My Irish Diatom Adventure (Part 1)

Part 1: Finding Samples

Last September, I travelled as a tourist for two weeks with my brother Russell in Ireland, visiting both the beautiful Republic of Ireland and Northern Ireland.

The Cliffs of Moher, on the west coast of Ireland in County Clare. Image: Joe Holmes © Canadian Museum of Nature

As a volunteer since 2013 for the Canadian Museum of Nature, working for Paul Hamilton with freshwater diatoms, I felt this trip was also an opportunity to collect Irish diatom samples from rivers, lakes, streams and ponds for the museum. I was successful, obtaining 21 samples from around the island.

Kylemore Castle and Pollacapall Lake, Connemara, County Galway, Ireland. Image: Joe Holmes © Canadian Museum of Nature

Although we were on an excellent bus tour, getting at freshwater samples was a bit of a challenge (unlike travelling by car at your own pace): I was limited to towns and cities on the itinerary, which were mainly along the coast. Our periodic stops were for an hour or so.

Joe Holmes among the hexagonal basalt columns at The Giant’s Causeway, County Moyle, Northern Ireland. Image: Russell Holmes © Canadian Museum of Nature

Rivers flowing through coastal towns tended to be tidal (with salt water), so it was necessary to find fresh water flowing from upstream. Also, rivers through cities and towns were often walled off with little or no public access; in rural areas, they were sometimes fenced off. Some were fast flowing, or the water was too deep. Nevertheless, I still had many good opportunities to find accessible lakes, streams and ponds on the tour.

Ancient mounds over 5000 years old at Knowth near the Boyne River, County Meath, Ireland. Image: Joe Holmes © Canadian Museum of Nature

To obtain and process a sample, mud from the bottom—which contains diatoms—was collected using a turkey baster and put into small bottles. Photos of the collection area were taken and a local tourist map obtained to mark the exact location of the sample.

Top: Blarney Castle in County Cork, Ireland, houses the famous Blarney Stone. Bottom: A diatom, Stauroneis cf. gracilis (size: 140 μm) from a creek on Garnish Island off the coast of Glengarriff. Diatoms are one-celled algae having a silica shell. Their study helps environmental scientists learn how humans can affect ecosystem health and biodiversity, whether through local urbanization or global climate change. Images: Joe Holmes © Canadian Museum of Nature

Back at the hotel, samples were filtered using a funnel and special filter paper and then dried overnight. Once dry, the samples were sealed in labelled baggies for the trip home. Latitude and longitude were determined later using Google Maps, which worked well.

Map of Ireland showing the Republic of Ireland and Northern Ireland. Image: © Tintazul, modified (licence: CC BY-SA 2.5)

Paul and I are looking forward to processing and photographing more of these Irish samples. They will provide the museum with a taste for what Irish diatoms are like and what further research may be done.