Biodiversity & Conservation

SS.SSa.IFiSa.TbAmPo

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Removal of the substratum would remove the entire benthic population and the tubes of the tube building species. A portion of the amphipod population would probably be able to escape the substratum loss through swimming but the majority of other species in the biotope would be lost and there would be a major decline in species richness. Recoverability is recorded as high (see additional information below).
Smothering
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Smothering with 5 cm of sediment would cover amphipod tubes and prevent suspension feeding. Some mortality of the population is likely. The tubes of polychaetes, including Polydora ciliata, would also be covered and the population would have to build new tubes at the new sediment surface, with some energetic cost. The infaunal burrowing polychaetes would probably be able to relocate to their preferred depth and hence are unlikely to be intolerant. Based on the intolerance of the amphipods, the biotope intolerance is assessed as intermediate but there is unlikely to be a decline in species richness. Recoverability is recorded as high (see additional information below).
Increase in suspended sediment
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Amphipods are tolerant of high turbidity and gather suspended sediment for the construction of tubes. Mills (1967) reported that feeding by Ampelisca vadorum and Ampelisca abdita was initiated by the turbidity of the water surrounding the tubes. However, the feeding structures of suspension feeders such as Ampelisca sp. and Haploops tubicola may become clogged by large increases in suspended sediment or feeding may be terminated, compromising growth. Intolerance is therefore assessed as low. Growth would quickly return to normal when suspended sediment returns to original levels so recoverability is recorded as very high.
Tube building polychaetes are not likely to be intolerant of high turbidity as they normally inhabit waters with high levels of suspended sediment which they actively fix in the process of tube making. For example, in the Firth of Forth, Polydora ciliata formed extensive mats in areas that had an average of 68 mg/l suspended solids and a maximum of approximately 680 mg/l indicating the species is able to tolerate different levels of suspended solids (Read et al., 1982; Read et al., 1983).
Decrease in suspended sediment
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Deposit feeders and tube builders rely on siltation of suspended sediment. A decrease in suspended sediment will reduce this supply and therefore may compromise growth and reproduction. The benchmark change only lasts for a month and so mortality is unlikely. Intolerance is therefore assessed as low. Growth would quickly return to normal when suspended sediment returns to original levels so recoverability is recorded as very high.
Desiccation
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The biotope occurs below 5 m depth and therefore desiccation is never likely to be a relevant factor.
Increase in emergence regime
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The biotope occurs below 5 m depth and therefore change in emergence regime is never likely to be a relevant factor.
Decrease in emergence regime
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The biotope occurs below 5 m depth and therefore change in emergence regime is never likely to be a relevant factor.
Increase in water flow rate
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The biotope occurs in areas of 'weak' tidal streams (Connor et al., 1997a) and is therefore likely to be intolerant of increases in water flow to some degree. An increase in water flow of 2 categories would place the biotope in areas of 'strong' flow. The increase would change the sediment characteristics in which the biotope occurs, primarily by re-suspending and preventing deposition of finer particles (Hiscock, 1983). The underlying sediment in the biotope has a high silt content; a substratum which would not occur in very strong tidal streams. There would be a decrease in tube building material and the lack of deposition of particulate matter at the sediment surface would reduce food availability for the deposit feeders in the biotope. The resultant energetic cost over one year would be likely to result in some mortality of tube builders and infauna. A biotope intolerance of intermediate is therefore recorded and species richness is expected to decline. Recoverability is assessed as high (see additional information below).
Decrease in water flow rate
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The biotope occurs in areas of 'weak' tidal streams (Connor et al., 1997a), the characterizing species are adapted to low flow conditions and hence the biotope is unlikely to be intolerant of a further reduction in water flow.
Increase in temperature
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Murina (1997) categorised Polydora ciliata as a eurythermal species because of its ability to spawn in temperatures ranging from 10.6-19.9°C. This is consistent with a wide global distribution. Amphipods, however, are reported to have low tolerance to temperature changes (Bousfield, 1973) although lethal limits are not given. Biotope intolerance is therefore recorded as intermediate and recoverability as high (see additional information below). Some amphipod species may be lost with a consequent minor decline in species richness. The infauna in the biotope are likely to be insulated from extreme changes of temperature.
Decrease in temperature
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Murina (1997) categorised Polydora ciliata as a eurythermal species because of its ability to spawn in temperatures ranging from 10.6-19.9°C. This is consistent with a wide global distribution. The species survived a drop in temperature from 11.5 to 7.5°C over the course of 15 hours (Gulliksen, 1977) and so it appears the species is tolerant of acute temperature decreases. During the extremely cold winter of 1962/63 when temperatures dropped below freezing point for several weeks, Polydora ciliata was apparently unaffected (Crisp (ed.), 1964). Amphipods, however, are reported to have low tolerance to temperature changes (Bousfield, 1973) although lethal limits are not given. Mills (1967) reported that gonadal growth of Ampelisca vadorum and Ampelisca abdita is retarded by low temperatures, thus delaying maturity, and feeding rate was reduced below 10°C. Biotope intolerance is therefore recorded as intermediate and recoverability as high (see additional information below). Some amphipod species may be lost with a consequent minor decline in species richness. The infauna in the biotope are likely to be insulated from extreme changes of temperature.
Increase in turbidity
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The biotope occurs in relatively turbid waters and therefore the species in the biotope are likely to be well adapted to turbid conditions. An increase in turbidity may affect primary production in the water column and therefore reduce the availability of diatom food, both for suspension feeders and deposit feeders. In addition, primary production by the microphytobenthos on the sediment surface may be reduced, further decreasing food availability for deposit feeders. However, primary production is probably not a major source of nutrient input into the system and, furthermore, phytoplankton will also immigrate from distant areas so the effect may be decreased. As the benchmark turbidity increase only persists for a year, decreased food availability would probably only affect growth and fecundity of the intolerant species so a biotope intolerance of low is recorded. As soon as light levels return to normal, primary production will increase and hence recoverability is recorded as very high.
Decrease in turbidity
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A decrease in turbidity will mean more light is available for photosynthesis by phytoplankton in the water column and microphytobenthos on the sediment surface. This would increase the primary production in the biotope and may mean greater food availability for deposit feeders and suspension feeders. However, primary production is probably not a major source of production in the biotope so the turbidity decrease is not likely to have a significant effect.
Increase in wave exposure
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The biotope occurs in 'sheltered' and 'very sheltered' areas (Connor et al., 1997a). This suggests that the biotope would be intolerant of wave exposure to some degree. An increase in wave exposure by two categories for one year would be likely to affect the biotope in several ways. Fine sediments would be eroded (Hiscock, 1983) resulting in the likely reduction of the habitat of the infaunal species, a decreased supply of tube building material and a decrease in food availability for deposit feeders. Furthermore, strong wave action is likely to cause damage or withdrawal of delicate feeding and respiration structures of species within the biotope resulting in loss of feeding opportunities and compromised growth. Mills (1967) reported that Ampelisca flats in Barnstable, USA, were damaged noticeably by winter storms. It is likely that high mortality would result and therefore an intolerance of high is recorded and species richness is expected to decline. Recoverability is recorded as high (see additional information below).
Decrease in wave exposure
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The biotope occurs in 'sheltered' and 'very sheltered' areas (Connor et al., 1997a). A decrease in wave exposure by 2 categories for a year would place a portion of the biotope in 'ultra sheltered' areas. The characterizing species are adapted to low flow conditions and are unlikely to be intolerant of this change. The consequent increased risk of smothering is detailed in the relevant section.
Noise
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There is no evidence to suggest that any of the species which characterize the biotope are sensitive to noise or vibration at the level of the benchmark.
Visual Presence
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Polydora ciliata responds to visual disturbance by withdrawing its palps into its burrow, believed to be a defence against predation. Since the withdrawal of the palps interrupts feeding and possibly respiration the species also shows habituation of the response (Kinne, 1970). Growth may be compromised by the interruption of feeding and so intolerance is assessed as low. Growth should quickly return to normal when the disturbance is over so recoverability is recorded as very high.
Abrasion & physical disturbance
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Many species in the biotope are vulnerable to physical abrasion. The tubes of the polychaetes and amphipods are bound only with mucous and are therefore likely to damaged or removed by the benchmark level of abrasion (a scallop dredge). The soft bodied polychaetes are most likely to suffer mortality, while the more robust amphipods are likely to be more resistant, and mobile enough to avoid impact. The infaunal annelids are predominantly soft bodied, live within a few centimetres of the sediment surface and may expose feeding or respiration structures where they could easily be damaged by a physical disturbance such as a dredge. Biotope intolerance is therefore recorded as intermediate. Recoverability is recorded as high (see additional information below).
Displacement
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Polydora ciliata is capable of tube building throughout its life and so is able to re-establish itself following displacement. In experimental removal of Polydora ciliata, individuals of all ages which were removed from their tubes all built new tubes (Daro & Polk, 1973). Similarly, amphipods are mobile animals which would be able to build new tubes or burrows following displacement. Time and energy would have to diverted to the tube building process at the expense of growth and reproduction so intolerance is assessed as low. Following displacement, the growth would quickly return to normal so recoverability is assessed as very high.

Chemical Factors

Synthetic compound contamination
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The tube building polychaetes appear to be not sensitive to synthetic chemicals. For example, spionid polychaetes were found by McLusky (1982) to be relatively tolerant of distilling and petrochemical industrial waste in Scotland and Polydora ciliata was abundant at polluted sites close to acidified, halogenated effluent discharge from a bromide-extraction plant in Amlwch, Anglesey (Hoare & Hiscock, 1974). However, gammaridean amphipods have been reported to be intolerant of tri-butyl tin (TBT), a previously common component of antifouling paints, with 10 day LC50 values of 1-48 ng/l (Meador et al., 1993). Biotope intolerance is therefore assessed as high. Recoverability is recorded as high (see additional information below) but is likely to depend on the length of time that synthetic chemicals persist in the sediment. Beaumont et al. (1989) concluded that TBT had a detrimental effect on the larval and/or juvenile stages of infaunal polychaetes and Arenicola marina was found to be intolerant of ivermectin through the ingestion of contaminated sediment (Thain et al., 1998; cited in Collier & Pinn, 1998). Beaumont et al. (1989) also concluded that bivalves are particularly intolerant of TBT. It is expected therefore that there would be a decline in species richness following exposure to synthetic chemicals.
Heavy metal contamination
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Experimental studies with various species suggests that polychaete worms are quite tolerant of heavy metals (Bryan, 1984). Crustaceans are generally regarded to be intolerant of cadmium (McLusky et al., 1986). In laboratory investigations, Hong & Reish (1987) observed 96 hour LC50 water column concentrations of between 0.19 and 1.83 mg/l for several species of amphipod. Biotope intolerance is therefore assessed as intermediate and, since heavy metals are likely to persist in sediments, recoverability as moderate (see additional information below). Bivalves are also intolerant of heavy metal contamination (e.g. Eisler, 1977; Kaschl & Carballeira, 1999) so species richness in the biotope would be expected to decline.
Hydrocarbon contamination
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Amphipods in general, and ampeliscid amphipods in particular seem particularly intolerant of contamination with oil. Dauvin (1998) reported the effects of the Amoco Cadiz oil spill on the fine sand Abra alba community in the Bay of Morlaix. Reductions in abundance, biomass and production of the community were very evident through the disappearance of the dominant populations of the amphipods Ampelisca sp. The spill occurred in 1978 and after 2 weeks, the level of hydrocarbons in subtidal sediments reached 200 ppm (Dauvin, 1984; cited in Poggiale & Dauvin, 2001). This caused the disappearance of the Ampelisca populations, leaving behind a single species, Ampelisca sarsi, in very low densities. The sediment rapidly depolluted and in 1981 benthic recruitment occurred in normal conditions (Dauvin, 1998). However, the recovery of the Ampelisca populations took up to 15 years. Intolerance is therefore recorded as high with a decline in species richness. In view of the recovery of the amphipod populations, recoverability is assessed as low.
Radionuclide contamination
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No evidence was found concerning the intolerance of the characterizing species to radionuclide contamination.
Changes in nutrient levels
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Polydora ciliata is often found in environments subject to high levels of nutrients (Sordino et al., 1989). For example, the species was abundant in areas of the Firth of Forth exposed to high levels of sewage pollution (Smyth, 1968) and, in an organically polluted fjord receiving effluent discharge from Oslo, Polydora ciliata settled in large numbers within the first month (Green, 1983, Pardal et al., 1993). Similarly, amphipods appear to be tolerant of, and indeed prefer, high nutrient levels. Haploops tubicola muds, for example, are indicative of organically enriched sediments (Le Bris & Glemarec, 1995). The biotope is therefore assessed as not sensitive.
Increase in salinity
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The biotope occurs in full salinity conditions and is therefore not likely to be subject to increases in salinity. No information was found concerning the reaction of the characterizing species to hypersaline conditions.
Decrease in salinity
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Polydora ciliata is a euryhaline species inhabiting fully marine and estuarine habitats. In an area of the western Baltic Sea, where bottom salinity was between 11.1 and 15.0 psu Polydora ciliata was the second most abundant species with over 1000 individuals per m² (Gulliksen, 1977). Of the amphipod species, Corophium has a very high tolerance of low salinity (Fish & Fish, 1996) but this might only be true of the species with estuarine distributions. It is likely that the marine species would be intolerant of salinity decreases in some way and so biotope intolerance is assessed as low. Some species in the biotope are highly intolerant of reduced salinity. For example, Arenicola marina is unable to tolerate salinities below 24 psu and is excluded from areas influenced by freshwater runoff or input (e.g. the head end of estuaries) (Hayward, 1994). There is therefore likely to be a minor decline in species richness in the biotope.
Changes in oxygenation
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Amphipods appear not to be tolerant of reduced oxygenation. Ampelisca agassizi, for example, is reported to be intolerant of hypoxia (see review by Diaz & Rosenberg, 1995) and Jassa falcata, another tube building amphipod species, was absent from Californian harbours with low oxygen concentrations (0-2.5 mg/l). There is therefore likely to be some mortality of amphipods after a week at the benchmark level of hypoxia. Polydora ciliata is apparently tolerant of hypoxia as the species is repeatedly found at localities with oxygen deficiency (Pearson & Rosenberg, 1978). For example, in polluted harbours in Los Angeles and Long Beach, Polydora ciliata was present in the oxygen range 0.0-3.9 mg/l and the species was abundant in hypoxic fjord habitats (Rosenberg, 1977). In view of the intolerance of amphipods, biotope intolerance is assessed as high and there would be a decline in species richness. Recoverability is recorded as high (see additional information below).

Biological Factors

Introduction of microbial pathogens/parasites
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No information was found concerning the infection of the characterizing species by microbial pathogens.
Introduction of non-native species
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There is no information to suggest that the biotope is threatened by invasion of alien species.
Extraction
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It is extremely unlikely that any of the species indicative of sensitivity would be targeted for extraction and we have no evidence for the indirect effects of extraction of other species on this biotope.

Additional information icon Additional information

Recoverability
Amphipods have a short life span, mature quickly and may have multiple generations per year (Mills, 1967; Dauvin & Bellan-Santini, 1990) suggesting that they would have strong powers of recoverability. However, fecundity is generally low, there is no larval stage and the embryos are brooded in a marsupium, beneath the thorax. Dispersal is limited to local movements of the subjuveniles and migration of the adults and hence recruitment is limited by the presence of local, unperturbed source populations (Dauvin, 1998). Poggiale & Dauvin (2001) reported that recovery of an Ampelisca population took up to 15 years, but this was following an oil spill, to which amphipods are particularly intolerant, and it is likely that this is an exceptional situation. It is expected that, in situations where there is no residual population, amphipods would normally recover within 5 years and so recoverability is assessed as high.
The tube building polychaetes, including Polydora ciliata, are moderately fecund, the planktonic larvae are capable of dispersal over long distances and the reproductive period is of several months duration. In colonization experiments in Helgoland, Polydora ciliata settled on panels within one month in the spring (Harms & Anger, 1983). Recovery and establishment of a mature community is likely to occur within 5 years and so recoverability is assessed as high.
Based on the recoverability of the characterizing species, biotope intolerance is assessed as high.

This review can be cited as follows:

Rayment, W.J. 2002. Semi-permanent tube-building amphipods and polychaetes in sublittoral mud or muddy sand. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 02/09/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=136&code=2004>