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

Pomatoceros triqueter is attached permanently to rocks, boulders or shingle. Removal of substratum will remove calcareous tubes and animals contained in them. Intolerance is assessed as high. Recoverability is likely to be high (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

Smothering with a 5 cm layer of sediment would completely cover the tubes of Pomatoceros triqueter that usually lie flat against the surface of the rock. It is also likely that too much sediment on the surface of rocks or shells would prevent settlement of larvae and impair the long term survival of populations. Intolerance has been assessed to be high. Recoverability is likely to be high (see additional information below).

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

Records show confusion as to whether Pomatoceros triqueter is tolerant of high suspended sediment levels. According to Bacescu (1972), sabellids are accustomed to turbidity and silt. Stubbings & Houghton (1964) found Pomatoceros triqueter in Chichester harbour, a muddy harbour, therefore agreeing with the previous statement. However, Pomatoceros triqueter has been noted to occur in areas where there is little or no silt present (Price et al., 1980) and according to Lewis (1957), Pomatoceros triqueter is highly susceptible to unfavourable conditions, always requiring stability and clean water. Moore (1937) and Nair (1962) agreed with this.
However, Pomatoceros triqueter has been recorded in areas where suspended sediment levels can be high; demonstrating that it can tolerate high suspended sediment concentrations. A supply of suspended sediment will probably also be important to Pomatoceros triqueter because the species requires a supply of particulate matter for suspension feeding. At the benchmark level of an increase of 100mg/l for one month, the likely impact would be an increase in cleaning costs. Intolerance has been assessed as low. Recoverability is likely to be high.

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

Pomatoceros triqueter has been noted to occur in areas where there is little or no silt present (Price et al., 1980). The species is an active suspension feeder and will probably not be highly intolerant of suspended sediment concentrations. As an energetic cost would probably be entailed to create currents to transport food particles, intolerance has been assessed to be low. On return to normal conditions, recoverability is likely to be high.

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

As Pomatoceros triqueter occurs in the subtidal region it will be tolerant to a certain amount of desiccation. The species probably survives by closing the operculum of the tube, however, the amount of time available for feeding and respiration will be reduced, and therefore the population's viability may be reduced. Some individuals are also likely to die. Intolerance has been assessed to be intermediate. Recoverability is likely to be high (see additional information below).

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

An increase in the emergence regime will increase the amount of time some individuals are exposed to air. At the benchmark level of an increase of one hour over the period of a year, those higher on shore are likely to die. Intolerance has been assessed to be intermediate. Recoverability is likely to be high (see additional information below).

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

A decrease in the emergence regime may mean that more time can be spent feeding, but is unlikely to have any adverse effects. Therefore Pomatoceros triqueter is likely to tolerate a decrease in emergence, and may actually benefit.

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

Pomatoceros triqueter has been noted to occur in areas with very sheltered to exposed water flow rates (Price et al., 1980). Wood (1988) observed Pomatoceros sp. in strong tidal streams and Hiscock (1983) found that in strong tidal streams or strong wave action where abrasion occurs, fast growing species such as Pomatoceros triqueter occur. Therefore, the species is probably tolerant of an increase in water flow rate, and the species may actually increase in abundance.

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

Pomatoceros triqueter has been noted to occur in areas with very sheltered to exposed water flow rates (Price et al., 1980). The species has been assessed to be tolerant.

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

Maximum sea surface temperatures around the British Isles rarely exceed 20 °C (Hiscock, 1998) and, as Pomatoceros triqueter occurs as far south as the Mediterranean, it will therefore be subject to a wider range of temperatures than experienced in the British Isles. Further information also backs this up. Castric-Fey (1983) found that animals settling during spring showed the best growth rate and the best larval settlement occurred in the summer months. Pomatoceros triqueter has been assessed as tolerant* to an increase in temperature.

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

Minimum surface sea water temperatures rarely fall below 5 °C around the British Isles (Hiscock, 1998). Below a temperature of 7°C Pomatoceros triqueter is unable to build calcareous tubes (Thomas, 1940). This means that, although adults may be able to survive a decrease in temperature, larvae would not be able to attach to the substratum. Intolerance has been assessed to be intermediate. Recoverability is likely to be high (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

According to Bacescu (1972), sabellids are accustomed to turbidity and silt. Pomatoceros triqueter has also recently been recorded by De Kluijver (1993) from Scotland in the aphotic zone, indicating that the species would not be sensitive to an increase in 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

According to Bacescu (1972), sabellids are accustomed to turbidity and silt. According to Lewis (1957), Pomatoceros triqueter is highly susceptible to unfavourable conditions, always requiring stability and clean water. Moore (1937) and Nair (1962) agreed with this. Therefore, Pomatoceros triqueter is unlikely to be sensitive 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

Pomatoceros triqueter has been noted to occur in areas with variable wave action; extremely sheltered to very exposed (Price et al., 1980). The hard calcareous tube is resistant to abrasion from sand, gravel and boulders (Wood, 1988; Hiscock, 1983) that are mobilised by wave action. With an increase in wave exposure over a period of a year the viability of the population may be reduced due to a reduction in feeding and larval settlement. Therefore intolerance of Pomatoceros triqueter to an increase in wave exposure is likely to be low. On return to normal conditions, 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

Pomatoceros triqueter has been noted to occur in areas with variable wave action; extremely sheltered to very exposed (Price et al., 1980). As the species can tolerate very low wave exposure, it is therefore probably tolerant of a decrease in wave exposure.

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

Polychaetes may be able to detect vibration, and withdraw into their tube. However, at the benchmark level the species is unlikely to be sensitive to noise.

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

Shadows detected by the photoreceptive surface of serpulid polychaetes may result in withdrawal of the worm back into its tube (Kinne, 1970). However, at the benchmark level the species is unlikely to be sensitive to visual presence.

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

Pomatoceros triqueter has a hard calcareous tube that is resistant to sand and gravel abrasion (Wood, 1988). Hiscock (1983) noted that a community, under conditions of scour and abrasion from stones and boulders moved by storms, developed into a community consisting of fast growing species such as Pomatoceros triqueter. Off Chesil Bank, the epifaunal community dominated by Pomatoceros triqueter, Balanus crenatus and Electra pilosa, decreased in cover in October, was scoured away in winter storms, and was recolonized in May to June (Warner, 1985). Warner (1985) reported that the community did not contain any persistent individuals, being dominated by rapidly colonizing organisms. But, while larval recruitment was patchy and varied between the years studied, recruitment was sufficiently predictable to result in a dynamic stability and a similar community was present in 1979, 1980, and 1983. Scour due to winter storms is probably greater than the benchmark level. Scour and abrasion will probably remove a proportion of the population, suggesting an intolerance of intermediate. However, it demonstrates rapid growth and recruitment so that it is not considered to be sensitive. The abundance of Pomatoceros triqueter may increase due to decreased competition from other species.

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

If tubes containing the worm are removed, the tubes will not be able to be reattached to the substratum surface. However, Thomas (1940) found that if Pomatoceros triqueter is removed from its tube, it will start to make a new one in a few hours. Therefore, it is likely that the worm will be able to leave the old tube to start constructing another. This would probably involve an added energetic cost, therefore population viability may be affected. Intolerance has been assessed to be low. Recoverability is likely to be high.

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

There is insufficient information to assess the intolerance of Pomatoceros triqueter to synthetic chemicals.

Heavy metal contamination

Evidence

Bryan (1984) suggested that, on evidence available for several species, that polychaetes are fairly resistant to heavy metals. However, there is insufficient information available to assess intolerance of Pomatoceros triqueter to heavy metal contamination.

Hydrocarbon contamination

Evidence

Large numbers of dead polychaetes and other fauna were washed up at Rulosquet marsh near Isle de Grand following the Amoco Cadiz oil spill in 1978 (Cross et al., 1978). However, no information was found relating to Pomatoceros triqueter in particular. Therefore, insufficient information was available to assess the species intolerance.

Radionuclide contamination

Evidence

There is insufficient information to assess the intolerance of Pomatoceros triqueter to radionuclides.

Changes in nutrient levels

Evidence

There is insufficient information to assess the intolerance of Pomatoceros triqueter to nutrient levels.

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

Pomatoceros triqueter occurs in fully saline waters and is probably relatively tolerant of an increase in salinity.

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

Pomatoceros triqueter occurs in fully saline coastal waters and has not been recorded from brackish or estuarine waters. Therefore, it is likely that the species will be very intolerant of a decrease in salinity. However, Dixon (1985) views the species as able to withstand significant reductions in salinity. The degree of reduction in salinity and time that the species could tolerate those levels were not recorded. Therefore, there is insufficient information available to assess the intolerance of Pomatoceros triqueter to a reduction in salinity.

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 2 mg/l. However, no information was found relating to intolerance of Pomatoceros triqueter to oxygen levels. Insufficient
information was available to assess intolerance of the species at the benchmark level of 2 mg/l for a week.

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

Thomas (1940) recorded parasites of Pomatoceros triqueter. Trichodina pediculus (a ciliate) was observed in fair numbers moving over the branchial crown. However, this is a commensal, not a parasite. Parasites found in the worm include gregarines & ciliated protozoa and parasites that had the appearance of sporozoan cysts. However, no information was found about the effects of microbial pathogens on Pomatoceros triqueter.

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

Although several species of serpulid polychaetes have been introduced into British waters none are reported to compete with Pomatoceros triqueter (Eno et al., 1997).

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

No extraction of Pomatoceros triqueter is known to occur.

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

No extraction of other species is likely to have any effect on Pomatoceros triqueter.