Alongside paleolimnology, there are many other areas that may use diatoms as a research tool, such as when studying climate change, or eutrophication. Measuring pH is another important usage, and one that I used as an example when discussing why diatoms are used as bioindicators: link.
When assessing climate change, it is important to look at the transitional area between two biomes, or ecotone. These transitional areas will shift over time as the climate changes. That means that the location of organisms, such as diatoms, will also shift, as they migrate to areas that were previously inhospitable. The high Arctic is an important reference region for studying climate change, as it is predicted to be more affected by rising temperatures than other areas of the world.
Diatoms were sampled from around the Cornwallis and Prince of Wales islands in the Canadian Arctic Archipelago. These two islands have different temperatures, as Cornwallis is high Arctic, whilst Prince of Wales island spans the transition between high and mid Arctic. There were different diatom assemblages were found around each of these islands.(Antoniades et al. 2014 – link to paper)
In the future this study could be replicated, and by assessing the types of diatoms present in the water, we will be able to track the moving ecotones and so have a greater understanding of the effects of climate change in that area. Changes that happen within the diatom community are likely to be mirrored in high organisms within the food chain, but it is much easier to assess these effects using a small, fast replicating species that it would be with fish, for example. We can only study climate change as well as the funding allows, so it is important to be as cost-effective as possible when collecting data. The cost effectiveness of diatom sampling was also mentioned in my podcast: link.
The Oxford Dictionary of Zoology defines eutrophication as: “the nutrient enrichment of an aquatic ecosystem, such that productivity ceases to be limited by nutrient availability.” This can cause major problems within an ecosystem, as the extreme success of an algal species is often at the cost of other species; algal blooms can drain the oxygen from a water body, causing the fish and other organisms to die.
Diatoms could be viewed as a ‘universal indicator’, with one metric could be used globally. However, a 2005 US study suggests that diatom metrics are only useful in the geographic area in which the samples were collected. Data was collected from five ‘ecoregions’ to create a diatom metric for measuring eutrophication. The ecoregions were 5 areas found to have similar physical factors and diatom species, this allowed them to test the ‘geographic area’ theory.
Indicator species were selected (see methods of paper for more information), and species lists were put together from the regional analyses. These regional species lists were considerably different from the national lists, suggesting that regional metrics can increase accuracy. These new metrics were also found to provide a more accurate assessment of US rivers than European metrics. (Potapova & Charles 2007 – link to paper)
Allaby, M. (2009). A dictionary of zoology. Oxford: Oxford Univ. Press.
Antoniades, D., Douglas, M., Michelutti, N. and Smol, J. (2014). Determining diatom ecotones and their relationship to terrestrial ecoregion designations in the central Canadian Arctic Islands. Journal of Phycology. (link)
Potapova, M. and Charles, D. (2007). Diatom metrics for monitoring eutrophication in rivers of the United States. Ecological Indicators, 7(1), pp.48–70.