Pre-Storm Transects

So I believe it is now Saturday afternoon (though we're all pretty tired, so maybe I should check on that). We've been sampling at stations non-stop as we're trying to beat a front approaching. We have sampled 2 transects offshore with 8 stations per transect from Thursday afternoon through Friday afternoon. At each station, we do at least 2 CTD casts to collect water at 2m increment water depths from the bottom to 12m off the bottom, as well as a surface sample. The first cast is sampled for chlorophyll, nutrients, and HPLC samples. 500mL of water is filtered and saved frozen for nutrient analysis, keeping the filter for chlorophyll analysis. Another 1500mL is filtered (500mL per filter) from the bottom water, 10m off the bottom water, and the surface water; the filters from this are stored in liquid nitrogen, and will be extracted and run on an HPLC (high performance liquid chromatography) to analyze pigments from the water to determine what types of plankton were present. The second cast is used for a net tow. 5L of water is poured through a net to isolate plankton at the bottom of the water column. By doing it this way, the sample isn't contaminated by towing the net off the side of the boat and collecting plankton in the water column on the way up. As with normal field work, some problems arose periodically with the CTD, but the ship's crew has been fantastic at getting it working again fairly quickly. Coring (box cores and multicores) has been attempted at several stations, but due to the sandy bottom with quite a bit of coral, there has been a lot of frustration prior to finally collecting some good cores to do flux chamber nutrient analysis. When a good core is obtained, we do a third CTD cast to collect water for the flux chambers off the bottom of the seabed. The flux chambers are being sampled at regular time intervals today (Saturday) for water to be analyzed for nutrients as biogeochemical reactions occur in the sediment and alter the water chemistry.

After the first station, the divers were deployed to dive to 50ft water depth to collect water from every 20cm off the bottom of the seabed using a specially designed micro-sampler controlled by using an air tank to provide pressure to simultaneously pull 16 syringes at 16 different depths off the bottom to collect the water and bring it aboard the ship for collection and freezing for detailed nutrient analysis.

The Acrobat and ADCP were launched overnight Friday to Saturday night, collecting nutrient, oxygen, current, fluorescence etc. data. This morning, we have deployed a drogue drifter to follow the bottom water to see where Karenia brevis populations would potentially be transported given current weather and conditions. We are now preparing to deploy the Mimics (autonomous drifters that mimic Karenia brevis behaviors in the water column) with some snorkelers to follow them. The mimics will be compared with the drogue drifter to see differences in behavior between the autonomous and drag drifters.