Native Herbivores Improve Sexual Propagation of Threatened Staghorn Coral Acropora cervicornis

Joseph A Henry,Keri L O’Neil,Joshua T Patterson

doi:10.3389/fmars.2019.00713

Joseph A Henry, Keri L O’Neil + Show 1 more

Open Access

https://doi.org/10.3389/fmars.2019.00713

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Abstract

Staghorn coral Acropora cervicornis was once spatially dominant on Caribbean reefs but is now threatened throughout its range. In recent years, advancements in ex-situ sexual propagation of Caribbean corals have increased the viability of this management strategy. Thus, improving culture methods for sexually propagated corals is important to bolster the overall coral restoration portfolio and increase genetic diversity in restored populations. In both natural systems and culture scenarios, algae proliferation negatively impacts coral growth and survival. Growing coral with native herbivores may represent a strategy for increased efficiency. We tested A. cervicornis recruits raised in replicate aquaria with identical densities of juvenile Lithopoma americanum or juvenile Batillaria minima snails plus a no-snail control. Each of three replicates per treatment contained tiles with similar numbers of recently settled, visually healthy, A. cervicornis. Tiles were photographed every three weeks for five months and coral growth, survivability, turf algae cover, and crustose coralline algae (CCA) cover were quantified. Labor time for cleaning was carefully recorded for each treatment. Results indicated improved growth and survival when A. cervicornis recruits were raised with either snail species in comparison to a no-herbivore control. Further, including snails decreased labor and eliminated turf algae cover. Interestingly, L. americanum significantly reduced CCA cover relative to the other treatments. We report some of the highest survival rates observed to date for sexually propagated Atlantic corals. Ultimately, results suggest that rearing sexually propagated A. cervicornis with native herbivores could improve the ability to employ these corals in reef restoration.

Highlights

Persistent global coral reef degradation continues to amplify the need to improve understanding of these ecosystems and develop new methodologies to aid in their restoration
Replicate aquaria containing L. americanum, B. minima, and no-snail controls began the experiment with 33.3 ± 0.9, 34.7 ± 1.2, and 35.7 ± 1.2 coral recruits, respectively
Our results support the hypothesis that native Caribbean herbivorous snails represent a viable means of increasing sexual propagation efficiency in A. cervicornis

Summary

Introduction

Persistent global coral reef degradation continues to amplify the need to improve understanding of these ecosystems and develop new methodologies to aid in their restoration. Coral Sexual Propagation for Restoration including climate change, disease, pollutants, and extreme weather events continue to place these vulnerable ecosystems on the edge of loss (Goreau and Hilbertz, 2005; Young et al, 2012). Many Caribbean reefs have reached a point at which natural processes are no longer capable of fully recovering the habitat (Goreau and Hilbertz, 2005). For this reason, active reef restoration is a vital tool for the future of coral reefs (Rinkevich, 2008; Van Oppen et al, 2017). Scaling-up out-planting capabilities and reducing associated costs are critical to the success of active reef restoration (Young et al, 2012)

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