ORCID Profile
0000-0002-8577-8174
Current Organisation
Nature Based Insetting
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Publisher: Wiley
Date: 05-08-2021
Abstract: Coral bleaching has impacted reefs worldwide and the predictions of near‐annual bleaching from over two decades ago have now been realized. While technology currently provides the means to predict large‐scale bleaching, predicting reef‐scale and within‐reef patterns in real‐time for all reef users is limited. In 2020, heat stress across the Great Barrier Reef underpinned the region's third bleaching event in 5 years. Here we review the heterogeneous emergence of bleaching across Heron Island reef habitats and discuss the oceanographic drivers that underpinned variable bleaching emergence. We do so as a case study to highlight how reef end‐user groups who engage with coral reefs in different ways require targeted guidance for how, and when, to alter their use of coral reefs in response to bleaching events. Our case study of coral bleaching emergence demonstrates how within‐reef scale nowcasting of coral bleaching could aid the development of accessible and equitable bleaching response strategies on coral reefs. Also see the video abstract here: youtu.be/N9Tgb8N-vN0
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.JENVMAN.2021.113919
Abstract: Coral bleaching has increasingly impacted reefs worldwide over the past four decades. Despite almost 40 years of research into the mechanistic, physiological, ecological, biophysical and climatic drivers of coral bleaching, metrics to allow comparison between ecological observations and experimental simulations still do not exist. Here we describe a novel metric - experimental Degree Heating Week (eDHW) - with which to standardise the persistently variable thermal conditions employed across experimental studies of coral bleaching by modify the widely used Degree Heating Week (DHW) metric used in ecological studies to standardise cumulative heat loading.
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.CUB.2019.06.077
Abstract: Severe marine heatwaves have recently become a common feature of global ocean conditions due to a rapidly changing climate [1, 2]. These increasingly severe thermal conditions are causing an unprecedented increase in the frequency and severity of mortality events in marine ecosystems, including on coral reefs [3]. The degradation of coral reefs will result in the collapse of ecosystem services that sustain over half a billion people globally [4, 5]. Here, we show that marine heatwave events on coral reefs are biologically distinct to how coral bleaching has been understood to date, in that heatwave conditions result in an immediate heat-induced mortality of the coral colony, rapid coral skeletal dissolution, and the loss of the three-dimensional reef structure. During heatwave-induced mortality, the coral skeletons exposed by tissue loss are, within days, encased by a complex biofilm of phototrophic microbes, whose metabolic activity accelerates calcium carbonate dissolution to rates exceeding accretion by healthy corals and far greater than has been documented on reefs under normal seawater conditions. This dissolution reduces the skeletal density and hardness and increases porosity. These results demonstrate that severe-heatwave-induced mortality events should be considered as a distinct biological phenomenon from bleaching events on coral reefs. We also suggest that such heatwave mortality events, and rapid reef decay, will become more frequent as the intensity of marine heatwaves increases and provides further compelling evidence for the need to mitigate climate change and instigate actions to reduce marine heatwaves.
Publisher: F1000 Research Ltd
Date: 10-08-2017
DOI: 10.12688/F1000RESEARCH.11522.2
Abstract: Polyp bailout is an established but understudied coral stress response that involves the detachment of in idual polyps from the colonial form as a means of escaping unfavourable conditions. This may influence both the mortality and asexual recruitment of coral genotypes across a range of species. It has been observed in response to numerous stressors including high salinity and low pH. Polyp expulsion in association with thermal stress has once been described in a geographically restricted, temperate species. We therefore cannot reliably apply this observation to tropical coral reefs around the world, which are increasingly under threat from thermal stress events. We present the first qualitative observation of polyp bailout following acute temperature shock in a near-natural mesocosm experiment. Detached polyps show similar characteristics to those described in previous studies, including the retention of endosymbiotic zooxanthellae and the ability to disperse across short distances. This finding strongly suggests that polyp bailout occurs in tropical coral reef environments and warrants further detailed research into the implication of this response in terms of in idual survival, rapid migration into cooler micro-habitats and local recruitment within the reef environment and its coral community.
Publisher: American Society for Microbiology
Date: 24-02-2021
Abstract: Microbial communities living inside the skeletons of living corals play a variety of important roles within the coral meta-organism, both symbiotic and parasitic. Properly contextualizing the contribution of these enigmatic microbes to the life history of coral reefs requires knowledge of how these endolithic biofilms vary between coral species.
Publisher: Copernicus GmbH
Date: 14-02-2022
Abstract: Abstract. Coral bleaching events continue to drive the degradation of coral reefs worldwide, causing a shift in the benthic community from coral- to algae-dominated ecosystems. Critically, this shift may decrease the capacity of degraded coral reef communities to maintain net positive accretion during warming-driven stress events (e.g., reef-wide coral bleaching). Here we measured rates of net ecosystem calcification (NEC) and net ecosystem production (NEP) on a degraded coral reef lagoon community (coral cover 10 % and algae cover 20 %) during a reef-wide bleaching event in February 2020 at Heron Island on the Great Barrier Reef. We found that during this bleaching event, rates of NEP and NEC across replicate transects remained positive and did not change in response to bleaching. Repeated benthic surveys over a period of 20 d indicated an increase in the percent area of bleached coral tissue, corroborated by relatively low Symbiodiniaceae densities (∼ 0.6 × 106 cm−2) and dark-adapted photosynthetic yields in photosystem II of corals (∼ 0.5) s led along each transect over this period. Given that a clear decline in coral health was not reflected in the overall NEC estimates, it is possible that elevated temperatures in the water column that compromise coral health enhanced the thermodynamic favorability for calcification in other ahermatypic benthic calcifiers. These data suggest that positive NEC on degraded reefs may not equate to the net positive accretion of a complex, three-dimensional reef structure in a future, warmer ocean. Critically, our study highlights that if coral cover continues to decline as predicted, NEC may no longer be an appropriate proxy for reef growth as the proportion of the NEC signal owed to ahermatypic calcification increases and coral dominance on the reef decreases.
Publisher: Oxford University Press (OUP)
Date: 2021
Abstract: The effects of thermal anomalies on tropical coral endosymbiosis can be mediated by a range of environmental factors, which in turn ultimately influence coral health and survival. One such factor is the water flow conditions over coral reefs and corals. Although the physiological benefits of living under high water flow are well known, there remains a lack of conclusive experimental evidence characterizing how flow mitigates thermal stress responses in corals. Here we use in situ measurements of flow in a variety of reef habitats to constrain the importance of flow speeds on the endosymbiosis of an important reef building species under different thermal regimes. Under high flow speeds (0.15 m s−1) and thermal stress, coral endosymbionts retained photosynthetic function and recovery capacity for longer compared to low flow conditions (0.03 m s−1). We hypothesize that this may be due to increased rates of mass transfer of key metabolites under higher flow, putatively allowing corals to maintain photosynthetic efficiency for longer. We also identified a positive interactive effect between high flow and a pre-stress, sub-lethal pulse in temperature. While higher flow may delay the onset of photosynthetic stress, it does not appear to confer long-term protection sustained exposure to thermal stress (eDHW accumulation equivalent to 4.9°C weeks) eventually overwhelmed the coral meta-organism as evidenced by eventual declines in photo-physiological function and endosymbiont densities. Investigating flow patterns at the scale of metres within the context of these physiological impacts can reveal interesting avenues for coral reef management. This study increases our understanding of the effects of water flow on coral reef health in an era of climate change and highlights the potential to learn from existing beneficial bio-physical interactions for the effective preservation of coral reefs into the future.
Publisher: Wiley
Date: 18-07-2020
Publisher: Springer Science and Business Media LLC
Date: 15-02-2021
Publisher: CSIRO Publishing
Date: 12-07-2021
DOI: 10.1071/MF21050
Abstract: Climate change is increasing the frequency of marine heatwaves around the world, causing widespread degradation of coral reefs. Endolithic microalgae inhabiting the coral skeleton have been highlighted as potentially important mediators of the consequences of heatwaves on coral reefs. These microalgae often bloom during heat stress due to greater light availability, theoretically delaying coral starvation by providing photoassimilates. However, these microalgae also dissolve coral skeletons at an accelerated rate during marine heatwaves, affecting the structural complexity of the reef. Despite their ecological role, no studies have examined endolithic algal blooms during a natural bleaching event. We quantified blooms of endolithic microalgae in the skeletons of lagoon corals bleaching on Heron Island in the austral summer of 2020. At the peak of heat stress, 20–30% of bleached corals across 9 genera at 3 sites had blooms. They were predominantly seen in branching Acropora spp. (37.8, 65.7 and 66.7% at three sites), which are primary reef builders at Heron Island. At the end of the bleaching event, the overall prevalence varied between 5 and 42%, and nearly all blooms were observed in acroporids. The relative high frequency of these blooms highlights the ongoing need to understand the role of these microbes during coral bleaching events.
Publisher: Frontiers Media SA
Date: 16-08-2019
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.TIM.2017.06.007
Abstract: In marine ecosystems microbial communities are critical to ocean function, global primary productivity, and biogeochemical cycles. Both prokaryotic and eukaryotic microbes are essential symbionts and mutualists, nonpathogenic invaders, primary pathogens, have been linked to disease emergence, and can underpin broader ecosystem changes. However, in the effort to determine coral-microbial interactions, the structure and function of the eukaryotic microbes of the microbiome have been studied less. Eukaryotic microbes are important members of the microbiome, constitute entire kingdoms of life, and make important contributions to ecosystem function. Here, we outline the roles of eukaryotic microbes in marine systems and their contribution to ecosystem change, and discuss the microeukaryotic microbiome of corals and coral reefs.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Alexander Fordyce.