Decadal shifts in traits of reef fish communities in marine reserves

Jeneen Hadj-Hammou,Tim R Mcclanahan,Nicholas A J Graham

doi:10.1038/s41598-021-03038-9

Jeneen Hadj-Hammou, Tim R Mcclanahan + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-03038-9

Copy DOI

Abstract

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.

Highlights

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
No-take marine reserves are a widely used management and conservation tool, the implementation of which has been linked to a range of outcomes including increases in fish abundance, biomass, diversity, and the presence of functionally important s pecies[1,2,3]
When the slope of the biomass curve was allowed to vary by marine reserve, the marine reserve trends remained very similar to the global trend

Summary

Introduction

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. 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. Such novel configurations can sometimes produce the same ecosystem processes as previous communities, result in the loss of some functioning, or a new balance of functions and services can establish[16,17,18] Key traits such as fish body size, trophic level, and life history strategies mediate the relationship between disturbance/recovery and abundance, biomass, and biomass production—all essential components for sustainable ecosystem functioning[19,20,21,22,23]

Methods

Results

Conclusion