The Marine Life Information Network

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.

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.

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*.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.