Environmental factors associated with the spatial distribution of crustose coralline algae on the Great Barrier Reef

• Published in: Coral reefs Vol. 19; no. 4; pp. 303 - 309
• Main Authors: FABRICIUS, K, DE'ATH, G
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-05-2001; Berlin
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Corallinales; Fundamental and applied biological sciences. Psychology; Marine; Plants and fungi; Rhodophyta; Coral Sea; Pacific Ocean; Tropical Pacific Ocean; Australia; Oceania; Great Barrier Reef; ISEW, Australia, Queensland, Great Barrier Reef; Marine environment; Rhodophyta; Spatial distribution; Algae; Turbidity; Environmental factor; Coral reef; Fouling organism; Spatial variation; Florideophyceae; Sedimentation; Thallophyta
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s003380000120

Crustose coralline algae (CCA) fulfill two key functional roles in coral reef ecosystems: they contribute significantly to reef calcification, and they induce larval settlement of many benthic organisms. Percentage cover of CCA, and environmental conditions, were visually estimated on 144 reefs of the Great Barrier Reef between 10 and 24 degree latitude S. Reefs were located across the shelf and ranged from turbid near-shore reefs close to rivers to clean-water reefs hundreds of kilometers from coastal influences. On each reef, two sites were surveyed between 0.5 and 18 m depth. Strong cross-shelf trends occurred in cover of CCA, amount of sediment deposited, water clarity, and slope angle. Relative distance across the shelf and sedimentation jointly explained 84% of variation in CCA cover. Three regions running parallel to the shore were identified, with a mean CCA cover of < 1% on the inner third of the shelf, and > 20% cover on the outer half of the shelf, with a narrow transition region between the two. Within each region, the cover of CCA was unrelated to distance across the shelf, but was related to the sedimentary environment, being relatively higher on reefs with low sediment deposits. On the inner third of the shelf, the most sediment-exposed reefs were unsuitable habitats for CCA. The inverse relationship between CCA and sediment has implications for the recruitment of CCA-specialised organisms, and for rates of reef calcification.