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Chlorophyll

This study looked

at the levels of chlorophyll

along the estuary in relation to

nutrient data and was used to

extrapolate phytoplankton populations.


Between salinity of 0-23 PSU the chlorophyll concentration is extremely low, with the highest value found being 0.0027µg/L at a salinity of 20.7, but after reaching around 23 PSU the concentration begins to increase. This suggests that chlorophyll is found at higher salinities, showing that the phytoplankton found are coping in environments with higher salinity better. The chlorophyll concentration peaked at a value8.6 and the phosphate concentration being of 0.088µg/L at a salinity of 26.9 at station A3. Chlorophyll concentrations are highest where silicate levels are low, with the silicate concentration at A3 being 8.6µMol/L.


The high chlorophyll suggests that the nutrients are being utilized more and therefore depleted in this area by phytoplankton. The flushing rates in the Tamar estuary are very slow.This is important because it means that the nutrients stay in the estuary for a longer period of time, allowing for them to be utilized by phytoplankton. This allows phytoplankton to bloom further up the estuary as the flow is not carrying nutrients through too quickly, which may be a reason why there are high chlorophyll concentrations in the mid estuary.


Different phytoplankton species are adapted to different salinities and have different metabolisms, meaning that their nutrient requirements differ. There is an input of arsenic into the estuary, which is utilized by marine phytoplankton, which could be a reason as to why the chlorophyll levels are highest at higher salinities. The reason as to why the chlorophyll concentration increases with increased salinity may be because the nutrients available such as arsenic benefit marine phytoplankton more than freshwater phytoplankton. This means that data must be collected on more nutrients in order to be able to see the full picture.



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