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

Psammechinus miliaris lives and feeds on a variety of substrata. Loss of substratum will cause mortality. Adult urchins are mobile but probably not active over large distances so recolonization is unlikely to occur through adult immigration. Psammechinus miliaris is quite long lived (up to 12 years) (Allain, 1978), and can breed within one year of settlement (Kelly, 2001). Breeding occurs in spring and summer each year (Mortensen, 1927; Sukarno et al., 1979; Kelly, 2000), fecundity is likely to be high (MacBride, 1903) and the larvae are long lived (20-40 days) (Jensen, 1969; Massin, 1999b; Kelly et al., 2000). Dispersal potential is therefore large and recoverability is likely to be high.

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

Psammechinus miliaris is an epibenthic species that, although mobile, is not highly active and moves using mobile spines. This urchin species is quite small (typically up to 40 mm) and is likely to be completely covered by 5 cm of sediment. It is probable that the urchin would be unable to 'dig out' of the sediment. Adult urchins are mobile but probably not active over large distances so recolonization is unlikely to occur through adult immigration. Psammechinus miliaris is quite long lived (up to 12 years) (Allain, 1978), and can breed within one year of settlement (Kelly, 2001). Breeding occurs in spring and summer each year (Mortensen, 1927; Sukarno et al., 1979; Kelly, 2000), fecundity is likely to be high (MacBride, 1903) and the larvae are long lived (20-40 days) (Jensen, 1969; Massin, 1999b; Kelly et al., 2000). Dispersal potential is therefore large and recoverability is likely to be high.

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

It is unlikely that changes in siltation rate will have a great effect on this species. Psammechinus miliaris grazes on macroalgae and some encrusting faunal species so increases in siltation are unlikely to affect feeding. Increases in siltation rate will increase the amount of sediment settling out onto the urchin. There may be an increased energetic cost to clearing these particles. Energetic expenditure may result in loss of condition or compromise gonadal and somatic growth. On removal of the factor, recovery should take only a short time.

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

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

Psammechinus miliaris is found subtidally and intertidally. In intertidal regions the urchin is typically found in crevices and under boulders or weed where the risk of desiccation is minimized. However, relative humidity and temperature strongly influence survivorship of Psammechinus miliaris. Cook (1999) found that Psammechinus miliaris from littoral populations were more tolerant of an increased temperature and decreased relative humidity during aerial exposure than those from subtidal populations. Psammechinus miliaris from the littoral zone show slightly more tolerance to exposure at 60% relative humidity and 10 °C than those from sublittoral populations. At high relative humidity (95%), 95% of Psammechinus miliaris can withstand 72 hours exposure to air if kept chilled at 5 °C. But at 20 °C and 95% humidity, no Psammechinus miliaris survived 72 hours exposure (Cook, 1999; Dr Maeve Kelly, pers comm.). Therefore, it is likely that individuals exposed to an increase in desiccation at the benchmark level will die. Therefore, an intolerance of high has been recorded. Recruitment to the remaining population will probably occur by larval settlement from the plankton. Recoverability is likely to be high (see additional information).

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

Psammechinus miliaris is unlikely to be intolerant of changes in emergence regime. Although not highly active, the species is sufficiently mobile to be able to relocate to more suitable conditions.

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

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

Psammechinus miliaris holds itself onto the substratum using suction pads at the end of its tube feet (Massin, 1999b) Large increases in water flow rate may make it more difficult to remain on the substratum. The urchin Echinus esculentus has been observed to be 'rolled' by water currents (Comely & Ansell, 1988). Displacement from the substratum is unlikely to cause damage or death. Relocation back to a suitable or preferred location will incur an energetic cost. Energetic expenditure may result in loss of condition or compromise gonadal and somatic growth. On removal of the factor, recovery should take only a short time.

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

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 recorded as occurring in water temperatures of between 4-17 °C. Ursin (1960) reported that Psammechinus miliaris had a high tolerance of low temperatures and that it is found in Limfjord, Denmark, where winter temperatures are just above zero. It reproduces in waters around the Faeroes where the summer temperatures seldom exceed 11 °C (Ursin, 1960). The geographical distribution of Psammechinus miliaris extends to the north and south of the British Isles into colder and warmer waters respectively. Consequently, long term chronic changes in temperature are unlikely to have a great effect on populations of Psammechinus miliaris in the British Isles. Therefore, an intolerance of low has been recorded. Recoverability is likely to be rapid. However, exposure to high temperatures in the intertidal will increase the risk of desiccation (see above).

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

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

Moore (1977) suggested that Echinus esculentus was unaffected by turbid conditions. Psammechinus miliaris can inhabit similar kelp habitats to Echinus esculentus and may be similarly tolerant. However, increased turbidity and resultant reduced light penetration is likely to affect macroalgal populations e.g. kelps, which are a preferred food species for Echinus esculentus. However, it can feed on alternative prey, detritus or dissolved organic material (Lawrence, 1975, Comely & Ansell, 1988). Conversely, decreases in turbidity may benefit algal growth. Reduced food availability may cause loss of condition or compromise gonadal and somatic growth. When food availability is returned to 'normal' recovery should take only a short time.

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

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

Psammechinus miliaris occurs both in subtidally and inter-tidally from coasts all round the British Isles but is typically found in more sheltered environments. It has a lower tolerance of wave exposure than Echinus esculentus and Paracentrotus lividus, the latter being found on the exposed. It is likely that high levels of wave exposure limits the distribution of Psammechinus miliaris in the intertidal and subtidal (Dr Maeve Kelly, pers comm.). As Psammechinus miliaris feeds on a wide selection of algae and encrusting organisms (Lawrence, 1975) its distribution is thought to be limited more by physical parameters than food availability (Faller-Fritsch & Emson, 1972; cited in Lawrence, 1975). Therefore, an increase in wave exposure at the benchmark level is likely to remove at least a proportion of the population and an intolerance of intermediate has been recorded. Recruitment to the remaining population will occur by larval settlement from the plankton. Recoverability is likely to be high.

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

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 evidence of 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

Psammechinus miliaris is likely to have slight intolerance to visual disturbance. Like many other echinoids it avoids bright light (Massin, 1999(b)). This species is recorded as having a behavioural response to changes in shading. Sudden shading results in withdrawal of the tube feet (Millott & Yoshida, 1956) The degree of response depends on light intensity and the degree of intensity change. Other echinoid species are also recorded as having a shading response, with spines being brought round to point in the direction of the stimulus as a protective mechanism. The reaction is likely to be short lived and insignificant. This response may interfere with feeding and if this occurs repeatedly then loss of condition or reduced somatic and gonadal may result. On removal of the stimulus, recovery of condition should not take long.

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

The test of Psammechinus miliaris is brittle and easily damaged by impact or abrasion. Spines and podia may be damaged or broken off. The spines may provide some degree of cushioning for the test. Beam trawling was reported to remove ca 20 to 50% of this species (Kaiser & Spencer, 1994a), and the impact of scallop dredging is likely to be similar. Damage to the test will generally be lethal, if not outright because internal organs become exposed to predators and possible infection. However, the frequency of occurrence of Psammechinus miliaris was reported to increase markedly over an 80 year period in trawled areas in the southern North Sea (Rumohr & Kujawski, 2000). Overall, the evidence from Kaiser & Spencer (1994a) suggests that a proportion of the population is likely to be removed and intolerance has been assessed as intermediate. Some repair and regrowth of minor damage to the test and spines may be possible. Recoverability is likely to be high (see additional information below).

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

Psammechinus miliaris is mobile and may be also regularly displaced by wave action or water currents. Some damage may be caused by loss of tube feet during a displacement event but this is repairable. As with Echinus esculentus (Lewis & Nichols 1979b), displaced specimens are able to relocate. This will probably have negligible effect on the species.

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

Considerable observations and work, mainly on Echinus esculentus but also on Psammechinus miliaris (Smith, 1968; Gomez & Miguez-Rodriguez, 1999; Dinnel et al., 1988 ) indicate high intolerance to synthetic contaminants. Newton & McKenzie (1995) state that echinoderms tend to be very intolerant of various types of marine pollution, but there is little more detailed information than this. Following the Torrey Canyon incident, large numbers of dead Psammechinus miliaris in the vicinity of Sennen, presumably due to the heavy spraying of dispersants in that area and exposure to the oil spill (Smith, 1968). Therefore, an intolerance of high has been reported. Recoverability is likely to be high (see additional information below).

Heavy metal contamination

Evidence

Little is known about the effects of heavy metals on adult echinoderms although Newton & McKenzie (1995) state that echinoderms tend to be very sensitive to various types of marine pollution. In an area around Naples, with high concentrations of lead, zinc and copper, the urchins Paracentrotus lividus and Arbacia lixula were smaller than those at unpolluted sites further along the coast (Sheppard & Bellamy, 1974) probably due to either restricted growth or individuals dying before reaching adult size. Abundance was also lower in polluted sites and so intolerance of adults has been assessed as intermediate. Echinoderm larvae are know to be especially intolerant of heavy metals (Bryan, 1974). Recoverability is likely to be high (see additional information below).

Hydrocarbon contamination

Evidence

Echinoderms seem especially sensitive to the toxic effects of oil, likely because of the large amount of exposed epidermis (Suchanek, 1993). Following the Torrey Canyon incident, large numbers of dead Psammechinus miliaris in the vicinity of Sennen, presumably due to exposure to the oil spill and the heavy spraying of hydrocarbon based dispersants in that area (Smith, 1968). Other significant effects have been observed in other species of urchins. For example, mass mortality of the echinoderm Echinocardium cordatum was observed shortly after the Amoco Cadiz oil spill (Cabioch et al., 1978) and reduced abundance of the species was detectable up to > 1000m away one year after the discharge of oil-contaminated drill cuttings in the North Sea (Daan & Mulder, 1996). In the Mediterranean around Naples, urchins were absent from areas which has visible signs of massive pollution of both sewage and oil. Echinus esculentus populations in the vicinity of an oil terminal in A Coruna Bay, Spain, showed developmental abnormalities in the skeleton. The tissues contained high levels of aliphatic hydrocarbons, naphthalenes, pesticides and heavy metals (Zn, Hg, Cd, Pb, and Cu) (Gomez & Miguez-Rodriguez 1999). But the observed effects may have been due to a single contaminant or synergistic effects of all present. However, it appears likely that echinoids such as Psammechinus miliaris are highly intolerant of hydrocarbon contamination. Recoverability is likely to be high (see additional information below).

Radionuclide contamination

Evidence

Insufficient
information

Changes in nutrient levels

Evidence

It is unlikely that changes in nutrient concentration will directly affect Psammechinus miliaris populations. The addition of nutrients may encourage the growth of ephemeral and epiphytic algae and therefore increase the food available to populations of grazing sea-urchins such as Psammechinus miliaris. Conversely, decreases in nutrient availability may limit growth of algae used as a nutrient source. Lawrence (1975) reported that sea urchins had persisted over 13 years on barren grounds near sewage outfalls, presumably feeding on dissolved organic material, detritus, plankton and microalgae, although individuals died at an early age. The ability to absorb dissolved organic material has been suggested by Comely & Ansell (1988). Reduced food availability may cause loss of condition or compromise gonadal and somatic growth. Increased food availability may cause the population to expand in number or extent. When food availability is returned to 'normal', recovery should take only a short time.

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 generally unable to tolerate low salinity (stenohaline) conditions and possess no osmoregulatory organ (Boolootian, 1966). There is some evidence for intracellular regulation of osmotic pressure due to increased amino acid concentrations. Populations of Psammechinus miliaris occur both in the sub-tidal and inter-tidal. The latter must encounter reduced salinity due to fresh water runoff or heavy rain and hence be able to tolerate variable salinity. Lindahl & Runnström (1929) showed through acclimatisation experiments that Psammechinus miliaris from the littoral (Z form) and sublittoral (S form) had different salinity optima. Gezelius (1962) showed that eggs from the Z and S forms of Psammechinus miliaris differed in the range of salinities they would tolerate and over which fertilization would successfully occur, 20-32 psu and 26-38 psu at 17-19 °C respectively. At low salinity urchins gain weight and the epidermis loses its pigment as patches are destroyed; prolonged exposure is fatal. Therefore, a short term acute decrease in salinity may cause mortality, especially in sublittoral populations, and an intolerance of intermediate has been recorded. Recoverability is likely to be high (see additional information below).

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

Changes in oxygenation

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

Evidence

Under hypoxic conditions echinoderms become less mobile and stop feeding. Death of a bloom of the phytoplankton Gyrodinium aureolum in Mounts Bay , Penzance in 1978 produced a layer of brown slime on the sea bottom. This resulted in the death of fish and invertebrates, including Echinus esculentus, presumably due to anoxia caused by the decay of the dead dinoflagellates (Griffiths et al., 1979). Spicer (1995) investigated the effects of environmental hypoxia on the oxygen and acid-base status of Psammechinus miliaris. Oxygen uptake is not regulated by this species during progressive hypoxia. The habitat of this species includes rock pools on the shore that can experience quite severe hypoxia or even anoxia. Psammechinus miliaris must be able to tolerate low oxygen conditions provided the event is brief. In prolonged events, subtidal Psammechinus miliaris would presumably react in a similar fashion to the Echinus esculentus above. Recoverability is likely to be high (see additional information below).

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

Psammechinus miliaris is susceptible to 'Bald-sea-urchin disease', which causes lesions, loss of spines, tube feet, pedicellariae, destruction of the upper layer of skeletal tissue and death (Maes et al., 1986). It is thought to be caused by the bacteria Vibrio anguillarum and Aeromonas salmonicida. This disease has been recorded from Psammechinus miliaris from the French Atlantic coast. Although associated with mass mortalites of Strongylocentrotus franciscanus in California and Paracentrotus lividus in the French Mediterranean there is no evidence of mass mortalities of Psammechinus miliaris associated with this disease around Britain and Ireland. an intolerance of intermediate has therefore been recorded. Recoverability is likely to be high (see additional information below).

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 alien or non-native species is known to prey on, compete with or adversely (or otherwise) affect Psammechinus miliaris.

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

Psammechinus miliaris is now targeted as a potential aquaculture species since when fed a nutritious diet in culture, the gonad biomass rapidly proliferates (Kelly et al., 1998). A study of a littoral and sublittoral population, Kelly (2000) concluded that there was no evidence of an opportunity for a commercial fishery because of the low gonad content of wild populations. However, some extraction of Psammechinus miliaris may conceivably develop for roe-enhancement through feeding artificial or nutrient enriched diets (Dr Maeve Kelly pers comm.). Therefore, an intolerance of intermediate has been recorded. The aquaculture potential of this smaller species is being investigated (Kelly et al., 1998). Recoverability is likely to be high (see additional information below).

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

Both sub-tidal and inter-tidal populations of Psammechinus miliaris are often intimately associated with macro algae, particularly with kelp beds, both attached and loose lying. Physical effects associated with removal of other species (such as kelp) are addressed in the relevant factors above. Therefore, extraction of seaweed species is likely to result in the loss of some individuals of Psammechinus miliaris. This species may also suffer as a result of trawling or dredging for other benthic species. Species with fragile tests such as urchins have been reported to be particuarly sensitive to damage from mobile fishing gear (see Jennings & Kaiser, 1998; Bergman & van Santbrink, 2000). Kaiser & Spencer (1994a) reported a ca 20 - 50% mortality in Psammechinus miliaris as a result of a single pass of an experimental 4 m beam trawl. However, the frequency of occurrence of Psammechinus miliaris was reported to increase markedly over an 80 year period in trawled areas in the southern North Sea (Rumohr & Kujawski, 2000). Overall, the evidence from Kaiser & Spencer (1994a) suggests that a proportion of the population is likely to be removed and intolerance has been assessed as intermediate. Recoverability is likely to be high (see additional information below).