Climate change impact on Asian coral reef ecosystems
Coral reefs are one of the highest biodiverse and productive marine ecosystem, which provide several ecosystem services, including tourisms and food resources. Meanwhile, coral reefs are now threatened by human impacts all over the world. Particularly, West-Pacific Asian reef is the central of biodiverse, but is one one of the most threatened area, due to the increase of human population and economy.
Our research aimed to understand the human impacts including global scale impacts such as “Ocean Acidification” and "Ocean Warming" as well as the change in water quality on the coral reef organisms and ecosystems. Research methods include ecological field works, measurement of carbon chemistry and water quality, and eco-physiological studies using tank experiments. Fieldworks are mainly conducted in Ryukyu Arquipelago, Palau, and Philippines. Goal of our study is to obtain scientific knowledge that contributes to understand and for better management and conservation of this fascinating coral reef ecosystem.
Research Themes:
Evaluation of climate change (ocean acidification/warming) impacts on coral reef organisms
Ecological studies at high-CO2 vent at Iwoutorishima Island, Okinawa
Ecological studies at natural high water temperature / high CO2 environment at Nikko Bay, Palau
Climate change impacts on seaweed bed
Impact of sewage on coral reefs at Malakal Bay, Palau
Water quality and benthic community structure at coral reef.
Ocean acidification impacts in coastal water and fisheries
Ocean acidification (OA) and warming are progressing with the increase of carbon dioxide concentration in the atmosphere, which is concerned to affect the whole marine ecosystem. Therefore, monitoring carbon chemistry is highly essential for better understanding and predicting the effect of climate change on marine organisms and ecosystems. However, there are still only very limited monitoring data at coastal water, particularly in Asian countries. Taking into account the high productivity and biodiversity at coastal water, and the high reliance on marine fisheries in Asian countries, it is highly essential to understand the progress of OA at coastal area.
For the aim of evaluating the effect of climate change on Japan coastal water and fisheries, we are conducting continuous monitoring of carbon chemistry at several sites along the coast of Japan.
Experimental studies evaluating the effect of OA on marine shellfishes including sea urchins, mollusks and crustaceans are conducted as well.
Coral reef biology
Coral reef is one of the most biodiverse ecosystems which habitat number of precious marine life. We aim to obtain scientific knowledge for better understanding the ecological and physiological aspects of these fascinating creatures.
Research Themes:
Soft coral
Soft corals belong to octocoral which lack of hard skeletons. Although soft corals are commonly found at coral reefs, relative less studies exist compared to hard corals. However, there are several observation suggesting that while the coverage of hard coral is decreasing, soft coral coverage is increasing at Okinawa reef. Furthermore, CO2 vent site at Iwotorishima Island, Okinawa, was found to be fully covered by soft corals, suggesting high tolerance to ocean acidification. We aim to understand the ecological and physiological characteristics of soft corals.
Blue coral
Like soft corals, blue coral (Heliopora coerulea) is a species of octocoral which is characterized by its blue skeleton. It has been known that blue corals include different morphological types, and recent molecular study has revealed the possibility of the existence of different species within the genus Heliopora. We aim to elucidate the physiological and ecological characteristics of these different types of blue corals and clarify the ecology of this species.
Coral mucus
Corals constantly release a large amount of mucus, which can protect the corals from UV and remove sediments from the surface of the corals. Furthermore, the mucus released into seawater is suggested to work as an important food source for the reef organisms and play important role in the organic carbon cycle. By the evaluation of coral mucus, we aim to further understand carbon cycle at coral reefs.
Seaweed bed