Patchy delivery of functions undermines functional redundancy in a high diversity system

Streit, Robert P., Cumming, Graeme S., and Bellwood, David R. (2019) Patchy delivery of functions undermines functional redundancy in a high diversity system. Functional Ecology, 33 (6). pp. 1144-1155.

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1. Globally, many ecosystems are being challenged and transformed by anthropogenic climate change. Future ecosystem configurations will be heavily influenced by the critical ecological functions that affect resilience. Robust measures of these functions will thus be essential for understanding and responding to ecological change.

2. Coral reefs are experiencing unprecedented ecological change due to global mass coral bleaching. After bleaching events and other disturbances, herbivorous fishes provide functions that are critical for reef resilience by controlling harmful proliferation of algae. Identifying functional diversity amongst herbivorous fishes has been a mainstay of reef fish research, but it has remained unclear how, and to what extent, functional diversity translates to functional impacts on reefs.

3. Rather than assessing the functional potential of the herbivorous fish community, we explicitly considered the delivery of herbivory to the reef by quantifying, in unprecedented detail, the spatial extent and overlap of feeding areas across different functional groups. Core feeding areas were highly concentrated and consistently covered just 14% of available reef space. Overlap across functional groups was limited, showing high spatial complementarity as functional groups tended to feed next to one another. Thus, the delivery of critical ecosystem processes was patchy, effectively reducing functional redundancy, even in the presence of a diverse fish assemblage.

4. Our findings caution against assumptions of spatial homogeneity in the delivery of critical ecosystem functions. The functional impact of local herbivorous fish assemblages in current approaches may be overestimated, potentially leading to skewed assessments of reef resilience. Our results highlight the need to incorporate collective animal behaviour and spatio-temporal scales into future assessments of ecosystem functions and ultimately ecological resilience.

Item ID: 59232
Item Type: Article (Research - C1)
ISSN: 1365-2435
Keywords: animal tracking, coral reef fishes, functional diversity, functional group, grazing pressure, herbivory, spatial resilience, structure-from-motion photogrammetry
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Copyright Information: © 2019 The Authors. Functional Ecology © 2019 British Ecological Society
Additional Information:

A version of this publication was included as Chapter 5 of the following PhD thesis: Streit, Robert Paul (2020) Space use by fishes on coral reefs: establishment, fidelity and reef resilience. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Australian Research Council (ARC)
Projects and Grants: ARC CE140100020
Research Data:
Date Deposited: 15 Apr 2020 02:59
FoR Codes: 41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410203 Ecosystem function @ 100%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960303 Climate Change Models @ 100%
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