Biodiversity & Conservation

LS.LGS.S.BarSnd

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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The biotopes represented by this key information review are characterized primarily by the type of substratum present. In the event that all of the substratum occupied by the biotope under consideration was removed, the biotope would no longer be identified and therefore intolerance has been assessed to be high. The amphipod and isopod species that may occur in the biotope would also be removed along with the substratum, so species richness would decline. The biotope is likely to recover from substratum removal. For instance, at Village Bay on St Kilda, an island group far out into the Atlantic west of Britain, an expanse of sandy beach was removed offshore as a result of winter storms to reveal an underlying rocky shore (Scott, 1960). Yet in the following summer the beach was gradually replaced when wave action was less severe. Eurydice pulchra was a species reported to be a frequent member of the re-colonizing fauna, its recovery being aided by the ability to survive in the shallow sublittoral zone where substrata may be deposited. In view of such observations, that many sandy beaches disappear in winter and reappear in spring, it is likely that recovery would occur in less than a year or six months. Therefore recoverability has been assessed to be very high assuming that sand remains available to be deposited.
Land claim could impact upon this biotope. In the event that the biotope was covered/claimed by construction it would not recover.
Smothering
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Smothering by a sediment that is atypical for the biotope would alter the composition of the surface substratum but owing to the hydrodynamic regime and mobility of the substrata, atypical materials are likely to be readily dispersed and the biotope remain unaffected. Also species present could probably escape readily. Therefore the biotope has been assessed to be not sensitive. A higher intolerance would be expected for viscous material such as oil. Oil penetrating coarse sands would destabilise the sediment and produce an oxygen demand where oxygen is available but degradation at depth would be minimal where aeration does not occur (Elliott et al., 1998).
Increase in suspended sediment
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Increased suspended sediment (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Decrease in suspended sediment
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Decreased suspended sediment (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Desiccation
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Desiccation (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Increase in emergence regime
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An increase in the emergence period of this biotope would make it even more inhospitable to marine invertebrates. Where the biotope occurs in the supralittoral zone, a reduction in saline spray and splash may favour the colonization of terrestrial plants, which if able fully to establish over the period of one year will have a stabilising effect on the substratum. Consequently, this factor has the potential to alter the LGS.BarSnd biotope so that its starts to become another biotope. The LGS.BarSnd biotope would not be recognized and intolerance has therefore been assessed to be high. On return to the prior emergence regime plants that may colonized the substratum and which are intolerant to saline splash and spray will probably decline. Therefore recoverability has been assessed to be high but variable (see additional information below).
Decrease in emergence regime
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An increase in the immersion period of this biotope may favour establishment of a less transient biological community of amphipods, as the increased water content of the substratum (and probable concomitant changes in the water table) would make conditions more hospitable. Consequently, this factor has the potential to alter the LGS.BarSnd biotope so that its starts to become another (but probably closely related) biotope. The LGS.BarSnd biotope would not be recognized and intolerance has therefore been assessed to be high. On return to prior conditions the abundance of amphipod species would probably decline and the biotope be easily identified as the barren sand biotope. Recovery has been assessed to be very high but variable (see additional information below).
Increase in water flow rate
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The nature of the substratum is, in part, determined by the hydrodynamic regime including water flow rate. However, the major hydrodynamic force is wave action and tidal flow will have a lesser effect. An increase in water flow rate may contribute to the redistribution or reduction of the coarse sandy substratum and, as a consequence, the biotope may not be recognized in a location where it was previously recorded. Therefore intolerance has been assessed to be high. The substratum is likely to be deposited on return to prior conditions, so intolerance has been assessed to be very high (see additional information below).
Decrease in water flow rate
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The nature of the substratum is, in part, determined by the hydrodynamic regime including water flow rate. A decrease in water flow rate is likely to effect the composition of the substratum by allowing deposition of finer grade material and stability would increase. The biotope would become more hospitable for colonization. Consequently, this factor has the potential to alter the LGS.BarSnd biotope so that its starts to become another (but probably closely related) biotope. The LGS.BarSnd biotope would not be recognized and intolerance has therefore been assessed to be high. On return to prior conditions the abundance of amphipod species would probably decline and the biotope be easily identified as the barren sand biotope. Recovery has been assessed to be very high (see additional information below).
Increase in temperature
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Increased temperature (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Decrease in temperature
(View Benchmark)
Decreased temperature (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Increase in turbidity
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Increased turbidity (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. Macroalgae are absent and the substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Decrease in turbidity
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Decreased turbidity (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. Macroalgae are absent and the substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Increase in wave exposure
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The LGS.BarSnd biotope typically occurs in moderately exposed to exposed locations. An increase in exposure at the benchmark level would subject the biotope to extreme wave exposure for a period of one year. Such wave action is likely to have a destructive effect on the biotope causing loss and redeposition of substrate. Consequently, the biotope may not be recognized in a location where it was previously recorded. Therefore intolerance has been assessed to be high. The substratum is likely to be deposited on return to prior conditions and recolonization by immigration is likely to be rapid, so intolerance has been assessed to be very high (see additional information below).
Decrease in wave exposure
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The LGS.BarSnd biotope typically occurs in moderately exposed to exposed locations. A decrease in exposure at the benchmark level would change conditions to sheltered for a period of one year. The substratum would become less mobile and sorting of the particles may become less defined causing concomitant changes in the drainage of the beach. Alterations of the shore gradient would also be expected. Increased water content of the substratum and decreased mobility would make the biotope more hospitable for colonization hence species richness may rise. Consequently, this factor has the potential to alter the LGS.BarSnd biotope so that its starts to become another (but probably closely related) biotope. The LGS.BarSnd biotope would not be recognized and intolerance has therefore been assessed to be high. On return to prior conditions the abundance of amphipod species would probably decline and the biotope be easily identified as the barren sand biotope. Recovery has been assessed to be very high (see additional information below).
Noise
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Noise (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Visual Presence
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Visual presence (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Abrasion & physical disturbance
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Barren coarse sand shores are naturally dynamic habitats subject to considerable physical disturbance due to wave action. The resident species and probably adapted to the conditions found in mobile sediments, and adapted to physical disturbance. The highly mobile species present in this biotope may only be found in extremely low abundance and are not specifically dependent on this biotope. Therefore, an overall biotope intolerance of low has been recorded with a very high recoverability.
Displacement
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Displacement (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope. These species are highly mobile and capable of rapid reburying if displaced.

Chemical Factors

Synthetic compound contamination
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Synthetic compound contamination (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Heavy metal contamination
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Heavy metal contamination (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Hydrocarbon contamination
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The effects that oil may have upon sediment stability have been considered under smothering (above). This factor (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Radionuclide contamination
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Radionuclide contamination (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Changes in nutrient levels
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Nutrient enrichment (as described in the benchmark) was not considered relevant to the intolerance assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Increase in salinity
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Increased salinity (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Decrease in salinity
(View Benchmark)
Decreased salinity (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Changes in oxygenation
(View Benchmark)
Oxygenation (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.

Biological Factors

Introduction of microbial pathogens/parasites
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Introduction of microbial pathogens or parasites (as described in the benchmark) was not considered relevant to the sensitivity assessment of this biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.
Introduction of non-native species
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No non-native species currently resident in the British Isles are likely to colonize the biotope and change its character.
Extraction
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Species that may be recorded within this biotope are not targeted for extraction, therefore the factor was not considered relevant to the sensitivity assessment of the biotope. The substratum type has been used to assess intolerance rather than the highly mobile species which may only be found in this biotope in extremely low abundance and are not specifically dependent on this biotope.

Additional information icon Additional information

Assessment of intolerance
It should be reiterated that the LGS.BarSnd and LGS.BarSh biotopes are primarily identified by the type of the substratum rather than the biological community, which may be absent, or if present, occur in extremely low abundance. This is because the biotopes are found on open wave exposed coasts and the continual mobility of the substratum inhibits the development of a permanent community. The mobile species that may be found in the LGS.BarSnd biotope occur throughout the littoral zone and are not dependent on this biotope. Therefore the substratum type has been used to indicate the intolerance of this biotope and no species indicative of intolerance were chosen. If amphipod or isopod crustaceans are found in any greater abundance, especially in the eulittoral zone, identification of the barren sand biotope should be reconsidered and it may be likely that reference to the £LGS.AEur£ (burrowing amphipods and Eurydice pulchra in well-drained clean sand shores) biotope intolerance assessment may be more appropriate.

Recoverability
Recovery of this biotope is wholly dependent on the physical processes of the hydrodynamic regime which are location specific, but owing to the dynamic nature of the habitat recovery would be expected. For instance, at Village Bay on St Kilda, an island group far out into the Atlantic west of Britain, an expanse of sandy beach was removed offshore as a result of winter storms to reveal an underlying rocky shore (Scott, 1960). In the following summer the beach was gradually replaced when wave action was less severe. Eurydice pulchra was a species reported to be a frequent member of the re-colonizing fauna, its recovery being aided by the ability to survive in the shallow sublittoral zone where substrata may be deposited. In view of such observations, that many sandy beaches disappear in winter and reappear in spring, it is likely that recovery would occur in less than a year or six months. Therefore recoverability has been assessed to be very high assuming that sand remains available to be redeposited.

This review can be cited as follows:

Budd, G.C. 2004. Barren coarse sand shores. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 19/04/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=16&code=1997>