|Basic Information||Biotope classification||Ecology||Habitat preferences and distribution||Species composition||Sensitivity||Importance|
Dead maerl beds recorded () and expected () distribution in Britain and Ireland (see below)
Temperature range preferences - Not relevant
Water clarity preferences - Data deficient
Limiting Nutrients - Data deficient
Other preferences - Not relevant
Extensive maerl beds are restricted to areas of moderate to strong currents protected from strong wave action, e.g. in bays and inlets. Lithothamnion coralloides is more tolerant of low water flow that Phymatolithon calcareum, so that the species composition varies with water flow. The depth at which live maerl can grow depends on light availability (and hence water clarity), and in the British Isles maerl can occur at 30m but larger beds occur at 15m or less. Species composition is also dependant on temperature. While maerl occurs from the tropics to Norway, Lithothamnion coralloides is restricted to southern waters while Lithothamnion glaciale is particularly abundant in Scotland (Birkett et al. 1998). Maerl beds are normally found at full salinity but can tolerate reduced salinities. Live maerls are intolerant of desiccation, so are rarely found or form beds in the intertidal (Birkett et al., 1998, Wilson et al., 2004).
The presence of ‘dead’ maerl beds is dependent of the prior growth and development of live maerl beds over decades or thousands of years. Therefore, dead maerl beds can only occur in areas that are presently, or were previously suitable for the growth of live maerl.
This review can be cited as follows:
Tyler-Walters, H. 2013. Beds of dead maerl. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 31/03/2015]. Available from: <http://www.marlin.ac.uk/habitatpreferences.php?habitatid=999&code=2004>