Benthic diatoms are a quality element used to assess the ecological status of streams. The current assessment criteria using benthic diatoms are based on two indices and two additional metrics:
Diatoms in WATERS
Diatoms are not currently used to assess the ecological status of lakes. In this sub-project, we will test whether the same method can be used for lakes as for streams, and determine the margin of error of the lake method.
Regarding diatoms in streams, it has been demonstrated that the current method does not indicate the impacts of toxins such as heavy metals and pesticides. In WATERS, we will test whether diversity, functional groups, or deformed diatom valves could be used as additional metrics in the diatom method to indicate toxin impact.
As part of the common field study (i.e., the gradient study), we will test whether or not changes in forestry or hydromorphology can affect benthic algae.
The current assessment criteria are based solely on the relative abundance of diatoms while the biomass of diatoms and other types of algae should also be considered as part of the assessment. However, such analyses are very time consuming and logistically demanding. As an alternative this sub-project will examine whether pigment data can be used as complementary data; a new instrument will be tested for this purpose.
Finally, the effectiveness and sensitivity of the benthic diatom method will be compared with the other biological quality elements and methods used to classify the ecological status of streams and lakes.
Taken together, the results should help minimize error in the ecological assessment of stream status using benthic diatoms, increase the possibility of assessing lake status, and use information on the entire benthic algal community in the assessment.
Frustulia crassinervia (large) och Eunotia incisa (small) - two diatom species that occur in limnic waters with low pH.
