SSV Corwith Cramer C294 (F2020-035)

Cruise summary report

Cruise Info. 
Ship name (ship code)SSV Corwith Cramer (33CC)
Cruise identifierC294 (F2020-035)
Cruise period2020-10-10 — 2020-11-18
Port of departureWoods Hole, United States
Port of returnStock Island, United States
ObjectivesWe collected data with 185 individual deployments from 56 discrete geographic stations along our cruise track. Comparison of the physical, chemical, geological and biological features of these regions represented the major scientific theme of this Sea Semester.

1. Physical oceanographic studies focused on the characterization of surface hydrographic features, ocean frontal boundaries and sub-surface water masses. Evidence of cyclonic and anticyclonic eddies associated with the Gulf Stream and Antilles currents were evaluated with ACDP data while associated areas of upwelling and downwelling were assessed with our continuous seawater flow-thru system measuring temperature and salinity and examination of mixed layer depth and thermocline position using CTD deployments.
2. Chemical oceanographic studies focused on broad characterization of water productivity using measurements of nutrients (phosphate and silicate) and chlorophyll-a; as well as water quality using measurements of incubated Escherichii coli bacteria and pH. These chemical parameters were related to patterns in physical hydrography at various scales: nearshore to offshore transitions, ocean fronts and eddies associated with ocean currents and water column stratification.
3. Biological studies focused the biogeographic patterns, abundance and diversity of charismatic megafauna (seabirds, sea turtles, flying fish, and marine mammals), several nektonic organisms (lantern fish – Family Myctophidae, and gelatinous organisms >2cm – i.e salps), meroplanktonic larvae including spiny lobster (phyllosoma) and eels (leptocephali), the floating macrophyte – Sargassum spp., the marine insect Halobates, and the density (mL/m2) and diversity (i.e. Shannon-Weiner index) of the aggregate zooplankton and phytoplankton communities were related to patterns in physical and chemical properties at various scales: nearshore to offshore transitions, ocean fronts and eddies associated with ocean currents and water column stratification.

Sea surface temperature, salinity, fluorescence (chlorophyll-a and CDOM) and transmissivity levels; along with barometric pressure, winds, bathymetry, and geographic position were recorded continuously along the cruise track. Surface samples (n=79) of nutrients (phosphate and silicate), chlorophyll-a, and pH were collected in conjunction with all noon and midnight neuston net tows, as well as dawn (0500) and dusk (1700) collections. From a subset of Surface Stations we assessed water quality by measuring Eschericia coli bacteria samples (n=12).

Routinely we visually observed and enumerated marine mammals, seabirds, flying fish, sea turtles, Sargassum abundance, and floating plastic debris. These hourly observations occurred only during daylight hours 0700-1900 and lasted only six minutes (n=174). Periodically, opportunistic sightings were also recorded when notable megafauna or marine debris were present (n=235). Additionally, nighttime observations of surface bioluminescent activity was periodically recorded (n=21). On several occasions we deployed a hydrophone to record the marine soundscape in hopes of identifying presence of marine mammals (2 stations).
Chief scientistJeffrey M Schell (Sea Education Association)
Cruise reportSSV Corwith Cramer C294 (F2020-035) cruise report corwithcramer_c294.pdf (0.13 MB) 
Ocean/sea areas 
GeneralCaribbean Sea
SpecificGulf of Maine, Cape Cod, Sargasso Sea, northern Caribbean islands (Bermuda, Turks and Caicos, Dominican Republic, Haiti, Bahamas)