Response of Algal Biomass to Large‐Scale Nutrient Controls in the Clark Fork River, Montana, United States¹

Abstract

Suplee, Michael W., Vicki Watson, Walter K. Dodds, and Chris Shirley, 2012. Response of Algal Biomass to Large‐Scale Nutrient Controls in the Clark Fork River, Montana, United States. Journal of the American Water Resources Association (JAWRA) 48(5): 1008‐1021. DOI: 10.1111/j.1752‐1688.2012.00666.x Abstract: Nutrient pollution is an ongoing concern in rivers. Although nutrient targets have been proposed for rivers, little is known about long‐term success of programs to decrease river nutrients and algal biomass. Twelve years of summer data (1998‐2009) collected along 383 km of the Clark Fork River were analyzed to ascertain whether a basin‐wide nutrient reduction program lowered ambient total nitrogen (TN) and total phosphorus (TP) concentrations, and bottom‐attached algal biomass. Target nutrient and algal biomass levels were established for the program in 1998. Significant declines were observed in TP but not TN along the entire river. Downstream of the city of Missoula, TP declined below a literature‐derived TP saturation breakpoint and met program targets after 2005; TN was below targets since 2007. Algal biomass also declined significantly below Missoula. Trends there likely relate to the city’s wastewater facility upgrades, despite its 20% population increase. Upstream of Missoula, nutrient reductions were less substantial; still, TP and TN declined toward saturation breakpoints, but no significant reductions in algal biomass occurred, and program targets were not met. The largest P‐load reduction to the river was from a basin‐wide phosphate laundry detergent ban set 10 years before, in 1989. We document that nutrient reductions in rivers can be successful in controlling algal biomass, but require achievement of concentrations below saturation and likely close to natural background.

Nutrient Limiting Factor for Enabling Algae Growth of Rawapening Lake, Indonesia

“…Based on these assessments, the growth of algae in the waters of Lake Rawapening be determined by TP and at times determined by the ratio TN/TP (Florida Lakewatch, 2000). In conditions where nitrogen is the limiting factor in the growth of aquatic algae, in general, the types of algae that grow are a group of blue algae are capable of nitrogen fixation from the air ( Suryono, 2006). The range of ratio TN/TP in Rawapening Lake presented in Figure 6 and Figure 7.…”

Quantifying Variability in Four US Streams Using a Long-Term Data Set: Patterns in Water Quality Endpoints

“…Flow measured at these stations served as a surrogate for relative flow variation at each site (including tributaries) for a given stream system even though some differences due to site-specific channel morphology and relative drainage area and land use exist. To evaluate the magnitude of the observed endpoint variation that was related to flow, non-parametric locally weighted scatterplot smoother (LOWESS, degree of smoothing = 0.5, 2 steps) lines were fit to each site-specific flow-endpoint scatter plot, and LOWESS residuals were calculated using this line (Helsel and Hirsch 2002;Jassby 2008;Suplee et al 2012). LOWESS was chosen for its flexibility in capturing a range of possible site-specific flow patterns.…”

“…Although examples exist in the literature, long-term studies of water quality and biological conditions in surface waters are difficult to implement and are relatively uncommon (Jassby 2002(Jassby , 2008Suplee et al 2012). Consequently, estimates of variability used as the basis for water quality-monitoring design and assessments may be frequently derived from short-term, spatially limited studies.…”

“…Using a 13-year data set of monthly measurements of 25 chemical, biological, and physical water properties to develop and examine trends in an index of water quality, the authors describe patterns in water quality endpoints at upstream and downstream locations by evaluating and comparing endpoint variability, relationships among endpoints and flow, and trends in endpoints over time and season which were used to support watershed management decisions. Suplee et al (2012) used 12 years of summer time nitrogen, phosphorus, and algal biomass data from the Clark Fork River (Montana, USA) to evaluate whether and how nutrient management programs had resulted in desirable reductions in these endpoints. The authors conclude that significant reductions in total phosphorus concentrations occurred as a result of nutrient reduction efforts, though similar reductions in total nitrogen concentrations did not occur.…”

Remote Sensing of Submerged Aquatic Vegetation in a Shallow Non-Turbid River Using an Unmanned Aerial Vehicle

“…The Clark Fork is a clear shallow 5th order Strahler [43] stream system with a long history of nuisance filamentous Cladophora growth [44][45][46]. In the spring, excessive bottom scour and turbidity remove much of the benthic biomass in the system, which is followed by a one to two month growing season when river conditions (e.g., temperature, velocity, and light) permit lush establishment of algal cover.…”