Environmental tolerances of free-living coralline algae (maerl): implications for European marine conservation

• Published in: Biological conservation Vol. 120; no. 2; pp. 279 - 289
• Main Authors: Wilson, Sian, Blake, Charmaine, Berges, John A, Maggs, Christine A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2004; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Burial; Conservation; Conservation, protection and management of environment and wildlife; Corallinaceae; Corallinales; Fish farm waste; Fragmentation; Fundamental and applied biological sciences. Psychology; Light; Maerl; Marine; Metal contamination; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Pulse amplitude modulated fluorometry; Salinity; Sewage discharge; Temperature; ANE, British Isles; Europe; Burial; Fish farm waste; Maerl; Temperature; Pulse amplitude modulated fluorometry; Light; Conservation; Sewage discharge; Metal contamination; Salinity; Fragmentation; Environmental factor; Metal; Marine environment; Habitat; Thallophyta; Rhodophyta; Algae; Interspecific association; Tolerance; Vulnerability; Contamination; Stress; Pollutant; Wastes; Environmental protection
• ISSN: 0006-3207
• DOI: 10.1016/j.biocon.2004.03.001

Maerl is a general term used for loose-lying subtidal beds of nodular coralline red algae. Maerl beds support high associated invertebrate and algal biodiversity, and are subject to European and UK conservation legislation. Previous investigations have shown European maerl to be ecologically fragile due to growth rates of approximately 1 mm per year. However, these very slow growth rates have hampered attempts to determine the key ecological requirements and sensitivity characteristics of living maerl. In this study, photosynthetic capacity determined by pulse amplitude modulated (PAM) fluorometry was used as a diagnostic of stress caused by various environmental conditions. Maerl species were exposed to a range of temperatures, salinities and light levels and to burial, fragmentation, desiccation and heavy metal treatment. Maerl was not as susceptible as previously assumed to extremes of salinity, temperature and heavy metal pollution, but burial, especially in fine or anoxic sediments, was lethal or caused significant stress. These data indicate that the main anthropogenic hazard for live maerl and the rich communities that depend on them is smothering by fine sediment, such as that produced by trawling or maerl extraction, from sewage discharges or shellfish and fish farm waste, and sedimentation resulting from disruption to tidal flow.