Response and Effect Traits of Coral Reef Fish

Marginal reefs sustain coral assemblages under conditions considered suboptimal for most corals, resulting in low coral abundance. These reefs are inhabited by numerous fishes with a generally unknown degree of association with corals that might lead to the assumption that corals play minor roles in determining fish occurrence, when corals could be actually sustaining diverse and resilient assemblages. Using site-occupancy models fitted to data of 113 reef fish species of different life stages (adults and juveniles) from 36 reefs distributed across the Southwestern Atlantic (0.87–27.6°S) we first assessed fish assemblage’s response to coral and turf algal cover, and identified coral-associated fish. Then, we simulated the loss of coral-associated fishes and contrasted it with random losses, providing inferences on the resilience of fish assemblage’s functional trait space to species loss. The entire fish assemblage responded more positively to coral than to turf algae, with 42 (37%) species being identified as coral-associated fish. The simulated loss of coral-associated fish reduced up to 5% the functional trait space and was not different from the random loss. These results reveal that marginal reefs of Southwestern Atlantic reefs host resilient fish assemblages that might preserve fundamental ecological functions and ecosystem services even with coral declines.

Section: Discussionmentioning

confidence: 99%

Low functional vulnerability of fish assemblages to coral loss in Southwestern Atlantic marginal reefs

Luza

Quimbayo

Ferreira

et al. 2022

“…‘Response framework’), as well as signaling potential shifts in core ecological processes that underpin the transfer of energy and materials (i.e. ‘Effect framework’) 69 (details on trait levels and their expected role are provided in Table S3 ). Missing trait values were inferred from conspecific species, generally from the same geographic area, based on the published literature and the author’s combined knowledge of the species.…”

Section: Methodsmentioning

confidence: 99%

Black coral forests enhance taxonomic and functional distinctiveness of mesophotic fishes in an oceanic island: implications for biodiversity conservation

Bosch

Espino

Tuya

et al. 2023

The degradation of shallow ecosystems has called for efforts to understand the biodiversity and functioning of Mesophotic Ecosystems. However, most empirical studies have been restricted to tropical regions and have majorly focused on taxonomic entities (i.e., species), neglecting important dimensions of biodiversity that influence community assembly and ecosystem functioning. Here, using a subtropical oceanic island in the eastern Atlantic Ocean (Lanzarote, Canary Islands), we investigated variation in (a) alpha and (b) beta functional (i.e., trait) diversity across a depth gradient (0–70 m), as a function of the presence of black coral forests (BCFs, order Antipatharian) in the mesophotic strata, a vulnerable but often overlooked ‘ecosystem engineer’ in regional biodiversity. Despite occupying a similar volume of the functional space (i.e., functional richness) than shallow (< 30 m) reefs, mesophotic fish assemblages inhabiting BCFs differed in their functional structure when accounting for species abundances, with lower evenness and divergence. Similarly, although mesophotic BCFs shared, on average, 90% of the functional entities with shallow reefs, the identity of common and dominant taxonomic and functional entities shifted. Our results suggest BCFs promoted the specialization of reef fishes, likely linked to convergence towards optimal traits to maximize the use of resources and space. Regional biodiversity planning should thus focus on developing specific management and conservation strategies for preserving the unique biodiversity and functionality of mesophotic BCFs.

“…Seven species-level fish traits were evaluated in this paper: body length (size), diet, schooling behaviour (gregariousness), position in the water column, reef association, and length at maturity. These traits were carefully selected according to whether they were likely to respond to protection from fishing and affect ecosystem functioning 11 (see trait inclusion justification; Supplementary Table S1 ). The trait-based analysis was based on abundance data, as species level biomass estimates were not possible from the survey methodology, and the literature on trait-based ecology favours abundance-weighting 15 .…”

Section: Methodsmentioning

confidence: 99%

“…“Functional traits” are suggestive of the mechanistic links between species’ responses to disturbances and management practices and their potential effects on ecosystem processes 11 . The first step in applying a trait-based approach is therefore to carefully select the traits most applicable to the ecological processes and research questions of interest.…”

Section: Introductionmentioning

confidence: 99%

Decadal shifts in traits of reef fish communities in marine reserves

Hadj‐Hammou

McClanahan

Graham

2021

Self Cite

Marine reserves are known to impact the biomass, biodiversity, and functions of coral reef fish communities, but the effect of protective management on fish traits is less explored. We used a time-series modelling approach to simultaneously evaluate the abundance, biomass, and traits of eight fish families over a chronosequence spanning 44 years of protection. We constructed a multivariate functional space based on six traits known to respond to management or disturbance and affect ecosystem processes: size, diet, position in the water column, gregariousness, reef association, and length at maturity. We show that biomass increased with a log-linear trend over the time-series, but abundance only increased after 20 years of closure, and with more variation among reserves. This difference is attributed to recovery rates being dependent on body sizes. Abundance-weighted traits and the associated multivariate space of the community change is driven by increased proportions over time of the trait categories: 7–15 cm body size; planktivorous; species low in the water column; medium-large schools; and species with high levels of reef association. These findings suggest that the trait compositions emerging after the cessation of fishing are novel and dynamic.