Corallina officinalis, often referred to as Coral Weed, is geniculate coralline alga, this means that its fronds are jointed and it is a type of calcified seaweed. Calcareous Seaweeds contain a mineral extract called Lithothamnion which is essentially calcium carbonate in their fronds and thallus. Lithothamnion contains three minerals 65% Calcite, 23% argonite and 12% vaterite shown in figure 1.
This chemical make-up is how it differs from calcium carbonate or limestone which is 100% calcite. The three minerals are very similar yet have different melting points and solubility. The Lithothamnion is deposited inside the cell of the algae and is used to strengthen and protect the thallus.
Corallina officinalis is vulnerable to ocean acidification as its chemical make-up includes Aragonite which is a softer material than calcite (the typical calcifying material) and is more vulnerable to ocean acidification. Ocean acidification is caused mainly by an increase of CO 2 dissolved into the ocean. Even 4% carbon dioxide dissolved into the ocean can cause the PH of sea water to drop from an average of 8 (slightly alkaline) to around 6.5 (slightly acidic). Argonite is eroded by acidic conditions so an increase in CO2, perhaps caused by global warming, may have a detrimental effect on Corallina officinalis.
Corallina officinalis is found extensively around the UK, the North Sea, much of Europe. It has also been recorded widely in the North Atlantic Ocean, specifically Norway, Morocco, Argentina and Greenland. It has also been noted to occur in Australasia, China and Japan. It is generally found in the lower and mid eulittoral zone and the sublittoral fringe.
Corallina officinalis is made up of flattened, calcified, jointed fronds which are stiff and coarse which can be seen in Picture 1.
Coral Weed attach to rocks by forming calcareous encrusting disc holdfasts. These holdfasts can be about 70 mm wide. The fronds of Corallina officinalis are irregularly branching which result in an appearance much like a feather. The fronds are flexible and used for churning seawater. Therefore it would be expected that Corallina officinalis would be found with greater abundance further down the shore in the lower eulittoral and sublittoral zones as these areas have greater time covered by the ocean. Some fronds can grow up to 12 cm however; exposure, desiccation, temperature and zone can have effects on the species. For example small, stunted specimens are found in high intertidal pools and long, feathery forms grow in the subtidal and sublittoral zones. This suggests that as the distance down the shore increases so will the average frond length.
Corallina officinalis ranges in colour from purple to red, to lilac, to yellow often with white extremities to the fronds. The algae’s colour results from the presence of phycoerythrin and phycocyanin pigments which dominants the other pigments, chlorophyll a beta-caratene, it also is lacking in chlorophyll b. This suggests that Corallina officinalis is more likely to be found lower down the shore where there is a shorter period of desiccation and a longer time covered in deeper water. This is because the phycoerythrin and phycocyanin pigments absorb blue and green light wavelengths which can penetrate through the water whereas red wavelengths cannot. High levels of phycoerythrin and phycocyanin pigments suggest an adaption to living in sublittoral or subtidal zones. These pigments can be affected by light or temperature induced stress, the species becomes paler in area of high light intensity and higher temperature.
Coral Weed’s optimum growing temperature is between 12 and 18 degrees and cannot grow below 6 degrees or above 25 degrees. This means they are very sensitive to temperature changes. Therefore Corallina officinalis is more likely to be found in the mid to lower littoral areas as these areas have a more stable temperature. This is due to the less frequent desiccation periods, where the zone is exposed to direct sunlight, these can cause big alterations in the areas temperature. Many organisms in the eulittoral or sublittoral zones are generally not well adapted to periods of dryness and temperature extremes. From the analysis of 58 samples its optimum temperature was shown to between 11.244 - 24.821°C. At this temperature the average growth rate of Corallina officinalis is around 2.2 mm/month. A study by Seapy and Littler in 1984 showed that the occurrence of the hot dry ‘Santa Ana’ winds in January and February, which caused a sudden 10 degree temperature increase, dramatically declined the number and length of the Corallina officinalis fronds. However by October there was a dense cover of summer regrowth suggesting that the crustose holdfasts were not affected by the temperature increase. Hawkins and Hartnoll also noted severe destruction of Coral Weed in the summer of 1983 due to an increase in temperature of between 4.8 and 8.5 degrees Celsius. The increased temperature had led to an increased level of desiccation, to which Corallina officinalis is particularly intolerant.
Coral Weed is very vulnerable to desiccation and cannot survive 15% water losses (which can occur after 40-45 minutes of exposure). Therefore Corallina officinalis is found in the lower areas of the intertidal zone and sublittoral areas to about 18m this is due to the more consistent level of water coverage and protection from desiccation. The removal of Corallina officinalis canopy species such as fucoids like bladder wrack, Irish moss and serrated wrack can cause increased desiccation due to the increased exposure times. A study conducted by Hawkins & Hartnoll in 1985 concluded that Coral Weed and other crustose red algae in the lower intertidal zones die when canopy algal species are removed. Specific extraction of other species may reduce the extent or abundance of Coral Weed. Therefore the abundance of fucoids such as Serrated Wrack may also affect the distribution of Corallina officinalis.
Coralline algaes are particularly tolerant and even flourish in polluted waters. In South California, 1980 Kindig & Littler showed that Corallina officinalis had improved health indices, improved productivity and lower mortality when they were exposed to primary and secondary sewage effluent. However it was noted that “specimens from unpolluted areas were less tolerant, suggesting physiological adaptation to sewage pollution.”
It has also been found that Corallina officinalis sometimes replaces mid and upper-intertidal algae around sewage outfalls or heavily polluted waters.
Corallina officinalis is vulnerable to ocean acidification as its chemical make-up includes Aragonite which is a softer material than calcite (the typical calcifying material) and is more vulnerable to ocean acidification. Ocean acidification is caused mainly by an increase of CO 2 dissolved into the ocean. Even 4% carbon dioxide dissolved into the ocean can cause the PH of sea water to drop from an average of 8 (slightly alkaline) to around 6.5 (slightly acidic). Argonite is eroded by acidic conditions so an increase in CO2, perhaps caused by global warming, may have a detrimental effect on Corallina officinalis.
Corallina officinalis is found extensively around the UK, the North Sea, much of Europe. It has also been recorded widely in the North Atlantic Ocean, specifically Norway, Morocco, Argentina and Greenland. It has also been noted to occur in Australasia, China and Japan. It is generally found in the lower and mid eulittoral zone and the sublittoral fringe.
Corallina officinalis is made up of flattened, calcified, jointed fronds which are stiff and coarse which can be seen in Picture 1.
Corallina officinalis ranges in colour from purple to red, to lilac, to yellow often with white extremities to the fronds. The algae’s colour results from the presence of phycoerythrin and phycocyanin pigments which dominants the other pigments, chlorophyll a beta-caratene, it also is lacking in chlorophyll b. This suggests that Corallina officinalis is more likely to be found lower down the shore where there is a shorter period of desiccation and a longer time covered in deeper water. This is because the phycoerythrin and phycocyanin pigments absorb blue and green light wavelengths which can penetrate through the water whereas red wavelengths cannot. High levels of phycoerythrin and phycocyanin pigments suggest an adaption to living in sublittoral or subtidal zones. These pigments can be affected by light or temperature induced stress, the species becomes paler in area of high light intensity and higher temperature.
Coral Weed’s optimum growing temperature is between 12 and 18 degrees and cannot grow below 6 degrees or above 25 degrees. This means they are very sensitive to temperature changes. Therefore Corallina officinalis is more likely to be found in the mid to lower littoral areas as these areas have a more stable temperature. This is due to the less frequent desiccation periods, where the zone is exposed to direct sunlight, these can cause big alterations in the areas temperature. Many organisms in the eulittoral or sublittoral zones are generally not well adapted to periods of dryness and temperature extremes. From the analysis of 58 samples its optimum temperature was shown to between 11.244 - 24.821°C. At this temperature the average growth rate of Corallina officinalis is around 2.2 mm/month. A study by Seapy and Littler in 1984 showed that the occurrence of the hot dry ‘Santa Ana’ winds in January and February, which caused a sudden 10 degree temperature increase, dramatically declined the number and length of the Corallina officinalis fronds. However by October there was a dense cover of summer regrowth suggesting that the crustose holdfasts were not affected by the temperature increase. Hawkins and Hartnoll also noted severe destruction of Coral Weed in the summer of 1983 due to an increase in temperature of between 4.8 and 8.5 degrees Celsius. The increased temperature had led to an increased level of desiccation, to which Corallina officinalis is particularly intolerant.
Coral Weed is very vulnerable to desiccation and cannot survive 15% water losses (which can occur after 40-45 minutes of exposure). Therefore Corallina officinalis is found in the lower areas of the intertidal zone and sublittoral areas to about 18m this is due to the more consistent level of water coverage and protection from desiccation. The removal of Corallina officinalis canopy species such as fucoids like bladder wrack, Irish moss and serrated wrack can cause increased desiccation due to the increased exposure times. A study conducted by Hawkins & Hartnoll in 1985 concluded that Coral Weed and other crustose red algae in the lower intertidal zones die when canopy algal species are removed. Specific extraction of other species may reduce the extent or abundance of Coral Weed. Therefore the abundance of fucoids such as Serrated Wrack may also affect the distribution of Corallina officinalis.
Coralline algaes are particularly tolerant and even flourish in polluted waters. In South California, 1980 Kindig & Littler showed that Corallina officinalis had improved health indices, improved productivity and lower mortality when they were exposed to primary and secondary sewage effluent. However it was noted that “specimens from unpolluted areas were less tolerant, suggesting physiological adaptation to sewage pollution.”
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