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USGS2005

Trends in hydrophobic organic contaminants in urban and reference lake sediments across the United States, 1970-2001

A shift in national policy toward stronger environmental protection began in the United States in about 1970. Conversely, urban land use, population, energy consumption, and vehicle use have increased greatly since then. To assess the effects of these changes on water quality, the U.S. Geological Survey used sediment cores to reconstruct water-quality histories for38 urban and reference lakes across the United States. Cores were age-dated, and concentration profiles of polycyclic aromatic hydrocarbons (PAHs) and chlorinated hydrocarbons were tested statistically. Significant trends in total DDT, p,p???-DDE, and total PCBs were all downward. Trends in chlordane were split evenly between upward and downward, and trends in PAHs were mostly upward. Significant trends did not occur in about one-half of cases tested. Concentrations of p,p???-DDE, p,p???-DDD, and PCBs were about one-half as likely to exceed the probable effect concentration (PEC), a sediment quality guideline, in sediments deposited in the 1990s as in 1965-1975, whereas PAHs were twice as likely to exceed the PEC in the more recently deposited sediments. Concentrations of all contaminants evaluated correlated strongly with urban land use. Upward trends in PAH concentrations, the strong association of PAH with urban settings, and rapid urbanization occurring in the United States suggest that PAHs could surpass chlorinated hydrocarbons in the threat they pose to aquatic biota in urban streams and lakes.

Environmental Science & Technology↗

USGS2005

Accumulation of contaminants in fish from wastewater treatment wetlands

Increasing demands on water resources in arid environments make reclamation and reuse of municipal wastewater an important component of the water budget. Treatment wetlands can be an integral part of the water-reuse cycle providing both water-quality enhancement and habitat functions. When used for habitat, the bioaccumulation potential of contaminants in the wastewater is a critical consideration. Water and fish samples collected from the Tres Rios Demonstration Constructed Wetlands near Phoenix, Arizona, which uses secondary-treated wastewater to maintain an aquatic ecosystem in a desert environment, were analyzed for hydrophobic organic compounds (HOC) and trace elements. Semipermeable membrane devices (SPMD) were deployed to investigate uptake of HOC. The wetlands effectively removed HOC, and concentrations of herbicides, pesticides, and organic wastewater contaminants decreased 40−99% between inlet and outlet. Analysis of Tilapia mossambica and Gambusia affinis indicated accumulation of HOC, including p,p ‘-DDE and trans -nonachlor. The SPMD accumulated the HOC detected in the fish tissue as well as additional compounds. Trace-element concentrations in whole-fish tissue were highly variable, but were similar between the two species. Concentrations of HOC and trace elements varied in different fish tissue compartments, and concentrations in Tilapia liver tissue were greater than those in the whole organism or filet tissue. Bioconcentration factors for the trace elements ranged from 5 to 58 000 and for the HOC ranged from 530 to 150 000.

Environmental Science & Technology↗

USGS2013

Geographic setting influences Great Lakes beach microbiological water quality

Understanding of factors that influence Escherichia coli (EC) and enterococci (ENT) concentrations, pathogen occurrence, and microbial sources at Great Lakes beaches comes largely from individual beach studies. Using 12 representative beaches, we tested enrichment cultures from 273 beach water and 22 tributary samples for EC, ENT, and genes indicating the bacterial pathogens Shiga-toxin producing E. coli (STEC), Shigella spp., Salmonella spp, Campylobacter jejuni/coli, and methicillin-resistant Staphylococcus aureus, and 108–145 samples for Bacteroides human, ruminant, and gull source-marker genes. EC/ENT temporal patterns, general Bacteroides concentration, and pathogen types and occurrence were regionally consistent (up to 40 km), but beach catchment variables (drains/creeks, impervious surface, urban land cover) influenced exceedances of EC/ENT standards and detections of Salmonella and STEC. Pathogen detections were more numerous when the EC/ENT Beach Action Value (but not when the Geometric Mean and Statistical Threshold Value) was exceeded. EC, ENT, and pathogens were not necessarily influenced by the same variables. Multiple Bacteroides sources, varying by date, occurred at every beach. Study of multiple beaches in different geographic settings provided new insights on the contrasting influences of regional and local variables, and a broader-scale perspective, on significance of EC/ENT exceedances, bacterial sources, and pathogen occurrence.

Great Lakes↗

USGS2026

Predictions of anthropogenic background PFAS concentrations in soil and relation to bedrock lithology and groundwater quality

Detectable concentrations of per- and polyfluoroalkyl substances (PFAS) have been observed in soils in remote areas and presumably originate from atmospheric deposition. These anthropogenic background concentrations may enable some PFAS to leach to groundwater at levels that exceed regulatory criteria for drinking water. However, anthropogenic background soil concentrations and their connection to groundwater are not well characterized. We developed a boosted regression tree model to predict perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) concentrations in shallow soils across northern New England. Low soil pH was the most important predictor of elevated anthropogenic PFOS and PFOA concentrations in background soils, rather than potential PFAS sources, land use, or population density. Total organic carbon (TOC) was also an important predictor for PFOS soil concentrations. Model predictions indicate that 73% of the shallow soils within Maine, Vermont, and New Hampshire exceed New Hampshire’s Soil Remediation Standard for PFOS (0.5 ng/g) and 41% exceed the PFOA standard (0.4 ng/g). Analysis of soil model results and groundwater data suggests that areas with high soil pH are associated with higher groundwater detection frequencies, illustrating how areas with less retention in soil are, conversely, also areas with potentially greater groundwater vulnerability. Further analysis indicates that groundwater may be more vulnerable in calcareous lithologies.

Maine, New Hampshire, Vermont↗

USGS2009

Measurement and modeling of polychlorinated biphenyl bioaccumulation from sediment for the marine polychaete neanthes arenaceodentata and response to sorbent amendment

Bioaccumulation rates of polychlorinated biphenyls (PCBs) for the marine polychaete Neanthes arenaceodentata were characterized, including PCB uptake rates from water and sediment, and the effect of sorbent amendment to the sediment on PCB bioavailability, organism growth, and lipid content. Physiological parameters were incorporated into a biodynamic model to predict contaminant uptake. The results indicate rapid PCB uptake from contaminated sediment and significant organism growth dilution during time-series exposure studies. PCB uptake from the aqueous phase accounted for less than 3% of the total uptake for this deposit-feeder. Proportional increase of gut residence time and assimilation efficiency as a consequence of the organism's growth was assessed by PCB uptake and a reactor theory model of gut architecture. Pulse-chase feeding and multilabeled stable isotope tracing techniques proved high sediment ingestion rates (i.e., 6?10 times of dry body weight per day) indicating that such deposit-feeders are promising biological indicators for sediment risk assessment. Activated carbon amendment reduced PCB uptake by 95% in laboratory experiments with no observed adverse growth effects on the marine polychaete. Biodynamic modeling explained the observed PCB body burdens for N. arenaceodentata, with and without sorbent amendment.

Environmental Science & Technology↗

USGS1998

Butyltin residues in southern sea otters (Enhydra lutris nereis) found dead along California coastal waters

Tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), were determined in liver, kidney, and brain tissues of adult southern sea otters (Enhydra lutris nereis) found dead along the coast of California during 1992a??1996. Hepatic concentrations of butyltin compounds (BTs = MBT + DBT + TBT) ranged from 40 to 9200 ng/g wet wt, which varied depending on the sampling location and gender. Concentrations of BTs in sea otters were comparable to those reported in stranded bottlenose dolphins from the U.S. Atlantic Coast during 1989a??1994. Greater accumulation of butyltins in sea otters was explained by their bottom-feeding habit and the diet that consists exclusively of invertebrates such as mollusks and gastropods. Livers of female sea otters contained approximately 2-fold greater concentrations of BTs than did those of males. The composition of butyltin compounds in sea otter tissues was predominated by TBT in most cases and suggestive of recent exposure. Large harbors such as Monterey Harbor that handle ships legally painted with TBT-containing antifouling paints continued to experience ecotoxicologically significant butyltin contamination. Sea otters, which were affected by infectious diseases, contained greater concentrations of BTs in their tissues than those that died from trauma and other unknown causes.

Californnia↗

USGS2015

Declining acidic deposition begins reversal of forest-soil acidification in the northeastern U.S. and eastern Canada

Decreasing trends in acidic deposition levels over the past several decades have led to partial chemical recovery of surface waters. However, depletion of soil Ca from acidic deposition has slowed surface water recovery and led to the impairment of both aquatic and terrestrial ecosystems. Nevertheless, documentation of acidic deposition effects on soils has been limited, and little is known regarding soil responses to ongoing acidic deposition decreases. In this study, resampling of soils in eastern Canada and the northeastern U.S. was done at 27 sites exposed to reductions in wet SO 4 2 – deposition of 5.7–76%, over intervals of 8–24 y. Decreases of exchangeable Al in the O horizon and increases in pH in the O and B horizons were seen at most sites. Among all sites, reductions in SO 4 2 – deposition were positively correlated with ratios (final sampling/initial sampling) of base saturation ( P < 0.01) and negatively correlated with exchangeable Al ratios ( P < 0.05) in the O horizon. However, base saturation in the B horizon decreased at one-third of the sites, with no increases. These results are unique in showing that the effects of acidic deposition on North American soils have begun to reverse.

Environmental Science & Technology↗

USGS2001

Effect of scale on the behavior of atrazine in surface waters

Field runoff is an important transport mechanism by which agricultural pesticides, including atrazine, move into the hydrologic environment. Atrazine is chosen because it is widely used, is transported in runoff relatively easily, is widely observed in surface waters, and has relatively little loss in the stream network. Data on runoff of atrazine from experimental plot and field studies is combined with annual estimates of load in numerous streams and rivers, resulting in a data set with 408 observations that span 14 orders of magnitude in area. The load as a percent of use (LAPU) on an annual basis is the parameter that is compared among the studies. There is no difference in the mean or range of LAPU values for areas from the size of experimental field plots (???0.000023 ha) and small watersheds (<100 000 ha). The relatively invariant LAPU value observed across a large range of watershed areas implies that the characteristics of atrazine itself (application method and chemical properties) are important in determining the extent of runoff. The variable influences on the extent of runoff from individual watershed characteristics and weather events are superimposed on the relatively invariant LAPU value observed across the range of watershed areas. The results from this study establish the direct relevance for agricultural field plot studies to watershed studies across the full range of scale.

Environmental Science & Technology↗

USGS2004

Zinc adsorption effects on arsenite oxidation kinetics at the birnessite-water interface

Arsenite is more toxic and mobile than As(V) in soil and sediment environments, and thus it is advantageous to explore factors that enhance oxidation of As(III) to As(V). Previous studies showed that manganese oxides, such as birnessite (??-MnO2), directly oxidized As(III). However, these studies did not explore the role that cation adsorption has on As(III) oxidation. Accordingly, the effects of adsorbed and nonadsorbed Zn on arsenite (As(III)) oxidation kinetics at the birnessite-water interface were investigated using batch adsorption experiments (0.1 g L-1; pH 4.5 and 6.0; I = 0.01 M NaCl). Divalent Zn adsorption on synthetic ??-MnO 2 in the absence of As(III) increased with increasing pH and caused positive shifts in electrophoretic mobility values at pH 4-6, indirectly suggesting inner-sphere Zn adsorption mechanisms. Arsenite was readily oxidized on birnessite in the absence of Zn. The initial As(III) oxidation rate constant decreased with increasing pH from 4.5 to 6.0 and initial As(III) concentrations from 100 to 300 ??M. Similar pH and initial As(III) concentration effects were observed in systems when Zn was present (i.e., presorbed Zn prior to As(III) addition and simultaneously added Zn-As(III) systems), but As(III) oxidation reactions were suppressed compared to the respective control systems. The suppression was more pronounced when Zn was presorbed on the ??-MnO 2 surfaces as opposed to added simultaneously with As(III). This study provides further understanding of As(III) oxidation reactions on manganese oxide surfaces under environmentally applicable conditions where metals compete for reactive sites.

Environmental Science & Technology↗

USGS1998

Effect of contaminant concentration on aerobic microbial mineralization of DCE and VC in stream-bed sediments

Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2- 14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2-14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.

Environmental Science & Technology↗

USGS2003

Nonylphenol ethoxylates and other additives in aircraft deicers, antiicers, and waters receiving airport runoff

Samples of nine different formulations of aircraft deicer and antiicer fluids (ADAF) were screened for the presence of selected surfactants. Nonylphenol ethoxylates (NPnEO) were identified in three ADAF formulations, octylphenol ethoxylates were identified in two formulations, and six formulations contained alcohol ethoxylates. A preliminary field study was conducted at General Mitchell International Airport, Milwaukee, WI, to quantify NPnEO (n = 1-15) and one of its byproducts, nonylphenol (NP), in airport runoff. Samples were collected from two airport outfalls, from the receiving stream, and from an upstream reference site during intensive ADAF application events. NPnEO was measured at concentrations up to 1190microg/L in airport outfall samples, up to 77 ug/L in samples from the receiving stream and less than 5.0 microg/L from the upstream reference. Concentrations of glycol and other ADAF-related constituents, including NPnEO, were reduced by approximately 1 order of magnitude between the outfall sites and the receiving stream site; however, concentrations of NP in the receiving stream remained similar to those from the outfalls (< 0.04 microg/L at the upstream reference, 0.98 and 7.67 microg/L at outfalls, and 3.89 microg/L in the receiving stream). The field data suggest that NP is generated through degradation of NPnEO from airport runoff.

Wisconsin↗

USGS2020

Effects-based monitoring of bioactive chemicals discharged to the Colorado River before and after a municipal wastewater treatment plant replacement

Monitoring of the Colorado River near the Moab, Utah, wastewater treatment plant (WWTP) outflow has detected pharmaceuticals, hormones, and estrogen-receptor (ER)-, glucocorticoid receptor (GR)-, and peroxisome proliferator-activated receptor-gamma (PPARγ)-mediated biological activities. The aim of the present multi-year study was to assess effects of a WWTP replacement on bioactive chemical (BC) concentrations. Water samples were collected bimonthly, pre- and post-replacement, at 11 sites along the Colorado River upstream and downstream of the WWTP and analyzed for in vitro bioactivities (e.g., agonism of ER, GR, and PPARγ) and BC concentrations; fathead minnows were cage deployed pre- and post-replacement at sites with varying proximities to the WWTP. Before the WWTP replacement, in vitro ER (24 ng 17β-estradiol equivalents/L)-, GR (60 ng dexamethasone equivalents/L)-, and PPARγ-mediated activities were detected at the WWTP outflow but diminished downstream. In March 2018, the WWTP effluent was acutely toxic to the fish, likely due to elevated ammonia concentrations. Following the WWTP replacement, ER, GR, and PPARγ bioactivities were reduced by approximately 60–79%, no toxicity was observed in caged fish, and there were marked decreases in concentrations of many BCs. Results suggest that replacement of the Moab WWTP achieved a significant reduction in BC concentrations to the Colorado River.

Utah↗

USGS2022

Perfluoroalkyl and polyfluoroalkyl substances in groundwater used as a source of drinking water in the eastern United States

In 2019, 254 samples were collected from five aquifer systems to evaluate per- and polyfluoroalkyl substance (PFAS) occurrence in groundwater used as a source of drinking water in the eastern United States. The samples were analyzed for 24 PFAS, major ions, nutrients, trace elements, dissolved organic carbon (DOC), volatile organic compounds (VOCs), pharmaceuticals, and tritium. Fourteen of the 24 PFAS were detected in groundwater, with 60% and 20% of public-supply and domestic wells, respectively, containing at least one PFAS detection. Concentrations of tritium, chloride, sulfate, DOC, and manganese+iron; percent urban land use within 500 m of the wells; and VOC and pharmaceutical detection frequencies were significantly higher in samples containing PFAS detections than in samples with no detections. Boosted Regression Tree models that consider 57 chemical and land-use variables show that tritium concentration, distance to the nearest fire-training area, percentage of urban land use, and DOC and VOC concentrations are the top five predictors of PFAS detections, consistent with hydrologic position, geochemistry, and land use being important controls on PFAS occurrence in groundwater. Model results indicate it may be possible to predict PFAS detections in groundwater using existing data sources.

Glacial aquifer, Mississippi Embayment aquifer, So↗

USGS2024

Wildfires influence mercury transport, methylation, and bioaccumulation in headwater streams of the Pacific Northwest

The increasing frequency and severity of wildfires are among the most visible impacts of climate change. However, the effects of wildfires on mercury (Hg) transformations and bioaccumulation in stream ecosystems are poorly understood. We sampled soils, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates in 36 burned (one-year post fire) and 21 reference headwater streams across the northwestern U.S. to evaluate the effects of wildfire occurrence and severity on total Hg (THg) and methylmercury (MeHg) transport and bioaccumulation. Suspended particulate THg and MeHg concentrations were 89 and 178% greater in burned watersheds compared to unburned watersheds and increased with burn severity, likely associated with increased soil erosion. Concentrations of filter-passing THg were similar in burned and unburned watersheds, but filter-passing MeHg was 51% greater in burned watersheds, and suspended particles in burned watersheds were enriched in MeHg but not THg, suggesting higher MeHg production in burned watersheds. Among invertebrates, MeHg in grazers, filter-feeders, and collectors was 33, 48, and 251% greater in burned watersheds, respectively, but did not differ in shredders or predators. Thus, increasing wildfire frequency and severity may yield increased MeHg production, mobilization, and bioaccumulation in headwaters and increased transport of particulate THg and MeHg to downstream environments.

Idaho, Oregon, Washington↗

USGS2015

Quantification of 15 bile acids in lake charr feces by ultra-high performance liquid chromatography–tandem mass spectrometry

Many fishes are hypothesized to use bile acids (BAs) as chemical cues, yet quantification of BAs in biological samples and the required methods remain limited. Here, we present an UHPLC–MS/MS method for simultaneous, sensitive, and rapid quantification of 15 BAs, including free, taurine, and glycine conjugated BAs, and application of the method to fecal samples from lake charr ( Salvelinus namaycush ). The analytes were separated on a C 18 column with acetonitrile–water (containing 7.5 mM ammonium acetate and 0.1% formic acid) as mobile phase at a flow rate of 0.25 mL/min for 12 min. BAs were monitored with a negative electrospray triple quadrupole mass spectrometer (Xevo TQ-S™). Calibration curves of 15 BAs were linear over the concentration range of 1.00–5,000 ng/mL. Validation revealed that the method was specific, accurate, and precise. The method was applied to quantitative analysis of feces extract of fry lake charr and the food they were eating. The concentrations of analytes CA, TCDCA, TCA, and CDCA were 242.3, 81.2, 60.7, and 36.2 ng/mg, respectively. However, other taurine conjugated BAs, TUDCA, TDCA, and THDCA, were not detected in feces of lake charr. Interestingly, TCA and TCDCA were detected at high concentrations in food pellets, at 71.9 and 38.2 ng/mg, respectively. Application of the method to feces samples from lake charr supported a role of BAs as chemical cues, and will enhance further investigation of BAs as chemical cues in other fish species.

Journal of Chromatography B: Analytical Technologi↗

USGS2015

Implications of climate change on the heat budget of lentic systems used for power station cooling: Case study Clinton Lake, Illinois

We use a numerical model to analyze the impact of climate change--in particular higher air temperatures--on a nuclear power station that recirculates the water from a reservoir for cooling. The model solves the hydrodynamics, the transfer of heat in the reservoir, and the energy balance at the surface. We use the numerical model to (i) quantify the heat budget in the reservoir and determine how this budget is affected by the combined effect of the power station and climate change and (ii) quantify the impact of climate change on both the downstream thermal pollution and the power station capacity. We consider four different scenarios of climate change. Results of simulations show that climate change will reduce the ability to dissipate heat to the atmosphere and therefore the cooling capacity of the reservoir. We observed an increase of 25% in the thermal load downstream of the reservoir, and a reduction in the capacity of the power station of 18% during the summer months for the worst-case climate change scenario tested. These results suggest that climate change is an important threat for both the downstream thermal pollution and the generation of electricity by power stations that use lentic systems for cooling.

Illinois↗

USGS2008

Ecohydrological factors affecting nitrate concentrations in a phreatic desert aquifer in northwestern China

Aerobic conditions in desert aquifers commonly allow high nitrate (NO 3-) concentrations in recharge to persist for long periods of time, an important consideration for N-cycling and water quality. In this study, stable isotopes of NO3- (??15N NO3 and ??18ONO3) were used to trace NO3- cycling processes which affect concentrations in groundwater and unsaturated zone moisture in the arid Badain Jaran Oesert in northwestern China. Most groundwater NO3- appears to be depleted relative to Cl- in rainfall concentrated by evapotranspiration, indicating net N losses. Unsaturated zone NO 3- is generally higher than groundwater NO 3- in terms of both concentration (up to 15 476 ??M, corresponding to 3.6 mg NO3--N per kg sediment) and ratios with Cl-. Isotopic data indicate that the NO3- derives primarily from nitrification, with a minor direct contribution of atmospheric NO3- inferred for some samples, particularly in the unsaturated zone. Localized denitrification in the saturated zone is suggested by isotopic and geochemical indicators in some areas. Anthropogenic inputs appear to be minimal, and variability is attributed to environmental factors. In comparison to other arid regions, the sparseness of vegetation in the study area appears to play an important role in moderating unsaturated zone NO3- accumulation by allowing solute flushing and deterring extensive N2 fixation. ?? 2008 American Chemical Society.

Environmental Science & Technology↗

USGS2012

Development and evaluation of a boat-mounted RFID antenna for monitoring freshwater mussels

Development of radio frequency identification (RFID) technology and passive integrated transponder (PIT) tags has substantially increased the ability of researchers and managers to monitor populations of aquatic organisms. However, use of transportable RFID antenna systems (i.e., backpack-mounted) is currently limited to wadeable aquatic environments (<1.4 m water depth). We describe the design, construction, and evaluation of a boat-mounted RFID antenna to detect individually PIT-tagged benthic aquatic organisms (mussels). We evaluated the effects of tag orientation on detection distances in water with a 32-mm half-duplex PIT tag. Detection distances up to 50 cm from the antenna coils were obtained, but detection distance was dependent on tag orientation. We also evaluated detection distance of PIT tags beneath the sediment to simulate detection of burrowing mussels with 23- and 32-mm tags. In sand substrate, the maximum detection distance varied from 3.5 cm and 4.5 cm (vertical tag orientation) to 24.7 cm and 39.4 cm (45° tag orientation) for the 23- and 32-mm PIT tags, respectively. Our results suggest a 1.4-m total detection width for tagged mussels on the substrate surface by the boat-mounted antenna system regardless of tag orientation. However, burrowed mussels may require multiple passes to increase detection that would be influenced by depth, tag orientation, and tag size. Construction of the boat-mounted antenna was relatively low in cost (<500 USD) and had several advantages (less labor and time intensive, increased safety) over traditional mussel sampling techniques (diving, snorkeling) in nonwadeable habitats.

Freshwater Science↗