May 30, 2018
I was surprised to wake up to a quiet morning today, without hearing the constant bleating of the Bigelow‘s foghorn which is what lulled me to sleep. Since first approaching and then crossing the Great South Channel yesterday we’ve been enveloped in thick fog, which is pretty typical for Georges Bank during the warmer months of the year.
Today however looks fairly clear, which bodes well for Charles Kovach, our man from NESDIS (National Environmental Satellite Data Information Services). His mission, to provide ground-truth in-situ light measurements by lowering hand-deployed radiometers into the water during satellite overpasses, has been a difficult one, with all the cloud and now fog cover that we’ve had during this survey limiting his measurements.
Another collaborative researcher, Andrew Cogswell, from the Canadian DFO (Department of Fisheries and Oceans), has been patiently waiting for us to reach his study area on the northeast peak of Georges Bank and the entire Gulf of Maine.
We are getting close now, having completed 61 stations and are now working our way across the southern flank of Georges Bank, just a dozen stations and one hundred sixty one nautical miles from the Northeast Channel. This year, with warm water anomalies having been discovered in the Gulf of Maine, this area has become the focus of increased interest as a gateway for the influx of this warm water.
We have both bongo tows and CTD rosette casts scheduled to be taken there, so we are hoping to gather some valuable data!
Susan Dee, our NOAA Teacher at Sea from May River High School in South Carolina, has, in addition to helping us with our plankton tows, been busy decorating a NOAA drifter buoy with her school’s name and logo, the Sharks. She is planning to launch it close to the northeast peak of Georges Bank, so perhaps it will also be able to contribute to our understanding of water movements and temperatures in this dynamic area. It will also offer her students a satellite connection via the internet to their teacher’s activities out here with us, as they monitor the buoy’s movements on the drifter website.
Looking ahead, we still have a couple more days of good weather which is helping to ensure our coverage of Georges Bank, but as the high pressure system over us slips off to the east we are facing more marginal conditions this weekend.
Together with the vessel command we’ve come up with a track that will take us across the Gulf of Maine closer to Nova Scotia, where we may get some lee shelter from the forecast northeast winds and be able to continue working, even if at a somewhat slower pace, depending on the seas.
HB18-03 Spring Ecosystems Monitoring Survey
The Henry Bigelow left from Pier 2 at the Newport Naval Station on Wednesday, May 23, under sunny skies to start the Spring Ecosystem Monitoring (EcoMon) Survey. With good weather forecast for the remainder of the week we are heading offshore to survey at the stations along the outer edge of the continental shelf as we head south for the first part of this cruise.
Cruising smoothly at 12 knots with its newly refurbished electric propulsion motors, the vessel is making excellent progress. The time spent approaching our first station is completely taken up by a whirlwind of activities: setting up and testing gear, attending a welcome aboard orientation meeting, and having fire and abandon-ship drills.
As is typical for these ecosystem monitoring surveys, we have a variety of researchers on board: a satellite specialist doing in-situ light measurements during satellite overpasses, a Canadian biologist from the Dept. of Fisheries and Oceans in Halifax, NS, a Maine Maritime Academy student volunteer, a NOAA Teacher-at-Sea from South Carolina, two seabird and marine mammal observers, and three scientists from the Northeast Fisheries Science Center.
Together we will gather as much data as we can on this voyage which will take us from southern New England to Delaware Bay, to Georges Bank and into the Gulf of Maine.
HB18-03 Spring Ecosystem Monitoring (EcoMon) Survey
Some have asked why we are sampling on our transit on the southeast US shelf. Many species fished in the northeast may spawn or in some other way originate in the southeast. For example, chub mackerel (Scomber colias) adults are fished in the northeast, but larvae have not been collected in our 40 years of sampling the shelf north of Cape Hatteras. Also, historically southeastern species, such as blueline tilefish (Caulolatilus microps), are beginning to occur in the northeast so regularly that fisheries are emerging in the northeast. Like the Slope Sea, this region has had relatively little plankton sampling as compared to the northeast US shelf and Gulf of Mexico.
There has been sampling on the southeast shelf; with ichthyoplankton (eggs and larvae of fish) collections going back at least to 1965-1968 from the R/V Dolphin cruises. There have also been a couple of monitoring and collaborative research programs. The Marine Resources Monitoring, Assessment and Prediction (MARMAP) program sampled portions of the southeast shelf in the 1970s and 1980s. During the 1990s and early-2000s, sampling was conducted from South Carolina to southern Virginia as part of the South Atlantic Bight Recruitment Experiment (SABRE). So, the absence of data points in the map below is due to infrequent sampling and also highlights the need to compile historic data to allow us to compare the past to the present. A new collaborative effort between the Oceans and Climate Branch from the NEFSC and the SEAMAP Plankton group from the Southeast Fisheries Science Center is beginning to compile these data and attempt to fill in gaps and compare historical data with current conditions with cruises like this.
We are sampling some cross-shelf transects on our transit south to compare with historical collections. Our first transect in Onslow Bay, North Carolina, along a frequently sampled transect from the SABRE project will provide important data on how distributions and oceanographic conditions are changing over time. We plan to collect as many plankton samples as possible before docking in Cape Canaveral on June 23.
NOAA Ship Gordon Gunter GU 1702
The Slope Sea portion of this cruise ended a little early due to storms and strong currents, but will provide important information on this poorly understood region of the ocean. We did not complete our entire planned cruise track for the Slope Sea, but we did complete 84 stations in the northeast for a total of 133 bongo and CTD tows and 13 water casts. The bongos will be used for our plankton analyses, including our hunt for bluefin tuna larvae.
Plankton sampling continued to catch scombrid larvae, including a few more potential bluefin larvae. We never hit a large enough patch to justify releasing drifters. We will save the drifters for another cruise that leaves in two weeks for the Slope Sea. The water samples from the water casts will be sent off for dissolved inorganic carbon (DIC) and total alkalinity analyses. Both DIC and total alkalinity are used by chemical oceanographers to estimate pH of the water, and examine current ocean acidification conditions of the ecosystem. The basic hydrographic data collected (temperature and salinity by depth) will be used to define ocean features in the Slope Sea and to help ground truth satellite data.
Weather and sea conditions required an adjustment to our planned cruise track, moving inshore one evening when winds and seas along the Gulf Stream made bongo sampling difficult. We normally send the bongo down to 200 meters deep ( about 660 feet), and use about 280 to 300-meters of wire, and still could not get the net to that depth. On the final tow of the evening, we deployed over 400 meters of wire and still could not get the net below a depth of 150 meters ( about 480 feet).
Like flying a kite on a breezy day, the current was pushing the net up with too much force or lift to overcome with our standard weight. The ship’s bridge and crew were safely able to deploy and tow the gear, but the sea conditions wouldn’t allow for us to collect samples that we could compare to all the others we had collected. After we moved inshore to escape the strong current, we continued to see a highly diverse plankton community in the waters just offshore of our standard sampling locations during EcoMon.
Even though we moved inshore, we could not escape the thunderstorms that were moving through the area. We had suspended operations at a station just north of Cape Hatteras due to lightning in the area. Have you ever wondered if lightning strikes the ocean? A few minutes after we arrived at the inshore station there was a very close strike, or the ship was struck by lightning ( it depends on who you ask). Everyone on board was safe, but we lost gyros and some other electronics. We steamed on to the next station, the second to last scheduled for the northeast part of the cruise, as the ship’s Electronics Technician (ET) began repairing systems. We discovered that the CTD would not talk to the computer when we resumed operations at the next station. Wherever the lightning hit, our science gear did not escape the damage.
We decided to move down to the southeast shelf, south of Cape Hatteras, North Carolina, to escape the marginal weather, and the unknown amount of time it would take to diagnose and fix the CTD problem. Thankfully, the CTD was repaired on the transit south thanks to the persistence and skill of Betsy Broughton (NEFSC scientist) and Kirk Andreopoulos (ET on the Gordon Gunter). We will continue to explore poorly understood parts of the western Atlantic during the second half of this cruise, this time in the waters off the southeast United States coast.
Check back on to read about what and why we are studying the ocean south of Cape Hatteras, North Carolina.
NOAA Ship Gordon Gunter GU 1702
The plankton sampling team for this cruise is made up of six researchers from NOAA Fisheries and regional universities. Each 12-hour watch has a team of three people, so that we can sample day and night. Betsy Broughton (NOAA Fisheries/NEFSC), Christine Hernandez (Woods Hole Oceanographic Institution [WHOI]), and Quentin Nichols (NOAA Fisheries/NEFSC summer intern, UMass Amherst) staff the night watch, 3-pm to 3-am. Ciara Willis (WHOI summer intern, Dalhousie University), Chris Gingrich (NOAA Fisheries/NEFSC summer intern, Washington College) and I stand the morning watch, 3-am to 3-pm.
There are still a lot of questions about this area as a spawning ground for Atlantic Bluefin tuna. One of the research questions being addressed on this cruise is how the currents of the Slope Sea affect the planktonic larval stage of bluefin tuna. Plankton are organisms that rely on the wind and ocean currents to move through the ocean (from the tiny algae and small amphipods to larval fish and crustaceans to jellyfish). We are hoping to find patches of larval bluefin tuna where we can release drifters that will track the movements of the water surrounding the larvae as they grow.
At each station, we sort a small portion of the sample we just collected for any fish larvae we can find. The larvae we’re looking for are tiny, 2-10mm (about 1/16 – 3/8 of an inch) long, so we need to use microscopes. We also have to work fast, so we don’t drift too far from where the larvae were caught. We have found one potential Bluefin larvae already, which we will verify with DNA analysis. We are hoping to find a larger patch to justify releasing the drifters. We’ve also seen plenty of cousins of Bluefin including bullet or frigate mackerel (Auxis spp.).
The influence of the warm Gulf Stream waters can be seen in the diversity of the fish community caught in the bongo nets. In addition to the tuna and mackerels, we are catching more tropical and subtropical species like driftfishes (family Nomeidae) and eyed flounder (Bothus spp.).
NOAA Ship Gordon Gunter, GU1702