Potential Acclimatization and Adaptive Responses of Adult and Trans-Generation Coral Larvae From a Naturally Acidified Habitat

Abstract

Coral reefs are one of the most susceptible ecosystems to ocean acidification (OA) caused by increasing atmospheric carbon dioxide (CO2). OA is suspected to impact the calcification rate of corals as well as multiple early life stages including larval and settlement stages. Meanwhile, there is now a strong interest in evaluating if organisms have the potential for acclimatization or adaptation to OA. Here, by taking advantage of a naturally acidified site in Nikko Bay, Palau where corals are presumably exposed to high CO2 conditions for their entire life history, we tested if adult and the next-generation larvae of the brooder coral Pocillopora acuta originating from the high-CO2 site are more tolerant to high CO2 conditions compared to the individuals from a control site. Larvae released from adults collected from the high-CO2 site within the bay and a control site outside the bay were reciprocally cultivated under experimental control or high-CO2 seawater conditions to evaluate their physiology. Additionally, reciprocal transplantation of adult P. acuta corals were conducted between the high-CO2 and control sites in the field. The larvae originating from the control site showed lower Chlorophyll-a content and lipid percentages when reared under high-CO2 compared to control seawater conditions, while larvae originating from the high-CO2 site did not. Additionally, all 10 individuals of adult P. acuta from control site died when transplanted within the bay, while all P. acuta corals within the bay survived at both control and high-CO2 site. Furthermore, P. acuta within the bay showed higher calcification and net photosynthesis rates when exposed to the condition they originated from. These results are one of the first results that indicate the possibility that the long-living corals could enable to show local adaptation to different environmental conditions including high seawater pCO2.

Potential Local Adaptation of Corals at Acidified and Warmed Nikko Bay, Palau

“…However, taking into account that only the calci cation rate of P. cylindrica at site M1 decreased when transplanted to site N5, potential epigenetic or genetic adaptation to the environmental conditions found within the bay appears to have occurred for Nikko Bay corals. This is also indicated by other ndings that showed Pocillopora acuta within Nikko Bay had higher calci cation rate when transplanted to their original site than out of the bay, while P. acuta from out of the bay were not able to survive when transplanted within the bay 33 .…”

Geographical Variation in Phenotypic Plasticity of Intertidal Sister Limpet’s Species Under Ocean Acidification Scenarios

“…According to the literature, differences in populations' metabolic responses might be related to their aerobic capacity as an adaptation to different habitats (Clarke and Fraser, 2004;Watson et al, 2014). Therefore, compared populations that occupy more stable environments (Los Molles) with populations that inhabit more variable environments appear to be more tolerant to extreme acute acidification events because of their higher metabolic limits (Osores et al, 2017;Jahnsen-Guzmán et al, 2020;Kurihara et al, 2020). However, many studies indicate that these populations may be at higher risk because of the adverse effects of chronic exposure to acidification, where higher metabolic costs may imply trade-offs (i.e., a decrease in calcification) (Lannig et al, 2010;Lagos et al, 2016;Osores et al, 2017).…”

The Bouraké semi-enclosed lagoon (New Caledonia) – a natural laboratory to study the lifelong adaptation of a coral reef ecosystem to extreme environmental conditions

“…In these environments, one or the combination of more environmental conditions differ from present-day values, providing an opportunity to assess the resilience of organisms and to study their adaptive mechanisms in a natural environment. Coral reefs, exposed to seawater pH and temperature values that are close to or even worse than those expected for the future, have likely developed physiological trade-offs and expressed molecular changes that allow them to survive suboptimal and extreme conditions (Kurihara et al, 2021). When using these natural laboratories to predict species responses to future environmental conditions, it is essential to take a multi-scale approach that incorporates the spatial and temporal variability in the key physical and chemical parameters characterizing the study site (e.g., Vizzini et al, 2013;Camp et al, 2018;Aiuppa et al, 2021).…”

“…However, some natural laboratories can host very rich reef communities. Examples of such sites have been documented in Palau (Golbuu et al, 2016;Barkley et al, 2017;Shamberger et al, 2018;Kurihara et al, 2021), Papua New Guinea (Pichler et al, 2019), the Kimberley region, Australia (Dandan et al, 2015;Schoepf et al, 2015), mangrove lagoons of New Caledonia (Camp et al, 2017), and the US Virgin Islands (Yates et al, 2014). These natural laboratories have become a common experimental asset in climate change research.…”