Biodiversity & Conservation

LS.LCS.Sh.Pec

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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The amphipod Pectenogammarus planicrurus live interstitially in the spaces between coarse sand/gravel particles. It is mobile within the substratum and would removed along with the substratum. Intolerance has been assessed to be high.
In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995)so, assuming that a proportion of the population survived in the locality, recovery might be reasonably expected to occur within a year following a return to prior conditions and good sorting of the beach substratum. A recoverability of very high has been recorded. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely removed recovery may take considerably longer.
Smothering
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Pectenogammarus planicrurus is likely to be highly intolerant of smothering by 5 cm of sediment not consistent with that of the biotope. There is a critical relationship between the size of interstitial spaces in the substratum through which the species can pass and the size of Pectenogammarus planicrurus (Morgan, 1970). In selection experiments, the species demonstrated a clear preference for a sediment grades between 3-6 mm in diameter. Its passage through finer grades of substratum (<3mm) was impaired and mortalities occurred as a consequence of suffocation. Intolerance has been assessed to be high.
Siltation may occur as a consequence of increased suspended sediment in the water column and reduced water movement (tidal and wave action) and is also likely to have a smothering effect on the amphipod.
In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995) so, assuming that a proportion of the population survived in the locality, recovery might be reasonably expected to occur within a year following a return to prior conditions and good sorting of the beach substratum. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are consequently isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely removed recovery may take considerably longer.
Increase in suspended sediment
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Pectenogammarus planicrurus lives in the interstitial spaces within coarse sand/gravel and is unlikely to be directly affected by an increased concentration of suspended matter in the water column. However, the effects of siltation (settling out) of such material has been assessed under smothering (see above).
Decrease in suspended sediment
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Pectenogammarus planicrurus lives in the interstitial spaces within coarse sand/gravel and is unlikely to be directly affected by a decrease in the concentration of suspended matter in the water column. The factor was not considered relevant.
Desiccation
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Pectenogammarus planicrurus lives interstitially in the coarse sand/gravel substratum. Its environmental position would therefore offer considerable protection against desiccation. Furthermore, the species is mobile within the substratum and may burrow deeper should the uppermost layers become too dry. At the benchmark level desiccation was not considered to be relevant.
Increase in emergence regime
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Pectenogammarus planicrurus lives interstitially within the coarse sand/gravel and is probably sufficiently mobile within it to avoid adverse effects of a change in emergence regime. For instance it can burrow deeper to avoid dryer surface layers. At the benchmark level an assessment of not sensitive has been made.
Decrease in emergence regime
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Pectenogammarus planicrurus lives interstitially within the coarse sand/gravel and is probably sufficiently mobile within it to avoid adverse effects of a change in emergence regime. At the benchmark level an assessment of not sensitive has been made.
Increase in water flow rate
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The nature of the substratum that Pectenogammarus planicrurus inhabits is determined by both wave action and water flow, although wave action may be particularly significant in terms of substratum stability. Both factors will influence the degree of sorting of the substratum. The species thrives in well-sorted sediment, with particles of a diameter between 3-6 mm (Morgan, 1970). Increased water flow rate may serve to increase the extent of available habitat by removing finer particulate matter, which is know to inhibit the movement of Pectenogammarus planicrurus and cause mortalities (Morgan, 1970). An assessment of not sensitive* has been made.
Decrease in water flow rate
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Wave action is likely to a more important factor than water flow rate in determining the nature of the substratum that Pectenogammarus planicrurus inhabits. Decreased water flow is unlikely to have any adverse effects on the species and an assessment of not sensitive has been made.
Increase in temperature
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Pectenogammarus planicrurus is found to the south of the British Isles so is likely to be tolerant of a chronic temperature increase of 2°C. No evidence was found concerning the species tolerance to acute temperature increases, however, as the species lives interstitially within the coarse sand/gravel substratum it may be protected to some extent by acute temperature increases at the surface. An intolerance assessment of low has been made as in avoiding higher surface temperatures the feeding efficiency of the species may be impaired (i.e. algal detritus deposited on the surface of the substratum). Recovery is likely to be immediate once surface temperatures decrease.
Decrease in temperature
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Records of Pectenogammarus planicrurus have not been reported to the north of the British Isles. Bell (1995) suggested that the northerly limit to the distribution of Pectenogammarus planicrurus is defined by the lowest temperature at which its life history is possible (see recruitment processes). A chronic decrease of 2°C may therefore affect the viability of the species.
Furthermore, in the intertidal acute decreases in temperature, e.g. during a severe winter, may cause freezing of the species within the substratum. Intolerance has been assessed to be intermediate, as a proportion of the population may be killed.
In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995), so assuming that a proportion of the population survived in the locality recovery might be reasonably expected to occur within a year following a return to prior conditions. A recoverability of very high has been recorded. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely killed recovery may take considerably longer.
Increase in turbidity
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The light attenuating effects of an increase in turbidity are unlikely to directly affect Pectenogammarus planicrurus. However, particles in suspension causing turbidity may have an indirect effect should they settle out. The effects are addressed under suspended sediment. An intolerance assessment was not considered relevant.
Decrease in turbidity
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Pectenogammarus planicrurus is unlikely to be affected by a reduction in turbidity in the water column as it is an interstitial species.
Increase in wave exposure
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Wave exposure is an important physical factor determining the composition of the substratum and its stability. Typically the biotope experiences moderate wave exposure. Increased wave exposure, so that the biotope experienced very wave exposed conditions over a period of a year would probably cause concomitant changes in the nature of the beach substratum. Smaller particles may be eroded or transported off the beach, leaving a much coarser grained substratum.
There is a critical relationship between the size of interstitial spaces in the substratum through which the species can pass and the size of Pectenogammarus planicrurus (Morgan, 1970). In selection experiments, the species demonstrated a clear preference for a sediment grades between 3-6 mm in diameter. Its passage through finer grades of substratum (<3mm) was impaired and mortalities occurred as a consequence of suffocation. Mortalities as a direct result of a much coarser substratum are unlikely, rather the interstitial environment (in terms of desiccation, food retention) may change significantly and the species be exposed to conditions outside of its preference and from which it will move. Intolerance to increased wave exposure has been assessed to be high.
In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995) so, assuming that a proportion of the population survived in the locality, recovery might be reasonably expected to occur within a year following a return to prior conditions and good sorting of the beach substratum. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are consequently isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely removed recovery may take considerably longer.
Decrease in wave exposure
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The amphipod, Pectenogammarus planicrurus is most abundant in well-sorted gravel with a predominant particle size of 4.0 mm but ranging between 3 and 6 mm and wave action is an important factor determining the degree of sorting of the substratum. In the event of decreased wave action the degree of sorting is likely to lessen and finer particulates occur in the substratum. There is a critical relationship between the size of interstitial spaces in the substratum through which the species can pass and the size of Pectenogammarus planicrurus (Morgan, 1970). In selection experiments, the species demonstrated a clear preference for a sediment grades between 3-6 mm in diameter. Its passage through finer grades of substratum (<3mm) was impaired and mortalities occurred as a consequence of suffocation.
It is likely that following a decrease in wave exposure over a year, that the important characterizing species of the biotope, Pectenogammarus planicrurus, would be exposed to conditions outside its habitat preferences and from which it would be excluded and would have to move elsewhere in order to survive. Some mortalities may occur owing to inhibition of movement and smothering. Intolerance has been assessed to be high.
In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995), so assuming that a proportion of the population survived recovery might be reasonably expected to occur within a year following a return to prior conditions and good sorting of the beach substratum. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are consequently isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely removed recovery may take considerably longer.
Noise
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Pectenogammarus planicrurus is unlikely to be able to detect noise at the benchmark level, so an assessment of not sensitive has been made.
Visual Presence
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Pectenogammarus planicrurus lives interstitially and probably lacks the visual acuity to detect movement outside of its visual plane. An assessment of not relevant has been made.
Abrasion & physical disturbance
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The biotope in which Pectenogammarus planicrurus lives is characterized by a high level of physical disturbance attributable to wave action. The important characterizing species is small, lives interstitially and is not of a form that is likely to be damaged by abrasion at the benchmark level. This biotope is characteristic of physically disturbed coarse sands and gravels, so that the habitat and its associated community is likely to be tolerant of physical disturbance and abrasion. Severe physical disturbance, for example due to extreme storms or extraction of the substratum will have the same effect as substratum loss discussed above.
Displacement
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The fauna of this biotope are not physically attached to the substratum and can not therefore be displaced. A sensitivity assessment was not considered relevant.

Chemical Factors

Synthetic compound contamination
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No information concerning synthetic chemical and specific effects on the important characterizing species, Pectenogammarus planicrurus, was found.
However, areas of the intertidal adjacent to industrialised and urbanised estuaries and coastlines may receive effluent discharges which contain a variety of synthetic contaminants. Bioaccumulation of conservative contaminants may occur within the infauna, but in coarse sand/gravel beaches contaminants are unlikely to accumulate owing to a relative absence of organic matter. Direct toxic effects would therefore be expected. In general, crustaceans are widely reported to be intolerant of synthetic chemicals (Cole et al., 1999) and intolerance to some specific chemicals has been observed in amphipods. Powell (1979) inferred from the known susceptibility of Crustacea to synthetic chemicals and other non-lethal effects, that there would probably also be a deleterious effect on isopod fauna as a direct result of chemical application. Toxicity tests conducted by Smith (1968), indicated that survival of Eurydice pulchra after oil detergent treatment was above average for crustaceans. All were killed at about 10 ppm BP 1002 after 24 hours exposure, whilst at 5 ppm four out of five individuals survived when transferred to clean sea water.
Species of a different genus are likely to differ in their susceptibility to synthetic chemicals and that this may be related to differences in their physiology (Powell, 1979). Consequently, in the absence of evidence to the contrary and owing to the diversity of synthetic chemicals to which the biotope may be exposed, intolerance has been assessed to be high. Recovery assumes dilution, biodegradation or removal of the contaminant from the sediments. In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995) so, assuming that a proportion of the population survived in the locality, recovery might be reasonably expected to occur within a year following a return to prior conditions and good sorting of the beach substratum. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely removed recovery may take considerably longer.
Heavy metal contamination
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No information concerning heavy metals and specific effects on Pectenogammarus planicrurus, was found. For most metals, toxicity to crustaceans increases with decreased salinity and elevated temperature, therefore marine species living within their normal salinity range may be less susceptible to heavy metal pollution than those living in salinities near the lower limit of their salinity tolerance (McLusky et al., 1986). Intolerance has been assessed to be intermediate specifically because alterations in salinity and temperature influence the effect of heavy metals on the important characterizing species. The entire population may not be destroyed but may experience sublethal effects which may reduce the viability of the population. Recovery assumes removal of the contaminant from the biotope. In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995) so, assuming that a proportion of the population survived in the locality, recovery might be reasonably expected to occur within a year following a return to prior conditions and good sorting of the beach substratum. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely removed recovery may take considerably longer.
Hydrocarbon contamination
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Pectenogammarus planicrurus is likely to have a high intolerance to hydrocarbon pollution. Oil penetrates deep in to coarse sand/gravel substratum. For example, the largest amount and least weathered oil arising from the Exxon Valdez oil tanker spill in Prince William Sound, Alaska was found eight years after the incident on gravel beaches at a depth between 25 and 50 cm (Hayes & Michel, 1999). Moderate wave exposure and unstable substratum characteristic of the biotope probably aid the penetration of oil in to the sediment. The smothering effect of oil is likely to cause mortality of Pectenogammarus planicrurus in advance of toxic effects. Oil would coat the substratum particles, lessening the interstitial voids through which the amphipod moves and to which it would probably stick. Intolerance has been assessed to be high. Recovery assumes removal of the contaminant from the biotope. In order to survive in the harsh gravel/coarse sand habitat the species has a high reproductive output at the population level (Bell, 1995), so assuming that a proportion of the population survived in the locality recovery might be reasonably expected to occur within a year following a return to prior conditions and good sorting of the beach substratum. However, the reported distribution of Pectenogammarus planicrurus is patchy, as is the occurrence of coarse sand/gravel, and populations are isolated. No information was found concerning the exchange of Pectenogammarus planicrurus between populations. Consequently, if a population was completely removed recovery may take considerably longer.
Radionuclide contamination
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Insufficient information.
Changes in nutrient levels
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Pectenogammarus planicrurus feeds on macroalgae carried in from elsewhere by the tide and deposited on the shore, it is also thought probable that the species is capable of feeding on suspended particles and phytoplankton in the intertidal waters (J.D. Fish & L. Rickard pers. comm. to Bell, 1995). Consequently the species may benefit indirectly from an increase in the dissolved nutrient concentration of the water column, as a food resource, phytoplankton, may increase in abundance as a result. An assessment of not sensitive* has been made.
Increase in salinity
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Pectenogammarus planicrurus lives in the intertidal in conditions of full salinity. In its habitat the species is unlikely to encounter hypersaline water (e.g. as a consequence of evaporation of 'pooled' surface water) as the substratum is very permeable and free draining. An intolerance assessment of not relevant has been made.
Decrease in salinity
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Experimental evidence suggests that Pectenogammarus planicrurus can withstand immersion in water of reduced salinity (20 psu) for 36 hours and freshwater for >18 hours (Morgan, 1970). Thus it is likely that the important characterizing species of the biotope would survive periodic flushing of the sediment with brackish or fresh water. As a mobile species it would also probably move from conditions which it found intolerable, so mortality is unlikely. An assessment of not sensitive has been made.
Changes in oxygenation
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In its intertidal habitat Pectenogammarus planicrurus is inundated by the tide and subject to emergence so, it is presumed that the species can live in both air and water. Within the interstitial environment of clean (low organic matter), coarse sand/gravel oxygen is unlikely to become limiting. The coarseness of the particles, bestows a high permeability, so that water percolates rapidly through and owing to the relative lack of organic matter, little oxygen is utilized for oxidization or respiration by micro-organisms (bacteria populations in sediments with a mean diameter greater than 0.2 mm typically support fewer bacteria (Dale, 1974)). Oxygen depletion tends to be a severe problem at all states of the tide on much finer grained beaches which support larger populations of bacteria (Hayward, 1994). At the benchmark level (a reduced dissolved oxygen concentration of 2 mg/l for 1 week) an assessment of not relevant has been made, primarily because the characteristics of the habitat make conditions of limiting oxygen unlikely and secondly, the important characterizing species, Pectenogammarus planicrurus, is sufficiently mobile to avoid conditions that it finds inhospitable.

Biological Factors

Introduction of microbial pathogens/parasites
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No information was found concerning the effects of microbial pathogens on the species colonizing this biotope.
Introduction of non-native species
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No alien species are know to have adverse effects on the species colonizing this biotope.
Extraction
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It is extremely unlikely that 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

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This review can be cited as follows:

Budd, G.C. 2002. Pectenogammarus planicrurus in mid shore well-sorted gravel or coarse sand. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25/07/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=151&code=2004>