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Salinity did not vary immensely, however, the surface waters were relatively fresh compared to the deeper waters. The pycnocline started at approximately 10m, and there was an increase within another 10m of 0.3 psu. Below the depth of 25m the salinity was remained constant throughout the rest of the depth profile. Overall we can conclude that the water column was stratified.

The halocline is caused by warm fresh water overlying cold saline water. The warm fresh surface water is relatively well mixed compare to the cold saline water which is highly stratified. This is shown by the closeness of the data points below the halocline and the relatively distanced data points above it.

The density levels also increase in depth with the pycnocline. The density increases from 1026 Kg/m3 to 1027 Kg/m3. The pycnocline occurs between 10-25m. Due to the close resemblance of the pycnocline to the halocline, it can be concluded that density at station B is affected more by salinity than temperature.

On all of the time series stations the thermocline can be seen between 10-25m. The water column was highly stratified. This is shown by the rapid decrease in temperature shown over a short depth span. The temperature dropped from 14.7°C to 11.7°C within 15m.  Below the thermocline the temperature is constant.

Physical Introduction

Thermocline

Halocline

Pycnocline

A CTD was deployed at each of our time series stations (station 29-32) to an approximate depth of 60m collected data on temperature, salinity and density every 30 seconds. From the data collected by the CTD graphs could be create with temperature, salinity and density against depth. From these graphs the thermocline, halocline and pycnocline could determine. Comparisons can be made between the graphs e.g. determining what effects density more in our time series either salinity or temperature. The results can also help explain some of the biological findings e.g. phytoplankton abundance.

Figure 3.9 Scatter graph of Temperature against Depth showing a distinct thermocline

Figure 3.10 Scatter graph of Salinity against Depth showing a distinct Halocline

Figure 3.11 Scatter graph of Density against Depth showing a distinct Pycnocline