Diatoms are excellent ecological indicators, sensitive to lake acidity, nutrients and salinity. Diatoms have a short life cycle and respond quickly to changes in aquatic conditions. Consequently, the diatom assemblage preserved within lake sediments can be used to reconstruct the changes in a water body's ecological state. This information can be used to establish lake reference conditions and inform restoration targets.
Gina Henderson has been using preserved diatoms from lake cores to reconstruct lake conditions from numerous lakes across a wide geographical area (see Publications) and a selection of her projects are listed below:
2013, Reference conditions for phosphorus runoff from forested areas with arable soil properties (Norwegian Research Council, led by Bioforsk).
2011-2014, BIOFRESH project (European Union).
2008, Palaeoecological assessment of fresh waters in SACs and ASSIs in Northern Ireland.
2007, Palaeoecological study of Lochs Arkaig, Huamavat and Shiel. Investigating the influence of fish farms (Marine Harvest, see case study below).
2006-2008, Environmental Improvement Plan (EIP) for impacted mesotrophic lochs, Palaeoecological study (SEPA).
For more information on these projects and the applicability of diatoms for ecological restoration please contact us.
Case Study- Loch Arkaig, Scotland
A sediment core was taken from Loch Arkaig, Scotland in order to investigate the impact of a fish farm in the Loch. The graph below illustrates the down core diatom assemblage. The core was dated using radiometric dating (Lead- 210 and Cesium 137) to provide a chronology for the past 150 years. The shaded area on the graph represents the period during which the fish farm has been in operation.
The obvious changes in the diatom community towards the top of the core (e.g. decreases in Cyclotella species and increases in A. subarctica), reflect the changes in nutrient loading to the the Loch and the changes in diatom inferred Total Phosphorus also reflect this. For more information on this study please see Publications or contact us.
Clarke et al., (2007) Palaeoecological study of Lochs Arkaig, Huamavat and Shiel. ECRC Final Report to Marine Harvest.