Spatial variation in algal biomass related to pulp and paper mill effluent in 4 US rivers: seasonal and annual patterns over a 6 year study

C.A. Flinders, T.J. Hall, W.J. Arthurs, J. Ikoma, and R.L. Ragsdale.National Council for Air and Stream Improvement, Anacortes, Washington, 98221, USA

Nutrient enrichment from point sources has been implicated in increased algal biomass downstream of inputs. Algal response depends on effluent nutrient quality/concentration and fine scale and regional habitat, and can vary within and between years. Benthic chlorophyll a (chla) concentration and water quality (color, turbidity, conductivity, hardness, TOC, TDS, COD, TN, TP) was monitored seasonally (spring, summer, fall) over 6 years at sites upstream and downstream of pulp/paper mills in 4 rivers (Codorus Creek, PA; Willamette and McKenzie Rivers, OR; Leaf River, MS) to determine the effects of effluent nutrients on algal biomass. Chlorophyll a concentrations were highly variable within and across sites on all rivers. River-specific ANOVA showed significant site-year and site-season differences in chla concentration. For all rivers, spatial patterns of algal biomass differed over the study period with no consistent relationship to pulp/paper mill location. Seasonal patterns of spatial chla concentration were river dependent with site differences unrelated to nutrient point sources. With the exception of Codorus Creek, water quality measures, including TN and TP, did not change appreciably in relation to effluent sources. Relationships between nutrient and chla concentration was weak in all study rivers. Results are discussed in terms of local and regional habitat.