Native Herbivores Improve Sexual Propagation of Threatened Staghorn Coral Acropora cervicornis

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 3 weeks for 5 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.

Optimizing sexual reproduction of Montipora capitata for restoration: effects of abiotic conditions and light acclimation on juvenile survival and growth

“…In order to prevent complete overgrowth of the juvenile corals, algae was manually removed from plugs and plug racks, and tanks were cleaned on a weekly basis. Importantly, this maintenance was solely to prevent corals from being smothered by mat-forming macroalgae and was not an attempt to represent any form of herbivory, a factor which can be influential when raising corals in an ex situ environment (Craggs et al 2019, Henry et al 2019. Despite these efforts, this algal bloom interfered with data collection and no data was recorded in September due to extensive algae cover.…”

Repeated ex situ Spawning in Two Highly Disease Susceptible Corals in the Family Meandrinidae

“…Coral larvae are easily transported across large distances in high numbers (Petersen et al, 2005), meaning that larvae produced under fully controlled conditions anywhere in the world can be used for direct re-seeding activities (Heyward et al, 2002;dela Cruz and Harrison, 2020). Alternatively, sexually propagated coral recruits and juvenile colonies can be reared in human care for periods of time ranging from a few weeks (Guest et al, 2014;Chamberland et al, 2015), to months (Henry et al, 2019), to a year or more (Craggs et al, 2020).…”

“…Further, Craggs et al (2020) recently reported the first completed life cycle (i.e., production of an F2 generation) for a broadcast spawning coral in a fully controlled system. Beyond spawning, recent advances in rearing techniques for early post-settlement coral recruits have improved sexually propagated coral survival and growth in land-based systems (Craggs et al, 2019;Henry et al, 2019). Altogether, these advances have made sexual coral propagation in land-based systems a viable strategy for augmenting the genetic diversity that is currently available to restoration programs.…”

Growth, calcification, and photobiology of the threatened coral Acropora cervicornis in natural versus artificial light

“…Coral reefs are one of the world's most diverse and fragile ecosystems. They are currently in global decline due to climate change, disease, and other stressors (Hoegh‐Guldberg et al, 2007; Hughes et al, 2003; Walton et al, 2018). The Caribbean region has been especially impacted by coral loss (Gardner et al, 2003).…”

“…As the general practice of active coral restoration expands, land-based nurseries are receiving increased attention. Such nurseries are archiving living genetic diversity being lost in the wild and contributing to successes in sexual coral propagation (Chamberland et al, 2016;Craggs et al, 2017;Henry et al, 2019). Furthermore, many public aquariums maintain exhibits featuring live corals.…”