Variation in growth rates of branching corals along Australia’s Great Barrier Reef

Abstract

Coral growth is an important component of reef health and resilience. However, few studies have investigated temporal and/or spatial variation in growth of branching corals, which are important contributors to the structure and function of reef habitats. This study assessed growth (linear extension, density, and calcification) of three branching coral species (Acropora muricata, Pocillopora damicornis and Isopora palifera) at three distinct locations (Lizard Island, Davies/Trunk Reef, and Heron Island) along Australia’s Great Barrier Reef (GBR). Annual growth rates of all species were highest at Lizard Island and declined with increasing latitude, corresponding with differences in temperature. Within locations, however, seasonal variation in growth did not directly correlate with temperature. Between October 2012 and October 2014, the highest growth of A. muricata was in the 2013–14 summer at Lizard Island, which was unusually cool and ~0.5 °C less than the long-term summer average temperature. At locations where temperatures reached or exceeded the long-term summer maxima, coral growth during summer periods was equal to, if not lower than, winter periods. This study shows that temperature has a significant influence on spatiotemporal patterns of branching coral growth, and high summer temperatures in the northern GBR may already be constraining coral growth and reef resilience.

Corallivory in the Anthropocene: Interactive Effects of Anthropogenic Stressors and Corallivory on Coral Reefs

“…Under future ocean acidification scenarios, the competitive dominance shifts from Pocillopora to Acropora (Horwitz et al, 2017). Rapid Acropora growth rates (Anderson et al, 2017) may allow Acropora to outcompete Pocillopora, further reinforcing the reversed competitive hierarchy under low pH. Understanding these complex feedbacks will require both time series data of coral community dynamics as well as targeted experimentation to understand the mechanisms of interspecific interactions and predation patterns.…”

Limited Cross-Shelf Variation in the Growth of Three Branching Corals on Australia’s Great Barrier Reef

“…Reef building, scleractinian ("hard") corals have specific environmental tolerances (Kleypas et al 1999 [1]), such that individual demography, population dynamics and community structure vary markedly along environmental gradients (e.g., Done 1982 [2]; Harriot 1999 [3]; Anderson et al 2017 [4]). Most notably, there are clear and well-defined latitudinal limits to growth and abundance of scleractinian corals, and therefore, reef accretion (Buddemeier and Kinzie 1976 [5]; Kleypas et al 1999 [1]; Muir et al 2015 [6]), which are constrained at high latitudes by lower temperature, aragonite saturation and light levels.…”

Mapping coral reef primary production and calcification from a light-use efficiency model with in-situ and remotely sensed data

“…Census-based approaches rely on previously published linear extension rates to up-scale coral calcification. However, variability in calcification rates for several coral species have been observed seasonally (Venti et al, 2014), while variability in linear extension and growth rates have been observed inter-annually and across different reefs (Anderson et al, 2015(Anderson et al, , 2017(Anderson et al, , 2018). In addition, there is strong evidence that community metabolism varies over time from day scale and longer (Falter et al, 2011(Falter et al, , 2012, and calcification rates have been observed to vary over decades (Silverman et al, 2012(Silverman et al, , 2014.…”

“…Although calcification is an important process across multiple functional-groups, including calcareous algae, cryptic presence and mixed occurrence with non-calcifying algae makes it difficult to separate additional functional-groups with remote sensing. Calcification varies by coral species and morpho-functional types (Anderson et al, 2017(Anderson et al, , 2018. However, obtaining individual calcification rates in relation to irradiance and absorptance in-situ is difficult.…”