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
Core EcoMon sampling includes “bongo” net tows to collect zooplankton, larval fish and fish eggs. These fine-mesh nets are attached to side-by-side steel rings, resembling bongo drums when deployed. During this survey, bongo net tows were conducted at 100 different stations. Samples from this survey will be used to update an index of Atlantic mackerel egg abundance, which is used in the stock assessment. To further support this effort, supplemental stations were added in the western Gulf of Maine.
Conductivity, Temperature, and Depth Profiles
Seawater conducts electricity. This “conductivity” varies by depth and other oceanographic factors and is used to estimate the salinity of seawater. The crew deployed an instrument that can measure conductivity, temperature, and depth at all 106 stations on this survey. The combination of temperature and salinity at various depths helps define marine habitat boundaries, track ocean circulation, and monitor changes in climate. This can help explain changes in marine species distribution and productivity.
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.
Special Collection Summary
Our EcoMon program collaborates with other agencies and institutions, supporting research that enhances core EcoMon sampling. While COVID-19 mitigation protocols limited external participation on this survey, the spring 2021 EcoMon cruise included sampling to support several ongoing projects with external partners:
- Two observers were aboard to watch for and record data on sea birds, marine mammals, and sea turtles encountered along the cruise track. This is part of the Atlantic Marine Assessment Program for Protected Species, a partnership among scientists from NOAA, the U.S. Fish and Wildlife Service, the Bureau of Ocean Energy Management and the U.S. Navy.
- An imaging flow cytobot was deployed aboard the ship and used to image and count phytoplankton cells continuously from surface waters during the ship’s transit. This work is part of a National Science Foundation project led by Woods Hole Oceanographic Institution with collaborators from the University of Massachusetts Dartmouth, the University of Rhode Island, Wellesley College, and NOAA Fisheries.
We regularly conduct outreach with K-12 schools, including hosting teachers on surveys through NOAA’s Teacher at Sea Program. While pandemic restrictions prevented teachers from participating in this spring’s EcoMon survey, we did have a project with a program alumna. Scientists conducted an experiment demonstrating the effects of water pressure on compressible materials using styrofoam cups provided by students from the Banner Academy in Arizona. Cruise chief scientist Jerry Prezioso also answered questions submitted by the students while underway.