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Estuarine

In order to collect data for the whole estuary as well as to be able to analyse change with tide state over time there were three different ‘vessels’ used, by two groups, over the course of the day. These were ‘Winnie the Pooh’ (a small fishing vessel with a draught of 0.5m), a pontoon and RV ‘Bill Conway’ (a research vessel used for the lower part of the estuary). Our group began in the upper estuary using ‘Winnie-the-Pooh’ and the pontoon, then progressed to RV ‘Bill Conway’ in the afternoon, while the other group did the opposite. The two groups data was then combined to allow analysis for the whole day.

Table 1: General information for each station in the survey carried out by group 6

Each of the vessels collected:

• Biological data: by deploying zooplankton nets and Niskin bottles at each station
• Chemical data: by deploying Niskin bottles at each station
• Physical data: by using either a T/S probe, CTD or ADCP at each station

‘Winnie the Pooh’ went upstream of the pontoon, where the depth of the estuary is low. A horizontal Niskin bottle was used to collect samples as well as temperature and salinity data by T/S probe. A flow meter was used to record flow direction and speed.

On the pontoon; chlorophyll samples were taken using a horizontal Niskin bottle, a PAR light sensor was used to determine light attenuation, a CTD was used to measure Oxygen percentage, salinity, turbidity, chlorophyll, temperature, and depth, and a flow meter was used to measure flow speed and direction.

RV ‘Bill Conway’ was used to sample stations lower down the estuary. As it is a larger vessel it is able to deploy a CTD rosette so more than one Niskin bottle could be fired at each depth. It also has an ADCP on board and this allowed a transect to be taken at each station showing flow direction and speed across the estuary. Secchi disk depths were taken at each station as well as the samples being processed in the wet lab in preparation for the dry lab. The CTD on board relayed constant information so water column profiles could be viewed as the CTD rosette was lowered. There was a zooplankton net on board and this was used at one station.

Table 1: Tide times for 10/7/2017

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Photo courtesy of University of Southampton

Map 1: Winnie the Pooh stations

Map 2: Bill Conway stations