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As the devastating impacts of global climate change and local anthropogenic stressors on shallow-water coral reefs are expected to rise, mesophotic coral ecosystems have increasingly been regarded as potential lifeboats for coral survival, providing a source of propagules to replenish shallower reefs. Yet, there is still limited knowledge of the capacity for coral larvae to adjust to light intensities that change with depth. This study elucidates the mechanisms underlying plasticity during early life stages of the coral Porites astreoides that enable survival across broad depth gradients. We examined physiological and morphological variations in larvae from shallow (8–10 m) and mesophotic (45 m) reefs in Bermuda, and evaluated differences in survival, settlement patterns and size among recruits depending on light conditions using a reciprocal ex situ transplantation experiment. Larvae released from mesophotic adults were found to have significantly lower respiration rates and were significantly larger than those derived from shallow adults, indicating higher content of energetic resources and suggesting a greater dispersal potential for mesophotic larvae compared to their shallow counterparts. Additionally, larvae released from mesophotic adults experienced higher settlement success and larger initial spat size compared to larvae from shallow adults, demonstrating a potential connection between parental origin, offspring quality, and recruitment success. Although both shallow and mesophotic larvae exhibited the capacity to survive and settle under reciprocal light conditions, all larvae had higher survival under mesophotic light conditions regardless of parental origin, suggesting that conditions experienced under low light may enable longer larval life, further extending the dispersal period. These results indicate that larvae from mesophotic Porites astreoides colonies are likely capable of reseeding shallow reefs in Bermuda, thereby supporting the Deep Reef Refugia Hypothesis.
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Species level identification of Antillogorgia spp. recruits identifies multiple pathways of octocoral success on Caribbean reefs
Successful recruitment is critical to the maintenance and resilience of populations and may be at the core of the transition from scleractinian to octocoral dominated faunas on some Caribbean reefs. For sessile invertebrates, recruitment incorporates the composite effects of larval supply, settlement and survival. The relative success of these processes differs between species and successful recruitment may be achieved through different life history strategies. Recruitment of six abundant and widespread Antillogorgia spp. was assessed at six sites on Little Bahama Bank from 2009–2012. Identification of recruits to species level, based on microsatellite analyses, revealed differences in recruitment and survival between species, sites and ears. The broadcast spawning species, A. americana and A. acerosa had low rates of early recruitment and postsettlement survival. Higher levels of recruitment success were achieved among brooding and surface brooding species following somewhat different patterns of early recruitment and survival. The internal brooder Antillogorgia hystrix had the highest recruitment at five of the sites but low survival dramatically reduced its abundance and after a year it had similar densities as the surface brooding species, A. elisabethae and A. bipinnata. The brooders have smaller colonies and will produce fewer larvae than the broadcast spawning species, but they release competent larvae which probably accounts for their higher recruitment rates. The Antillogorgia illustrate the diversity of successful reproductive strategies exhibited by octocorals, and differences in the life history strategies among these congeners are best characterized by their mode of larval development.
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- PAR ID:
- 10203140
- Date Published:
- Journal Name:
- Coral Reefs
- ISSN:
- 0722-4028
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s00338-020-02014-5
