Understanding the influence of nutrients on stream ecosystems in agricultural landscapes

Munn, Mark D.; Frey, Jeffrey W.; Tesoriero, Anthony J.; Black, Robert W.; Lee, Kathy E.; Maret, Terry R.; Mebane, Christopher A.; Waite, Ian R.; Zelt, Ronald B.

doi:10.3133/cir1437

Cited by 24 publications

(18 citation statements)

References 25 publications

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“…In contrast, we did not observe a clear pattern in benthic chl-a response across the range of mean TN and TP. In accordance with the Nutrient-Algal Biomass Conceptual model, we would not necessarily expect such a pattern [63,77] due to the different environments in which benthic and sestonic algae tend to dominate (and thus be measured). Our review included responses from streams that ranged from oligotrophic to eutrophic and that encompassed many stream habitat types, all of which may have benthic algae communities that fail to respond to variation in nutrient concentration as a result of nutrient saturation or confounding environmental factors such as canopy cover, according to the model.…”

Section: Implications For Policy/managementmentioning

confidence: 62%

Response of chlorophyll a to total nitrogen and total phosphorus concentrations in lotic ecosystems: a systematic review

et al. 2021

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Background Eutrophication of freshwater ecosystems resulting from nitrogen and phosphorus pollution is a major environmental stressor across the globe. In this systematic review, we compiled and synthesized literature on sestonic and benthic chlorophyll a (chl-a) responses to total nitrogen (TN) and total phosphorus (TP) concentrations in the water column in streams and rivers to provide a state-of-the-science summary of nutrient impacts on these endpoints. This review was motivated by the need for comprehensive information on stressor-response relationships for the most common nutrient and biotic response measures used by state-level environmental managers in the United States to assess eutrophication of lotic ecosystems and support environmental decision making. Methods Searches for peer-reviewed and non-peer-reviewed articles were conducted using bibliographic databases, specialist websites, and search engines. These returns were supplemented with citation mapping and requests for material from experts. Articles were screened for relevance using pre-determined eligibility criteria, and risk of bias was evaluated for each included article based on study type-specific criteria. Narrative summaries and meta-analysis were used to evaluate four primary stressor-response relationships: TN-benthic chl-a, TP-benthic chl-a, TN-sestonic chl-a, and TP-sestonic chl-a. Potential effects of modifying factors and study validity on review conclusions were assessed via sensitivity and sub-group analysis and meta-regression. Results Meta-analysis of 105 articles, representing 439 cause-effect pairs, showed that mean effect sizes of both benthic and sestonic chl-a responses to TN and TP were positive. Of the four stressor-response relationships examined, TP-sestonic chl-a had the most positive relationship, followed by TN-benthic chl-a, TN-sestonic chl-a, and TP-benthic chl-a. For individual U.S. states, mean effect sizes for the four stressor-response relationships were mostly positive, with a few exceptions. Chlorophyll measurement method had a moderately significant influence on mean effect size for TP-sestonic chl-a, with chl-a responding more strongly to TP if fluorometry versus spectrophotometry was used. Year of publication had a significant negative effect on mean effect size, as did mean nutrient concentration for both sestonic chl-a nutrient relationships. When the same study measured both TN and TP, chl-a tended to respond similarly to both nutrients. Sensitivity analysis indicated that conclusions are robust to studies with high risk of bias. Conclusions This systematic review confirms that nutrients consistently impact primary producer biomass in streams and rivers worldwide. It builds on previous literature syntheses evaluating chl-a responses to nutrient concentrations and confirms that benthic and sestonic chl-a respond positively to nutrients across a range of stream and river conditions, but also points to limits on these relationships (e.g., potential saturation at high nutrient concentrations). Lack of consistent reporting of contextual data limited our ability to examine how moderating factors influenced these stressor-response relationships. Overall, we provide nutrient managers responsible for protecting the quality of lotic ecosystems with a comprehensive evidence base for chl-a responses to TN and TP concentrations in the water column.

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Section: Implications For Policy/managementmentioning

confidence: 62%

Response of chlorophyll a to total nitrogen and total phosphorus concentrations in lotic ecosystems: a systematic review

et al. 2021

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“…We evaluated changes in nitrate retention for three reaches of the Lumbee River using a modified Lagrangian sampling design (e.g., Battaglin, et al., 2001; Deutsch et al., 2009; Gruberts et al., 2012; Moody, 1993; Schwientek & Selle, 2016) to capture stream nitrate concentrations and to compute retention and areal uptake before and after Hurricane Matthew. Other forms of nitrogen may be present within the watershed, but nitrate is generally the dominant species of inorganic nitrogen in most surface waters (Munn et al., 2018) including the Lumbee River, as confirmed by water sampling by state regulators between 2010 and 2014 and after Hurricane Matthew (North Carolina Department of Water Resources 2017). Thus, our study focused on nitrate and did not consider other components of total nitrogen fluxes in the Lumbee River.…”

Section: Introductionmentioning

confidence: 98%

Extreme Flooding and Nitrogen Dynamics of a Blackwater River

Neville¹,

Emanuel²,

Nichols³

et al. 2021

Water Resources Research

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Nitrogen is an important nutrient for aquatic ecosystems, but excess nitrogen poses major concerns for environmental quality. In addition to atmospheric deposition from fossil fuel combustion and transport via soil erosion (Burns et al., 2009;Howarth, 2008), human activities contribute to excess nitrogen in water bodies via over-fertilization or poorly timed fertilization of agricultural lands and even residential lawns (Loecke et al., 2016;Vitousek et al., 1997). From these sources, excess nitrogen may travel to surface waters slowly and persistently via groundwater (

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“…Eutrophication due to nutrient enrichment and associated excessive growth of algae or aquatic plants is a well-known and persistent water quality concern across many agricultural or urbanized regions [1][2][3]. In the United States, nutrient management efforts are implemented to restore and maintain the chemical, physical, and biological integrity of surface waters in accordance with the Clean Water Act's total maximum daily load (TMDL) program.…”

Section: Introductionmentioning

confidence: 99%

Nutrient limitation of algae and macrophytes in streams: Integrating laboratory bioassays, field experiments, and field data

2021

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Successful eutrophication control strategies need to address the limiting nutrient. We conducted a battery of laboratory and in situ nutrient-limitation tests with waters collected from 9 streams in an agricultural region of the upper Snake River basin, Idaho, USA. Laboratory tests used the green alga Raphidocelis subcapitata, the macrophyte Lemna minor (duckweed) with native epiphytes, and in situ nutrient-limitation tests of periphyton were conducted with nutrient-diffusing substrates (NDS). In the duckweed/epiphyte test, P saturation occurred when concentrations reached about 100 μg/L. Chlorophyll a in epiphytic periphyton was stimulated at low P additions and by about 100 μg/L P, epiphytic periphyton chlorophyll a appeared to be P saturated. Both duckweed and epiphyte response patterns with total N were weaker but suggested a growth stimulation threshold for duckweed when total N concentrations exceeded about 300 μg/L and approached saturation at the highest N concentration tested, 1300 μg/L. Nutrient uptake by epiphytes and macrophytes removed up to 70 and 90% of the N and P, respectively. The green algae and the NDS nutrient-limitation test results were mostly congruent; N and P co-limitation was the most frequent result for both test series. Across all tests, when N:P molar ratios >30 (mass ratios >14), algae or macrophyte growth was P limited; N limitation was observed at N:P molar ratios up to 23 (mass ratios up to 10). A comparison of ambient periphyton chlorophyll a concentrations with chlorophyll a accrued on control artificial substrates in N-limited streams, suggests that total N concentrations associated with a periphyton chlorophyll a benchmark for desirable or undesirable conditions for recreation would be about 600 to 1000 μg/L total N, respectively. For P-limited streams, the corresponding benchmark concentrations were about 50 to 90 μg/L total P, respectively. Our approach of integrating controlled experiments and matched biomonitoring field surveys was cost effective and more informative than either approach alone.

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Understanding the influence of nutrients on stream ecosystems in agricultural landscapes

Cited by 24 publications

References 25 publications

Response of chlorophyll a to total nitrogen and total phosphorus concentrations in lotic ecosystems: a systematic review

Response of chlorophyll a to total nitrogen and total phosphorus concentrations in lotic ecosystems: a systematic review

Extreme Flooding and Nitrogen Dynamics of a Blackwater River

Nutrient limitation of algae and macrophytes in streams: Integrating laboratory bioassays, field experiments, and field data

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