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

Loss of its substratum would result in loss of the resident population and an intolerance of high has been recorded. Once the habitat has returned to suitable conditions, recovery may 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

Aphrodita aculeata is an active burrowing species living in the surface sediment. Deposition of 5 cm of similar sediment is unlikely to adversely affect the species directly. Deposition of sediment that differs from that present is likely to modify the sediment structure, which may affect this species, depending on the nature of the change. However, at the benchmark level an intolerance of low has been recorded. Recovery is likely to be rapid.

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

Aphrodita aculeata is an active predator and unlikely to be directly affected by changes in suspended sediment levels. It preys predominantly on other worms (Mettam, 1980) some of which are likely to be suspension feeders. Suspension feeders may benefit, or be adversely affected by changes in suspended sediment levels, depending on the species. However, Aphrodita aculeata can feed on a variety of prey and would probably not be adversely affected.

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

Aphrodita aculeata is an active predator and unlikely to be directly affected by changes in suspended sediment levels. It preys predominantly on other worms (Mettam, 1980) some of which are likely to be suspension feeders. Suspension feeders may benefit, or be adversely affected by changes in suspended sediment levels, depending on the species. However, Aphrodita aculeata can feed on a variety of prey and would probably not be adversely affected.

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

Stranded Aphrodita aculeata would undoubtedly die due to desiccation and predation. However, it is normally a subtidal species unlikely to be exposed to the air. Therefore, not relevant has been recorded.

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 emergence could potentially decrease the upper extent of the population. However, Aphrodita aculeata is a mobile species likely to migrate to deeper water. Therefore, an intolerance of low has been recorded.

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 emergence could potentially increase the habitat available to Aphrodita aculeata, assuming suitable substratum was present. Therefore, tolerant* has been recorded.

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

Changes in water flow rate are unlikely to affect Aphrodita aculeata directly. However, water flow rate and other hydrodynamic factors have a significant effect on the distribution of sediments of different grain size in sedimentary habitats. Increased water flow deposits coarser sediments whereas reduced water flow rates will deposit finer sediments. Aphrodita aculeata has been recorded in habitats subject to very weak to moderately strong tidal streams (JNCC, 1999). An increase in water flow rate from for instance moderately strong to very strong (see benchmark) is likely to significantly alter the nature of the substratum. Therefore, an increase in water flow rate is likely to change the distribution and extent of Aphrodita aculeata populations and an intolerance of intermediate has been recorded. Once the habitat has returned to suitable conditions recovery is may be rapid (see additional information below).

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

Changes in water flow rate are unlikely to affect Aphrodita aculeata directly. However, water flow rate and other hydrodynamic factors have a significant effect on the distribution of sediments of different grain size in sedimentary habitats. Increased water flow deposits coarser sediments whereas reduced water flow rates will deposit finer sediments. Aphrodita aculeata has been recorded in habitats subject to very weak to moderately strong tidal streams (JNCC, 1999). Therefore, a further decrease in water flow rate is unlikely.

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

Aphrodita aculeata is a subtidal species and unlikely to be exposed to extreme temperature change due to natural events. It is also widespread, occurring off Newfoundland, in the North Sea, Baltic and the Mediterranean. Therefore, it is unlikely to be adversely affected by chronic temperature change at the benchmark level in British and Irish waters. Therefore, not sensitive has been recorded.

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

Aphrodita aculeata is a subtidal species and unlikely to be exposed to extreme temperature change due to natural events. It is also widespread, occurring off Newfoundland, in the North Sea, Baltic and the Mediterranean. Therefore, it is unlikely to be adversely affected by chronic temperature change at the benchmark level in British and Irish waters. Therefore, not sensitive has been recorded.

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

Light intensity is unlikely to affect Aphrodita aculeata directly.

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

Light intensity is unlikely to affect Aphrodita aculeata directly.

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

Wave exposure and other hydrodynamic factors have a significant effect on the distribution of sediments of different grain size in sedimentary habitats, especially in shallow waters. Aphrodita aculeata has been recorded from extremely wave sheltered to wave exposed habitats (JNCC, 1999), although probably at greater depths in wave exposed locations. An increase in wave exposure from, for instance, exposed to extremely exposed, is likely to increase the erosion of fine sediments and favour coarse sediments and/or increase the mobility of the sediments. Mobile sediments are dynamic and harbour an impoverished fauna in comparison with stable sediments. Overall, an increase in wave exposure is likely to change the nature of the sediment, and reduce the extent of habitat suitable for Aphrodita aculeata. Therefore, an intolerance of intermediate has been recorded. Recoverability may be high (see additional information).

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

Wave exposure and other hydrodynamic factors have a significant effect on the distribution of sediments of different grain size in sedimentary habitats, especially in shallow waters. Aphrodita aculeata has been recorded from extremely wave sheltered to wave exposed habitats (JNCC, 1999), although probably at greater depths in wave exposed locations. Therefore, a decrease in wave exposure from exposed to sheltered is unlikely to have an adverse effect.

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

There is little information on the effects of underwater noise or vibration on invertebrates (Vella et al., 2001). Although Aphrodita aculeata is likely to respond to the pressure wave or vibrations caused by potential predators, it is unlikely to be affected by noise at the benchmark level.

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

Mettam (1980) noted that, in the laboratory, Aphrodita aculeata only took prey overnight. This observation may suggest that it is either nocturnal or has a dislike of background lighting (as found in a laboratory). However, it probably has very poor visual acuity and is unlikely to be affected by shading or visual presence at the benchmark level.

Abrasion & physical disturbance

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

Evidence

Large Aphrodita aculeata (>7 cm in length) were reported to suffer up to 31% mortality due to beam or otter trawls in sandy sediments of the North Sea (Bergman & van Santbrink, 2000). No mortality was reported in smaller individuals, presumably because they could pass through the trawls unharmed. Bergman & van Santbrink (2000) also reported an annual mortality for Aphrodita aculeata of up to 20% due to trawling in the Dutch sector of the North Sea in 1994. Kaiser et al. (1998) examined the immediate effects of beam trawling north east of Anglesey. They reported that, in stable sediments, the community significantly altered immediately after the trawl. The reduction in the abundance of Aphrodita aculeata and Nephtys spp. contributed significantly to the difference between trawled and control areas. However, no significant difference between trawled and control sites were detectable six months later, in part due to seasonal changes in the community during that period (Kaiser et al., 1998). In another experiment, only 7-8% of Aphrodita aculeata caught in a beam trawl died while the majority were not damaged (Kaiser & Spencer, 1995). Storms are also known to cause physical disturbance in sedimentary habitats. For example, moderate numbers of Aphrodita aculeata were reported to be stranded after the 1975 to 1976 storms in Red Wharf Bay, Anglesey (Rees et al., 1976).
Therefore, a proportion of the population is likely to be removed and/or displaced by physical disturbance and an intolerance of intermediate has been recorded. Recoverability is probably high (see additional information).

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

Aphrodita aculeata is an active predator (Mettam, 1980) and probably capable of rapid burrowing. Therefore, if displaced to a suitable habitat, this species would probably burrow quickly to avoid predation. Therefore, an intolerance of low has been recorded. Recoverability is probably immediate.

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

Residues of organochlorines have been detected in the tissues of Aphrodita aculeata in the northwest of the Dutch coast, an area in which incineration occurred before 1991 (Dethlefsen et al., 1996). Residues of DDT and PCBs were detected however no information on their potential effects was noted. Little information on the effects of synthetic contaminants on Aphrodita aculeata was found. Bryan & Gibbs (1991) noted that polychaetes vary in their response, with some species exhibiting relative tolerance, while other species were moderately sensitive. However, in the absence of any further information, no assessment has been attempted.

Heavy metal contamination

Evidence

Bryan (1984) suggested that polychaetes are fairly resistant to heavy metals, based on the species studied. Short term toxicity in polychaetes was highest to Hg, Cu and Ag, declined with Al, Cr, Zn and Pb whereas Cd, Ni, Co and Se the least toxic. However, no information concerning Aphrodita aculeata was found and no assessment has been made.

Hydrocarbon contamination

Evidence

Suchanek (1993) reviewed the effects of oil spills on marine invertebrates and concluded that, in general, on soft sediment habitats, infaunal polychaetes, bivalves and amphipods were particularly affected. Aphrodita aculeata inhabits sublittoral sediments which are unlikely to be affected by oil spills directly, although hydrocarbons adsorbed onto particulates may be deposited. However, no information concerning the effects of hydrocarbon contamination on Aphrodita aculeata was found and no assessment has been made.

Radionuclide contamination

Evidence

No information found

Changes in nutrient levels

Evidence

Increasing nutrient levels may result in a change from the typical sediment community, to a community dominated by opportunist species (e.g. capitellids) with increased abundance but reduced species richness and in extreme situations to anoxic abiotic sediments (Pearson & Rosenberg, 1978). However, Aphrodita aculeata is a predator and unlikely to be directly affected, although it may suffer as a result of reduced oxygen levels in the sediment surface (see oxygenation below). However, no information concerning the effect of nutrient enrichment on Aphrodita was found and no assessment has been made.

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

Kinne (1971b) suggested that marine polychaetes had limited capacity for osmoregulation and noted that the ionic concentration of the coelomic fluid in Aphrodite aculeata was very similar to that of ambient seawater. This evidence, although limited, suggests that it would be sensitive to an increase in salinity from full salinity, especially short term acute change. Therefore, an intolerance of high has been recorded, albeit at very low confidence.

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

Aphrodita aculeata has been recorded only from habitats with full salinity (JNCC, 1999). Kinne (1971b) suggested that marine polychaetes had limited capacity for osmoregulation and noted that the ionic concentration of the coelomic fluid in Aphrodite aculeata was very similar to that of ambient seawater. This evidence, although limited, suggests that it would be sensitive to a decrease in salinity, especially short term acute change. Therefore, an intolerance of high has been recorded, albeit at very low confidence.

Changes in oxygenation

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

Evidence

Aphrodita aculeata is a shallow burrower living in the surface sediment layer, which may be expected to be well oxygenated. However, no information on its tolerance of hypoxic conditions was found and no assessment has been made.

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

While the spines and scales are known to harbour several species of entoproct (see general biology), they are thought to be commensal rather than parasitic. No information concerning diseases in Aphrodita was found.

Introduction of non-native species

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

Evidence

No information on competing or potentially competing non-native species was found.

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

Aphrodita aculeata is unlikely to be the subject of targeted fisheries. However, it can be adversely affected by fishing activities for other species (see 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

Large Aphrodita aculeata (> 7 cm in length) were reported to suffer up to 31% mortality due to beam or otter trawls in sandy sediments of the North Sea (Bergman & van Santbrink, 2000). No mortality was reported in smaller individuals, presumably because they could pass through the trawls unharmed. Bergman & van Santbrink (2000) also reported an annual mortality for Aphrodita aculeata of up to 20% in the Dutch sector of the North Sea in 1994. Kaiser et al. (1998) examined the immediate effects of beam trawling north east of Anglesey. They reported that, in stable sediments, the community significantly altered immediately after the trawl. The reduction in the abundance of Aphrodita aculeata and Nephtys spp. contributed significantly to the difference between trawled and control areas. However, no significant difference between trawled and control sites were detectable six months later, in part due to seasonal changes during that period (Kaiser et al., 1998). In another experiment, only 7-8% of Aphrodita aculeata caught in a beam trawl died while the majority were not damaged (Kaiser & Spencer, 1995). Veale et al. (2000) examined epifaunal assemblages in the North Irish Sea in areas subject to different intensities of scallop dredging. Areas subject to high fishing effort were correlated with decreased species richness and diversity. In addition, Aphrodita aculeata was not found in areas subject to high fishing effort but present in relatively high abundance in areas subject to medium or low fishing effort (Veale et al., 2000; Figure 3).
Therefore, a proportion of the population is likely to be removed and/or displaced by fishing or shellfishing activities and suggests an intolerance of intermediate. Based on the single event, experimental evidence above, recoverability is likely to be high. However, the evidence present by Veale et al. (2000) suggests that Aphrodita aculeata would be highly intolerant of, or not recover from, continuous or prolonged frequent trawling activity.