Marine Heatwaves and Their Impact on Ocean Ecosystems

Marine heatwaves are environmental phenomena that significantly affect ecosystems and carbon movement in the oceans. A group of researchers studied the impact of these heatwaves on marine ecosystems in the Gulf of Alaska, which experienced two major marine heatwaves. The study aims to understand how these phenomena affect microorganisms and their role in the oceanic carbon cycle.

Overview of Marine Heatwaves

Marine heatwaves are events that cause ocean temperatures to rise abnormally for extended periods. The first of these waves, known as “The Blob,” occurred between 2013 and 2015, while the second wave happened between 2019 and 2020. These phenomena cause drastic changes in marine ecosystems, affecting organisms of various sizes, from microorganisms to large marine animals.

Microorganisms such as bacteria and plankton form the base of the marine food chain, converting carbon dioxide into organic materials. When larger marine organisms feed on these microorganisms, the resulting waste turns into carbon particles that sink into the deep oceans, helping to sequester carbon away from the atmosphere for long periods.

Techniques Used in the Study

The researchers relied on data collected from the Global Ocean Biogeochemical Array project, supported by the U.S. National Science Foundation. This project uses robotic floats to periodically measure temperature, salinity, nitrates, oxygen, chlorophyll, and molecular organic carbon throughout the water column. Additionally, the researchers used field studies from Canada’s Department of Fisheries and Oceans’ Line P program to collect and analyze seasonal samples using pigment chemistry and environmental DNA sequencing techniques.

Through these techniques, the researchers were able to track changes in microorganisms and understand how heatwaves affect carbon movement in the oceans.

Study Results

The study showed that marine heatwaves disrupt the base of the marine food chain and alter how carbon moves through the waters. During the 2013-2015 wave, plankton productivity increased in the second year, but carbon particles accumulated at a depth of about 200 meters instead of sinking deeper. In contrast, during the 2019-2020 wave, carbon particles initially accumulated near the surface, associated with the recycling of organic materials by marine organisms and debris accumulation.

These changes may increase the likelihood of carbon returning to the atmosphere rather than being sequestered in the deep oceans, raising climate change risks.

Conclusion

The study concluded that marine heatwaves significantly impact marine ecosystems and carbon movement. The research shows that these waves are not uniform, with their effects varying depending on changes in plankton communities. These findings highlight the need for continuous and long-term monitoring of the biological and chemical conditions of the oceans to understand the full range of these phenomena’s effects. Collaboration between advanced technologies and scientific research can provide important insights into ocean health and help predict the future impacts of marine heatwaves on ecosystems and climate.