Spatio – temporal patterns and controls on cold-water coral reef development: The Moira Mounds, Porcupine Seabight, offshore Ireland
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Date
2017
Authors
Lim, Aaron
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Publisher
University College Cork
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Abstract
Cold-water corals (CWC) are sessile, filter-feeding organisms that develop a three dimensional framework. Where sediment supply is significant, it acts as a major influence on the development of cold-water coral reefs through sediment baffling by corals and hydrodynamic-topographic interactions. While previous work has demonstrated this effect on a regional scale or across large coral carbonate mound structures, this study examines an individual CWC reef, Piddington Mound, and a chain of small reefs, the westernmost (or downslope) chain of the Moira Mounds, and their sedimentary environment on a discrete area of seabed (<10 km in length) to better constrain the specific processes which affect CWC reef development and variability. Here, we utilise ROV-based video data, full reef coverage video mosaics, 30 kHz side-scan sonar backscatter, ROV-mounted bathymetry, water column data (CTD's) and surface sediment samples to investigate mound development and processes at various scales (reef and reef-chain). Analyses of three distinct seabed zones across the downslope Moira Mounds area show that the optimum area for reef development here is between 38 and 41 cm s-1. Using high resolution video mosaics and microbathymetry, the first full-reef facies distribution model is developed. With this detailed facies distribution model, a series of recommendation are put forward for studying similar sized reefs in the future. Using this information, the minimum number of samples and how to best collect these samples are identified. This methodology is reapplied to the reef 4 years later suggesting that over 20 years, the entire mound surface may change. This provides implications for the studying these reefs using both individual samples and temporally-distal samples.
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Keywords
Cold water coral reef , Habitat mapping , Sediments , Currents , Seabed mapping , Spatial analysis , Reef development
Citation
Lim, A. 2017. Spatio – temporal patterns and controls on cold-water coral reef development: The Moira Mounds, Porcupine Seabight, offshore Ireland. PhD Thesis, University College Cork.