Direct and Indirect Effects of Climate Change‐Amplified Pulse Heat Stress Events on Coral Reef Fish Communities

Magel, Jennifer M.T.; Dimoff, Sean A.; Baum, Julia K.

doi:10.1002/bes2.1706

Cited by 12 publications

(10 citation statements)

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“…Prior to heat stress, there was a strong signal of human disturbance on coral symbioses across Kiritimati's reefs. Villages and human activities are located at one end of the atoll, while the rest of it remains largely unvisited by people, creating a gradient of chronic local human disturbance that we quantified based on population density and fishing pressure 21 (Fig. 1a, see "Methods").…”

Section: Resultsmentioning

confidence: 99%

Dynamic symbioses reveal pathways to coral survival through prolonged heatwaves

et al. 2020

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Prospects for coral persistence through increasingly frequent and extended heatwaves seem bleak. Coral recovery from bleaching is only known to occur after temperatures return to normal, and mitigation of local stressors does not appear to augment coral survival. Capitalizing on a natural experiment in the equatorial Pacific, we track individual coral colonies at sites spanning a gradient of local anthropogenic disturbance through a tropical heatwave of unprecedented duration. Unexpectedly, some corals survived the event by recovering from bleaching while still at elevated temperatures. These corals initially had heat-sensitive algal symbiont communities, endured bleaching, and then recovered through proliferation of heat-tolerant symbionts. This pathway to survival only occurred in the absence of strong local stressors. In contrast, corals in highly disturbed areas were already dominated by heat-tolerant symbionts, and despite initially resisting bleaching, these corals had no survival advantage in one species and 3.3 times lower survival in the other. These unanticipated connections between disturbance, coral symbioses and heat stress resilience reveal multiple pathways to coral survival through future prolonged heatwaves.

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Section: Resultsmentioning

confidence: 99%

Dynamic symbioses reveal pathways to coral survival through prolonged heatwaves

et al. 2020

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“…Various environmental and ecological factors might alter the mean rate at which fish respond to reductions in coral cover (e.g. [24–26]). Although bleached coral provides reef habitat until reefs erode [27,28], we made the simplifying assumption that bleached reefs had no coral habitat.…”

Section: Resultsmentioning

confidence: 99%

Global tropical reef fish richness could decline by around half if corals are lost

et al. 2021

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Reef fishes are a treasured part of marine biodiversity, and also provide needed protein for many millions of people. Although most reef fishes might survive projected increases in ocean temperatures, corals are less tolerant. A few fish species strictly depend on corals for food and shelter, suggesting that coral extinctions could lead to some secondary fish extinctions. However, secondary extinctions could extend far beyond those few coral-dependent species. Furthermore, it is yet unknown how such fish declines might vary around the world. Current coral mass mortalities led us to ask how fish communities would respond to coral loss within and across oceans. We mapped 6964 coral-reef-fish species and 119 coral genera, and then regressed reef-fish species richness against coral generic richness at the 1° scale (after controlling for biogeographic factors that drive species diversification). Consistent with small-scale studies, statistical extrapolations suggested that local fish richness across the globe would be around half its current value in a hypothetical world without coral, leading to more areas with low or intermediate fish species richness and fewer fish diversity hotspots.

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“…We sampled coral colonies at 11 fore reef sites (all 10–12 m depth) on Kiritimati, in the central equatorial Pacific (Figure ). The sites span a gradient of chronic local human disturbance (Magel, Burns, Gates, & Baum, 2019; Magel, Dimoff, & Baum, 2020). Sites on the northwest coast of the atoll near the largest villages are exposed to the highest levels of subsistence fishing pressure and sewage runoff, as well as dredging (there is a port at site VH1), while sites at remote ends of the atoll experience virtually no local disturbances.…”

Section: Methodsmentioning

confidence: 99%

“…This metric accounts for the more diffuse, but still important, effects of subsistence fishing on the reef ecosystem. We weighted each metric equally, and from this combined metric we grouped sites into four distinct disturbance categories, termed very low, low, medium and very high (Figure ; Magel et al, 2020); note the sites included in this study are a subset of those in our broader ecological monitoring programme, which also includes sites in a high disturbance category. We sampled sites in August 2014, with one additional site collected in January 2015 to expand the geographical and human disturbance range.…”

Section: Methodsmentioning

confidence: 99%

Increased diversity and concordant shifts in community structure of coral‐associated Symbiodiniaceae and bacteria subjected to chronic human disturbance

et al. 2020

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Both coral‐associated bacteria and endosymbiotic algae (Symbiodiniaceae spp.) are vitally important for the biological function of corals. Yet little is known about their co‐occurrence within corals, how their diversity varies across coral species, or how they are impacted by anthropogenic disturbances. Here, we sampled coral colonies (n = 472) from seven species, encompassing a range of life history traits, across a gradient of chronic human disturbance (n = 11 sites on Kiritimati [Christmas] atoll) in the central equatorial Pacific, and quantified the sequence assemblages and community structure of their associated Symbiodiniaceae and bacterial communities. Although Symbiodiniaceae alpha diversity did not vary with chronic human disturbance, disturbance was consistently associated with higher bacterial Shannon diversity and richness, with bacterial richness by sample almost doubling from sites with low to very high disturbance. Chronic disturbance was also associated with altered microbial beta diversity for Symbiodiniaceae and bacteria, including changes in community structure for both and increased variation (dispersion) of the Symbiodiniaceae communities. We also found concordance between Symbiodiniaceae and bacterial community structure, when all corals were considered together, and individually for two massive species, Hydnophora microconos and Porites lobata, implying that symbionts and bacteria respond similarly to human disturbance in these species. Finally, we found that the dominant Symbiodiniaceae ancestral lineage in a coral colony was associated with differential abundances of several distinct bacterial taxa. These results suggest that increased beta diversity of Symbiodiniaceae and bacterial communities may be a reliable indicator of stress in the coral microbiome, and that there may be concordant responses to chronic disturbance between these communities at the whole‐ecosystem scale.

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Direct and Indirect Effects of Climate Change‐Amplified Pulse Heat Stress Events on Coral Reef Fish Communities

Cited by 12 publications

References 0 publications

Dynamic symbioses reveal pathways to coral survival through prolonged heatwaves

Dynamic symbioses reveal pathways to coral survival through prolonged heatwaves

Global tropical reef fish richness could decline by around half if corals are lost

Increased diversity and concordant shifts in community structure of coral‐associated Symbiodiniaceae and bacteria subjected to chronic human disturbance

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