Common brittlestar (Ophiothrix fragilis)

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

Summary

Description

A large brittlestar whose disk may reach up to 2 cm in diameter. The five arms are long (about five times the disk diameter) and spiny. The upper disk surface has a 5-rayed pattern of spines. This species is very varied in colour, commonly brown or grey but ranging through purple, red, orange, yellow, and white. Colouration may be plain or banded (particularly on the arms). The arms are fragile and often broken.

Recorded distribution in Britain and Ireland

All British and Irish coasts.

Global distribution

Widely distributed in the eastern Atlantic from northern Norway to the Cape of Good Hope.

Habitat

Found from the lower shore to circalittoral offshore habitats on hard substrata including bedrock, boulders and on coarse sediment. Most abundant on tideswept rock and on mixed coarse sediments. In the intertidal the species is found in crevices and under boulders.

Depth range

0-85

Identifying features

  • Large, long-armed brittle star
  • Pentagonal disk up to 2 cm in diameter.
  • Conspicuous radial shields and 5-rayed pattern of small spines on disk.
  • Arm length about 5 times diameter of disk with seven serrated spines on each segment.
  • Keel on naked dorsal arm plates.

Additional information

No text entered

Listed by

- none -

Biology review

Taxonomy

LevelScientific nameCommon name
PhylumEchinodermata
ClassOphiuroidea
OrderAmphilepidida
FamilyOphiotrichidae
GenusOphiothrix
Authority(Abildgaard in O.F. Müller, 1789)
Recent Synonyms

Biology

ParameterData
Typical abundanceHigh density
Male size range2-20 mm
Male size at maturity
Female size rangeMedium(11-20 cm)
Female size at maturity
Growth formRadial
Growth rateSee additional information
Body flexibilityLow (10-45 degrees)
MobilityCreeper
Characteristic feeding methodPassive suspension feeder
Diet/food sourceOmnivore
Typically feeds onPhytoplankton
SociabilityNo information
Environmental positionEpibenthic
DependencyIndependent.
SupportsHost

symbiotic sub-cuticular bacteria

Is the species harmful?No

Little evidence of toxicity (McClintock, 1989 cited in Sköld, 1998)

Biology information

  • This species can be found in very high densities of up to 2000 individuals per square metre (Davoult, 1989).
  • The smallest brittle stars found have a disk diameter of 2 mm and two segments per arm.
  • Some gonad development is present in individuals with disks of 3 mm although full sexual maturity is probably achieved at about 10 mm disk diameter (Gage, 1990).
  • Growth rate estimates vary considerably. Growth in juveniles may be between 1.6-3.1 and 3.5-10.3 increase in body disk diameter per day (Davoult et al., 1990) On average the body disk diameter is estimated to increase by 1.1 mm per month. Other growth rate estimates are much slower (Gage, 1990)
  • Optimal feeding can occur at water flow rates below 20 cm per second (Davoult & Gounin, 1995). Water moving at above 25 cm per second causes the arms to be brought down from being extended in the water column (Warner & Woodley, 1975; Hiscock, 1983). Water flow rates refer to water movements at the seabed. Surface flow rates will be considerably higher.
  • Although not an important dietary component, Ophiothrix fragilis may be found in the stomach contents of most common predators (Warner, 1971). Ophiothrix fragilis avoids predation by moving away from sources of mechanical disturbance (Warner, 1971). The escape response of Ophiothrix fragilis is slow in comparison to other brittle stars and it avoids visual predation through sheltering in crevices etc. and cryptic colouration (Sköld, 1998). Predatory starfish such as Asterias rubens and Marthasterias glacialis produce steroid glycoside chemicals that elicit an avoidance response in Ophiothrix fragilis (Mackie, 1970). Although not toxic, Ophiothrix fragilis achieves unpalatability through heavy calcification and possession of glassy spines (Sköld, 1998).
  • Brittle stars, such as Ophiothrix fragilis, have symbiotic subcuticular bacteria. The host-bacteria association can be perturbed by acute stress and changes in bacterial loading may be used as an indicator of sub-lethal stress (Newton & McKenzie, 1995)
  • The strong tidal current, coarse sediment communities from the English Channel are dominated by Ophiothrix fragilis, Urticina felina and Alcyonium digitatum (Migné & Davoult, 1997(c)).

Habitat preferences

ParameterData
Physiographic preferencesOffshore seabed, Open coast, Strait or Sound
Biological zone preferencesLower circalittoral, Lower eulittoral, Lower infralittoral, Sublittoral fringe, Upper circalittoral, Upper infralittoral
Substratum / habitat preferencesBedrock, Cobbles, Crevices / fissures, Gravel / shingle, Large to very large boulders, Maerl, Muddy gravel, Other species, Pebbles, Small boulders, Under boulders
Tidal strength preferencesModerately strong 1 to 3 knots (0.5-1.5 m/sec.), Strong 3 to 6 knots (1.5-3 m/sec.), Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferencesExposed, Extremely exposed, Moderately exposed, Sheltered, Very exposed, Very sheltered
Salinity preferencesFull (30-40 psu), Low (<18 psu), Reduced (18-30 psu), Variable (18-40 psu)
Depth range0-85
Other preferencesNo text entered
Migration PatternNon-migratory or resident

Habitat Information

  • Ophiothrix fragilis may be found in low densities on Crepidula fornicata (slipper limpet) beds (Bourgoin et al., 1985) or also overlying Modiolus shells (Magorrian et al., 1995)
  • Wolff, (1968) notes the species occurring in normal salinities of 16 psu and even persisting down to 10 psu.

Life history

Adult characteristics

ParameterData
Reproductive typeGonochoristic (dioecious)
Reproductive frequency Annual episodic
Fecundity (number of eggs)No information
Generation timeInsufficient information
Age at maturity6-10 months - see additional information.
SeasonJune - October
Life span5-10 years

Larval characteristics

ParameterData
Larval/propagule type-
Larval/juvenile development Planktotrophic
Duration of larval stage11-30 days
Larval dispersal potential Greater than 10 km
Larval settlement periodAugust to September

Life history information

  • Longevity estimates vary from nine months (Davoult et al., 1990) to over 10 years (Gage, 1990). Work by Gage (1990) on skeletal growth bands in Ophiothrix fragilis indicates a slow rate of growth and considerable longevity suggesting that individuals with a disk diameter of 13 mm are around 10 years old (disk diameters reach 20 mm). N.B. This is not yet a validated age-determination mechanism.
  • Davoult et al., (1990) consider development to maturity to take 6-10 months depending on the cohort and time of recruitment. Gonads are most developed in May-July (George & Warwick, 1985). Some gonad development is present in individuals with disks of 3 mm although full sexual maturity is probably achieved at about 10 mm disk diameter (Gage, 1990). Development of sexual maturity is dependent on day length and temperature although temperature is not believed to be a trigger for spawning (Davoult, et al., 1990).
  • Gamete release - Davoult et al., (1990) record spawning in the eastern Channel from mid-July to mid-August. Spawning in the Plymouth area has been recorded from June to the start of September (Davoult et al., 1990) and in October (Marine Biological Association 1957). In Kinsale Harbour on the south coast of Ireland Ball et al. (1995) found that Ophiothrix fragilis had a long breeding season, extending from May to January, with peak activity in summer/autumn, a small percentage of the population can breed throughout most of the year in certain regions. The evidence suggests that each animal spawns only once during a breeding season, although spawning may take place as several bursts over the period based on the presence of a number of different size classes of oocytes within the gonad at any particular time. Further north, in Sweden, spawning is recorded from August and September (Davoult et al., 1990).
  • Recruitment from the planktonic larvae occurs from August to September (Allain, 1974). Davoult et al., (1990) consider there to be multiple recruitments in the eastern Channel, a primary one in September and three secondary ones in February, April and June. Individual cohorts can be followed for 4 to 6 months after which variable growth rates and overlap in size preclude their separation. These multiple recruitments indicate more than one discrete spawning episode.
  • Larvae appear in the water column about a week after gamete release and fertilisation of the eggs. The larvae metamorphose into juvenile brittlestars whilst still in the plankton. The pelagic phase lasts about 26 days (MacBride, 1907).
  • The larvae may undertake a passive migration in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). Here, with water that may move over 4 km per day and a larval duration of 26 days, the larvae can disperse up to 70-100 km. This may preclude the auto-recruitment of local populations (Davoult et al., 1990).
  • Mean disk diameter can decrease by up to 20% during gamete production (Davoult et al., 1990).
  • Although the species is gonochoristic Davoult et al., (1990) record a 1% incidence of hermaphroditism.
  • Recruitment success is heavily dependent on environmental conditions including temperature and food availability. In years after mild winters Ophiothrix fragilis occurred in extremely high densities in the Oosterschelde estuary in Holland (Smaal, 1994). Populations seem to be stable in the long-term although there may be strong variation from year to year. A multi-annual cycle of around four years may exist in the eastern English Channel (Davoult et al., 1993). However, Holme (1984) notes long-term changes in Ophiothrix fragilis populations in the western Channel, possibly linked with predator abundance (Luidia ciliaris and Luidia sarsi) and water quality.

    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

    Ophiothrix fragilis is an epibenthic species so substratum loss would result in mortality. Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    High High 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

    Although Ophiothrix fragilis is an epibenthic crawling species, it has a low level of locomotory activity and lacks muscular development. Smothering by 5 cm of sediment would probably cause death as it is unlikely that the brittle star would be able to burrow out of the covering material. Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    High High Moderate 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

    Ophiothrix fragilis is a passive suspension feeder. Increases in siltation of inorganic particles may interfere with the feeding of this species (Aronson, 1992 cited in Hughes, 1998), particularly in non current-swept areas. Respiration rate is low and the species can tolerate considerable loss of body mass during reproductive periods (Davoult et al., 1990) so restricted feeding may be tolerated. Once normal feeding recommences it may take a short time for condition to be regained.
    Low Very high Very Low Low
    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

    No information
    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

    Although mainly subtidal, this species may also be found on the lower shore, sheltering under boulders etc. Consequently the brittle star may be tolerant to some degree of desiccation. However, increased desiccation through exposure to air and sunlight may kill part of the intertidal population. Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. This may preclude auto-recruitment of local populations (Davoult at al., 1990) Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    Intermediate High Low Low
    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

    Ophiothrix fragilis is a mobile epibenthic crawler and should be able to relocate to a suitable location on the shore should the emergence regime be altered.
    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

    No information
    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

    Ophiothrix fragilis frequently inhabits areas with strong tidal currents e.g. up to 1.5 m/s in the Dover Straits (Hughes, 1998b) (although water flow rate will not be continuously high e.g. during periods of slack water). A certain degree of water movement is important to the feeding mechanism of this species. However, above a certain water speed (25 cm/s) the feeding arms are withdrawn from the water column (Warner & Woodley, 1975; Hiscock, 1983). At water speeds above about 28 cm/s individuals or even small groups may be displaced from the substratum and they have been observed being rolled along the seabed by the current (Warner, 1971). Living in dense aggregations may reduce displacement by strong currents (Warner & Woodley, 1975). Water flow rates refer to water movements at the seabed. Surface flow rates will be considerably higher. Respiration rate is low and the species can tolerate considerable loss of body mass during reproductive periods (Davoult et al., 1990) so restricted feeding may be tolerated. Once normal feeding recommences it may take a short time for condition to be regained. Ophiothrix fragilis also has specific behaviours and abilities to relocate conspecifics following displacement (Broom, 1975).
    Low Very high Very Low 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

    No information
    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

    Changes in temperature can have a considerable effect on Ophiothrix fragilis populations. In years following mild winters Ophiothrix fragilis may recruit in very high numbers (Smaal, 1994). However, the distribution of Ophiothrix fragilis is large, ranging from northern Norway south to the Cape of Good Hope. Consequently this species is exposed to temperatures both above and below those found in the British Isles. In the long term, some populations in the English Channel have remained stable (Davoult et al., 1993). In other areas of the Channel considerable fluctuations have been noted over the last century, believed to be due to variations in water masses present (Holme, 1984). Long term chronic changes in temperature will probably have little effect on the species. Short term acute changes in temperature are noted to cause a reduction in the loading of subcutaneous symbiotic bacteria in echinoderms such as Ophiothrix fragilis. Reductions in these bacteria are probably indicative of levels of stress and may lead to mortality (Newton & McKenzie, 1995). The species is noted to exist in shallow, enclosed waters that regularly drop to 3 °C but is absent from areas where temperatures drop to 0 °C. Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. This may preclude auto-recruitment of local populations (Davoult at al., 1990). Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    Intermediate High Low Low
    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

    No information
    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

    Ophiothrix fragilis is likely to have poor facility for visual perception and consequently is probably not directly sensitive to changes in turbidity. However, the main food source of this species is phytoplankton which have a requirement for light. Increases in turbidity may limit the amount of phytoplankton available to the brittle stars. Food availability is one of the main factors controlling growth and development (Migné & Davoult, 1997; Davoult et al., 1990). Once normal feeding recommences it may take a short time for condition to be regained.
    Low Very high Very Low 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

    No information
    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

    The species occurs in a wide range of wave exposures as well as on offshore seabeds where wave action is less important. Increases in wave exposure may cause increases in the incidence of damaged individuals (Ophiothrix fragilis arms are brittle). Strong wave action may cause displacement of brittle stars. Ophiothrix fragilis has specific behaviours and abilities to relocate conspecifics following displacement (Broom, 1975). Brittle stars often have broken arms but are capable of arm and even some disk regeneration (Sköld, 1998).
    Low Very high Very Low 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

    No information
    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

    Ophiothrix fragilis reacts to mechanical disturbance (predator evasion response) (Warner, 1971). Although there are no records of reaction to noise, sound vibrations may trigger this sort of behaviour. There is some evidence of autotomy of arms in response to predator threat (Emson & Wilkie, 1980). Brittle stars are capable of arm and even some disk regeneration (Sköld, 1998).
    Low Very high Very Low Low
    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

    Ophiothrix fragilis is likely to have poor facility for visual perception and consequently is probably not sensitive to visual disturbance. Movement of a hand near to Ophiothrix fragilis elicits no escape response (Skö, 1998).
    Tolerant Not relevant Not sensitive High
    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 that are likely to be damaged by abrasion. Brittlestars can tolerate considerable damage to arms and even the disk without suffering mortality and are capable of arm and even some disk regeneration (Sköld, 1998). Fishermen tend to avoid brittlestar beds since the animals clog their nets (Jones et al., 2000). However, a passing scallop dredge is likely to remove, displace, or damage brittlestars caught in its path. Although several species of brittlestar are reported to increase in abundance in trawled areas, Bradshaw et al. (2002) noted that the relatively sessile Ophiothrix fragilis decreased in the long term in areas subject to scallop dredging. Overall, a proportion of the population is likely to be damaged or removed and an intolerance of intermediate has been recorded.
    Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70 -100 km and establish populations elsewhere. This may preclude auto-recruitment of local populations (Davoult at al., 1990). Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    Intermediate High Low Moderate
    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, Ophiothrix fragilis is a crawling epibenthic species. Following displacement from a brittlestar bed, individuals will crawl back and forth across water currents until a conspecific is found (Broom, 1975). This may preclude auto-recruitment of local populations (Davoult at al., 1990).
    Tolerant Not relevant 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 be very intolerant of various types of marine pollution (Newton & McKenzie, 1995) but there is no more detailed information than this broad statement. Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    No information Not relevant No information Not relevant
    Heavy metal contamination [Show more]

    Heavy metal contamination

    Evidence

    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). 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

    Echinoderms tend to be very sensitive to various types of marine pollution (Newton & McKenzie, 1995). Adult Ophiothrix fragilis have documented intolerance to hydrocarbons (Newton & McKenzie, 1995). The sub-cuticular bacteria that are symbiotic with Ophiothrix fragilis are reduced in number following exposure to hydrocarbons. Exposure to 30,000 ppm oil reduces the bacterial load by 50 % and brittle stars begin to die (Newton & McKenzie, 1995). However, there are no field observations of mortalities caused by exposure to hydrocarbons. Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    High High Moderate High
    Radionuclide contamination [Show more]

    Radionuclide contamination

    Evidence

    Adult echinoderms such as Ophiothrix fragilis are known to be efficient concentrators of radionuclides (Hutchins et al., 1996). There is no information available regarding the effects of this bioaccumulation.
    No information Not relevant No information Not relevant
    Changes in nutrient levels [Show more]

    Changes in nutrient levels

    Evidence

    Decreases in sub-cuticular bacteria have also been recorded following nutrient limitation. Reductions in these bacteria are probably indicative of levels of stress and may lead to mortality (Newton & McKenzie, 1995). Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move over several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. This may preclude auto-recruitment of local populations (Davoult at al., 1990). Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    Intermediate High Low Moderate
    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

    Ophiothrix fragilis is predominantly a marine species. However, in the Dutch Oosterschelde Estuary, Wolff, (1968) notes dense aggregations of the species occurring in normal salinities of 16 psu and even persisting down to 10 psu. Therefore, the species may be tolerant of some change in salinity so intolerance is assessed as low.
    Low High Low Moderate
    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

    No information
    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

    Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. Although the species is known to have a low respiration rate (Migné & Davoult, 1997(b)), particularly during colder winter temperatures extreme hypoxia is known to cause mass mortality (Stachowitsch, 1984). Breeding occurs annually and there may be multiple recruitment phases (Davoult et al., 1990). The larvae of this species can disperse over considerable distances in areas such as the English Channel where there are strong water flow rates (Davoult et al., 1990). With water that may move over several kilometres per day due to residual flow (e.g. see Pingree & Maddock, 1977) and a larval duration of 26 days, the larvae can disperse up to 70-100 km and establish populations elsewhere. This may preclude auto-recruitment of local populations (Davoult at al., 1990). Adults, although mobile, are not highly active. Some immigration of adults from nearby populations may be possible. Longevity estimates vary from 9 months (Davoult et al., 1990) to over 10 years (Gage, 1990). Reproductive capability may be reached in 6-10 months depending on time of recruitment (Davoult et al., 1990).
    High High Moderate Low

    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

    The brittle star Ophiothrix fragilis has symbiotic subcuticular bacteria. The host-bacteria association can be perturbed by acute stress and changes in bacterial loading may be used as an indicator of sub-lethal stress (Newton & McKenzie, 1995). The dense aggregations of brittlestars seen in certain habitats probably provide the ideal conditions for the spread of diseases or parasites. Although no such infestations have been recorded for O. fragilis brittlestar beds there are several examples of echinoderm populations, that have been dramatically reduced by sudden outbreaks of epidemic diseases. Therefore, although an intolerance rank of low is reported epidemic disease does have the potential to significantly affect the biotope.
    Low High Low Low
    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

    There are no records of any non-native species that may compete with or predate upon Ophiothrix fragilis and so the species is assessed as not sensitive. However, as several species have become established in British waters there is always the potential for this to occur.
    Tolerant Not relevant Not sensitive Low
    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 and limited research value.
    Not relevant Not relevant Not relevant Low
    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

    Ophiothrix fragilis has no known obligate relationships with other species so removal of these species will not have any direct effect. The physical effects caused by removal of other species are addressed in the factors above.
    Tolerant Not relevant Not sensitive Low

    Additional information

    Importance review

    Policy/legislation

    - no data -

    Status

    Non-native

    ParameterData
    Native-
    Origin-
    Date Arrived-

    Importance information

    • Benthic suspension feeders such as Ophiothrix fragilis can occur in very high densities and can have a dominant role in the main nutrient exchanges in estuarine and coastal ecosystems (Dame 1993 cited in Smaal 1994; Lefebvre & Davoult, 1997).
    • Suspension feeders are important in coastal ecosystems because they can remove large amounts of suspended particulate matter (Davoult & Gounin, 1995).
    • Ophiothrix fragilis may be considered a keystone species in the coastal marine ecosystem of the eastern Channel and a dominant species of gravel communities (Lefebvre & Davoult, 1997).
    • Dense brittle star beds form an area of considerable physical complexity with many crevices and places to shelter. Despite the apparent dominance of Ophiothrix fragilis, up to 78 species have been recorded from a brittle star bed (of which half the biomass was O. fragilis) the most common of which was the bivalve Abra alba (Warner, 1971).
    • Ophiothrix fragilis has been recorded as representing up to 62 % of the biomass in coarse sediment communities (Migné & Davoult, 1997(b)).
    • Precipitation of calcium carbonate in skeletal ossicles is a source of carbon dioxide in sea water (Ware et al., 1992). The Ophiothrix fragilis community in the English Channel could provide 35 % of the phytoplankton carbon requirements (Migné & Davoult, 1997(b)).

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    3. Bourgoin, A., Guilloum, M. & Morvan, C., 1985. Étude préliminaire de l'épifaune des sédiments meubles de la Rade de Brest (Finistère, France) à l'aide d'une caméra vidéo sous-marine. Annals de l'Institut Océanographique, 61, 39-50.

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    8. Davoult, D., 1989. Demographic structure and production of the Ophiothrix fragilis population in the Dover Strait (French part). Proceedings of the 6th international symposium on Echinodermata. Echinoderms: living and fossils. Ile des Embiez (Var. France) 19-22 September, 1988. Vie Marine. Hors Series,10, 116-127.

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    10. Davoult, D., Dewarumez, J.M., & Frontier, S., 1993. Long-term changes (1979-90) in 3 benthic communities (eastern English Channel): Use of factor analysis and rank frequency diagrams for studying structural developments. Netherlands Journal of Aquatic Ecology, 27, 415-426.

    11. Davoult, D., Gounin, F. & Richard, A., 1990. Dynamique et reproduction de la population d'Ophiothrix fragilis (Abildgaard) du détroit du Pas de Calais (Manche orientale). Journal of Experimental Marine Biology and Ecology, 138, 201-216.

    12. Emson, R.H., & Wilkie, I.C., 1980. Fission and autotomy in echinoderms. Oceanography and Marine Biology: an Annual Review, 18, 155-250.

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    14. Gage, J.D., 1990. Skeletal growth bands in brittle stars: microstructure and significance as age markers. Journal of the Marine Biological Association of the United Kingdom, 70, 209-224. DOI https://doi.org/10.1017/S0025315400034329

    15. George, C.L. & Warwick, R.M., 1985. Annual macrofauna production in a hard-bottom reef community. Journal of the Marine Biological Association of the United Kingdom, 65, 713-735.

    16. Gorzula, S.J., 1976. The distribution of epibenthic ophiuroids in Cumbrae waters. The Western Naturalist, 5, 71-80.

    17. Gounin, F., Davoult, D., & Richard, A., 1995. Role of a dense bed of Ophiothrix fragilis (Abildgaard) in the transfer of heavy metals at the water-sediment interface. Marine Pollution Bulletin, 30, 736-741.

    18. Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.

    19. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

    20. Hiscock, K., 1983. Water movement. In Sublittoral ecology. The ecology of shallow sublittoral benthos (ed. R. Earll & D.G. Erwin), pp. 58-96. Oxford: Clarendon Press.

    21. Holme, N.A., 1984. Fluctuations of Ophiothrix fragilis in the western English Channel. Journal of the Marine Biological Association of the United Kingdom, 64, 351-378.

    22. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

    23. Hughes, D.J., 1998b. Subtidal brittlestar beds. An overview of dynamics and sensitivity characteristics for conservation management of marine SACs. Natura 2000 report prepared for Scottish Association of Marine Science (SAMS) for the UK Marine SACs Project., Scottish Association for Marine Science. (UK Marine SACs Project, Vol. 3). Available from: http://ukmpa.marinebiodiversity.org/uk_sacs/pdfs/britstar.pdf

    24. Hutchins, D.A., Teyssié, J-L., Boisson, F., Fowler, S.W., & Fisher, N.S., 1996. Temperature effects on uptake and retention of contaminant radionuclides and trace metals by the brittle star Ophiothrix fragilis. Marine Environmental Research, 41, 363-378.

    25. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line] http://www.jncc.gov.uk/mermaid

    26. Kaiser, M.J., Ramsay, K., Richardson, C.A., Spence, F.E. & Brand, A.R., 2000. Chronic fishing disturbance has changed shelf sea benthic community structure. Journal of Animal Ecology, 69, 494-503.

    27. Lefebvre, A., & Davoult, D., 1997. Recrutement d'Ophiothrix fragilis (Échinoderme: ophiuride) en Manche orientale: Étude biométrique. Journal Recherche Océanographique, 22, 109-116.

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    29. Mackie, A.M., 1970. Avoidance reactions of marine invertebrates to either steroid glycosides of starfish or synthetic surface-active agents. Journal of Experimental Marine Biology and Ecology, 5, 63-69.

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    32. Migné, A. & Davoult, D., 1997b. Carbon dioxide production and metabolic parameters in the ophiurid Ophiothrix fragilis. Marine Biology, 127, 699-704.

    33. Migné, A., & Davoult, D., 1997c. Distribution quantitative de la macrofaune benthique du peuplement des cailloutis dans le détroit du Pas de Calais (Manche orientale, France). Oceanologica Acta, 20, 453-460.

    34. Migné, A., Davoult, D., & Gattuso, J-P., 1998. Calcium carbonate production of a dense population of the brittle star Ophiothrix fragilis (Echinodermata: Ophiuroidea): role in the carbon cycle of a temperate coastal ecosystem. Marine Ecology Progress Series, 173, 305-308.

    35. Newton, L.C. & McKenzie, J.D., 1995. Echinoderms and oil pollution: a potential stress assay using bacterial symbionts. Marine Pollution Bulletin, 31, 453-456.

    36. Pedrotti, M.L., 1993. Spatial and temporal distribution and recruitment of echinoderm larvae in the Ligurian Sea. Journal of the Marine Biological Association of the United Kingdom, 73, 513-530.

    37. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin.

    38. Pingree, R.D. & Maddock, L., 1977. Tidal residuals in the English Channel Journal of the Marine Biological Association of the United Kingdom, 57, 339-354.

    39. Sides, E.M. & Woodley, J.D., 1985. Niche separation in three species of Ophiocomina (Echinodermata: Ophiuroidea) in Jamaica, West Indies. Bulletin of Marine Science, 36, 701-715.

    40. Sköld, M., 1998. Escape responses in four epibenthic brittle stars (Ophiuroidea: Echinodermata). Ophelia, 49, 163-179.

    41. Smaal, A.C., 1994. Theme V: The response of benthic suspension feeders to environmental changes. The Oosterschelde Estuary (The Netherlands): A case study of a changing ecosystem. Hydrobiologia, 282-283, 355-357.

    42. Stachowitsch, M., 1984. Mass mortality in the Gulf of Trieste: the course of community destruction. Marine Ecology, Pubblicazione della Statione Zoologica di Napoli, 5, 243-264.

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    45. Warner, G.F., 1971. On the ecology of a dense bed of the brittle star Ophiothrix fragilis. Journal of the Marine Biological Association of the United Kingdom, 51, 267-282.

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    Datasets

    1. Centre for Environmental Data and Recording, 2018. IBIS Project Data. Occurrence dataset: https://www.nmni.com/CEDaR/CEDaR-Centre-for-Environmental-Data-and-Recording.aspx accessed via NBNAtlas.org on 2018-09-25.

    2. 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.

    3. Cofnod – North Wales Environmental Information Service, 2018. Miscellaneous records held on the Cofnod database. Occurrence dataset: https://doi.org/10.15468/hcgqsi accessed via GBIF.org on 2018-09-25.

    4. Environmental Records Information Centre North East, 2018. ERIC NE Combined dataset to 2017. Occurrence dataset: http://www.ericnortheast.org.ukl accessed via NBNAtlas.org on 2018-09-38

    5. Fenwick, 2018. Aphotomarine. Occurrence dataset http://www.aphotomarine.com/index.html Accessed via NBNAtlas.org on 2018-10-01

    6. Fife Nature Records Centre, 2018. St Andrews BioBlitz 2014. Occurrence dataset: https://doi.org/10.15468/erweal accessed via GBIF.org on 2018-09-27.

    7. Fife Nature Records Centre, 2018. St Andrews BioBlitz 2015. Occurrence dataset: https://doi.org/10.15468/xtrbvy accessed via GBIF.org on 2018-09-27.

    8. Fife Nature Records Centre, 2018. St Andrews BioBlitz 2016. Occurrence dataset: https://doi.org/10.15468/146yiz accessed via GBIF.org on 2018-09-27.

    9. Isle of Wight Local Records Centre, 2017. IOW Natural History & Archaeological Society Marine Invertebrate Records 1853- 2011. Occurrence dataset: https://doi.org/10.15468/d9amhg accessed via GBIF.org on 2018-09-27.

    10. Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: https://www.kentwildlifetrust.org.uk/ accessed via NBNAtlas.org on 2018-10-01.

    11. Manx Biological Recording Partnership, 2017. Isle of Man wildlife records from 01/01/2000 to 13/02/2017. Occurrence dataset: https://doi.org/10.15468/mopwow accessed via GBIF.org on 2018-10-01.

    12. Manx Biological Recording Partnership, 2018. Isle of Man historical wildlife records 1990 to 1994. Occurrence dataset:https://doi.org/10.15468/aru16v accessed via GBIF.org on 2018-10-01.

    13. National Trust, 2017. National Trust Species Records. Occurrence dataset: https://doi.org/10.15468/opc6g1 accessed via GBIF.org on 2018-10-01.

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

    15. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-05-18

    16. Outer Hebrides Biological Recording, 2018. Invertebrates (except insects), Outer Hebrides. Occurrence dataset: https://doi.org/10.15468/hpavud accessed via GBIF.org on 2018-10-01.

    17. South East Wales Biodiversity Records Centre, 2018. SEWBReC Marine and other Aquatic Invertebrates (South East Wales). Occurrence dataset:https://doi.org/10.15468/zxy1n6 accessed via GBIF.org on 2018-10-02.

    18. Yorkshire Wildlife Trust, 2018. Yorkshire Wildlife Trust Shoresearch. Occurrence dataset: https://doi.org/10.15468/1nw3ch accessed via GBIF.org on 2018-10-02.

    Citation

    This review can be cited as:

    Jackson, A. 2008. Ophiothrix fragilis Common 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 18-05-2024]. Available from: https://www.marlin.ac.uk/species/detail/1198

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    Last Updated: 08/05/2008