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Key Findings

Zooplankton

There was an unusually high abundance of siphonophores at Station b. Copepods were also abundant, as expected, in all three samples.

Phytoplankton

Phytoplankton were the most abundant at 13.45, and cerataulina was the dominant phytoplankton in the first two samples at 12.58 and 13.45. However skeletonema was the most consistently abundant phytoplankton throughout the entire period of sampling.

Nitrate

Station 32 has a rapid decrease in the first 18m depth, the other stations all have a relatively small decrease in this area.

Phosphate

All stations decrease in phosphate concentration up to a depth of 30m, here station 29 and 32 level out whereas station 28 increases dramatically.

Silicon

All three stations show a slight increase over the first 30m, then station 28 has a rapid increase and station 29 and 32 only increase very slightly.

Temperature

The thermocline is found between 10-25m with a temperature change from 14.5°C to 11.7°C. The water above the thermocline is slightly stratified fresher warmer compare to the colder saline stratified water found below the halocline. Although the recordings were taken from the same site there is a slight variation in temperature, this could be due to a number of factors e.g. temperature above the water.

Halocline

The halocline is found between 10-25m with a salinity difference of 35-35.3PSU. The water above the halocline is less saline and more mixed than the saline stratified water below the halocline. Just like the readings for the thermocline each measurement varies slightly although being taken at the same station.

Pycnocline

The pycnocline is more similar to the halocline than thermocline suggesting that density is more affected by salinity than temperature. The pycnocline is found between 10-25m with density increasing from 1260.1-1027Kg/m3. The water above the pycnocline is less dense and more mixed compared to the stratified dense water below. Again there is variation between each measurement in the time series

Met data

Date: 25.06/.16

Time Range. 13:00 BST - 17:45 BST

Co-ordinates: : 50°05.67N, 4°58.70W

Air Temperature: 16°C

Sea State: Mild with whitecaps

Cloud Cover: 4/8

High Tide: 09:14 BST

              21:30 BST

Low Tide: 03:24 BST

              15:41 BST

Introduction to Offshore

Offshore data was collected from the RV Callista, factors investigated included phytoplankton levels, and salinity at varying depth. The results of this data collection is displayed in the accompanying tabs. Once the data was collected then it was taken back to labs at the marine school to be analysed

Our aim was to create a time series data set offshore of Falmouth in order to analyse the structure of the water column and to assess the distribution of both phytoplankton and zooplankton. The offshore site which we sampled at was at 50°05.67N, 4°58.70W on the 25/06/16. To achieve this, a rosette of Niskin bottles with a CTD probe was deployed every half an hour along with a zooplankton net. Ascension of the rosette from depth enabled a depth profile to be created along with water samples to be taken at specific depths. The water samples and phytoplankton net samples were then chemically preserved in a wet lab ready for further analysis.

Aims and Objectives