Biological Response to Nutrients

Science Center Objects

Eutrophication, or excess nutrients in streams, is typically one of the top reasons that a stream is listed as impaired on the 303(d) list as part of the Clean Water Act. 

USGS IN staff collecting biological samples

Initially it was hoped that a strong linear relation would be found between nutrient and algal biomass concentrations, such as chlorophyll a, that would allow standards to be set to improve water quality. Unlike in lakes, a strong correlation has not been found and it has become important to use biological community response to nutrient concentrations to show improvements in water quality.

The Ohio-Kentucky-Indiana WSC has had several projects with multiple collaborators to assess the biological response to nutrients since 2001. The first collaboration was with the Indiana Department of Environmental Management (IDEM) that added an assessment of algal biomass, both sestonic and periphytic chlorophyll a (CHLa) to the sites being sampled by IDEM for macroinvertebrate and fish community data. The goals of this early work were to provide an algal biomass assessment in Indiana streams and rivers as well as assess if algal biomass would correlate to biological community variables. Over 300 sites were sampled in Indiana between 2001 and 2005 in order to investigate the effects of nutrients on algal biomass and biological communities. The results from these studies will be used by IDEM to develop nutrient criteria for Indiana rivers and streams.

 A second major study was done in Indiana and Ohio as part of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Nutrient Enrichment Effects (NEET) study. The analysis in this study relates algal-, invertebrate-, and fish-community composition to habitat, nutrients, and land-use variables along a previously determined nutrient-concentration gradient. The study was conducted in 30 agriculturally dominated watersheds within the U.S. Environmental Protection Agency (USEPA) Level III Eastern Corn Belt Plains (Ecoregion 55). Study sites were selected to minimize differences in the physical habitat while maximizing differences in nutrient concentration along a nutrient (TP and TN) gradient. In regional-gradient studies of biological communities, it is important to minimize the effects of natural variables that can mask the relations between the variables of interest, in this case nutrients, and their effects on the biological community. These natural variables can include geology, soils, land use, basin size, and physical habitat. Information from this study may help determine which biological-community-composition group or groups are most appropriate in nutrient-assessment studies and nutrient-criteria development.

Major Findings

Nutrient, habitat, and basin-characteristics data and relations with fish- and invertebrate communities in Indiana streams (1998-2000)

  • several significant but weak relations were found between nutrients and fish and invertebrate attributes and metrics
  • the strength of the relations increased in the fish data when the data was analyzed by basin size
Field collection in Indiana

Relations of principal components analysis site scores to algal-biomass, habitat, basin-characteristics, nutrients, and biological-community data in the West Fork White River Basin, Indiana (2001)

  • no significant relations between the periphyton principal component sites scores with nutrients
  • there were significant relations with fish and invertebrate attributes and metrics 
  • seston principal component sites scores were significantly related to nutrients and fish and invertebrate attributes

Relations of principal components analysis site scores to algal-biomass, habitat, basin-characteristics, nutrient, and biological-community data in the Whitewater River and East Fork White River Basins (2002)

  • similar to the 2001 study in the White River Basin, there were no significant relations between the periphyton principal component sites scores with nutrients
  • there were significant relations with fish attributes and metrics
  • Seston principal component sites scores were significantly related to nutrients and fish and invertebrate attributes

Relations of principal components analysis site scores to algal-biomass, habitat, basin-characteristics, nutrient, and biological-community data in the Upper Wabash River Basin, Indiana (2003)

  • no significant relations between the periphyton principal component sites scores with nutrients
  • there were significant relations with fish and invertebrate attributes and metrics
  • unlike the 2001 and 2001 studies, seston principal component sites scores were not significantly related to nutrients nor fish and invertebrate attributes and metrics

Occurrence and distribution of algal biomass and its relations to nutrients and selected basin characteristics in Indiana streams

  • the frequency and magnitude of stream discharge varied seasonally and annually and greatly influenced algal biomass concentrations through algal scour and drift
  • Median concentrations of algal biomass in Indiana streams were 41.2 mg/m2 for periphyton chlorophyll a (CHLa); 52.1 g/m2 for ash-free-dry mass; 2.44 mg/L for seston CHLa; 0.75 mg/L for particulate organic carbon
  • Approximately 32 percent of the periphyton CHLa and 6 percent of the seston CHLa samples would be considered eutrophic according to Dodds and others (1998) nutrient boundary levels
  • no significant relations among nutrients and periphyton or seston CHLa parameters
  • only significant positive relations were observed between summer POC and summer TP as well as summer POC and summer TKN

Breakpoint Analysis and Assessment of Selected Stressor Variables on Benthic Macroinvertebrate and Fish Communities in Indiana Streams: Implications for Developing Nutrient Criteria

  • biological communities from 321 sites in Indiana were dominated by eutrophic species and the initial relations between the causal (total nitrogen, total phosphorus, periphyton and seston chlorophyll a, and turbidity) and response (biological communities and attributes) variables were weak
  • analytical and ecological censoring methods were used, which strengthened the relations between the causal and response variables
  • breakpoints were calculated for the ecological and statistical significant relations
  • total nitrogen breakpoints ranged from 2.4 to 3.3 mg/L, suggesting hypereutrophic conditions and the total phosphorus breakpoints ranged from 0.042 to 0.129 mg/L, suggestion mesotrophic to eutrophic conditions when compared to Dodds trophic classifications
Documenting field observations

Phytoplankton growth and assembly in relation to nutrient supply and other environmental factors in the White River Basin, Indiana

  • two evenly sized basins with similar flow and annual loadings of Total Nitrogen and Total Phosphorus provide an example of differences between basins driven by point source and non-point sources of nutrients
  • West Fork White River, which has a constant source of nutrients from point sources, had 2-4 times greater algal biomass compared to the non-point driven East Fork White River

Assessment of nutrient enrichment by use of algal-, invertebrate-, and fish-community attributes in wadeable streams in ecoregions surrounding the Great Lakes

  • the algal, invertebrate, and fish taxa and community attributes that best reflect the effects of nutrients along a gradient of low to high nutrient concentrations in wadeable, primarily Midwestern streams within Nutrient Ecoregions VI, VII, and VIII were assessed
  • the breakpoints from all biological communities were generally about 3–5 times higher in the south than the north
  • in the north, breakpoints with similar lower concentrations were found for TN from all biological communities (around 0.60 milligram per liter) and for TP (between 0.02 and 0.03 milligram per liter) for the algae and invertebrate communities

Algal-biomass data for each specific year of the IDEM/USGS study

 

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