The community of algae and bacteria growing on stream and river beds is referred to as periphyton. The National Policy Statement for Freshwater Management (NPS-FM) contains a periphyton attribute requiring councils to monitor periphyton chlorophyll-a on a monthly basis. The monitoring results are then compared to chlorophyll-a limits in the NPS-FM allowing the assignment of attribute states.
There are a number of factors influencing periphyton growth that need to be considered before representative' monitoring sites can be chosen. The influence of two of these factors, stream bed shading and meso habitat, were assessed in a one-year trial within a short reach of the Omaka River. Periphyton chlorophyll-a was monitored monthly at five sites with varying degree of shading by riparian vegetation within riffle and run habitats. Visual bank-side assessment of percentage periphyton cover was also carried out.
