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Plymouth Field Course 2019
Group 7
Plymouth Field Course 2019
Group 7
The practical took place on 08/07/2019 from 0830 UTC to 1400 UTC in the Plymouth Sound and Tamar Estuary , as well as investigating 2 of the 3 main tributaries, the Rivers Tamar and Tavy.
The primary zone of interest, the Tamar estuary is partially mixed and is described as a flood dominated estuary (Uncles et al 1985).
The aim of this practical was to investigate the changes in dissolved oxygen, salinity, nitrate, phytoplankton and zooplankton throughout the rcourse of the river and Estuary, from the normal tidal limit near Calstock down to the breakwater. All aspects of the practical were performed from rigid-hulled inflatable boats (RIBs) by groups of 4 and 5 persons. Two separate teams worked independently from one another ,with one group sampling the lower estuary on the ‘Flying Pig’ and the second on the ‘Miss Piggy’ coming down the river from Calstock. Between the two vessels, samples were taken at 23 Stations along the River Tamar.
UPPER ESTUARY METHODOLOGY OUTLINE
A T/S probe was deployed by hand at all sites and salinity, oxygen, depth, and location, recorded.
A zooplankton net was deployed (mesh 200μm, diameter 50cm) at three sites during the data collection. Each deployment involved 30 seconds trawl and then recovery. The resulting samples were fixed with 100% formalin in order to preserve them.
Surface samples were taken at all sites and Nitrate and silicate samples collected at all sites and tested in the laboratory. Samples were stored in a cool box and later frozen to preserve them.
For Chlorophyll we took three 50ml samples at each station with the resulting filter folded in half and placed in separate tubes containing 90% acetone solution, stored in a cool box and later put into a freezer.
LOWER ESTUARY METHODOLOGY OUTLINE
Using the T-S probe, the water column was sampled for temperature, salinity and dissolved oxygen from the sea bed to the surface, sampling at one metre intervals.
Surface water samples were collected which were then filtered and stored in labelled bottles in a freezer. These samples taken were then analysed in the lab for Nitrate, Phosphate and Silicate.
For Chlorophyll three 50ml samples were taken at each station with the resulting filter folded in half and placed in separate tubes containing 90% acetone solution, stored in a cool box and later in a freezer.
Using a Zooplankton net (mesh 120μm, diameter 50cm) towed behind the boat, samples were taken to measure Zooplankton and Phytoplankton. The resulting bottle of seawater was fixed with 100% formalin as a preservation. Due to a limitation of the number of bottles available, Zooplankton and Phytoplankton were sampled at the lower part of the estuary to determine if there were any major differences between there and the upper course.
Figure 1 - a satellite images with markers depicting the station measurements that were taken at a) the upper estuary of the River Tamar and b) the lower estuary of the River Tamar and the Plymouth Sound
a)
b)
Table 1 - Latitude, Longitude, surface salinity and time of sample collection at each station