“Oceans – and the impact of humans and climate change” - OIST-Tohoku U. 2nd Joint Workshop on Marine Science

North Pacific subtropical mode water, which is water mass of vertically uniform temperature that is a few hundred meters thick and distributed widely in the subtropical subsurface ocean, has warmed over the past seven decades. The rate of the warming is 1.13 ± 0.27 °C per century, which is twice as large than the surface. The enhanced warming can be traced back to the surface warming in the formation regions of subtropical mode water along the western boundary current extensions, which suggests that it is a robust feature of global warming.

Fisheries are a key source of protein for billions of people around the world and are of particular importance to coastal communities. Even though the need for sustainable fisheries management has become widely recognized, current practices of assessment and management are still focused almost exclusively on the demography of target stocks. This narrow perspective misses out on the wider biological impacts of fisheries, on the socio-economic implications of ecosystem services, and on the plurality of stakeholder interests. In this presentation, I will describe innovative approaches for broadening this focus by (1) addressing multiple eco-evolutionary impacts, (2) examining multiple societal objectives, and (3) reconciling multiple stakeholder groups. Practices of sustainable fisheries management will need to account for and integrate these three dimensions if they are to achieve their objectives and serve all sectors of society.

Understanding biodiversity and its responses to climate change or human activities is becoming one of the most important challenges of Anthropocene. However, the complexity and enormity of ecological system make it an extremely challenging field. In this talk I propose a data-driven, model-free approach that combines a biodiversity monitoring data and nonlinear time-series analysis as a powerful tool to overcome these research difficulties and make ecology a more practical discipline. Recently developing environmental DNA-based biodiversity survey can grow as a core technology contributing to such an approach not only by providing “ecological big data”, but also by empowering citizens involved in biodiversity conservation. I would like to introduce our current efforts of establishing a nationwide eDNA monitoring network, ANEMONE. 

Canopy-forming large brown algae such as kelps and fucoids are creating seaweed beds that provide biomass, habitat, and food for associated species and are some of the most productive and biodiverse ecosystems on rocky shore reefs. However, in recent global warming, decline, and loss of seaweed beds, distributional shifts of canopy-forming algae have been widely reported around the world. I will introduce the changes in seaweed beds based on long-term monitoring projects in Japan, the shift of seaweed beds based on prediction models, and the expansion mechanism of tropical species based on population genetic analysis in comparison with temperate species.

Aquaculture is an important contributor in global food production and food security. Seafood is globally the third most important food source and is of especial importance in Asia. While global wild caught fisheries have been stagnating over the last 20 years, farmed seafood has been one of the fastest growing industries in the world. However, like organisms in the ocean, aquaculture species are under threat of Climate Change. And while there has been some research into how species deal with increased temperatures, the effect on the associated microbiomes has been limited. In my talk I will cover our research to date in this area, as well as our future research plans focusing on the locally important Malabar grouper in Okinawa.

Anemonefish live symbiotically with host anemones in shallow waters of the tropical and subtropical regions of the Indo-Pacific Oceans. They are among the most vulnerable to the effects of human activities (land reclamation, pollution, etc.) and global warming. Community analysis in the Ryukyu Archipelago revealed that Amphiprion ocellaris, especially near the coast, has been reduced by reclamation, thereby degrading the diversity of anemonefish-host anemone ecosystem. Population genetic study by mt-DNA suggested that they are mixed genetically across the Ryukyu Archipelago, and all haplotype in CR are included in the group found in Sulawesi. Amphiprion ocellaris has a very high dispersal capacity, so the best conservation measures may be to preserve the coastal environment and wait for natural recovery.

Reducing local stressors allows for better protection of valuable ecosystem services that coral reef ecosystems provide. The nearshore reefs of Okinawa Island experience a wide gradient of anthropogenic stressors. We introduce recent research on how ongoing coastal development impacts coral reefs around Okinawa Island. Coastal development such as land reclamation, port construction, and coastal hardening are implicated in coral and fish community shifts, coral reef compression, and potential losses of unique, site-specific diversity. These impacts are not limited to hard corals and fishes, but occur across the taxonomic diversity and different trophic levels of coral reef organisms. More effective conservation of remaining pristine coral reef locations will become only increasingly important as climate change progresses into the future.

Climate change including ocean warming and acidification is suspected to critically affect marine organisms and ecosystems at near future. Here, we will give some examples of studies and some present projects aiming to evaluate potential impacts of those environmental change on the marine organisms and its potential impact on the ecosystem services such as food sources, coastal protection and tourism which we benefit from our coastal ocean.