Biodiversity & Conservation

IR.EIR.KFaR.LsacSac

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Species characteristic of this biotope are attached to the substratum and will be lost when the substratum is lost. For recoverability, see additional information below.
Smothering
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Smothering could reduce light availability and therefore lower growth rates of the sporophytes and gametophytes of kelps (for instance Norton, 1978 for Saccorhiza polyschides) and may cause some damage to the growing or mature plant. For instance, the impact of sedimentation on Saccharina latissima (studied as Laminaria saccharina) has been studied by Lyngby & Mortensen (1996). They recorded that deposition of a 1 to 2 mm thick layer of fine-grained material on the plants caused direct physical damage and rotting. 25 percent of the plants died after 4 weeks. On the other hand, Santos (1993) observed that Saccorhiza polyschides were abundant in areas of high siltation. Therefore, the species may tolerate high levels of settled silt. Norton (1978) observed that when spores of Saccorhiza polyschides settled on silt they continued development but failed to form attachments and would be easily washed off. Encrusting coralline algae survive under a layer of silt. Overall, smothering by silt is likely to have an adverse effect on growth and result in some damage to plants including possible mortality. Intolerance is, therefore, assessed as intermediate. Smothering by impermeable materials would have an more severe effect. Condition would recover rapidly and recolonization would be rapid (see additional information below).
Increase in suspended sediment
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There are very few suspension feeders likely to occur in this biotope and so clogging of feeding structures through high levels of suspended sediment is not relevant. Increased levels of suspended sediment are likely to result in deposition of sediment but not at levels likely to cause the effects described under smothering. Also, this biotope occurs in wave exposed conditions where even high levels of suspended sediment may be unable to settle. Effects in diminishing light penetration are addressed under 'Turbidity'. Overall, some effects on photosynthesis might occur and some energy expenditure in the production of mucus to clear deposited sediment but nothing likely to cause loss of species.
Decrease in suspended sediment
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Although suspended sediment is only considered to be of minor importance in this biotope, decrease is likely to improve photosynthesis and reduce energy expenditure in clearing deposited silt.
Desiccation
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intolerance to desiccation is assessed on the basis of the main characterizing species in the biotope. Saccharina latissima can tolerate a small level of desiccation because the species can extend into the lower eulittoral in wave exposed conditions. An increase in the level of desiccation would lead to a depression in the upper limit of the species distribution. Saccorhiza polyschides is intolerant of desiccation. Norton (1970) observed that when adult plants were exposed to air by an extreme low water spring tide on a hot summers day, they rapidly dried out and died. An increase in the level of desiccation would depress the upper limit of the species distribution. Occurrence of encrusting calcareous algae seems to be critically determined by exposure to air and sunlight. Colonies survive in damp conditions under algal canopies or in pools but not on open rock where desiccation effects are important. Canopy removal experiments in the Isle of Man, noted that encrusting corallines died within a week of removal of the protection canopy of Fucus serratus (Hawkins & Harkin, 1985). Removal of the Laminaria digitata canopy lower on the shore resulted in bleaching of encrusting corallines (Hawkins & Hartnoll, 1985) probably due to increased light intensity (see turbidity). Hawkins & Hartnoll (1985) reported extensive damage to encrusting and articulate corallines during the hot summer of 1983 at several sites in the Britain. Sea urchins and other mobile species such as starfish are likely to migrate into deeper water to avoid desiccation. Overall, desiccation is an important factor limiting the distribution of EIR.Lsac.Sac and an intolerance of high has been recorded. For recoverability, see additional information below.
Increase in emergence regime
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Increased emergence will increase the risk of desiccation (see above) and decrease the upper limit of the biotope.
Decrease in emergence regime
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The biotope is predominantly subtidal and may increase in extent to previously intertidal areas.
Increase in water flow rate
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The biotope occurs in situations where the effects of strong wave action most likely overwhelm any effect of tidal flow. Although, therefore, increased water flow rate is unlikely to have a direct effect, in times of calm conditions, silt will be more prevented from settling and possibly causing adverse effects (see suspended sediment).
Decrease in water flow rate
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The biotope occurs in situations where the effects of strong wave action most likely overwhelm any effect of tidal flow. Although, therefore, decreased water flow rate is unlikely to have a direct effect, in times of calm conditions, silt will more likely settle in low tidal flow conditions and possibly cause adverse effects (see suspended sediment). However, silt would take some time to build to harmful levels and effects might mainly be in causing increased expenditure of energy in cleaning fronds. Therefore an intolerance of low has been recorded.
Increase in temperature
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The species that comprise this biotope are in the middle of their geographic range in the UK so the biotope is unlikely to be affected by a change of 2 °C for a year (the benchmark). However, a change of 5 °C may put the species outside its lethal limits damaging plants in particular. For instance, the upper temperature tolerance for gametophytes and young sporophytes of Saccharina latissima is 22 °C. Temperature ecotypes are formed in which the temperature tolerance of the species varies with location depending on the local conditions to which the plant is adapted. Mature sporophytes from the Isle of Man have been found to have an upper temperature tolerance of 17 °C, whereas those from New York can tolerate 20 °C. In the unusually hot summer of 1983, when temperatures were 8.3 °C higher than normal, Saccharina latissima (studied as Laminaria saccharina) showed signs of drought bleaching (Hawkins & Hartnoll, 1985). The southern lethal boundary of Saccorhiza polyschides occurs where temperatures rise above 25 °C for more than a few weeks ( Hoek van den, 1982). Of the animal species likely to be important in the biotope, Bishop (1985) suggested that Echinus esculentus cannot tolerate high temperatures for prolonged periods due to increased respiration rate and resultant metabolic stress. Therefore, Echinus esculentus is likely to exhibit a 'low' intolerance to chronic long term temperature change but would probably be more intolerant of sudden or short term acute change (e.g. 5 C for 3 days) in temperature. Overall, it seems likely that short-term acute rise in temperature during summer may cause some damage to plants and animals in the biotope and possibly kill some although the biotope would not be changed. An intolerance of intermediate is therefore suggested but with a low confidence. Recovery is likely to be very high (see additional information).
Decrease in temperature
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The species that comprise this biotope are in the middle of their geographic range in the UK and, even taking account of short term acute change in temperature, are unlikely to be adversely affected within the benchmarks. For instance, the minimum temperature required for growth and reproduction of Saccorhiza polyschides is 5 °C although the species survives. The 'northern lethal boundary' of the species occurs where the temperature falls below 4 °C for a period of 2 months (Hoek van den, 1982). For Saccharina latissima, its occurrence in the Arctic suggests that it can tolerate -2 degrees C. Encrusting calcareous algae are a common component of arctic communities. For the animals, Echinus esculentus occurred at temperatures between 0 - 18 C in the Limfjord, Denmark (Ursin 1960). Therefore not sensitive is recorded.
Increase in turbidity
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An increase in the level of turbidity would decrease light available for photosynthesis and so reduce growth rates of algae. It may also reduce the depth limit at which the species can grow and therefore reduce the downward extent of the biotope. For short term acute change in turbidity, there would be no noticeable effect but for a long term decrease, the biotope is likely to be reduced in extent and therefore intolerance is assessed as intermediate. On return to normal turbidity levels growth rates would quickly return to normal and settlement of component species would be likely to occur immediately or within a few months (see additional information below).
Decrease in turbidity
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A decrease in the level of turbidity may allow the algae to grow at greater depths suggesting that the biotope might extend to greater depths if the main determining factor, scour, occurs there.
Increase in wave exposure
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The biotope occurs in areas of moderate wave exposure where wave action is sufficiently reduced for part of the year for the dominant component species (Saccharina latissima and Saccorhiza polyschides) to establish and grow. Increased wave exposure is likely to maintain scour conditions more frequently so that the kelps do not establish and grow. Without the kelps, a different biotope will become established and therefore intolerance is recorded as high. Species richness is likely to decline as few species can survive frequent or continuous scour. For recoverability, see additional information.
Decrease in wave exposure
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The biotope occurs in areas of moderate wave exposure where wave action is essential in maintaining the biotope as one of fast growing initial colonizers. A decrease in wave exposure would most likely lead to the growth to maturity of Laminaria hyperborea kelps and of perennial foliose algae so that a different biotope would become established. Intolerance is therefore assessed as high and there is likely to be an increase in the variety of species present as more stable conditions occur. For recoverability, see additional information.
Noise
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Seaweeds and other characteristic species in the biotope have no known mechanism for perception of noise. Species that occur in the biotope or visit it (for instance two-spot gobies Gobiusculus flavescens, cuttlefish Sepia officinalis do but are not critical to the biotope and would return rapidly if disturbed.
Visual Presence
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Seaweeds and other species recorded as characteristic of the biotope have no known mechanism for visual perception. Species that occur in the biotope or visit it (for instance two-spot gobies Gobiusculus flavescens, cuttlefish Sepia officinalis do but are not critical to the biotope and would return rapidly if disturbed.
Abrasion & physical disturbance
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This biotope is created through abrasion and physical disturbance but disruption of the succession and growth of characteristic species may occur by abrasion occurring during months of the year when the substratum is stable or unaffected by wave-induced scour. Kelp plants are likely to be damaged and removed. Littler & Kauker (1984) suggested that crustose algal forms were resistant to predation, sand scour and wave shear. Colonies on rock may be completely removed over part of the area affected but recolonize from parts protected in crevices or unaffected parts. Remaining parts of the crust will expand once the source of abrasion is removed. Spores will settle and new colonies will arise rapidly on bare substratum but growth rate is slow (2-7 mm per annum - see Irvine & Chamberlain, 1994). Physical disturbance will probably result in displacement, loss of spines and some damage to tests of sea urchins. Adults can repair non-lethal damage to the test and spines can be re-grown. However, Bradshaw et al. (2000) suggested that fragile species such as urchins (e.g. Echinus esculentus), suffered badly from impact with a passing scallop dredge. Therefore, Echinus esculentus is probably of intermediate intolerance to abrasion. Overall, some characteristic species may be lost at a time of year when stability might be expected and therefore species in the biotope will be lost although the biotope will remain the same. An intolerance of intermediate, applicable to the time of year when substrata are usually stable, is suggested. For recoverability, see additional information.
Displacement
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The main characterizing species are attached to the rock and would not re-attach if lost. If displacement is of the cobble or boulder with the algae and other species attached, survival is likely to be high. However, for the purpose of intolerance assessment, it is assumed that the algae are detached and will be unable to reattach so intolerance is high. For recoverability, see additional information.

Chemical Factors

Synthetic compound contamination
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Little evidence is available for species characteristic of the biotope. A mixed laboratory detergent quickly stopped Saccharina latissima (studied as Laminaria saccharina) zoospores swimming at 50 mg/l, but settling and development was normal at 10 mg/l (Kain, 1979). Laminaria hyperborea, a related species of kelp, is thought to be fairly robust in terms of chemical pollution (Holt et al., 1995). All of the kelp species contain alginates which seem capable of storing chemicals in inert forms. However, it is likely that the gametophytes and very young sporophytes are more intolerant. Hopkin & Kain (1978) observed that growth of gametophytes and very young sporophytes of Laminaria hyperborea was inhibited at low levels of atrazine, sodium pentachlorophenate and phenol. Overall, it is likely that adverse effects will be limited to reduction of viability and intolerance is therefore low. Once pollutants are removed, the component species should recover rapidly.
Heavy metal contamination
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Some evidence is available on the effects of heavy metals on important species in the biotope. 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. Whilst no studies have been found describing effects on Saccorhiza polyschides, Laminaria hyperborea, a related species of kelp, is thought to be fairly robust in terms of chemical pollution (Holt et al., 1995). Both species contain alginates which seem capable of storing metals in inert forms. However, it is likely that the gametophytes and very young sporophytes are more intolerant. Hopkin & Kain (1978) observed that growth of gametophytes and very young sporophytes of Laminaria hyperborea was inhibited at low levels of mercury, cadmium, copper and zinc. For Echinus esculentus, Kinne (1984) reported developmental disturbances when exposed to waters containing 25 g / l of copper (Cu). Echinus esculentus populations in the vicinity of an oil terminal in La Coruna Bay, Spain, showed developmental abnormalities in the skeleton. The tissues contained high levels of aliphatic hydrocarbons, naphthalenes, pesticides and heavy metals (Zn, Hg, Cd, Pb, and Cu) (Gomez & Miguez-Rodriguez, 1999). However, the observed effects may have been due to a single contaminant or synergistic effects of all present. Sea-urchins, especially the eggs and larvae, are used for toxicity testing and environmental monitoring (reviewed by Dinnel et al. 1988). Taken together it is likely that Echinus esculentus is intolerant of heavy metal contamination. Overall, it seems unlikely that mortality will occur as a result of heavy metal pollution but sublethal effects on growth and physiology may be important. Therefore an intolerance of low has been recorded. Recovery would not be immediate as heavy metals are stored in tissues and are likely to cause continued adverse effects although, particularly in a community with high turnover rates, recovery would be expected to be very high.
Hydrocarbon contamination
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A number of workers have reported little effect of oil on sublittoral kelp, due to the lack of penetration of oil into the water column (Holt et al., 1995). Drew et al. (1967) recorded that the kelp forest escaped undamaged after the Torrey Canyon oil spillage. Kelp may also be protected by the mucilaginous slime which covers the frond, by preventing damage from coating by oil (Birkett et al., 1998). However, the situation may be different for other components of the biotope. Where exposed to direct contact with fresh hydrocarbons, encrusting calcareous algae have a high intolerance. Crump et al. (1999) describe "dramatic and extensive bleaching" of 'lithothamnia' following the Sea Empress oil spill. Observations following the Dona Marika oil spill (K. Hiscock, own observations) were of rockpools with completely bleached coralline algae. However, Chamberlain (1997) observed that Lithophyllum incrustans recovered within about a year following the Sea Empress oil spill through regeneration of thallus filaments below the destroyed area. Echinus esculentus is subtidal and unlikely to be directly exposed to oil spills, except from dissolved oil or oil adsorbed to particulates. However, large numbers of dead Echinus esculentus were found between 5.5 and 14.5 m in the vicinity of Sennen Cove during the Torrey Canyon spill, presumably due to a combination of wave exposure and heavy spraying of dispersants in that area (Smith,1968). Echinus esculentus populations in the vicinity of an oil terminal in La Coruna Bay, Spain, showed developmental abnormalities in the skeleton. The tissues contained high levels of aliphatic hydrocarbons, naphthalenes, pesticides and heavy metals (Zn, Hg, Cd, Pb, and Cu) (Gomez & Miguez-Rodriguez, 1999). However, the observed effects may have been due to a single contaminant or synergistic effects of all present. Overall, it seems that some components of the biotope will be killed by fresh oil although the main characterizing species will not. Therefore an intolerance of intermediate is given. Recoverability is expected to be very high in view of the low intolerance of dominant species, the recoverability of encrusting corallines and the likelihood that mobile species such as Echinus esculentus will migrate in.
Radionuclide contamination
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Insufficient information.
Changes in nutrient levels
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An increase in nutrient levels may enhance the growth of algae but in excess it may be detrimental. The effects of eutrophication on Saccharina latissima (studied as Laminaria saccharina) have been studied by Conolly & Drew (1985) on the east coast of Scotland. Plants at most the eutrophicated site, where nutrient levels were 25 percent higher than average, exhibited higher growth rates suggesting that growth is nutrient limited. However the growth rate of mature plants of Saccharina latissima (studied as Laminaria saccharina) was lower in water collected near a sewage sludge dumping ground in Liverpool Bay, Irish Sea (Burrow, 1971) and 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 on rocky shores from which it was previously absent. Encrusting coralline algae may suffer from overgrowth by foliose and filamentous algae. As an algal dominated biotope, species abundance and growth rate may be enhanced by increased nutrients.
Increase in salinity
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The biotope occurs in full salinity (Connor et al., 1997a) and so increase in salinity is considered not relevant.
Decrease in salinity
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It has been observed that Saccharina latissima growth is fastest at 31 psu, is severely retarded at 16 psu and plants do not survive below 8 psu. However, the photosynthetic rate of plants from the White Sea was quickly reduced at 2 psu and less quickly at 6 and 8 psu (Kain, 1979). In contrast, Saccorhiza polyschides is not found in areas of reduced salinity. In culture, lowered salinities have been found to reduce growth rate and development is irreversibly inhibited below 9 psu (Norton & South, 1969), so that Saccorhiza polyschides is regarded as intolerant of this factor. Little direct information on the effect of salinity change on encrusting coralline algae was found but red seaweeds are generally more intolerant of reduced salinity conditions than brown or green algae (Kain & Norton 1990). However, in the case of short-term change, encrusting coralline algae must be able to withstand the effects of heavy rain in diluting seawater in pools and in run-off as entirely freshwater over exposed corallines and so are most likely tolerant. Echinoderms are generally unable to tolerate low salinity (stenohaline) and possess no osmoregulatory organ (Boolootian, 1966). At low salinity urchins gain weight, and the epidermis loses its pigment as patches are destroyed; prolonged exposure is fatal. Overall, it is likely that some species will be lost if salinity is decreased but the biotope will most likely remain EIR.LsacSac. Therefore an intolerance of intermediate has been reported. For recoverability, see additional information below.
Changes in oxygenation
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The effect of low oxygen levels on the species in this biotope is poorly studied. Saccorhiza polyschides can grow in almost stationary water (Norton, 1978) and can generate its own oxygen by photosynthesis, so it is unlikely to be intolerant of this factor. Under hypoxic conditions echinoderms become less mobile and stop feeding. 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, presumably due to anoxia caused by the decay of the dead dinoflagellates (Griffiths et al., 1979). Effects of reduced oxygenation are likely to be that a few species will die and an intolerance of intermediate has been recorded. For recoverability, see additional information below.

Biological Factors

Introduction of microbial pathogens/parasites
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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). It is not expected that microbial pathogens will cause mortality of species in the biotope.
Introduction of non-native species
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At present, no non-native species are known to occur in this biotope. The Japanese kelp Undaria pinnatifida has recently spread to the south coast of England from Brittany, where it was introduced for aquaculture. It is thought that Undaria may compete with Saccorhiza polyschides (Birkett et al., 1998b). At present, not sensitive is appropriate.
Extraction
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It is extremely unlikely that the majority of 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. Saccharina latissima is not harvested at present in Britain and Ireland, but it may be eaten as a sea vegetable. Extraction would remove larger plants leaving smaller ones to thrive in their place. Collecting 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 remained. Overall, it is possible that both species may experience a small loss and intolerance has therefore been assessed as intermediate although species diversity is not expected to decline. Recovery is expected to be high (see additional information).

Additional information icon Additional information

Recoverability
Most of the species that characterize the biotope will settle and grow or migrate into the area rapidly so that it will appear recovered as little as a year later. Experiments have shown that Saccorhiza polyschides colonized cleared areas of the substratum within 26 weeks and it has a very fast growth rate. However, if clearance takes place in August, when no spores of the species are released the substratum may become colonized by red algae (Kain, 1975). Kain (1975) also recorded that Saccharina latissima (studied as Laminaria saccharina) was abundant six months after substratum was cleared. However, the crust of encrusting coralline algae will take much longer to recolonize and grow. For Lithophyllum incrustans, spores will settle and new colonies will arise rapidly on bare substratum but growth rate is slow (2-7 mm per annum - see Irvine & Chamberlain 1994). However, within the time scales for recoverability, 'high' recoverability is expected for encrusting coralline algae.

This review can be cited as follows:

Hiscock, K. 2002. Laminaria saccharina and/or Saccorhiza polyschides on exposed infralittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 21/12/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=237&code=1997>