Diatom Research in Lymington River

My name is Zoe and I am a student at the University of Nottingham. I study Geography and am currently conducting research for my dissertation on sewage contamination in the Lymington River. My focus is on diatoms and how species change with different levels of pollution in the river.

Diatoms are microscopic algae found in water, damp soils and wet surfaces. They are widely used in water quality research because different species respond differently to pollution. When a river is heavily affected by pollution, water conditions become favourable to only a few specialised diatom species. This causes a drop in species diversity, as many species are not well adapted to polluted environments. Therefore, when counting diatom species in more polluted water, most species found will belong to more pollution-tolerant genera, indicating contamination.

I am currently in the early stages of data collection and analysis. The findings below are from the first round of samples, collected in April 2026. The next samples will be collected in September 2026. Comparing the two sets of samples will help show any changes in water quality over time.

In the Lymington River, three samples were collected downstream in the lagoon area and three samples were collected upstream along the Ober Water tributary.

The diatoms found downstream with the highest counts belonged to the genera Sellaphora, Planothidium, Nitzschia and Navicula. The species identified were:

• Sellaphora saugerresii

• Planothidium lanceolatum (indicates eutrophic, moderately polluted water)

• Planothidium frequentissimum (a pollution-tolerant species)

• Navicula cryptocephala

• Navicula goersii

• Nitzschia palea

  
  

These diatoms are moderately to highly pollution resistant and can therefore survive in nutrient-rich and sewage-affected environments. The initial data suggests that sewage is present downstream in the Lymington River.

The diatoms found upstream show a marked difference in species. Although some of the genera are the same, the species themselves can have very different water quality preferences. The species most commonly found in the upstream samples were:

• Cocconeis placentula

• Nitzschia perminuta

• Gomphonema variostriatum

• Navicula cryptofallax

• Nitzschia alpina

  
  

These are all recognised as bioindicators of good water quality.

The difference in species is notable and indicates a substantial difference in water quality between the upstream and downstream areas of the Lymington River. However, much work remains to be done and without further research into diatom species and their habitats, the results cannot yet be considered fully conclusive.