Diatoms – Why are they so special?

Diatoms – Why are they so special?

Whether you have the luxury of being on, beside or near the ocean or miles inland, there is one thing you should know about the ocean – diatoms basically rule the seas, and without them we’d have 50% less oxygen to breathe.

But they don’t just produce oxygen. On top of being responsible for 20% of global carbon fixation and 40% of marine primary productivity, these eukaryotic microalgae are also phenomenally beautiful.

A unique feature of diatom anatomy is that they are surrounded by a cell wall made of silica and they are the largest class of silicifying organisms on the planet! It is estimated that the number of diatom species range from 20,000 to 2 million, with new species being discovered every year.

^{Figure 1:Species Odontella sinensis from the harbour of Lauwersoog in the Netherlands.}

These little plants are one of the main food sources for zooplankton as well as freshwater snails, caddis fly larvae, small crustaceans and filter feeders like clams.

What is also amazing about them is they can tell us a lot about the quality of water that they inhabit. For example, species have distinct range of pH and salinity where they will grow. Diatoms also have ranges and tolerances for other environmental variables, including nutrient concentration, suspended sediments and others. This makes them super useful in monitoring the biotic conditions of our bodies of water.

^{Figure 2: Meridion circulare in phase contrast}

These incredible photographs were captured by Anne Gleich, who first saw her very first diatom 10 years ago and fell in love with their architectural design. With a keen interest in nature, microscopy and microphotography, this was the start of her collecting water samples from all over the world and learning about fossil and recent diatoms. Anne is also the legacy of the homepage from her wonderful friend Nigel Charles for the fossil diatoms from Oamaru: https://www.oamarudiatoms.co.uk/