Biomonitoring Using Algae
Bio-monitoring of lakes and streams is an important part of any monitoring effort. A majority of agencies and states focus only on fish and macroinvertebrates. This is likely due in part to the cultural significance of fish and what they feed on. Bio-monitoring of algal communities possess a distinct advantage over other biota monitoring.
Benthic algal communities are generally early warning indicators of environmental changes in water quality. By using near-shore algae communities in bio-monitoring efforts the scientist gains an effective monitoring tool that can indicate changes due to anthropogenic disturbances. Algae are the base of the aquatic food-web, thus they play a huge part in influencing the rest of the food-web. Benthic algae readily utilize biological available nutrients, in a matter of days to weeks. Water chemistry monitoring is not as sensitive, only gives you what is happening at that moment, and generally closely matches what is happening in offshore locations and are influenced by open water conditions.
The physiological optima and tolerance levels of a variety of algal species is known for freshwater algae. Many useful metrics have been created, tested and can be utilized for determining anthropogenic sources, and changes in water quality.
The first step to utilizing algae in bio-monitoring is defining reference conditions. This is primarily conducted by data collection at natural, undisturbed sites within the region. Both field analysis of biomass and collection of samples should be conducted, coupled with water chemistry analysis, the geological substrates and documenting riparian/shoreline area alterations. From this data, a community similarity index can be created.
For study sites the first step is field observations, and collection of a multi-habitat sample. From these the algal taxonomist will identify and enumerate the forms of algae and apply specific metrics. There are many metrics that have been created and tested, some specifically for diatoms or stream periphyton. European countries have created metrics for near-shore areas of lakes that can be tweeked and applied in the United States.
Useful metrics based on algal composition include: Species and generic richness, number of divisions, presence and forms of Cyanobacteria, % Sensitive diatoms, PercentAchnanthes m., Pollution tolerance index, Trophic index, Salinity index, Siltation index, Palmer pollution Index, Percent community similarity index, Impairment of ecological conditions index, % Cyclotella sp., Area-specific cell densities and bio-volumes and Waste-water similarity index.
All forms of algae should be identified, both diatoms and soft-algae. While it is best to identify all forms down to species level, much information can be gathered by genus level only. This is important for financial reasons, as the cost for analysis can be very substantial if it has to be sent out to be analyzed. It is also difficult and time consuming to identify some forms of algae down to species level, as a fruiting body is necessary for many Chlorophyta forms.
By coupling both field assessments with laboratory identification and application of metrics, researchers can determine changes in water quality, and the possible upland sources.
