Biodiversity & Conservation

COS.COS.AmpPar

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Most species are infaunal or epifaunal and will be lost if the substratum is removed so the overall intolerance of the biotope is high. Although there are many mobile species in the biotope that may be able to escape, most, such as Amphiura sp. brittlestars and small spider crabs, are not very fast moving and so are also likely to be removed. See additional information for recovery.
Smothering
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Smothering by 5 cm of sediment is likely to lead to the death of some of the organisms in the biotope. The populations of tube dwelling polychaete Ampharete falcata will probably be unable to feed or respire and will die. Some individuals may be able rise through the sediment but survival is probably dependent on the speed at which new tubes can be built. Some of the burrowing fauna, such as the Amphiura spp. brittlestars and Nephrops norvegicus and the small bivalve Parvicardium ovale, will not be affected by smothering beyond re-establishing burrow openings or moving up through the sediment. Therefore, the overall impact of the factor on the biotope is likely to be the loss of the key polychaete species and so intolerance is reported to be high.
Increase in suspended sediment
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Many species in the biotope are either infaunal or deposit feeders that are not expected to be intolerant of an increase in suspended sediment at the level of the benchmark. Some species may benefit from increased food supply if suspended sediment has a high organic content. There may be additional cleaning costs for suspension feeders but this will not affect survival of animals. Intolerance of the biotope is therefore reported to be low. Recovery is likely to be very rapid as affected animals clean away sediment particles.
Decrease in suspended sediment
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Many species in the biotope are either infaunal or deposit feeders that are not expected to be intolerant of a decrease in suspended sediment at the benchmark level for a month. Food availability for some suspension feeding species may decline but this will not affect survival of animals. Intolerance of the biotope is therefore reported to be low.
Desiccation
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The biotope is an offshore community so changes in desiccation are not relevant.
Increase in emergence regime
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The biotope is an offshore community so an increase in emergence is not relevant.
Decrease in emergence regime
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The biotope is an offshore community so a decrease in emergence is not relevant.
Increase in water flow rate
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The biotope habitat is fine sediment that only develops in areas of weak tidal streams. A long term increase in water flow rate is likely to affect the nature of the substratum as fine particles are washed away and a coarser sediment type remains. The species in the biotope may disappear as the substratum becomes unsuitable for tube building and burrowing. Intolerance of the biotope is reported to be high because most species are not expected to be able to survive a long term increase in water flow rates. Recovery could take a long time and is set to moderate - see additional information below for rationale.
Decrease in water flow rate
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The biotope occurs in weak tidal streams. A decrease may reduce the supply of particles to the suspension feeders and tube builders in the biotope. However, effects are only expected to be sub-lethal so intolerance is reported to be low. Normal feeding and tube building will resume on return to normal conditions.
Increase in temperature
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There is no information on the response of the biotope to an increase in temperature. The biotope is found in relatively deep sublittoral habitats where the temperature may fluctuate by a maximum of about 10°C over the period of a year because of seasonal changes. Species are widely distributed in the north east Atlantic. Therefore, the biotope is likely to be able to tolerate a long term increase in temperature. However, some species may be more intolerant of a short term increase of 5°C. Intolerance to an increase in temperature is expected to be low but confidence in this assessment is low.
Decrease in temperature
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There is no information on the response of the biotope to a decrease in temperature. The biotope is found in relatively deep sublittoral habitats where the temperature may fluctuate by a maximum of about 10°C over the period of a year because of seasonal changes. Species are widely distributed in the north east Atlantic. Therefore, the biotope is likely to be able to tolerate a long term decrease in temperature. However, some species may be more intolerant of a short term decrease of 5°C. Intolerance is expected to be low but confidence in this assessment is low.
Increase in turbidity
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An increase in turbidity, reducing light availability may reduce primary production by phytoplankton in the water column. However, productivity in the COS.AmpPar biotope is secondary (detritus) and is not likely to be significantly affected by changes in turbidity and so intolerance is assessed as low. On return to normal turbidity levels recovery will be high as food availability returns to normal.
Decrease in turbidity
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A decrease in turbidity, increasing light availability may increase primary production by phytoplankton in the water column. However, productivity in the COS.AmpPar biotope is secondary (detritus) and is not likely to be significantly affected by changes in turbidity and so intolerance is assessed as low. Nephrops novegicus avoid bright light and exposure to high intensities causes blindness (Loew, 1976) and so a decrease in light attenuation resulting from decreased turbidity may affect the depth at which the species is present or more likely that Nephrops will only feed at night
Increase in wave exposure
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The biotope develops in sheltered areas and the depths at which the biotope is found will be rarely affected by wave disturbance. Thus, the biotope is likely to be highly intolerant of wave disturbance. The substratum is cohesive muddy sand or sandy mud which is likely to be mobilised by wave action removing both animals and the finer element of the substratum. Many of the species have a preference for fine sediments and may not be able to inhabit coarser material. Ampharete tubes form turfs on the surface of the sediment which are likely to be washed away if exposure were to increase by two exposure scales for a year. The small bivalve Parvicardium ovale could also be thrown into suspension by wave action. Loss of either one of the key species will result in the loss of the biotope so intolerance is assessed as high. See additional information for recovery.
Decrease in wave exposure
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The depths at which the biotope are found means that the community is rarely affected by wave disturbance. The substratum is cohesive muddy sand or sandy mud, further evidence that wave exposure is not a factor in this biotope and so a decrease in wave exposure is not relevant.
Noise
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Ampharete falcata, Parvicardium ovale and some of the other species in the biotope may respond to vibrations from predators or excavation by retracting their palps into their tubes. However, most species in the biotope are unlikely to sensitive to noise and so the biotope is assessed as not sensitive.
Visual Presence
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The biotope occurs in deep water where available light is very low. Most species are likely to have no or poor visual perception or are burrowing and so are unlikely to be affected by visual disturbance such as shading. Epifauna such as crabs have well developed visual acuity and are likely to respond to movement in order to avoid predators. However, it is unlikely that the species in the biotope will be affected by visual disturbance at the benchmark level and so a rank of not sensitive is reported.
Abrasion & physical disturbance
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Fauna that inhabit or construct tubes, such as Ampharete falcata are likely to be particularly vulnerable to damage or disturbance by beam trawls (Kaiser & Spencer, 1996). The biotope is also likely to be sensitive to physical disturbance by a passing scallop dredge However, it is not expected to remove the whole population of Ampharete spp. in the biotope and so intolerance is reported to be intermediate. Ramsay et al. (1998) suggest that Amphiura spp. may be less susceptible to beam trawl damage than other species like echinoids or tube dwelling amphipods and polychaetes. See additional information for recovery.
Displacement
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Most species in the biotope are free-living and will be unaffected by displacement to a suitable substratum. However, although Ampharete spp. are probably able to rebuild a tube, the time to do so would probably leave individuals susceptible to predation and so most would not survive. With the loss of the polychaetes the biotope will no longer exist so intolerance is reported to be high. See additional information for recovery.

Chemical Factors

Synthetic compound contamination
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Insufficient information.
Heavy metal contamination
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There is no information on the intolerance of the key species in the biotope. Experimental studies with various species suggests that polychaete worms are quite tolerant of heavy metals (Bryan, 1984). However, there is insufficient information to assess the intolerance of the biotope.
Hydrocarbon contamination
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Insufficient information.
Radionuclide contamination
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Insufficient information.
Changes in nutrient levels
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The biotope is found in areas of fine sediment where organic content will generally be higher than coarse sediments. Parvicardium exiguum and Ampharete grubei are both found in areas rich in silt and organic content (Lastra et al., 1993; Holme, 1949) and so the key species are likely to be similar. An increase in nutrients in subtidal habitats of this depth will not cause the biotope to become overgrown with ephemeral algae so the smothering effects often associated with eutrophication will not occur. Intolerance of the biotope to a 50% increase in nutrients is expected to be low and recovery will be rapid on return to normal conditions.
Increase in salinity
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COS.AmpPar is a subtidal biotope, has not been recorded from hypersaline waters and so is probably intolerant of an increase in salinity and so a rank of high has been reported. See additional information for recovery.
Decrease in salinity
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COS.AmpPar is a subtidal biotope, has not been recorded from estuaries for brackish waters and so is probably intolerant of a decrease in salinity and so a rank of high has been reported. See additional information for recovery.
Changes in oxygenation
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There is no information regarding the effect of deoxygenation on the key species in the biotope or the biotope as a whole. Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. Different species in the biotope will have varying responses to deoxygenation. Rosenberg et al. (1991) suggests that some part of the benthic community, including Amphiura filiformis, can withstand oxygen concentrations of around 1 mg/l for several weeks and Amphiura chiajei is more tolerant of hypoxia (Nilsson, 1999).

Biological Factors

Introduction of microbial pathogens/parasites
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There were no records found of any diseases or parasites affecting the species or the biotope. However, there is always the potential for this to occur in the future.
Introduction of non-native species
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Although several non-native species of polychaete and mollusc have invaded British waters there are none that are likely to affect the COS.AmpPar biotope. However, there is always the potential for this to occur.
Extraction
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It is extremely unlikely that any of the species indicative of sensitivity would be targeted for extraction. Even in areas where Nephrops norvegicus is present, trawlers tend to avoid this type of community because the high densities of Ampharete tubes clog the nets.

Additional information icon Additional information

Recoverability
If the total population of the polychaete Ampharete falcata has been removed, recovery of the biotope will probably be very poor. Populations are often separated by great distances and recruitment from other populations is unlikely because the dispersal potential of larvae is restricted because the larvae are benthic. Thus, if total populations are lost recovery has been recorded as moderate. It is possible that other ampharetid polychaetes such as Melinna critata may replace Ampharete spp. so a functionally similar biotope could develop in a much shorter period. If some adults remain in the biotope after a perturbation, recovery will be more likely and would be recorded as high because local recruitment from benthic larvae can take place to return populations to previous abundance. The other key species in the biotope, Parvicardium ovale, is very widespread and reproduces every year so populations would be more likely to recover from loss. Other species such as the brittlestars are also very widespread and populations should recover within five years.

This review can be cited as follows:

Hill, J.M. 2001. Ampharete falcata turf with Parvicardium ovale on cohesive muddy very fine sand near margins of deep stratified seas. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 20/04/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=75&code=1997>