Report | March 12, 2024
Habitat characterization, anthropogenic impacts andconservation of rhodolith beds off southeastern Malta
Rhodolith beds, including maerl, are structurally complex perennial habitats that support a high species diversity but are threatened by numerous human activities, particularly in the Mediterranean Sea. Despite their global ecological importance, increased research efforts are needed to facilitate development of effective measures to conserve these habitats.
Two areas hosting rhodolith beds are known to occur off the coast of Malta (central Mediterranean), but only one has been previously studied. Through analysis of video footage collected from 56 different stations coupled with a desk study on human activities, the present study characterized the rhodolith bed located off the southeastern coast of Malta, including its extent, rhodolith morphotype composition, associated megabiota and impacts of anthropogenic activities thereon.
Rhodoliths are unattached nodules formed by calcareous red algae that can take various forms and sizes, generally with a mean diameter of 2–250 mm (Bosellini & Ginsburg, 1971; Ginsburg & Bosellini, 1973). Two main types occur: those where the algal thallus forms the entire nodule and those where the red alga settles on a sediment granule and then grows to completely encrust it. Rhodoliths are known to have a very wide geographical distribution, having been recorded from polar to tropical environments (Foster, 2001). The water depth at which rhodoliths occur varies from one area to another, mostly depending on the degree of light penetration. Generally, rhodoliths are found in the mesophotic zone but have been recorded at depths of 1–10 m in turbid waters off the British Isles (Irvine & Chamberlain, 1994), as well as at a water depth of 290 m in the Bahamas (Littler et al., 1991).
