Biodiversity & Conservation

LR.ELR.FR.Coff

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Removal of the substratum would result in loss of the coralline turf and its associated community. Therefore an intolerance of high has been recorded. Recoverability is likely to be high (see additional information below).
Smothering
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Seapy & Littler (1982) examined the effects of smothering of the intertidal with a layer of sediment in Santa Cruz, California after unusually heavy rainfall. In the 3 months that followed the total macrophyte cover decreased from 45.3 to 37.3% while macroinvertebrates, especially barnacles, were adversely effected declining from 15.8 to 6.5% cover. The Corallina spp. turf suffered a substantial decline, while the taller red alga Gigartina canaliculata was relatively unaffected. But in the following 6 months, the die back of higher shore species, e.g.. barnacles and Pelvetia spp, allowed the coralline turf and associated red algae to expand up the shore, and Corallina officinalis var. chilensis became the primary cover organism (Seapy & Littler, 1982). In ELR.Coff smothering may adversely affect the resident barnacle species. Smothering sediment will probably fill the interstices in the coralline turf excluding mobile invertebrates and interfering with feeding and respiration is tubicolous amphipods and worms, so that species diversity is likely to decrease. But in the wave exposed conditions characterized by this biotope, smothering is likely to be short lived. Therefore, an intolerance of intermediate has been recorded, and recovery is likely to be very high (see additional information below).
Increase in suspended sediment
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Corallina spp. accumulate more sediment than any other alga (Hicks, 1985). Hence an increase in suspended sediment is likely to accumulate in the coralline turf. A significant increase may result in smothering (see above). An accumulation of sediment within the turf may attract more sediment dwelling interstitial invertebrates such as nematodes, harpacticoids and polychaetes although, in this wave exposed habitat, accumulation of sediment is likely to be minimal. Increased suspended sediment is likely to result in increased scour, especially if the sediment is sand, which may adversely affect the fleshy red algae, and interfere with settling spores and recruitment if the factor is coincident with their major reproductive period. However, coralline algae, especially the crustose forms are thought to be resistant of sediment scour (Littler & Kauker, 1984), and will probably not be adversely affected at the benchmark level. Therefore, an increase in suspended sediment may reduce the epiphytic species diversity in the immediacy, and adversely affect the cover of fleshy red algae and an intolerance of intermediate has been recorded. Recoverability is likely to be very high (see additional information below).
Decrease in suspended sediment
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This community is unlikely to be dependant on suspended sediment. Although accumulated sediment within coralline turf habitats has been shown to increase the species diversity of the epiphytic fauna (see habitat complexity), in very wave exposed habitat the accumulated sediment is likely to be minimal. A reduction in suspended sediment will probably reduce the risk of scour, and reduce food availability for the few suspension feeding species in the biotope (e.g. barnacles and spirorbids if present). Therefore not sensitive has been recorded.
Desiccation
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Finely branched fronds or cushion-like turfs may hold water, reducing desiccation stress. Corallina officinalis inhabits damp or wet gullies and rock pools and does not inhabit the upper shore, suggesting that it is intolerant of desiccation. Desiccation risk is reduced in wave exposed habitats, and with increasing wave exposure the coralline turf may extend further up the shore. However, its upper limit is probably determined by competition, since Seapy & Littler (1982) found that die back of higher shore species allowed coralline species and associated foliose red algae to extend up the shoe. On moderately wave exposed shores ELR.Coff is probably restricted to gentle sloping or horizontal substrata that drain slowly.

Fronds of Corallina officinalis are highly intolerant of desiccation and do not recover from a 15% water loss, which might occur within 40 -45 minutes during a spring tide in summer (Wiedemann, 1994). An abrupt increase in temperature of 10 °C caused by the hot, dry 'Santa Anna' winds (between January and February) in Santa Cruz, California resulted in die back of several species of algae exposed at low tide (Seapy & Littler, 1982). Although fronds of Corallina spp. dramatically declined, summer regrowth resulted in dense cover by the following October, suggesting that the crustose bases survived. The red alga Gigartina canaliculata decreased at its upper limit but increased lower on the shore (Seapy & Littler, 1982). Severe damage was noted in Corallina officinalis as a result of desiccation during unusually hot and sunny weather in summer 1983 (an increase of between 4.8 and 8.5 °C above normal) (Hawkins & Hartnoll, 1985). Similarly, red algae such as Mastocarpus stellatus and Osmundea pinnatifida were damaged or killed at their upper limits. Hawkins & Harkin (1985) found that Corallina officinalis and encrusting corallines often die when their protective canopy of other algal species is removed. Overall, the evidence suggests that this community is likely to be highly intolerant of increased desiccation, equivalent to being raised one level on the shore, and would probably be lost. Recovery is likely to be rapid (see additional information below).

Increase in emergence regime
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Bleached corallines were observed 15 months after the 1964 Alaska earthquake which elevated areas in Prince William Sound by 10 m. Similarly, increased exposure caused by upward movement of 15 cm due to nuclear tests at Armchitka Island, Alaska adversely affected Corallina pilulifera (Johansen, 1974). An increase in emergence is likely to result in decreased wetting and hence increased risk of desiccation. Therefore, the upper limit of this biotope is likely to be depressed and an intolerance of intermediate has been recorded. Recoverability is probably very high (see additional information below).
Decrease in emergence regime
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A decrease in emergence will reduce the risk of desiccation, and increase the average wetness of the shore, potentially allowing the community to expand further up the shore. Therefore, not sensitive* has been recorded. However, it is also likely that the lower extent of the biotope would change to a kelp dominated community.
Increase in water flow rate
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This biotope occurs in moderately strong to very weak tidal streams. Water movement is probably an important structuring feature of the biotope as dense coralline turfs only develop on open bedrock in wave exposed conditions. Wave action is of greater importance than water flow in this biotope and it is unlikely that increased water flow will have an impact. Therefore, not sensitive has been recorded.
Decrease in water flow rate
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In low water flow, wave action is probably the most important cause of water movement within the biotope. Therefore, not relevant has been recorded.
Increase in temperature
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Lüning (1990) reported that Corallina officinalis from Helgoland survived one week exposure to temperatures between 0 °C and 28 °C. An abrupt increase in temperature of 10 °C caused by the hot, dry 'Santa Anna' winds (between January -and February) in Santa Cruz, California resulted in die back of several species of algae exposed at low tide (Seapy & Littler, 1984). Although fronds of Corallina spp. dramatically declined, summer regrowth resulted in dense cover by the following October, suggesting that the crustose bases survived. Severe damage was noted in Corallina officinalis as a result of desiccation during unusually hot and sunny weather in summer 1983 (an increase of between 4.8 and 8.5 °C) (Hawkins & Hartnoll, 1985). Littler & Kauker (1984) suggested that the crustose base was more resistant of desiccation or heating than fronds.

Most of the other species within the biotope are distributed to the north and south of Britain and Ireland and unlikely to be adversely affected by long-term temperature change. But Hawkins & Hartnoll (1985) suggested that typical understorey red algae were susceptible to hot dry weather and that occasional damaged specimens of Palmaria palmata, Osmundea pinnatifida and Mastocarpus stellatus were observed after the hot summer of 1983.

It is likely that Corallina officinalis fronds are intolerant of abrupt short term temperature increase although they may not be affected by long term chronic change and the crustose bases are probably more tolerant than fronds. Epiphytic species will decline due to loss of coralline turf cover. Similarly, acute increases in temperature will probably reduce the cover of the characterizing red algae. Therefore, an intolerance of intermediate has been recorded, although recoverability in likely to be very high.

Decrease in temperature
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Lüning (1990) reported that Corallina officinalis from Helgoland survived one week exposure to temperatures between 0 °C and 28 °C. New Zealand specimens were found to tolerate -4 °C (Frazier et al., 1988, cited in Lüning, 1990). Lüning (1990) suggested that most littoral algal species were tolerant of cold and freezing. For example, the photosynthetic rate of Chondrus crispus recovered after 3hrs at -20 °C but not after 6hrs exposure (Dudgeon et al., 1990). The photosynthetic rate of Mastocarpus stellatus higher on the shore fully recovered from 24hrs at -20 °C. Lüning reported that optimal growth and temperature were between 10-20 °C for Lomentaria articulata, consistent with their peak spore production in summer. Little information was found on the effects on the epiphytic fauna but all species are adapted to the extreme fluctuations in temperature that occur in the intertidal and are probably tolerant of acute temperature change. Overall, the biotope is unlikely to be adversely affected by long term temperature change at the benchmark level. Short term acute change my result in loss of a few individuals of more intolerant species e.g. Semibalanus balanoides and Patella species (see MarLIN reviews) but otherwise not adversely affect the biotope. Therefore an intolerance of low has been recorded.
Increase in turbidity
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Red algae and coralline algae especially are known to be shade tolerant and are common components of the understorey on seaweed dominated shores. Therefore, a decrease in light intensity is unlikely to adversely affect the biotope, especially as it is emersed regularly with the tide. Hence, not sensitive has been recorded.
Decrease in turbidity
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An increase in light intensity is unlikely to adversely affect the biotope. The community is regularly uncovered by the receding tide and experiences full sunlight, which may bleach the tips of algal fronds. Therefore, not sensitive has been recorded.
Increase in wave exposure
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Wave exposure is an important determining factor in this biotope, removing competition from fleshy red algae and fucoids and allowing a dense coralline turf to develop. The biotope occurs in extremely wave expose to moderately wave exposed habitats so that any further increase in wave exposure is unlikely. Hence, not sensitive has been recorded. In records of ELR.Coff in moderately wave exposed habitats an increase in wave exposure may decrease the species richness of the epiphytic fauna.
Decrease in wave exposure
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Wave exposure is an important determining factor in this biotope, removing competition from fleshy red algae and fucoids and allowing a dense coralline turf to develop. The biotope occurs in extremely to moderately wave exposed habitats. A decrease in wave exposure from e.g. very exposed to moderately exposed may increase the abundance or fleshy red algae, and diversity of the epiphytic fauna and probably reduce the height and width of the coralline turf zone in the intertidal. But a decrease in wave exposure from e.g. exposed to sheltered would result in major changes in the community, probably favouring fucoid dominated biotopes and resulting in loss of the biotope as described. Therefore, an intolerance of high has been recorded. Recoverability could be high (see additional information below) but may only occur once the dominant species in the replacement biotope have died or been removed by wave action, which may take more than five years. Therefore, a recoverability of moderate has been recorded in this instance.
Noise
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None of the species in this biotope are know to respond to noise or vibration at the benchmark level, and live in a habitat that experiences the severe noise and turbulence caused by wave action.
Visual Presence
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The mobile invertebrates are probably capable of responding to localized shading, experienced by the approach of a predator. But their visual acuity is likely to be low and they are unlikely to respond to visual disturbance at the benchmark level.
Abrasion & physical disturbance
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Abrasion by an anchor or mooring may remove some fronds of the foliose red algae and coralline turf, although most species would grow back from their remaining holdfasts. Trampling may be more damaging. For example, moderate (50 steps per 0.09 sq. metre) or more trampling on intertidal articulated coralline algal turf in New Zealand reduced turf height by up to 50%, and the weight of sand trapped within the turf to about one third of controls. This resulted in declines in densities of the meiofaunal community within two days of trampling. Although the community returned to normal levels within 3 months of trampling events, it was suggested that the turf would take longer to recover its previous cover (Brown & Taylor, 1999). Similarly, Schiel & Taylor (1999) noted that trampling had a direct detrimental effect on coralline turf species on the New Zealand rocky shore. At one site, coralline bases were seen to peel from the rocks (Schiel & Taylor 1999), although this was probably due to increased desiccation caused by loss of the algal canopy. The crustose base has nearly twice the mechanical resistance (measured by penetration) of fronds (Littler & Kauker, 1984). Brosnan & Cumrie (1994) also reported that foliose algae, e.g. Mastocarpus papillatus showed significant declines in cover in response to trampling, although recovery was rapid, probably from remaining holdfasts. Therefore, physical abrasion due to trampling is likely to result in a significant decline in the cover of the coralline turf, red algae and epiphytic fauna and an intolerance of intermediate has been recorded. The dominant algae are likely to recover rapidly by regrowth from remaining fronds and holdfasts, and epiphytic fauna will colonize the turf relatively quickly.
Displacement
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The majority of the epiphytic fauna, such as the isopods, amphipods and harpacticoid copepods are highly mobile are unlikely to be adversely affected by displacement. But the dominant macroalgae are permanently attached to the substratum and if removed will be lost, resulting in loss of the biotope overall. If their holdfasts and bases are also removed then recovery will be prolonged but still relatively rapid.

Chemical Factors

Synthetic compound contamination
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Smith (1968) reported that oil and detergent dispersants from the Torrey Canyon spill affected high water specimens of Corallina officinalis more than low shore specimens and some specimens were protected in deep pools. In areas of heavy spraying, however, Corallina officinalis was killed, and was affected down to 6m depth at one site, presumably due to wave action and mixing (Smith, 1968). However, regrowth of fronds had begun within 2 months after spraying ceased (Smith, 1968). O'Brien & Dixon (1976) suggested that red algae were the most sensitive group of algae to oil or dispersant contamination, possibly due to the susceptibility of phycoerythrins to destruction. They also report that red algae are effective indicators of detergent damage since they undergo colour changes when exposed to relatively low concentration of detergent. Smith (1968) reported that red algae such as Chondrus crispus, Mastocarpus stellatus, and Laurencia pinnatifida were amongst the algae least affected by detergents, whereas other species, including Lomentaria articulata were either killed or unhealthy. Smith (1968) reported that 10 ppm of the detergent BP 1002 killed the majority of specimens in 24hrs in toxicity tests. Laboratory studies of the effects of oil and dispersants on several red algal species concluded that they were all sensitive to oil/dispersant mixtures, with little difference between adults, sporelings, diploid or haploid life stages (Grandy, 1984; cited in Holt et al., 1995). Cole et al. (1999) suggested that herbicides were, not surprisingly, very toxic to algae and macrophytes. Hoare & Hiscock (1974) noted that all red algae except Phyllophora sp. were excluded from near to an acidified halogenated effluent discharge in Amlwch Bay, Anglesey and that intertidal populations of Corallina officinalis occurred in significant amounts only 600 m east of the effluent.

Most pesticides and herbicides were suggested to be very toxic for invertebrates, especially crustaceans (amphipods isopods, mysids, shrimp and crabs) and fish (Cole et al., 1999). For example, Lindane was shown to be very toxic to gobies (Gobius spp.: see Pomatoschistus minutus) (Ebere & Akintonwa, 1992). The pesticide ivermectin is very toxic to crustaceans, and has been found to be toxic towards some benthic infauna such as Arenicola marina (Cole et al., 1999). The evidence suggests that, on balance, red algae are probably very intolerant to synthetic chemicals and biotope intolerance is assessed as high. Recoverability is probably also high (see additional information below).

Heavy metal contamination
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Bryan (1984) suggested that the general order for heavy metal toxicity in seaweeds is: organic Hg > inorganic Hg > Cu > Ag > Zn > Cd >Pb. Cole et al. (1999) reported that Hg was very toxic to macrophytes. The sub-lethal effects of Hg (organic and inorganic) on the sporelings of an intertidal red algae, Plumaria elegans, were reported by Boney (1971). 100% growth inhibition was caused by 1 ppm Hg. Burdin & Bird (1994) reported that both gametophyte and tetrasporophyte forms of Chondrus crispus accumulated Cu, Cd, Ni, Zn, Mn and Pb when immersed in 0.5 mg/l solutions for 24 hours. No effects were reported however, and no relationship was detected between hydrocolloid characteristics and heavy metal accumulation.

Cole et al. (1999) suggested that Pb, Zn, Ni and As were very toxic to algae, while Cd was very toxic to Crustacea (amphipods, isopods, shrimp, mysids and crabs), and Hg, Cd, Pb, Cr, Zn, Cu, Ni, and As were very toxic to fish. Bryan (1984) reported sublethal effects of heavy metals in crustaceans at low (ppb) levels. In laboratory investigations Hong & Reish (1987) observed 96hr LC50 (the concentration which produces 50% mortality) of between 0.19 and 1.83 mg/l in the water column for several species of amphipod. The intolerant of crustaceans to heavy metal contaminants suggests that amphipod and isopod grazers would be lost, allowing rapid growth of epiphytes, and perhaps reduced growth of Corallina officinalis.

In the absence of evidence of mortalities in red or coralline algae and intolerance of low has been recorded to represent the potential loss of epiphytic grazers, albeit with very low confidence.
Hydrocarbon contamination
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Oil and detergent dispersants affected high water specimens of Corallina officinalis more than low shore specimens and some specimens were protected in deep pools. In areas of heavy spraying, however, Corallina officinalis was killed, and was affect down to 6 m in one site, presumably due to wave action and mixing (Smith, 1968). However, regrowth of fronds had begun within 2 months after spraying ceased (Smith, 1968). Crump et al. (1999) noted a dramatic bleaching of encrusting corallines and signs of bleaching in Corallina officinalis, Chondrus crispus and Mastocarpus stellatus at West Angle Bay, Pembrokeshire after the Sea Empress oil spill. However, encrusting corallines recovered quickly and Corallina officinalis was not killed. It seems likely, therefore, that Corallina officinalis was more intolerant of dispersants used during the Torrey Canyon oil spill than the oil itself.

O'Brien & Dixon (1976) suggested that red algae were the most intolerant group of algae to oil or dispersant contamination, possibly due to the susceptibility of phycoerythrins to destruction. Laboratory studies of the effects of oil and dispersants on several red algal species concluded that they were all sensitive to oil/dispersant mixtures, with little difference between adults, sporelings, diploid or haploid life stages (Grandy, 1984; cited in Holt et al., 1995). Smith (1968) reported that red algae such as Chondrus crispus, Mastocarpus stellatus, and Laurencia pinnatifida were amongst the algae least affected by detergents, whereas other species, including Lomentaria articulata were either killed or unhealthy.

Suchanek (1993) noted that gastropods, amphipods, infaunal polychaetes and bivalves were particularly sensitive to oil spills. Amphipods in particular are known to be sensitive to oil spills (Suchanek, 1993).

Overall, hydrocarbon contamination and oil spills are likely to reduce the cover of the dominant macrophytes in the biotope, due to bleaching and subsequent loss of fronds. But the resistant bases of Corallina officinalis will probably survive and facilitate recovery. Some of the dominant fleshy red algae are likely to survive while other may be killed. But the epiphytic fauna is likely to be adversely affect due to loss of habitat, smothering by oil, and direct effects of oil contamination on amphipods, and other crustaceans, limpet and gastropods in particular. Therefore, an intolerance of intermediate has been recorded, while species richness is likely to decline markedly. Once the oil has been removed, which is probably rapid in a wave exposed habitat, subsequent recovery is probably rapid.

Radionuclide contamination
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No information found.
Changes in nutrient levels
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Corallines seem to be tolerant and successful in polluted waters. Kindig & Littler (1980) demonstrated that Corallina officinalis var. chilensis in South California showed equivalent or enhanced health indices, highest productivity and lowest mortalities (amongst the species examined) when exposed to primary or secondary sewage effluent. Little difference in productivity was noted in chlorinated secondary effluent or pine oil disinfectant. However, specimens from unpolluted areas were less tolerant, suggesting physiological adaptation to sewage pollution (Kindig & Littler, 1980).

Johansson et al. (1998) suggested that one of the symptoms of large scale eutrophication is the deterioration of benthic algal vegetation in areas not directly affected by land-runoff or a point source of nutrient discharge. Altered depth distributions of algal species caused by decreased light penetration (turbidity) and/or increased sedimentation through higher pelagic production have been reported in the Baltic Sea (Kautsky et al., 1986; Vogt & Schramm, 1991). An increase in abundance of red algae, including Delesseria sanguinea, was associated with eutrophication in the Skagerrak area, Sweden, especially in areas with the most wave exposure or water exchange (Johansson et al., 1998). However, where eutrophication resulted in high siltation rates, the delicate foliose red algae such as Delesseria sanguinea were replaced by tougher, erect red algae (Johansson et al., 1998).

Eutrophication in the intertidal is likely to favour ephemeral algae such as Ulva spp., Ulva lactuca and Porphyra spp., which in turn may favour epiphytic grazers. However, The coralline turf will probably survive and may even benefit from nutrient enrichment, and although the dominant red algae may change, favouring fast growing species, the biotope will probably remain recognizable. Therefore, an intolerance of low has been recorded.
Increase in salinity
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This biotope occurs in the intertidal of fully saline waters, and organisms will be exposed to increased salinities due to evaporation during emersion. In addition, Corallina officinalis inhabits rock pools and gullies from mid to low water. Therefore, it is likely to be exposed to short term hypersaline (evaporation) events. Kinne (1971) cites maximal growth rates for Corallina officinalis between 33 and 38 psu in Texan lagoons. Overall, little information on hypersaline tolerance of other species was found, however it appear that the coralline turf will probably survive, and the biotope has been assessed as not sensitive, albeit at low confidence.
Decrease in salinity
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This biotope occur in the intertidal of fully saline waters. Corallina officinalis is likely to be exposed to short term hyposaline (freshwater runoff and rainfall) and hypersaline (evaporation) events where it occurs in rock pools. But the distribution of Corallina officinalis in the Baltic is restricted to increasingly deep water as the surface salinity decreases, suggesting that it requires full salinity in the long term (Kinne, 1971), although the coralline turf communities described by Bamber 1993) occurred in waters between 24 and 28psu. Gessner & Schramm (1971) summarize the effects of salinity changes on marine algae. Most sublittoral red algae cannot withstand salinities below 15 psu. Therefore, a reduction in salinity in the long term, from full to reduced is likely to result in a decline in the abundance of the coralline turf and red algae below about 24 psu, and hence its associated community. Therefore, an intolerance of intermediate has been recorded. Recoverability is likely to be very high.
Changes in oxygenation
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This biotope occurs in wave exposed conditions with considerable mixing of the water column and wave crash. Therefore, hypoxic or anoxic conditions are unlikely to occur.

Biological Factors

Introduction of microbial pathogens/parasites
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Several coralline and non-coralline species are epiphytic on Corallina officinalis. Irvine & Chamberlain (1994) cite tissue destruction caused by Titanoderma corallinae. However, no information on pathogenic organisms in the UK was found. In Rhodophyta, viruses have been identified by means of electron microscopy (Lee, 1971) and it is obvious that they are widespread. But nothing is known of their effects on growth or reproduction in red algae and experimental transfer from an infected to an uninfected specimen has not been achieved (Dixon & Irvine, 1977). Overall, insufficient information was found to make an assessment.
Introduction of non-native species
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No information found.
Extraction
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Corallina officinalis was used in Europe as a vermifuge although it no longer seems to be collected for this purpose (Guiry & Blunden, 1991). Corallina officinalis is collected for medical purposes; the fronds are dried and converted to hydroxyapatite and used as bone forming material (Ewers et al., 1987). It is also sold as a powder for use in the cosmetic industry. An European research proposal for cultivation of Corallina officinalis is pending as of May 2000 (Wiedemann, pers. comm.). Both Chondrus crispus and Mastocarpus stellatus are collected as 'carragheen' by hand picking and racking in Europe (Guiry & Blunden, 1991). Removal of any of the macroalgal community would obviously reduce its extent and cover but also significantly reduce the resident epiphytic fauna. Intolerance has been assessed as intermediate. However, as long as holdfasts remain recovery will probably be rapid.

Additional information icon Additional information

Recoverability
Corallina officinalis probably has good recruitment and settled on artificial substrata within 1 week of their placement in the intertidal during summer in New England (Harlin & Lindbergh, 1977). New fronds of Corallina officinalis appeared on sterilised plots within six months and 10% cover was reached with 12 months (Littler & Kauker, 1984). Bamber (1993) reported that new plants grew back in scraped transects within 12 months, although the resistant crustose bases were probably not removed. Similarly, in experimental plots, up to 15% cover of Corallina officinalis fronds returned within 3 months after removal of fronds and all other epiflora/fauna but not the crustose bases (Littler & Kauker, 1984). Although new crustose bases may recruit and develop quickly the formation of new fronds from these bases and recovery of original cover may take longer, and it is suggested that a the population is likely to recover within a few years.

If the holdfasts of red algae remain, they are likely to recover quickly, as if damaged by winter storms. For example, following experimental harvesting by drag raking in New Hampshire, USA, populations of Chondrus crispus recovered to one third of their original biomass after 6 months and totally recovered after 12 months (Mathieson & Burns, 1975). Raking is designed to remove the large fronds but leave the small upright shoots and holdfasts. The authors suggested that control levels of biomass and reproductive capacity are probably re-established after 18 months of regrowth, although time to recovery was much extended if harvesting occurred in the winter, rather than the spring or summer (Mathieson & Burns, 1975). Minchinton et al. (1997) documented the recovery of Chondrus crispus after a rocky shore in Nova Scotia, Canada, was totally denuded by an ice scouring event. Initial recolonization was dominated by diatoms and ephemeral macroalgae, followed by fucoids and then perennial red seaweeds. After 2 years, Chondrus crispus had re-established approximately 50% cover on the lower shore and after 5 years it was the dominant macroalgae at this height, with approximately 100% cover. Therefore, recovery by Chondrus crispus will be relatively rapid (approximately 18 months) in situations where intolerance to a factor is intermediate and some holdfasts remain for regeneration of fronds. In situations of high intolerance, where the entire population of Chondrus crispus is removed, recovery will be limited by recruitment from a remote population and would be likely to take up to 5 years. Similarly, clearance studies of concrete blocks in the shallow subtidal showed that Rhodophyceae colonized and grew in the winter months, presumably at their peak of spore availability (Kain, 1975). It is probably that most of the characterizing red algae would grow back from remaining holdfasts and recruit well in winter and where bases are removed they will probably take a few years to regain their original cover, although in this biotope their percentage cover is low.

The epiphytic fauna are mainly composed of mobile species, that will recruit quickly from surrounding habitats, and will therefore, recover quickly once the coralline turf has developed.

Overall, where upright fronds of the red algal turf are removed, recovery will probably be very rapid, within about 12 months. If the holdfasts are removed, recovery of their original cover is likely to be prolonged but the biotope would probably be recognizable within less than 5 years.


This review can be cited as follows:

Tyler-Walters, H. 2005. Corallina officinalis on very exposed lower eulittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 22/10/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=130&code=1997>