assessment. Further details

Evidence

Although not highly active, Amphiura chiajei is a crawling, burrowing, infaunal species. Following displacement and return to suitable sediments burrowing amphiuroids start almost immediately to dig downwards (Buchanan, 1964). Amphiura chiajei would be exposed to predators for a short time but as fish only tend to take their legs, intolerance has been assessed to be low.

Low Immediate Not sensitive High

Chemical pressures

Use [show more] / [show less] to open/close text displayed

 IntoleranceRecoverabilitySensitivityEvidence / Confidence
Synthetic compound contamination [Show more]

Synthetic compound contamination

Sensitivity is assessed against the available evidence for the effects of contaminants on the species (or closely related species at low confidence) or community of interest. For example:

  • evidence of mass mortality of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as high sensitivity;
  • evidence of reduced abundance, or extent of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as intermediate sensitivity;
  • evidence of sub-lethal effects or reduced reproductive potential of a population of the species or community of interest will be assessed as low sensitivity.

The evidence used is stated in the rationale. Where the assessment can be based on a known activity then this is stated. The tolerance to contaminants of species of interest will be included in the rationale when available; together with relevant supporting material. Further details.

Evidence

Echinoderms tend to very sensitive to various types of marine pollution (Newton & McKenzie, 1995). However, there is insufficient information on the direct intolerance of Amphiura chiajei to synthetic chemicals, although it is known to bioaccumulate PCBs (Gunnardsson & Skold, 1999). Loizeau & Menesguen (1993) showed that 8-15% of the PCB burden in dab, Limanda limanda, from the Bay of Seine could be explained by ophiuroid consumption. Thus Amphiura communities may play an important role in the accumulation, remobilization and transfer of PCBs and other sediment associated contamination to higher trophic levels.
Walsh et al. (1986) examined the influence of chronic exposure to tributyltin (TBT) and triphenyltin oxide on arm regeneration in another brittlestar, Ophioderma brevispina, and found some evidence of inhibition at 10 ng/l and significant inhibition at 100 ng/l. It is suggested that TBT acts via the nervous system, although direct action on the tissues at the point of breakage could not be excluded.

No information Not relevant No information Not relevant
Heavy metal contamination [Show more]

Heavy metal contamination

Evidence

Information concerning the effects of heavy metals on echinoderms is limited and no details specific to Amphiura chiajei were found. However, adult echinoderms, such as Ophiothrix fragilis are known to be efficient concentrators of heavy metals including those that are biologically active and toxic (Hutchins et al., 1996). However, there is no information available regarding the effects of this bioaccumulation.

No information Not relevant No information Not relevant
Hydrocarbon contamination [Show more]

Hydrocarbon contamination

Evidence

Newton & McKenzie (1998) studied the effects of oil-based drill cuttings on burrowing brittlestars, Amphiura chiajei and Amphiura filiformis and observed responses at both acute and chronic levels. Acute toxicity tests showed that drill cuttings containing oil based muddy drill cuttings had a very low toxicity (LC50= 52,8000 ppm total hydrocarbons in test sediment). A decrease in brittlestar burrowing activity was also recorded at 4,800 and 1,200 ppm total hydrocarbons in sediment. However, Newton & McKenzie (1993) suggested that these were a poor predictor of chronic response. Chronic sub-lethal effects were detected around the Beryl oil platform in the North Sea where the hydrocarbon content of the sediment was very low (<3 ppm total hydrocarbons in sediment), and Amphiura chiajei was excluded from areas nearer the platform with higher sediment hydrocarbon content (> 10 ppm). However, the authors did suggest that deleterious effects may also be related to the non-hydrocarbon element of the cuttings such as metals, physical disturbance or organic enrichment.
Amphiura chiajei is also host to symbiotic sub-cuticular bacteria (Kelly & McKenzie, 1995). After exposure to hydrocarbons, loadings of such bacteria were reduced indicating a possible sub-lethal stress to the host (Newton & McKenzie, 1995).
intolerance of Amphiura chiajei to hydrocarbon contamination has been assessed to be high, owing to field evidence for exclusion, death and migration by adults and poor colonization by juveniles. Recovery to a pre-impact population structure is likely to take longer than five years (see additional information below) and so recovery has been assessed to be moderate.

High Moderate Moderate High
Radionuclide contamination [Show more]

Radionuclide contamination

Evidence

There is insufficient information concerning the intolerance of Amphiura chiajei to radionuclides, although adult echinoderms, such as Ophiothrix fragilis are known to be efficient concentrators of radionuclides (Hutchins et al., 1996). No information concerning the effects of such bioaccumulation was found.

No information No information No information Not relevant
Changes in nutrient levels [Show more]

Changes in nutrient levels

Evidence

Nilsson (1999) reported a positive response by Amphiura chiajei to increased organic enrichment (27 and 55 g C m², applied four times over eight weeks) demonstrable by an increase in arm tip regeneration rate. In the Skagerrak in the North Sea, Josefson (1990) reported a massive increase in abundance and biomass of Amphiura species between 1972 and 1988 attributable to organic enrichment. Sköld & Gunnarsson (1996) reported enhanced growth and gonad development in response to short-term enrichment of sediment cores containing Amphiura chiajei maintained in laboratory mesocosms. Thus increased nutrient availability promoting phytoplankton productivity and an increase in the organic matter reaching the sea bed is likely to be beneficial to Amphiura chiajei. For benthic deposit feeders, food is suggested to be a limiting factor for body and gonad growth, at least between events of sedimentation of fresh organic matter (Hargrave, 1980; Tenore, 1988). Nilsson (1999) also found that Amphiura chiajei was able to utilise an increased input of organic matter for growth in conjunction with moderate hypoxia. Therefore, it appears that Amphiura chiajei is tolerant of an increase in nutrient levels and may indirectly benefit. At the benchmark level Amphiura chiajei has been considered to be tolerant.

Tolerant Not relevant Not sensitive High
Increase in salinity [Show more]

Increase in salinity

  1. A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced.
  2. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details.

Evidence

Echinoderms are stenohaline owing to the lack of an excretory organ and a poor ability to osmo- and ion-regulate (Stickle & Diehl, 1987). The preferred habitat of Amphiura chiajei is found offshore in waters of full salinity where an increase of salinity is not likely to occur.

Not relevant Not relevant Not relevant Low
Decrease in salinity [Show more]

Decrease in salinity

  1. A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced.
  2. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details.

Evidence

Echinoderms are stenohaline owing to the lack of an excretory organ and a poor ability to osmo- and ion-regulate (Stickle & Diehl, 1987). Pagett (1979) examined the tolerance of Amphiura chiajei to brackish water (0.5-30 psu) in specimens taken from Loch Etive, Scotland. Loch Etive is a sealoch subject to periods of reduced salinities owing to heavy rain and fresh-water runoff. Pagett (1979) found that specimens nearer freshwater influxes were more tolerant of reduced salinities than those nearer the open sea. Amphiura chiajei taken from an area of 24 psu had an LD50 of > 21 days for a 70% dilution (17 psu) and an LD50 of 8.5 days for a 50% dilution (12 psu). In comparison, specimens taken from an area with salinity 28.9 psu, had an LD50 of > 12.5 days for a 70% dilution (20 psu) and an LD50 of 6 days for a 50% dilution (14 psu). As Amphiura chiajei is mobile and burrows it may be able to avoid changes in salinity outside its preference, e.g. burrowing may help Amphiura chiajei to withstand depressed salinities owing to the 'buffering' effect of the substratum. However, as some mortalities were recorded for decreases in salinity over a time period less than the benchmark level, it is likely that Amphiura chiajei would be highly intolerant of a decrease of one category from the MNCR salinity scale for one year.
With a reduced population, recovery is likely to be achieved through migration and a heavy settlement of juveniles from the plankton, which is likely to be more successful in the absence of competition from established adults (Künitzer, 1989; O'Connor et al., 1983). However, as recruitment tends to be sporadic recoverability has been assessed to be moderate.

High Moderate Moderate High
Changes in oxygenation [Show more]

Changes in oxygenation

Benchmark.  Exposure to a dissolved oxygen concentration of 2 mg/l for one week. Further details.

Evidence

In experiments exposing benthic invertebrates to decreasing oxygen levels Amphiura chiajei only left its protected position in the sediment when oxygen levels fell below 0.54 mg O2L-1 (Rosenberg et al., 1991). This escape response increases its risk to predators. Mass mortality in a superficially similar species of ophiuroid, Amphiura filiformis from the south-east Kattegat has been observed during severe hypoxic events (< 0.7 mg/l), while the abundance of Amphiura chiajei remained unchanged at the same site and time (Rosenberg & Loo, 1988).
In laboratory conditions, Nilsson (1999) maintained specimens of Amphiura chiajei in hypoxic conditions (1.8-2.2 mg O2 L-1 for eight weeks and recorded no deaths or witnessed specimens escaping to the surface. Rosenberg et al. (1991) suggested that Amphiura chiajei had a higher tolerance to hypoxia than Amphiura filiformis owing to a respiration rate five times lower (0.011 ml O2 per g wet /wt h-1 compared to 0.058 ml O2 per g wet /wt h-1 respectively, at 6°C).
This evidence suggests the intolerance of Amphiura chiajei to the benchmark level of 2 mg/l for one week to be low.

Low Very high Very Low High

Biological pressures

Use [show more] / [show less] to open/close text displayed

 IntoleranceRecoverabilitySensitivityEvidence / Confidence
Introduction of microbial pathogens/parasites [Show more]

Introduction of microbial pathogens/parasites

Benchmark. Sensitivity can only be assessed relative to a known, named disease, likely to cause partial loss of a species population or community. Further details.

Evidence

No information concerning infestation or disease related mortalities was found.

No information Not relevant No information Not relevant
Introduction of non-native species [Show more]

Introduction of non-native species

Sensitivity assessed against the likely effect of the introduction of alien or non-native species in Britain or Ireland. Further details.

Evidence

No non-native species are known to compete with Amphiura chiajei.

Not relevant Not relevant Not relevant Moderate
Extraction of this species [Show more]

Extraction of this species

Benchmark. Extraction removes 50% of the species or community from the area under consideration. Sensitivity will be assessed as 'intermediate'. The habitat remains intact or recovers rapidly. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details.

Evidence

It is extremely unlikely that this species would be subject to extraction as it has no commercial value, although dredging / fishing operations may affect populations in some habitats.

Not relevant Not relevant Not relevant Moderate
Extraction of other species [Show more]

Extraction of other species

Benchmark. A species that is a required host or prey for the species under consideration (and assuming that no alternative host exists) or a keystone species in a biotope is removed. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details.

Evidence

Amphiura chiajei has no known obligate relationships so is not directly intolerant of the removal of another species. However, it may constitute a component of demersal fishing trawl by-catch. Whilst some individuals may die, many more may suffer physical injury. Munday (1993) observed that 99% of Amphiura chiajei showed evidence of arm tip regeneration in the population off Killary Harbour. Whilst benthic trawling may contribute to arm damage, sub-lethal levels of predation appeared to be the main causative factor for regeneration and was a persistent experience. It is likely that Amphiura chiajei would be resistant to damage caused by the extraction of other species and intolerance has been assessed to be low.
Recoverability has been considered to be high owing to the regenerative capability of established adults.

Low High Low Low

Additional information

Recoverability. Amphiura chiajei is a long-lived (> 10 years), slow-growing species. As a result, an area may become dominated over many years by adults representative of one larval settlement (Munday & Keegan, 1992; Buchanan, 1964). The species has an annual reproductive cycle and is likely to be quite fecund owing to its planktonic development, but juvenile recruitment tends to be very sporadic. In the laboratory, Fenaux (1970) observed the completion of larval development within eight days at 18°C. It is not clear whether this is representative of field conditions, but such a short planktonic existence would limit the species' powers of dispersal. In addition, the local current regimes of its preferred habitat, e.g. fjordic embayments, would also serve to locally confine planktonic larvae (Pearson, 1970). In long-lived, dense, adult-dominated populations in apparently very stable areas, Künitzer (1989) suggested that the survival of recruits was low owing to competition with established adults, which, as a non-selective surface deposit feeders, may take their own juveniles as a food item at the earliest settlement stage (0.33 mm disc diameter). In contrast, in areas which experience periodic instability, such as the Bay of Concarneau, France, populations of Amphiura species are prevented from reaching carrying capacity owing to periodic reduction of the population density (Bourgoin & Goillou, 1988). Likewise, Munday & Keegan (1992) only recorded successful recruitment of juveniles following the significant demise of adults after depressed winter temperatures in Killary Harbour, Ireland. Therefore, it appears that after the removal of all or most of the population by a factor, recovery is possible through larval settlement. However, owing to evidence of a short planktonic existence and the fact that a new settlement will take 4-5 years to reach maturity, the recoverability of Amphiura chiajei has been assessed to be Moderate.

Importance review

Policy/legislation

- no data -

Status

Non-native

ParameterData
Native-
Origin-
Date Arrived-

Importance information

-none-

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Datasets

  1. Centre for Environmental Data and Recording, 2018. Ulster Museum Marine Surveys of Northern Ireland Coastal Waters. Occurrence dataset https://www.nmni.com/CEDaR/CEDaR-Centre-for-Environmental-Data-and-Recording.aspx accessed via NBNAtlas.org on 2018-09-25.

  2. NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.

  3. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-10-08

  4. South East Wales Biodiversity Records Centre, 2023. SEWBReC Marine and other Aquatic Invertebrates (South East Wales). Occurrence dataset:https://doi.org/10.15468/zxy1n6 accessed via GBIF.org on 2024-09-27.

Citation

This review can be cited as:

Budd, G.C. 2006. Amphiura chiajei A brittlestar. In Tyler-Walters H. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 08-10-2024]. Available from: https://www.marlin.ac.uk/species/detail/1657

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Last Updated: 15/11/2006