Thanks to a combination of favorable weather and a well-run vessel, the 2021 Northeast spring ecosystem monitoring survey aboard NOAA Ship Gordon Gunter is complete.
During May, researchers returned to sea for the ecosystem monitoring cruise. This was the first ecosystem monitoring cruise since operations were stopped in 2020 to reduce risks posed by the COVID-19 pandemic. This one-year hiatus is the longest gap in sampling in the nearly 45-year record of oceanographic observations made on this recurring cruise.
Scientists and crew aboard the NOAA Ship Gordon Gunter sampled at 106 stations. They achieved near-complete coverage of the survey area from Delaware through Southern New England.
Fewer days were available for the cruise than originally planned, so the scientific crew dropped all stations south of Delaware Bay to accommodate the time available. Coverage was also reduced on the Scotian Shelf, in the northern Gulf of Maine, and on Georges Bank, when a fast-moving storm front passed through, making sampling impossible. Instead, the team moved into the western Gulf of Maine to keep working, and collected more mackerel eggs and larvae.
Samples of zooplankton—tiny animals and very young stages of some larger ones—provide information about the food chain supporting fisheries and marine mammals. Scientists use larval fish and egg samples to learn more about fish stock spawning and help estimate stock abundance. Measurements of physical and chemical conditions like temperature and salinity help us describe ecosystem productivity, spawning, larval recruitment, fish condition, and species distributions.
Together, the core measurements conducted by our ecosystem monitoring (EcoMon) cruises help researchers understand and predict changes in the Northeast shelf ecosystem and its fisheries. Researchers are scheduled to sail on the next EcoMon survey in August aboard NOAA Ship Pisces.
Core Sampling Summary
Survey area and stations for the 2021 Northeast spring ecosystem monitoring cruise. Credit NOAA Fisheries
Ocean Acidification Monitoring
To monitor marine carbon cycling and ocean acidification, scientists collected water samples and measured dissolved inorganic carbon, total alkalinity, pH, and nutrients at 25 stations. Increases in dissolved carbon dioxide can increase acidity of the water, which can in turn affect shellfish and other sensitive organisms. Pteropods, a planktonic shelled mollusk, were collected from the water column. The condition of the pteropod shells will be examined to measure the biological effects of ocean acidification. This is the first EcoMon cruise where pteropods were studied in this way. The NOAA Ocean Acidification Program funded this work, and it is conducted in partnership with NOAA’s Atlantic Oceanographic and Meteorological Laboratory in Miami. The pteropod measurements are conducted in partnership with the Bermuda Institute of Ocean Science, where the measurement technique was developed by Dr. Amy Maas.
NOAA, Northeast Fisheries Science Center, 23 June 2021. Full article.