About us
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We focus on the interactions between marine organisms and their ambient environment, aiming to elucidate the principles of the marine biogeochemical cycle. Additionally, our study also contributes to predicting the responses of organisms and ecosystems to global climate change.
Study
01 Blue Carbon in Macrophytes bed
01 Blue Carbon in Macrophytes bed
Macrophyte beds, including seaweed and seagrass, are one of the productive biota on the Earth's surface. Their contribution to Blue Carbon (carbon sequestered by marine organisms) has recently gained attention, necessitating an analysis of carbon flow. We have studied to evaluate processes such as photosynthesis, dislodgement, release of dissolved organic matter, and decomposition. These efforts will enhance predictions related to climate change and aid in establishing adaptation strategies for marine ecosystems.
Dislodgement of algae was assessed based on disappearance of tags attached on their holdfast.
Iso-yake has been frequently observed in recent years. It is necessary to predict the effects of Iso-yake on coastal ecosystems.
Fluorescent spectra of macroalgal DOM showed several peaks in the seawater samples.
02 Responses of Ecosystems for Ocean Acidification
02 Responses of Ecosystems for Ocean Acidification
Approximately one-third of anthropogenic CO2 is absorbed by the ocean, contributing to the mitigation of global warming. However, shifts in carbonate chemistry will have serious effects on marine organisms and ecosystems. In recent years, we have discovered volcanic CO2 seeps around Shikine Island, which is used as natural analogues for ocean acidification. We have assumed the area around the CO2 vent as future ecosystems and have tested potential responses of ecosystems and biogeochemical processes. An international network, ICONA (International CO2 & Natural Analogues Network), was established in April 2021. We are collaborating with research institutes studying natural analogues such as CO2 seeps.
The photo shows an area with bubbles of CO2 gas emerging from the seafloor. There is gradients of CO2 concentrations extending outward from the CO2 seep.
In the area near the CO2 vent, the CO2 concentration levels approximate those expected by the end of the 21st century. There has been a decrease in the abundance of coral and large seaweed, with low-profile and turf algae now covering the seafloor.
The present ecosystem is established at the reference site, unaffected by volcanic CO2. Because Shikine Island is located in a warm-temperate region, we can observe a mixed community of coral and seaweed there.
This is one of the CO2 seeps. We cover the ocean floor with a chamber to measure photosynthesis.
03 Dynamics of marine snow
03 Dynamics of marine snow
Marine snow plays a crucial role as a carrier of biogenic carbon to the ocean interior and helps regulate atmospheric CO2 levels. Despite its importance, the dynamics of marine snow remain largely unknown. We have focused particularly on organic aggregates, exploring the physicochemical processes involved in their formation and breakdown, which underlie marine biogeochemical processes.
Bubbles appeared after a strong wind, potentially scavenging organic matter.
Couette chamber: The adhesion and breakup of aggregates depend heavily on hydrodynamic forces. This device generates a constant laminar shear flow.
Stained marine snow: The blue-colored particles are marine snow stained with alcian blue, which binds to acidic polysaccharides.
Large-sized sediment trap: To collect a large amount of sinking particles within a short period, we utilized a sediment trap approximately 1 meter in size.
Approaches for our study
Surveys
Seawater collection and analysis of water chemistry using sensors
Diving in algal beds and CO2 seeps
Analysis
Chromatographies (GC, HPLC etc.)
Analyses of elements and compounds based on colorimetric and fluorometric methods
Tracing organic matter using stable isotopes
Contacts us
If you are interested in Ocean, you can enjoy studying in our lab.
Please contact us when you have any questions.
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