Thesis working title:

Tracing nitrogen sources in the water column by looking at nitrogen isotope ratios in macroalgal tissue.

Research Summary:

I’ll be comparing old and new growth tissue to see how nitrogen isotope ratios change when algae are supplied with different nitrogen sources.

Two sources will be used, one with pure nitrogen 14N and the other with an increased proportion of 15N.

Before I start I’ll be taking tissue samples from all experimental specimens (Hormosira banksii) and by using mass spectrometry, the initial 15N: 14N ratio will be determined.

The specimens will be split into two groups, one being treated with 14N and the other with 15N.

At the end of the trial the plant tissue will be analysed to see if the 15N: 14N ratio has changed. The old and new growth tissues of the plants will also be compared to see if there is a difference.

With increasing human population, coastal eutrophication is becoming a greater problem world-wide. Nitrogen from human inputs has contributed to this problem. Different sources of nitrogen have different isotopic 15N: 14N ratios, therefore macroalgae could be used to trace important nitrogen sources in coastal environments.