At each site species community and algal percent coverage of an area of 50x50 m is determined. To determine biomass, ten replicates samples per site (10x10 cm) are taken by removing the algae from the sediment surface. In the laboratory, biomass (ash free dry weight) of each species within the samples is determined by drying the algae at 75°C for three days followed by ashing at 500°C for six hours.