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Updated: Jul 15, 2025
05:04
Author Spotlight: Understanding Riverine Nitrogen Impacts and Primary Productivity for Effective Nutrient Management
Published on: July 14, 2023
428
Linking watershed nutrient loading to estuary water quality with generalized additive models.
1Texas A&M AgriLife Research, Texas Water Resources Institute, Texas A&M University, College Station, TX, United States of America.
Peerj
|October 2, 2023
Summary
Nutrient loads in Lavaca Bay, Texas, were primarily driven by natural rainfall, not management actions. Estuary water quality showed no long-term changes, but nitrogen increases are concerning for future eutrophication.
Area of Science:
- Estuarine Ecology
- Water Quality Assessment
- Environmental Modeling
Background:
- Estuary water quality responses to nutrient loading are complex, influenced by environmental drivers and non-linear relationships.
- Lavaca Bay, Texas, faces potential eutrophication and water quality degradation.
- Evaluating management impacts requires disentangling natural variations from anthropogenic sources.
Purpose of the Study:
- To apply generalized additive models for calculating watershed nutrient loads in Lavaca Bay.
- To assess estuary water quality responses to freshwater inflow and flow-adjusted nutrient loads.
- To evaluate the influence of anthropogenic nutrient sources on water quality.
Main Methods:
- Utilized generalized additive models (GAMs) for nutrient load prediction and water quality assessment.
- Employed flow-adjusted nutrient loads to isolate anthropogenic impacts.
- Analyzed long-term trends in dissolved oxygen, chlorophyll-a, and nutrient concentrations.
Main Results:
- Annual nutrient loads varied significantly, but flow-normalized loads showed minimal change, indicating natural drivers dominated.
- No long-term changes were detected in dissolved oxygen or chlorophyll-a levels.
- Site-specific increases in organic and inorganic nitrogen were observed, posing a eutrophication risk.
Conclusions:
- Nutrient loading in Lavaca Bay is primarily driven by natural precipitation and runoff, not nonpoint source management.
- Freshwater inflow significantly influences nutrient and chlorophyll-a concentrations, but not dissolved oxygen.
- Semiparametric models offer a robust methodological approach for estuary assessments and load estimations.
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