Falmouth Group 8
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Water samples recovered from the Niskin bottles were transferred into collection bottles at the surface. After being thoroughly washed with the sampled water, a syringe was used to collect samples of known volume for analysis. These samples were run through a 25mm glass filter to remove any particulate matter before being transferred into either glass or plastic numbered bottles for nitrate and silicon samples respectively. These were also thoroughly rinsed with the sampled water before storage.
Survey Instruments and Methods Used
Water samples were taken from the Niskin bottles. A syringe was used to collect a known volume of sample water (50ml) and this was passed through a glass fibre filter. The chlorophyll containing particles in the water sample were trapped in the filter, which was removed and immersed in 90% acetone solution. These filters were frozen overnight in preparation for the lab the following day.
The CTD rosette frame was equipped with a CTD, a light transmission meter and a flourometer, as well as six 2L Niskin bottles connected via cable to a computerised triggering mechanism controlled on the RV Conway. The frame was lowered from the surface to the bed, and raised immediately back to the surface, collecting data on salinity, temperature, light transmission and chlorophyll and plotting with depth. This was to ensure that the data in the depth profiles for each characteristic were uniform between raises and to identify interesting features in the water column to be sampled using the Niskin bottles. The frame was then lowered down to the surface and a bottle was fired at the bottom, at the surface and at regular intervals between these two depths.
Contents
Water samples were obtained from the Niskin bottles. Sample bottles were rinsed with water from the Niskin bottle and then filled with sample water through a tube in order to reduce the contact with the atmosphere. 1 ml of the reagents * and * were added and mixed thoroughly throughout the container. The sample container was incubated in a warm bucket of water. Care was taken to ensure that the sample was exposed to as little air as possible, in order to keep the concentration of dissolved oxygen constant.
Phytoplankton samples were collected directly from the Niskin bottles and placed into labelled brown glass bottles. Each sample had 1ml of Lugol’s iodine solution already added to the sample bottles. Six samples were collected in total; at stations 1, 2, 3, 4, 5, and 8. The depths from which the samples were taken were chosen at the optimal photosynthetic depth based on secchi depth measurements. The samples were transported in a chilled cooler and stored in a refrigerated unit for analysis the following day.
Zooplankton trawls were taken at stations *, * and 8. The plankton net was towed
behind the boat for 5 minutes; the net extracts everything smaller than 200μm from
the cylinder of water. Phytoplankton is small enough to pass through this mesh ,
which ensured that only zooplankton species were collected. The volume of seawater
that passed through the cylinder was recorded (*****needed), as well as the diameter
of the net opening (50 cm). After trawling, the outside of the mesh was rinsed with
in-
