Potential local adaptation of corals at acidified and warmed Nikko Bay, Palau

Ocean warming and acidification caused by increases of atmospheric carbon dioxide are now thought to be major threats to coral reefs on a global scale. Here we evaluated the environmental conditions and benthic community structures in semi-closed Nikko Bay at the inner reef area in Palau, which has high pCO2 and seawater temperature conditions with high zooxanthellate coral coverage. Nikko Bay is a highly sheltered system with organisms showing low connectivity with surrounding environments, making this bay a unique site for evaluating adaptation and acclimatization responses of organisms to warmed and acidified environments. Seawater pCO2/Ωarag showed strong gradation ranging from 380 to 982 µatm (Ωarag: 1.79–3.66), and benthic coverage, including soft corals and turf algae, changed along with Ωarag while hard coral coverage did not change. In contrast to previous studies, net calcification was maintained in Nikko Bay even under very low mean Ωarag (2.44). Reciprocal transplantation of the dominant coral Porites cylindrica showed that the calcification rate of corals from Nikko Bay did not change when transplanted to a reference site, while calcification of reference site corals decreased when transplanted to Nikko Bay. Corals transplanted out of their origin sites also showed the highest interactive respiration (R) and lower gross photosynthesis (Pg) to respiration (Pg:R), indicating higher energy acquirement of corals at their origin site. The results of this study give important insights about the potential local acclimatization and adaptation capacity of corals to different environmental conditions including pCO2 and temperature.

Transient demographic approaches can drastically expand the toolbox of coral reef science

Coral communities are threatened by an increasing plethora of abiotic and biotic disturbances. Preventing the ensuing loss of coral coverage and diversity calls for a mechanistic understanding of resilience across coral species and populations that is currently lacking in coral reef science. Assessments into the dynamics of coral populations typically focus on their long-term (i.e. asymptotic) characteristics, tacitly assuming stable environments in which populations can attain their long-term characteristics. Instead, we argue that greater focus is needed on investigating the transient (i.e. short-term) dynamics of coral populations to describe and predict their characteristics and trajectories within unstable environments. Applying transient demographic approaches to the evaluation and forecasting of the responses of coral populations to disturbance holds promise for expediting our capacity to predict and manage the resilience of coral populations, species, and communities.

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

Ocean warming and acidification caused by the increase of atmospheric carbon dioxide are now thought to be major threats to coral reefs on a global scale. Here we evaluated the environmental conditions and benthic community structures in semi-closed Nikko Bay at the inner reef area in Palau, which has high pCO2 and seawater temperature conditions with high zooxanthellate coral coverage. This bay is a highly sheltered system with organisms showing low connectivity with surrounding environments, making this bay a unique site for evaluating adaptation and acclimatization responses of organisms to warmed and acidified environments. Seawater pCO2/Ωarag showed strong graduation ranging from 380 to 982 µatm (Ωarag: 1.79-3.66) and benthic coverage, including soft corals and turf algae, changed along with Ωarag while hard coral coverage did not. In contrast to previous studies, net calcification was maintained in Nikko Bay even under very low mean Ωarag (2.44). Reciprocal transplantation of the dominant coral Porites cylindrica showed that the calcification rate of corals from Nikko Bay did not change when transplanted to a reference site, while calcification of reference site corals decreased when transplanted to Nikko Bay. Corals transplanted out of their origin sites also showed the highest interactive respiration (R) and lower photosynthesis (P) to respiration (P:R). The results of this study give important insights about the potential local acclimatization and adaptation capacity of corals to different environmental conditions including pCO2 and temperature.

Coral cover and rubble cryptofauna abundance and diversity at outplanted reefs in Okinawa, Japan

Global climate change is leading to damage and loss of coral reef ecosystems. On subtropical Okinawa Island in southwestern Japan, the prefectural government is working on coral reef restoration by outplanting coral colonies from family Acroporidae back to reefs after initially farming colonies inside protected nurseries. In order to establish a baseline for future comparisons, in this study we documented the current status of reefs undergoing outplanting at Okinawa Island, and nearby locations where no human manipulation has occurred. We examined three sites on the coast of Onna Village on the west coast of the island; each site included an outplanted and control location. We used (1) coral rubble sampling to measure and compare abundance and diversity of rubble cryptofauna; and (2) coral reef monitoring using Line Intercept Transects to track live coral coverage. Results showed that rubble shape had a positive correlation with the numbers of animals found within rubble themselves and may therefore constitute a reliable abundance predictor. Each outplanted location did not show differences with the corresponding control location in terms of rubble cryptofauna abundance, but outplanted locations had significantly lower coral coverage. Overall, differences between sites (Maeganeku1, Maeganeku2 and Manza, each including both outplanted and control locations) were significant, for both rubble cryptofauna and coral coverage. We recommend (1) to outplant colonies from more stress-resistant genera in place of Acropora, and (2) to conduct regular surveys to monitor the situation closely. With a lack of baseline data preceding impacts, rigorous monitoring over time can highlight trends towards increases or decreases in evaluated variables, allowing to obtain a clearer idea of the effects of transplants and on the trajectory of impacts due to climate change and local stressors . Finally, we also recommend (3) to establish conservation and sustainable practices that could aid the ongoing restoration efforts such as installing anchoring buoys to reduce impacts from anchoring, which could reduce coral mortality of both outplanted and native coral colonies.

Relationship Between Species Composition of Butterflyfishes and Coral Cover (Study case: Taka Bonerate National Park)

The coral reef environment has a strong influence on associated organisms such as fishes, mollusks, and others. Wherein, the butterflyfishes are marine fishes which closely associated with the tropic group as dietary specialization i.e. obligate coral feeder, facultative, and generalist. The obligate may respond only to change in preferred corals and not indicate others. However, generalist show in different response in habitat deteriorates and may allow switching feeding to a less preferred one. Many questions remain about food specific at the species level which may potentially as bio-indicator for coral conditions. Here, we studied the species composition among coral coverage. We explore the environmental degradation in Taka Bonerate National Park impact on food resources and fishes especially for butterflyfishes community. This study focused on family Chaetodontidae with UVC method and UPT method for coral cover. This study was carried out at Taka Bonerate National Park, South Sulawesi between May and June 2019. There were 342 individuals observed and dominated by Chaetodon kleinii, Hemitaurichthys polylepis, Heniochus chrysostomus, C. lunulatus, C. melannotus, C punctatofasciatus, and Forcipiger flavissimus. However, we found a site with diversity index and coral cover has across conditions. Whilst, these benthic communities mostly dominated by Acropora, which may be preferenced by specific species. Butterflyfishes have several types of foraging tasks and may impact in utilizing the coral reef and other social habitats used. The species composition and abundance of butterflyfishes had relations not only by coral coverage but also benthic compositions. However, factors that regulate its specific species distribution and species compositions are still under study.

Effect of coral reef restoration on demersal biodiversity in Okinawa, Japan

Global climate change is leading to damage and loss of coral reef ecosystems. On subtropical Okinawa Island in southwestern Japan, the prefectural government is working on coral reef restoration by outplanting coral colonies from family Acroporidae back to reefs after initially farming colonies inside protected nurseries. In this study we evaluated the ongoing restoration efforts by comparing outplanted locations with nearby control locations with no restoration activity. We examined 3 sites on the coast of Onna Village on the west coast of the island; each site included an outplanted and control location. We used 1) coral rubble sampling to evaluate and compare abundance and diversity of rubble cryptofauna; and 2) coral reef monitoring using photograph transects to track live coral coverage. Results showed that rubble shape had a positive correlation with the numbers of animals found within rubble themselves and may therefore constitute a reliable abundance predictor. Outplanted locations did not show differences with the controls in rubble cryptofauna abundance, but had significantly lower coral coverage. Differences between sites were significant, for both rubble cryptofauna and coral coverage.We recommend; 1) to evaluate outplanting colonies from more stress-resistant genera in place of Acropora, 2) to conduct regular surveys to monitor the situation closely, and 3) to establish conservation and sustainable practices that could aid restoration efforts, reducing coral mortality of both outplanted and native colonies.

Effect of coral reef restoration on demersal biodiversity in Okinawa, Japan

Global climate change is leading to damage and loss of coral reef ecosystems. On subtropical Okinawa Island in southwestern Japan, the prefectural government is working on coral reef restoration by outplanting coral colonies from family Acroporidae back to reefs after initially farming colonies inside protected nurseries. In this study we evaluated the ongoing restoration efforts by comparing outplanted locations with nearby control locations with no restoration activity. We examined 3 sites on the coast of Onna Village on the west coast of the island; each site included an outplanted and control location. We used 1) coral rubble sampling to evaluate and compare abundance and diversity of rubble cryptofauna; and 2) coral reef monitoring using photograph transects to track live coral coverage. Results showed that rubble shape had a positive correlation with the numbers of animals found within rubble themselves and may therefore constitute a reliable abundance predictor. Outplanted locations did not show differences with the controls in rubble cryptofauna abundance, but had significantly lower coral coverage. Differences between sites were significant, for both rubble cryptofauna and coral coverage.We recommend; 1) to evaluate outplanting colonies from more stress-resistant genera in place of Acropora, 2) to conduct regular surveys to monitor the situation closely, and 3) to establish conservation and sustainable practices that could aid restoration efforts, reducing coral mortality of both outplanted and native colonies.

A FORMULATION APPROACH TO QUANTIFY THE ABUNDANCE OF CORAL GENERA

A formulation approach to quantify the abundance of coral genera is considered important to obtain basic information necessary in determining the potency and condition of coral, and one application can also be used to set quota for coral trade. The line intercept method has been used in five different area throughout Indonesian archipelago representing prestine area to heavy disturbances. Based on the number of occurrence, the genera dominance, the size of colony and the coral coverage in each study area was assigned scale, weight and value. The calculation gave the range of Total Value (TV) from 5 -20 and the assignment abundance category of coral genera is 17-20 very common, 14-16 common, 11-13 uncommon, 8 -10 rare, and 5-7 very rare. The categorization of each coral genus of certain area can be used to consider whether it can be harvested or not. Suggestion based on this study as follow: coral genera categorized as "very common" can be harvest, coral genera categorized as "common" can be harvest with caution, coral genera categorized as "uncommon", harvest are limited, coral genera as "rare", harvest are strictly limited and coral genera as "very rare" are prohibited to harvest.