Cross-scale habitat structure driven by coral species composition on tropical reefs

Richardson, Laura E.; Graham, Nicholas A. J.; Hoey, Andrew S.

doi:10.1038/s41598-017-08109-4

Cited by 53 publications

(49 citation statements)

References 75 publications

(127 reference statements)

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“…With widespread coral bleaching across habitats, our results illustrate the differential susceptibility of distinct reef fish assemblages, governed primarily by the vulnerability of particular fish traits associated with specific coral configurations. Coral habitats provide a range of niche spaces for the coexistence of diverse but functionally unbalanced fish assemblages (Brandl, Emslie, Ceccarelli, & Richards, ; Mouillot et al., ; Richardson, Graham, & Hoey, ). Some provide particular niche habitat to specialist guilds of fishes (Richardson, Graham, Pratchett, et al., ), such that relatively small habitat disturbance may incur disproportionate change in fish assemblage structure.…”

Section: Discussionmentioning

confidence: 99%

Mass coral bleaching causes biotic homogenization of reef fish assemblages

Richardson

Graham

Pratchett

et al. 2018

Global Change Biology

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Global climate change is altering community composition across many ecosystems due to nonrandom species turnover, typically characterized by the loss of specialist species and increasing similarity of biological communities across spatial scales. As anthropogenic disturbances continue to alter species composition globally, there is a growing need to identify how species responses influence the establishment of distinct assemblages, such that management actions may be appropriately assigned. Here, we use trait-based analyses to compare temporal changes in five complementary indices of reef fish assemblage structure among six taxonomically distinct coral reef habitats exposed to a system-wide thermal stress event. Our results revealed increased taxonomic and functional similarity of previously distinct reef fish assemblages following mass coral bleaching, with changes characterized by subtle, but significant, shifts toward predominance of small-bodied, algal-farming habitat generalists. Furthermore, while the taxonomic or functional richness of fish assemblages did not change across all habitats, an increase in functional originality indicated an overall loss of functional redundancy. We also found that prebleaching coral composition better predicted changes in fish assemblage structure than the magnitude of coral loss. These results emphasize how measures of alpha diversity can mask important changes in the structure and functioning of ecosystems as assemblages reorganize. Our findings also highlight the role of coral species composition in structuring communities and influencing the diversity of responses of reef fishes to disturbance. As new coral species configurations emerge, their desirability will hinge upon the composition of associated species and their capacity to maintain key ecological processes in spite of ongoing disturbances.

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Section: Discussionmentioning

confidence: 99%

Mass coral bleaching causes biotic homogenization of reef fish assemblages

Richardson

Graham

Pratchett

et al. 2018

Global Change Biology

Self Cite

159

133

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show abstract

“…It is therefore unlikely that coral cover alone captures the variability in reef structure and community calcification mediated by different coral taxa (Alvarez‐Filip, Dulvy, Cote, Watkinson, & Gill, ; Perry, Murphy, et al., ). For instance, reefs dominated by species with high structural complexity and high growth rates are likely to not only maintain more diverse communities but also regulate the functional structure of reef communities (Alvarez‐Filip, Gill, & Dulvy, ; Richardson, Graham, & Hoey, ).…”

Section: Impacts Associated With Eco‐morphological Taxa Transitions (mentioning

confidence: 99%

Changing geo‐ecological functions of coral reefs in the Anthropocene

2018

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The ecology of many coral reefs has changed markedly over recent decades in response to various combinations of local and global stressors. These ecological changes have important implications for the abundance of taxa that regulate the production and erosion of skeletal carbonates, and thus for many of the geo‐ecological functions that coral reefs provide, including reef framework production and sediment generation, the maintenance of reef habitat complexity and reef growth potential. These functional attributes underpin many of the ecosystem goods and services that reefs provide to society. Rapidly changing conditions of reefs in the Anthropocene are likely to significantly impact the capacity of reefs to sustain these geo‐ecological functions. Although the Anthropocene footprint of disturbance will be expressed differently across ecoregions and habitats, the end point for many reefs may be broadly similar: (a) progressively shifting towards net neutral or negative carbonate budget states; (b) becoming structurally flatter; and (c) having lower vertical growth rates. It is also likely that a progressive depth‐homogenisation will occur in terms of these processes. The Anthropocene is likely to be defined by an increasing disconnect between the ecological processes that drive carbonate production on the reef surface, and the net geological outcome of that production, that is, the accumulation of the underlying reef structure. Reef structures are thus likely to become increasingly relict or senescent features, which will reduce reef habitat complexity and sediment generation rates, and limit reef potential to accrete vertically at rates that can track rising sea levels. In the absence of pervasive stressors, recovery of degraded coral communities has been observed, resulting in high net‐positive budgets being regained. However, the frequency and intensity of climate‐driven bleaching events are predicted to increase over the next decades. This would increase the spatial footprint of disturbances and exacerbate the magnitude of the changes described here, limiting the capacity of many reefs to maintain their geo‐ecological functions. The enforcement of effective marine protection or the benefits of geographic isolation or of favourable environmental conditions (“refugia” sites) may offer the hope of more optimistic futures in some locations. A >plain language summary is available for this article.

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“…For example, in the Hawaiian Islands the arrangement and composition of seafloor topography, benthic community cover, and wave exposure are important predictors of coral reef fish assemblages (Friedlander et al 2003, Wedding et al 2008. The patterns in the distribution and abundance of marine fishes are evident across multiple spatial scales, as coral reef ecosystems demonstrate spatial heterogeneity at centimeter (Barott et al 2012), meter (Richardson et al 2017) and kilometer scales (Gove et al 2015). However, the spatial scales at which biophysical drivers influence and predict coral reef benthic community seascapes has not been as well studied, and a multi-scaled approach is needed to understand the resulting spatial patterns and processes (Williams, G. J. et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Scale‐dependent spatial patterns in benthic communities around a tropical island seascape

et al. 2018

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Understanding and predicting patterns of spatial organization across ecological communities is central to the field of landscape ecology, and a similar line of inquiry has begun to evolve sub-tidally among seascape ecologists. Much of our current understanding of the processes driving marine community patterns, particularly in the tropics, has come from small-scale, spatially-discrete data that are often not representative of the broader seascape. Here we expand the spatial extent of seascape ecology studies and combine spatially-expansive in situ digital imagery, oceanographic measurements, spatial statistics, and predictive modeling to test whether predictable patterns emerge between coral reef benthic competitors across scales in response to intra-island gradients in physical drivers. We do this around the entire circumference of a remote, uninhabited island in the central Pacific (Jarvis Island) that lacks the confounding effects of direct human impacts. We show, for the first time, that competing benthic groups demonstrate predictable scaling patterns of organization, with positive autocorrelation in the cover of each group at scales < ~1 km. Moreover, we show how gradients in subsurface temperature and surface wave power drive spatially-abrupt transition points in group dominance, explaining 48-84% of the overall variation in benthic cover around the island. Along the western coast, we documented ten times more sub-surface cooling-hours than any other part of the coastline, with events typically resulting in a drop of 1-4°C over a period of < 5 h. These high frequency temperature fluctuations are indicative of upwelling induced by internal waves and here result in localized nitrogen enrichment (NO 2 + NO 3 ) that promotes hard coral dominance around 44% of the island's perimeter. Our findings show that, in the absence of confounding direct human impacts, the spatial organization of coral reef benthic competitors are predictable and somewhat bounded across the seascape by concurrent gradients in physical drivers.

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Cross-scale habitat structure driven by coral species composition on tropical reefs

Cited by 53 publications

References 75 publications

Mass coral bleaching causes biotic homogenization of reef fish assemblages

Mass coral bleaching causes biotic homogenization of reef fish assemblages

Changing geo‐ecological functions of coral reefs in the Anthropocene

Scale‐dependent spatial patterns in benthic communities around a tropical island seascape

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