Biodiversity & Conservation

IR.SIR.K.Lsac.Pk

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Most of the species characteristic of this biotope are permanently attached to the substratum and would be removed upon substratum loss. For recoverability, see Additional Information.
Smothering
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Some species, especially Saccharina latissima, are likely to protrude above smothering material whilst some, such as Lithophyllum incrustans, will most likely survive under smothering material. Mobile species such as urchins and brittle stars will be able to migrate out of most smothering material. Others such as the active suspension feeders and low-growing foliose algae are likely to be killed by smothering. However, since keystone species are likely to survive an intolerance of intermediate has been indicated. For recoverability, see Additional Information.
Increase in suspended sediment
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Increase in suspended sediment is likely to have a significant effect in the low water movement regime in which this biotope lives. Settling silt may smother organisms or clog respiratory and feeding organs (especially sea squirts). However, many of the species in this biotope live in areas of high silt content and be able to survive. For effects on light penetration, see turbidity. For recoverability, see Additional Information.
Decrease in suspended sediment
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Decrease in suspended sediment levels is not likely to have a significant effect on this biotope although suspension and deposit feeders that gain nutrients from silt may be adversely affected. On the other hand, suspension feeders may be less affected by clogging by silt. For effects on light penetration, see turbidity.
Desiccation
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The biotope is predominantly sublittoral but does extend onto the shore and therefore shows some ability to resist desiccation. On a sunny day at low water of spring tides, damage (bleaching) is likely to occur to the Saccharina latissima plants but not destroy them completely. Species living below the kelp fronds will be protected by them from the worst effects of desiccation. There may be a minor loss of species. For recoverability, see Additional Information.
Increase in emergence regime
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The biotope is predominantly sublittoral and the dominant species (Saccharina latissima) and many of the subordinate species, especially solitary sea squirts, are unlikely to survive an increased emergence regime. Several mobile species such as sea urchins, brittle stars and feather stars are likely to move away. However, providing that suitable substrata are present, the biotope is likely to re-establish further down the shore within a similar emergence regime to that which existed previously.
Decrease in emergence regime
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The biotope is sublittoral and so decrease in emergence is not relevant.
Increase in water flow rate
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It is unlikely that species in the biotope will be killed by an increase in flow rate. Existing organisms are likely to persist although conditions will not be ideal. A few mobile species such as brittle stars might be swept away. However, in situations where the substratum on which Saccharina latissima occurs is of cobbles or pebbles, it is likely that kelp plants might cause sufficient drag for plants and attached organisms to be swept away. In that case, a different biotope is likely to develop.
Decrease in water flow rate
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The biotope exists in areas with very little or no tidal flow.
Increase in temperature
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The species characteristic of the biotope are well within the range of temperatures in which they occur geographically and are unlikely to be lost as a result of higher temperatures occurring in the long term. However, exposure to high temperatures for several days may produce stress in some components but recovery would be rapid.
Decrease in temperature
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The species characteristic of the biotope are well within the range of temperatures in which they occur geographically and are unlikely to be lost as a result of lower temperatures occurring in the long term. However, exposure to low temperatures for several days may result in some mortality. Records in Crisp (1964) suggest that the species in the biotope are likely to be of low susceptibility to cold although Psammechinus miliaris was adversely affected by the 1962/63 winter and Antedon bifida is believed to have been lost from the Menai Strait following the 1947 winter (D.J. Crisp pers. comm. to K. Hiscock).
Increase in turbidity
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Several of the characteristic species are algae that rely on light for photosynthesis. Decrease in light penetration as a result of higher turbidity is unlikely to be fatal in the short term but in the long term will result in a reduction in downward extent and therefore overall extent of the biotope.
Decrease in turbidity
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The biotope is characterized especially by algae which are likely to increase in downward extent if light penetration increases.
Increase in wave exposure
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This is a fundamentally sheltered coast biotope with species that do not appear to occur in wave exposed situations. Increased wave action is likely to dislodge Saccharina latissima plants, especially if they are attached to cobbles, dislodge brittle stars and feather stars and interfere with feeding in solitary tunicates.
Decrease in wave exposure
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Some small amount of wave action is most likely required to prevent stagnation occurring in this biotope. Stagnation would most likely result is some localized de-oxygenation. And some species in sheltered pockets would be lost.
Noise
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The macroalgae characterizing the biotope have no known sound or vibration sensors. The response of macroinvertebrates is not known.
Visual Presence
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Macrophytes have no known visual sensors. Most macroinvertebrates have poor or short range perception and are unlikely to be affected by visual disturbance such as shading.
Abrasion & physical disturbance
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Saccharina latissima, other algae and the large solitary tunicates are likely to be especially intolerant of physical disturbance and to be removed from the substratum. Sea urchins, brittlestars, and feather stars are likely to be damaged. However, the main species covering rock, encrusting coralline algae, will survive increased abrasion including if cobbles are moved around. Overall, some keystone species are likely to be lost but some will remain and an intolerance of intermediate is suggested. For recoverability, see additional information below.
Displacement
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Although many of the species in the biotope are sessile and would therefore be killed if removed from their substratum, displacement will often be of the boulders or cobbles on which the community occurs in which case survival will be high. The 'Intermediate' ranking given here supposes that some individuals sessile organisms will be removed and die. Mobile organisms such as the echinoderms in the biotope are likely to survive displacement. Recovery rate assumes that the characteristic species of the biotope will remain, albeit in lower numbers.

Chemical Factors

Synthetic compound contamination
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Several of the species characteristic of the biotope are reported as having high intolerance to synthetic chemicals. For instance, Cole et al. (1999) suggested that herbicides such as Simazine and Atrazine were very toxic to macrophytic algae. Hoare & Hiscock (1974) noted that almost all red algal species and many animal species were absent from Amlwch Bay in North Wales adjacent to an acidified halogenated effluent. Red algae have also been found to be sensitive to oil spill dispersants (O'Brien & Dixon, 1976; Grandy quoted in Holt et al. 1995). Recovery is likely to occur fairly rapidly - see Additional Information.
Heavy metal contamination
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Sporophytes of Saccharina latissima have a low intolerance to heavy metals, but the early life stages are more intolerant. The effects of copper, zinc and mercury on Saccharina latissima (studied as Laminaria saccharina) have been investigated by Thompson & Burrows (1984). They observed that the growth of sporophytes was significantly inhibited at 50 µg Cu /l, 1000 µg Zn/l and 50 µg Hg/l. Zoospores were found to be more intolerant and significant reductions in survival rates were observed at 25 µg Cu/l, 1000 µg Zn/l and 5 µg/l. Little is known about the effects of heavy metals on echinoderms. Bryan (1984) reported that early work had shown that echinoderm larvae were intolerant of heavy metals, e.g. the intolerance of larvae of Paracentrotus lividus to copper (Cu) had been used to develop a water quality assessment. Kinne (1984) reported developmental disturbances in Echinus esculentus exposed to waters containing 25 µg / l of copper (Cu). Sea-urchins, especially the eggs and larvae, are used for toxicity testing and environmental monitoring (reviewed by Dinnel et al. 1988). Taken together with the findings of Gomez & Miguez-Rodriguez (1999) above it is likely that echinoderms are intolerant of heavy metal contamination. Overall, the biotope is may show some minor change following heavy metal contamination at the level of the baseline.
Hydrocarbon contamination
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Red algae have been found to be intolerant of oil and oil spill dispersants (O'Brien & Dixon 1976; Grandy quoted in Holt et al. 1995). Foliose red algae in the biotope may be subject to bleaching and death and, in lower shore/shallow sublittoral situations, encrusting calcareous algae are likely to be bleached and by 'fresh' oil. However, observations following the Sea Empress oil spill (Chamberlain, 1997) suggest that regeneration from below the destroyed area of crustose corallines repairs damage and recovery occurred within a year. Holt et al. (1995) report that Saccharina latissima (studied as Laminaria saccharina) has been seen to show no discernible effects from oil spills. Feather stars and sea urchins have both been observed to be killed by oil or oil and dispersant. For recoverability, see additional information below. Whilst some keystone (grazing) species might be killed, the overall character of the biotope will most likely remain and an intolerance of 'Intermediate' has been indicated.
Radionuclide contamination
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Changes in nutrient levels
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Evidence is equivocal. For Saccharina latissima (studied as Laminaria saccharina), Conolly & Drew (1985) found that plants at the most eutrophic site in a study on the east coast of Scotland where nutrient levels were 25% higher than average exhibited a higher growth rate. However, Read et al. (1983) reported that, after removal of a major sewage pollution in the Firth of Forth, Saccharina latissima (studied as Laminaria saccharina) became abundant where previously it had been absent. Increased nutrients may increase the abundance of ephemeral algae and result in smothering or changing the character of the biotope. Any recovery is likely to be high as species are unlikely to be completely lost: see Additional Information.
Increase in salinity
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The biotope occurs in full salinity conditions and so increase in salinity from variable or low would not adversely affect it.
Decrease in salinity
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The biotope occurs in situations that are naturally subject to fluctuating or low salinities: it grows in areas where freshwater run-off dilutes near-surface waters and most components are likely to survive reduced salinity conditions. For instance, Saccharina latissima (studied as Laminaria saccharina) can survive in salinities of 8 psu although growth is retarded below 16 psu (Kain 1979). Delesseria sanguinea is also tolerant of salinities as low as 11 psu in the North Sea. The brittle star Ophiothrix fragilis occurs in salinities of 16 psu and even down to 10 psu (Wolff 1968) and the feather star Antedon bifida is typically present in situations of high freshwater outflow such as at the entrance to the Tamar (own observations). However, some species in the biotope such as the sea urchin Echinus esculentus are unlikely to survive in lower salinity and may perish. Most characteristic species are likely to survive. Species that are lost are likely to have planktonic larvae and recolonize rapidly.
Changes in oxygenation
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The biotope occurs in areas where still water conditions occur and therefore some hypoxia is likely. However, in severe conditions, death of constituent species is likely. Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. For instance, death of a bloom of the phytoplankton Gyrodinium aureolum in Mounts Bay, Penzance in 1978 produced a layer of brown slime on the sea bottom. This resulted in the death of fish and invertebrates, including Echinus esculentus, a characterizing species, presumably due to anoxia caused by the decay of the dead dinoflagellates (Griffiths et al. 1979). For recoverability, see Additional Information.

Biological Factors

Introduction of microbial pathogens/parasites
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There is little information on microbial pathogen effects on the characterizing species in this biotope. However, Saccharina latissima may be infected by the microscopic brown alga Streblonema aecidioides. Infected algae show symptoms of Streblonema disease, i.e. alterations of the blade and stipe ranging from dark spots to heavy deformations and completely crippled thalli (Peters & Scaffelke, 1996). Infection can reduce growth rates of host algae.Echinus esculentus is susceptible to 'Bald-sea-urchin disease', which causes lesions, loss of spines, tube feet, pedicellariae, destruction of the upper layer of skeletal tissue and death. It is thought to be caused by the bacteria Vibrio anguillarum and Aeromonas salmonicida. Bald sea-urchin disease was recorded from Echinus esculentus on the Brittany Coast. Although associated with mass mortalities of Strongylocentrotus franciscanus in California and Paracentrotus lividus in the French Mediterranean it is not known if the disease induces mass mortality (Bower 1996). However, no evidence of mass mortalities of Echinus esculentus associated with disease have been recorded in Britain and Ireland. It is likely that microbial pathogens will have only a minor possible impact on this biotope.
Introduction of non-native species
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This assessment of intolerance relates to known non-native species in October 2001. Although non-native species may colonize the biotope they are unlikely to significantly displace or affect native species.
Extraction
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Extraction of Saccharina latissima may occur but the plant rapidly colonizes cleared areas of the substratum: Kain (1975) recorded that Saccharina latissima (studied as Laminaria saccharina) was abundant six months after the substratum was cleared so recovery should be rapid. Associated species are unlikely to be affected by removal of Saccharina latissima unless protection from desiccation on the lower shore is important. Echinus esculentus may also be collected. The collection of Echinus esculentus for the curio trade was studied by Nichols (1984). He concluded that the majority of divers collected only large specimens that are seen quickly and often missed individuals covered by seaweed or under rocks, especially if small. As a result, a significant proportion of the population remains.

An intermediate intolerance has been suggested to reflect the possibility that either of these two species may experience some loss. Given the majority of each is likely to remain however, recovery has been assessed as high.

Additional information icon Additional information

Recoverability
SIR.Lsac.Pk is likely to be naturally disturbed and damaged during storms where the substratum is of mobile cobbles. None of the species present are likely to be long-lived or slow growing and recolonization will be fairly rapid. The main characterizing species, Saccharina latissima, rapidly colonizes cleared areas of the substratum and Kain (1975) recorded that Saccharina latissima (studied as Laminaria saccharina) was abundant six months after the substratum was cleared so recovery should be rapid. However, the main group covering rock, encrusting coralline algae represented by Lithophyllum incrustanswhich grows at a rate of <7mm a year (Irvine & Chamberlain, 1994) will take much longer to cover rocks. Most other characterizing species have a planktonic larva and/or are mobile and so can migrate into the affected area. Development of a balance between grazing species and algae may be of critical importance to recovery. Because some species might not have recovered full abundance within five years and there are likely still to be changes in the algae-grazers balance after five years, recoverability is likely to be only moderate after catastrophic loss but high if only a portion of the biotope is lost.

This review can be cited as follows:

Hiscock, K. 2001. Laminaria saccharina park on very sheltered lower infralittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 23/08/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=357&code=1997>