TY - JOUR

T1 - Thermal stress induces persistently altered coral reef fish assemblages

AU - Robinson, J.P.W.

AU - Wilson, S.K.

AU - Jennings, S.

AU - Graham, N.A.J.

N1 - This is the peer reviewed version of the following article: Robinson, JPW, Wilson, SK, Jennings, S, Graham, NAJ. Thermal stress induces persistently altered coral reef fish assemblages. Glob Change Biol. 2019; 25: 2739– 2750. https://doi.org/10.1111/gcb.14704 which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14704 This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.

PY - 2019/8/1

Y1 - 2019/8/1

N2 - Ecological communities are reorganizing in response to warming temperatures. For continuous ocean habitats this reorganization is characterized by large-scale species redistribution, but for tropical discontinuous habitats such as coral reefs, spatial isolation coupled with strong habitat dependence of fish species imply that turnover and local extinctions are more significant mechanisms. In these systems, transient marine heatwaves are causing coral bleaching and profoundly altering habitat structure, yet despite severe bleaching events becoming more frequent and projections indicating annual severe bleaching by the 2050s at most reefs, long-term effects on the diversity and structure of fish assemblages remain unclear. Using a 23-year time series spanning a thermal stress event, we describe and model structural changes and recovery trajectories of fish communities after mass bleaching. Communities changed fundamentally, with the new emergent communities dominated by herbivores and persisting for >15 years, a period exceeding realized and projected intervals between thermal stress events on coral reefs. Reefs which shifted to macroalgal states had the lowest species richness and highest compositional dissimilarity, whereas reefs where live coral recovered exceeded prebleaching fish richness, but remained dissimilar to prebleaching compositions. Given realized and projected frequencies of bleaching events, our results show that fish communities historically associated with coral reefs will not re-establish, requiring substantial adaptation by managers and resource users.

AB - Ecological communities are reorganizing in response to warming temperatures. For continuous ocean habitats this reorganization is characterized by large-scale species redistribution, but for tropical discontinuous habitats such as coral reefs, spatial isolation coupled with strong habitat dependence of fish species imply that turnover and local extinctions are more significant mechanisms. In these systems, transient marine heatwaves are causing coral bleaching and profoundly altering habitat structure, yet despite severe bleaching events becoming more frequent and projections indicating annual severe bleaching by the 2050s at most reefs, long-term effects on the diversity and structure of fish assemblages remain unclear. Using a 23-year time series spanning a thermal stress event, we describe and model structural changes and recovery trajectories of fish communities after mass bleaching. Communities changed fundamentally, with the new emergent communities dominated by herbivores and persisting for >15 years, a period exceeding realized and projected intervals between thermal stress events on coral reefs. Reefs which shifted to macroalgal states had the lowest species richness and highest compositional dissimilarity, whereas reefs where live coral recovered exceeded prebleaching fish richness, but remained dissimilar to prebleaching compositions. Given realized and projected frequencies of bleaching events, our results show that fish communities historically associated with coral reefs will not re-establish, requiring substantial adaptation by managers and resource users.

KW - beta diversity

KW - biodiversity

KW - biotic homogenization

KW - bleaching

KW - community structure

KW - coral reef ecology

KW - regime shifts

KW - thermal stress

KW - Anthozoa

U2 - 10.1111/gcb.14704

DO - 10.1111/gcb.14704

M3 - Journal article

VL - 25

SP - 2739

EP - 2750

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

IS - 8

ER -