Cryopreservation can assist gene flow on the Great Barrier Reef

Jonathan Daly,Mary Hagedorn,Jessica Bouwmeester,Justine K O’Brien,Nikolas Zuchowicz,Rebecca J Hobbs,Kate Quigley,Line Bay

doi:10.1007/s00338-021-02202-x

Abstract

AbstractMaintaining genetic diversity and biodiversity is key to sustaining healthy ecosystems and their capacity for adaptation. Assisted Gene Flow (AGF) is a management approach to translocate adaptive genes among populations to restore faltering and at-risk habitats, especially on coral reefs. Cryopreserved sperm can facilitate AGF via selective breeding at a lower cost and with fewer risks than sourcing colonies from the wild or moving adult corals (translocation) . Here, we present a proof-of-concept study demonstrating that cryopreserved sperm from northern and central Great Barrier Reef (GBR) locations can be used to make intrapopulation and interpopulation crosses to underpin AGF. The results of this study support the importance of assessing the concentration of motile sperm in post-thaw samples, with a minimum of approximately 30,000 motile cryopreserved sperm per egg required to achieve fertilisation. Mean per cent motility values post-collection and without artificial activation (northern colonies 14 ± 3.2%; central colonies 19 ± 3.6%) were considerably lower than previous observations of sperm from Acropora tenuis on the Great Barrier Reef, and may represent a lag effect from recent ocean warming events at the level of coral populations. Coral reefs with relatively high species and genetic diversity and coral cover are good places to preserve biodiversity through cryopreservation. Such cryo-collections build a genetic resource to optimise strategies available to reef managers to support natural recovery rates and reef restoration and adaptation efforts.

Highlights

The survival of populations and species impacted by the effects of climate change will depend on their ability to adapt to rapidly changing environments
The negative impact of ocean warming on coral reproduction is well-documented (Ward et al 2000; Omori et al 2001; Levitan et al 2014; Hagedorn et al 2016), which can reduce opportunities for genetic recombination and potentially result in long-term declines in the composition and amount of recruitment of new corals (Hughes et al 2019)
Colonies of Acropora tenuis were collected in November 2018 from central and northern regions of the GBR (Fig. 1a, Great Barrier Reef Marine Park Authority Permit Numbers G12/35236.1 and G18/41667.1, respectively) by staff from the Australian Institute of Marine Science (AIMS) and Great Barrier Reef Legacy

Summary

Introduction

The survival of populations and species impacted by the effects of climate change will depend on their ability to adapt to rapidly changing environments. When the rate of environmental change exceeds the capacity for adaptation species are likely to suffer severe population declines. The effects of ocean warming, acute heat events, and subsequent mass bleaching have devastated species on reefs throughout the tropics (Eakin et al 2019). The negative impact of ocean warming on coral reproduction is well-documented (Ward et al 2000; Omori et al 2001; Levitan et al 2014; Hagedorn et al 2016), which can reduce opportunities for genetic recombination and potentially result in long-term declines in the composition and amount of recruitment of new corals (Hughes et al 2019). Corals around the world will likely experience a significant loss of

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