Temporal and spatial variation in the growth of branching corals

• Main Author: Anderson, Kristen Deanna
• Format: Thesis
• Language: unknown
• Published: 2016
• Subjects: Ocean acidification
• Online Access: https://researchonline.jcu.edu.au/47479/6/47479-anderson-2016-thesis.pdf

Life-history traits (e.g., growth rates) of reef-building corals are fundamental in structuring populations and communities. Importantly, growth rates of corals have been shown to vary with changes in environmental gradients, such as sea surface temperature (SST), light, and aragonite saturation. Accordingly, ongoing changes in environmental conditions due to climate change (e.g., ocean warming and acidification) may be causing long-term changes in coral growth. Corals are particularly sensitive to changing temperature regimes, such that sustained increases in ocean temperatures are generally expected to have negative consequences on coral growth and survivorship. At high-latitude reefs however, projected increases in ocean temperature may actually lead to increases in annual growth rates, by relaxing constraints imposed by cool winter temperatures. This will however, depend upon on the rate and extent of declines in aragonite saturation, which is already much lower at high latitudes. Generally, it is expected that increasing temperature stress will be compounded by ocean acidification, leading to ongoing declines in abundance and survivorship of corals. However, the relative contribution of ocean warming versus ocean acidification on coral growth is poorly understood. The overarching objective of this thesis was to quantify growth rates of branching corals at multiple spatial and temporal scales on Australia's Great Barrier Reef (GBR), to understand how changing environmental conditions may impact on growth of common branching corals. The first step towards improved understanding of the likely effects of climate change on coral growth was the compilation of extensive data on the growth of corals, testing for spatial, temporal, and taxonomic differences in linear extension versus calcification. Results from the extensive meta-analysis reveal that rates of linear extension vary greatly among coral species and morphologies, but were highest among arborescent Acropora species. Despite large variations in growth ...