Assessment of the effectiveness of best management practices for streams draining agricultural landscapes using diatoms and macroinvertebrates

Abstract

In this study, a bioassessment was conducted to determine the effectiveness of best management practices (BMPs) implemented in farms in the Upper Delaware River watershed, NY (USA). Diatom and macroinvertebrate communities were analyzed across 17 low-order streams, designated as reference, BMP, or non-BMP. Streams lacking improvements (non-BMP) had significantly greater specific conductance, pH, TDP, NH 4 ? -N, and NO 3 --N than did reference streams. Diatom model affinity (DMA) values were significantly greater in reference and BMP streams than in non-BMP streams; non-BMP streams bordered on a ''severely impacted'' rating. The Trophic Diatom Index (TDI) varied two-fold among stream classes, with non-BMP [ BMP [ reference. TDI and DMA values were highly correlated, and both varied significantly with conductance, TDP, NH 4 ? -N, and NO 3 --N. Macroinvertebrate taxa, EPT richness, and Simpson's diversity did not differ significantly among stream classes. Macroinvertebrate metrics (HBI, Bioassessment Profile, Percent Model Affinity) varied by stream class, but none indicated greater water quality in BMP sites. Nonetheless, each correlated significantly with conductance and TDP in the directions predicted by each model. Our data suggest that diatoms are more sensitive to moderate increases in nutrients, conductivity, and pH in highgradient agricultural streams, and may be more useful in assessing stream management practices.

Agricultural Best Management Practice Abundance and Location does not Influence Stream Ecosystem Function or Water Quality in the Summer Season

“…However, the average nutrient concentrations of all collected samples (TN = 2.69 mg/L, NH 4 = 0.185 mg/L, NO 2 -NO 3 = 1.66 mg/L, TP = 0.27 mg/L, SRP = 0.18 mg/L, TDP = 0.19 mg/L) were comparable to results of studies on other small agricultural streams in the North American Great Lakes region. For example, Gabel et al [21] reported concentrations of 0.087, 0.179, and 1.101 mg/L for TDP, NH 4 , and NO 3 respectively, among seven agricultural streams with abundant BMPs. Additionally, Chambers et al [54] found an average TN concentration of 2.68 mg/L and TP concentration of 0.08 mg/L along a gradient of agricultural catchments in Southern Ontario (6.7%-100% cover).…”

“…BMPs assessed in past studies have been shown to reduce nutrient levels in agricultural streams (e.g., [21,[57][58][59][60][61][62]). However, results from our study did not suggest that BMPs were enhancing water quality in the studied streams.…”

“…However, past studies exploring the relationship between BMPs and stream ecological condition have shown more equivocal results, despite also frequently reporting reduced concentrations of nutrients and sediments associated with BMP use [14,15,[17][18][19][20][21]. To date, past studies have largely focused on taxonomic based measures of community condition, particularly aquatic invertebrates.…”

Effect of land use and environmental variables on phytoplankton community structure in high-elevation river, upper Yangtze river, China

“…This indicates that LUT had no directly effect on the abundance of phytoplankton, but indirectly through the input of nutrients (TN, TP) (Peng et al, 2021). In the upper Delaware River basin of New York State, the influence of LUT on algae was explored through the input of TN, TP and other substances, which were closely related to the abundance of diatoms (Gabel et al, 2012). SEM confirmed this view that LUT indirectly affected the growth of phytoplankton by increasing nutrients in rivers (Figure 7).…”

Structure of potamoplankton along a gradient of preservation of riparian vegetation in subtropical streams

“…Several studies have reported on the influence of riparian vegetation on the water quality and on the response of the phytoplankton community (Naiman et al 2005, Dudgeon 2008 on the community of diatoms in tropical and temperate rivers (Vázquez et al 2011, Gabel et al 2012) has been observed, and an increase in the proportion of N and P when compared to silicate (Si), may result in a decline of diatoms (Conley andMalone 1992, Cugier et al 2005). Moreover, changes in the nutrient loadings caused by deforestation of up to 50% of riparian forests may enhance eutrophication and probably increase the frequency of algal blooms (Perry et al 1999).…”