Invisible Wonders

Diatoms of life

February 5, 2010 – They are over 160 million years old. They are microscopic and can be found anywhere there is water, including mud and soil. They are diatoms, and Mount Allison University biologist Irena Kaczmarska is an expert studying the big impact of these tiny life forms on planet ecology.

Diatoms are plant-like organisms that form the base of the food chain for the entire planet. As a by-product of photosynthesis, these single-celled “grasses of the sea” provide up to one quarter of the oxygen in the atmosphere. “That means that every fourth breath you take you owe to diatoms,” says Dr. Kaczmarska. If that weren’t impressive enough, they also provide one quarter of all food on the planet. In short, much of life on Earth, directly or indirectly, is reliant on these little wonders that are invisible to the naked eye.

It was once thought that any species of diatom could be found anywhere on the planet. It is now apparent that biogeography applies to these microorganisms, and different species of diatoms reside in different locations. The threat of invasive diatoms being introduced to a new environment could pose serious risks for the local ecology.

Dr. Kaczmarska has turned her attention to recently discovered harmful diatoms. Some species produce compounds that can affect the neural systems of other organisms, including humans. There have been instances of people becoming sick, even dying, from eating mussels that became toxic from harmful diatoms. The problem is that no one fully knows how they produce these compounds, but Dr. Kaczmarska and her students are hard at work to find the answer.

“When we thought all diatoms were everywhere, we didn’t have to worry. Maybe if they aren’t harmful they can be left alone, but if they are harmful, we need protective measures,” says Dr. Kaczmarska, who is also one of the principal investigators in the NSERC-funded Canadian Aquatic Invasive Species Network.

The students are comparing the DNA of different diatoms to determine if there are genetic differences between native, alien, harmless and harmful species. This is reminiscent of a project Dr. Kaczmarska and her team contributed to last year: the NSERC-funded Canadian Barcode of Life Network ( www.bolnet.ca). For this project, the team collected samples from diatoms in the Bay of Fundy region to gather DNA barcodes. A DNA barcode is a short standard DNA sequence used as a reference for species-level identification. These barcodes are added to the Barcode of Life database, which aims to catalogue the DNA of all species of life on the planet. This will provide researchers and students with a ready, globally consistent reference to identify and monitor organisms. In the case of Dr. Kaczmarska, consulting the database could allow her and her team to differentiate between harmless and harmful, as well as foreign and native, species of diatoms.

Dr. Kaczmarska is also studying the evolution of diatoms and how they have evolved to become more specific from their earliest ancestors. This work is funded by an NSERC Discovery Grant, which she calls one of the most important grants for basic research.

“NSERC funds curiosity-driven research. This is essential first-step knowledge development because you never know which of your discoveries will lead to new applications,” she says.

Dr. Kaczmarska’s research explores one of the foundations for all ecology on the planet. Her work could lead to new discoveries relating to our planet’s ecosystem and the development of life. One thing is certain: her work will continue on the little wonders that affect, directly or indirectly, all life on Earth.