Biodiversity & Conservation

LS.LBR.Sab.Salv

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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All the key and important species in the biotope exhibit high intolerance to substratum loss. Sabellaria alveolata, the key structural species has moderate recoverability.
Smothering
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Sabellaria alveolata, the key structural species has only low intolerance to smothering. Wilson (1971) reported Sabellaria reefs surviving burial for a few days or even weeks. However, the important structural (Fucus serratus) and functional species (Littorina littorea) are both highly intolerant. Both Sabellaria alveolata and Fucus serratus are likely to recover from smothering within a few years.
Increase in suspended sediment
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The intermediate intolerance of the functional grazing species Littorina littorea means that siltation may indirectly cause increased growth of algae on Sabellaria alveolata reefs, contributing to their more rapid breakdown through water action. Variability in recruitment of Sabellaria alveolata (dependent on suitable environmental conditions) means that recovery could take a few years. The presence of some remaining adult worms will assist in Sabellaria alveolata larval settlement as this is the preferred substratum (Wilson, 1929).
Decrease in suspended sediment
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Desiccation
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The key structural species Sabellaria alveolata is intermediately intolerant of increases in desiccation. Fucus serratus occurs in a fairly specific zone on the lower shore. Increases in desiccation will probably result in high intolerance of this seaweed. Lower densities of algae growing on Sabellaria alveolata reefs may increase the time that the reef remains intact before being broken up through wave action. Loss of the seaweed will have consequential effects such as the loss of other species using the weed as substratum, including Littorina littorea. Sabellaria alveolata, the key structural species has moderate recoverability.
Increase in emergence regime
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The key structural species Sabellaria alveolata is intermediately intolerant of increases in emergence. Fucus serratus occurs in a fairly specific zone on the lower shore. Increases in emergence will probably result in high intolerance of this seaweed. Lower densities of algae growing on Sabellaria alveolata reefs may increase the time that the reef remains intact before being broken up through wave action. Loss of the seaweed will have consequential effects such as the loss of other species using the weed as substratum, including Littorina littorea. Sabellaria alveolata, the key structural species has moderate recoverability.
Decrease in emergence regime
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Increase in water flow rate
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Decreases in water flow rate will result in lower levels of suspended sediment and intermediate intolerance for Sabellaria alveolata but will have no effect on Fucus serratus or Littorina littorea. Increases in water flow may benefit Sabellaria alveolata but be detrimental for the other important species.
Decrease in water flow rate
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Increase in temperature
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Sabellaria alveolata, the key structural species is intermediately intolerant of short term acute decreases in temperature. Variability in recruitment of Sabellaria alveolata (dependent on suitable environmental conditions) means that recovery could take a few years. The presence of some remaining adult worms will assist in Sabellaria alveolata larval settlement as this is the preferred substratum (Wilson 1929).
Decrease in temperature
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Increase in turbidity
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Fucus serratus and Littorina littorea have low intolerance to increases in turbidity. Recoverability and restoration of condition should occur in less than six months.
Decrease in turbidity
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Increase in wave exposure
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Increases in wave exposure cause high intolerance in Fucus serratus and intermediate intolerance in Littorina littorea and Sabellaria alveolata. Variability in recruitment of Sabellaria alveolata (dependent on suitable environmental conditions) means that recovery could take a few years. The presence of some remaining adult worms will assist in Sabellaria alveolata larval settlement as this is the preferred substratum (Wilson, 1929). Recoverability of both the seaweed and the snail is high.
Decrease in wave exposure
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Noise
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None of the selected important or characterizing species in the biotope are recorded as sensitive to noise.
Visual Presence
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None of the selected important or characterizing species in the biotope are recorded as sensitive to visual presence.
Abrasion & physical disturbance
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Cunningham et al. (1984) examined the effects of trampling on Sabellaria alveolata reefs. The reef recovered within 23 days from the effects of trampling, (i.e. treading, walking or stamping on the reef structures) repairing minor damage to the worm tube porches. However, severe damage, estimated by kicking and jumping on the reef structure, resulted in large cracks between the tubes, and removal of sections (ca 15x15x10 cm) of the structure (Cunningham et al., 1984). Subsequent wave action enlarged the holes or cracks. However, after 23 days, at one site, one side of the hole had begun to repair, and tubes had begun to extend into the eroded area. At another site, a smaller section (10x10x10 cm) was lost but after 23 days the space was already smaller due to rapid growth. Cunningham et al. (1984) reported that Sabellaria alveolata reefs were more tolerant of trampling than expected but noted that cracks could leave the reef subsceptible to erosion and lead to large sections of the reef being washed away. However, eroded sections can survive and may lead to colonization of previously unsettled areas. The strange sculpturing of colonies in some areas is probably due to a combination of erosion and recovery (Cunningham et al., 1984).

Continuous trampling may be more detrimental. For example, Holt et al. (1998) reported that, in Brittany, damage to reefs on popular beaches was limited to gaps created by trampling through the reef. Once gaps are formed, they may be enlarged by wave action. The main cause of colony destruction is through wave action. Cunningham et al. (1984) also noted that collection of Sabellaria alveolata, although a rare occurrence, may be particularly damaged as it will involve removal of sections of the reef. Trampling has been reported to reduce fucoid cover (Holt et al., 1997). Similarly, littorinids will be probably displaced and very occasionally crushed by trampling, although at the population level the effects are probably minimal. Therefore, trampling and other physical disturbance can potentially remove a proportion of the reef and an intolerance of intermediate has been recorded. Variability in Sabellaria alveolata recruitment (dependent on suitable environmental conditions) means that recovery could take a several years. The presence of remaining adults will assist in larval settlement, as this is the preferred substratum (Wilson, 1929). Therefore recoverability has been assessed as high.

Displacement
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Sabellaria alveolata, the key structural species of the biotope has high intolerance to and moderate recoverability from displacement.

Chemical Factors

Synthetic compound contamination
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Littorina littorea has low intolerance to Tri-butyl tin. There is insufficient information to make an assessment for the other two selected species. The biotope intolerance and recoverability is therefore represented by the periwinkle.
Heavy metal contamination
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Because there is insufficient information on Sabellaria alveolata (key species) intolerance to heavy metal contamination, biotope intolerance is represented by the intolerance of the important species, Littorina littorea to mercury chloride contamination.
Hydrocarbon contamination
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Because there is insufficient information on Sabellaria alveolata (key species) intolerance to hydrocarbon contamination, biotope intolerance is represented by the intolerance of the important species, Littorina littorea and Fucus serratus. Gastropods have been noted to recover quite quickly (by the next year) from oil spill events such as Amoco Cadiz.
Radionuclide contamination
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There is insufficient information available on all three selected species to be able to make an intolerance assessment for the biotope.
Changes in nutrient levels
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Nutrient availability is a very important factor in regulating Fucus serratus growth. Increases in nutrient levels may favour growth of the seaweed and decreases may limit growth. Following resumption of normal nutrient conditions, the seaweed will probably recover within a few months.
Increase in salinity
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Sabellaria alveolata inhabits fully marine environments and has intermediate intolerance to decreases in salinity. The species must though be able to tolerate some variation in salinity due to exposure to precipitation in the intertidal.
Decrease in salinity
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Changes in oxygenation
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Sabellaria alveolata has intermediate intolerance to decreases in oxygenation. Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. There is no information about Sabellaria alveolata tolerance to increases in oxygenation.

Biological Factors

Introduction of microbial pathogens/parasites
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Insufficient information
Introduction of non-native species
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Insufficient information
Extraction
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Extraction of Sabellaria alveolata by bait digging is a possibility. Fucus serratus and Littorina littorea are also subject to extraction. Bait digging for other species, such as crabs, that live within crevices and cracks of Sabellaria alveolata reefs (as has been noted to occur in Portugal) may cause damage to other species in the biotope. Overall, it is more than likely that individuals of each species will remain and intolerance has been assessed as intermediate. Recovery is likely to be high.

This review can be cited as follows:

Jackson, A. 2005. Sabellaria alveolata reefs on sand-abraded eulittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 01/08/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=351&code=2004>