AOML scientists and partners from an assortment of universities and Cooperative Institutes successfully completed the most comprehensive ocean acidification sampling of the Gulf of Mexico to date with the conclusion of the fourth Gulf of Mexico Ecosystems and Carbon Cruise, also known as the GOMECC-4 cruise. The research effort aboard the NOAA Ship Ronald H. Brown began out of Key West, Florida on September 13, 2021 with 25 scientists and graduate students aboard. It ended 39 days later on October 21 with a port stop in St. Petersburg, Florida.
The multi-institutional effort, undertaken in support of NOAA’s Ocean Acidification Program, monitored ocean acidification conditions across the Gulf of Mexico to assess acidification trends and potential impacts to coastal ecosystems. Observations from approximately 140 stations were collected to measure the extent of ocean acidification throughout the Gulf’s water column, as well as key carbon, physical, and biogeochemical parameters.
Ocean acidification occurs as greater amounts of carbon dioxide (CO2) from atmospheric emissions are absorbed by the oceans, lowering pH levels and making seawater more acidic. Although the ocean’s uptake of CO2 helps to regulate atmospheric CO2 levels, the lower pH negatively impacts a wide range of marine organisms, impairing their ability to thrive.
In addition to quantifying the increase of CO2 in near surface coastal waters, the science team studied the abundance, diversity, and health of a variety of marine species. Plankton studies were conducted using net tows at select stations to capture the onshore-to-offshore variability in fish distributions and abundance, as well as larval fish age, growth, condition, diet, and evidence of microplastic ingestion.
Environmental DNA or eDNA samples were gathered from both coastal and open-ocean sites to study patterns in biodiversity and composition among populations of bacteria, plankton, and fish. The sampling was coordinated with biological, ocean acidification, and other physico-chemical measurements, allowing for statistical predictions of the relationships between ocean acidification and biodiversity.
A sediment corer was also deployed to collect samples from the ocean floor. These samples will be analyzed in relation to ocean acidification, as well as used in paleoceanographic studies. Additionally, four biogeochemical Argo profiling floats were deployed to measure a host of biological and chemical parameters—pressure, temperature, pH, salinity, oxygen, nitrate, chlorophyll-a, and backscattering—in the upper 2000 meters of the water column. These new observations will fill vital gaps in understanding Gulf waters and deliver data to improve weather and climate predictions, as well as forecasts.
The cruise was part of AOML’s ocean acidification research and was led by Leticia Barbero, PhD, a University of Miami-Cooperative Institute for Marine and Atmospheric Studies scientist.