In Situ Growth and Bioerosion Rates of Lophelia pertusa in a Norwegian Fjord and Open Shelf Cold-water Coral Habitat

• Main Authors: Büscher, Janina, Wisshak, Max, Form, Armin, Titschack, Jürgen, Nachtigall, Kerstin, Riebesell, Ulf
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2019
• Subjects: BIOACID; Bioerosion; Biological Impacts of Ocean Acidification; cold-water corals; growth; in situ study; Lophelia pertusa; North Atlantic; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.903093; https://doi.org/10.1594/PANGAEA.903093

Coral reef resilience depends on the balance between carbonate precipitation, leading to reef growth, and carbonate degradation, e.g. through bioerosion. Changes in environmental conditions are likely to affect the two processes differently, thereby shifting the balance between reef growth and degradation. In cold-water corals estimates of accretion-erosion processes in their natural habitat are scarce and solely live coral growth rates were studied with regard to future environmental changes in the laboratory so far, limiting our ability to assess the potential of cold-water coral reef ecosystems to cope with environmental changes. In the present study, growth rates of the two predominant colour morphotypes of live Lophelia pertusa as well as bioerosion rates of dead coral framework were assessed in different environmental settings in Norwegian cold-water coral reefs in a one-year in situ experiment. Net growth (in weight gain and linear extension) of live L. pertusa was in the lower range of previous estimates and did not significantly differ between inshore (fjord) and offshore (open shelf) habitats. However, slightly higher net growth rates were obtained inshore. Bioerosion rates were significantly higher on-reef in the fjord compared to off-reef deployments in- and offshore. Besides, on-reef coral fragments yielded a broader range of individual growth and bioerosion rates, indicating higher turnover in live reef structures than off-reef with regard to accretion-bioerosion processes. Moreover, if the higher variation in growth rates represents a greater variance in (genetic) adaptations to natural environmental variability in the fjord, inshore reefs could possibly benefit under future ocean change compared to offshore reefs. Although not significantly different due to high variances between replicates, growth rates of orange branches were consistently higher at all sites, while mortality was statistically significantly lower, potentially indicating higher stress-resistance than the less pigmented white ...