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Blasting used in construction of waterborne infrastructure may impact fish eggs in adjacent spawning habitats through introduction of mechanical vibrations as peak particle velocities (PPV). However, there are limited studies applying risk-based approaches to evaluate and mitigate these impacts. A navigation improvement project in the Soo Locks near the St. Marys Rapids provided an opportunity to evaluate existing data to inform blasting risks to fish eggs. To assess this risk, existing data were used to calculate species sensitivity distributions that were used to estimate a hazardous concentration for 5% of the salmon and trout species evaluated (HC5) and predicted no effect concentrations (PNEC). The HC5 ranged from 14.0 to 89.2 cm/s PPV, and the ‘safe level’ PNEC thresholds ranged from 2.8 to 17.8 cm/s PPV. This study provides a demonstration of how a risk-based approach can be effectively used to assess and manage dry blasting effects on underwater biota.

The US Army Corps of Engineers (USACE) maintains breakwaters in Milwaukee Harbor. USACE’s Engineering With Nature® (EWN®) breakwater demonstration project created rocky aquatic habitat with cobbles (10–20 cm) covering boulders (6–8 metric tons) along a 152 m section. A prolific population of Hemimysis anomala, an introduced Pontocaspian mysid and important food source for local pelagic fishes, was significantly (p < .05) more abundant on cobbles versus boulders. Food-habits data of alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) provided evidence that H. anomala were a common prey item. Night surveys and gill netting confirmed O. mordax preferred foraging on the cobbles (p < .05) and consumed more H. anomala than at the reference site (p < .05). H. anomala comprised a significant portion of the diets of young-of-the-year (YOY) yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris) caught on the breakwater. The natural features’ construction on the breakwater increased the available habitat for this benthopelagic macroinvertebrate and created a novel ecosystem benefiting forage fish and a nursery habitat benefiting nearshore game fish juveniles. These data will encourage the application of EWN concepts during structural repairs at other built navigation infrastructure.

The US Army Corps of Engineers (USACE) repairs aging breakwater structures as part of routine maintenance to maintain safe navigation in Great Lakes commercial ports. A USACE repair to an existing breakwater structure in Milwaukee Harbor (WI) implementing Engineering With Nature (EWN) principles created complex rocky habitat by strategically placing cobble-sized stone over conventional 5.4 to 9.1 metric ton boulders, thus creating "control" (boulder) and "treatment" (cobble) habitats. We evaluated the resultant nature-based breakwater (NBBW) developing food web versus an adjacent reference site on the same breakwater and determined that, unexpectedly, locally abundant Hemimysis anomala were impacting the food-web dynamics and feeding ecology of fishes occupying the structure. Fish and forage communities were sampled using gillnets, night scuba diving surveys, rock collections, and a novel trap to capture invertebrates. The resultant NBBW became home to a prolific population of nonindigenous Hemimysis, with indications that they were more abundant on cobble versus boulders, based on rainbow smelt feeding. This lithophilic/cave swelling mysid provided an important new food resource in Milwaukee Harbor for two introduced pelagic prey fishes: alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax). Gillnetting and night scuba diving surveys confirmed that rainbow smelt preferred to forage on the cobble section (p 0.05). Hemimysis were also the primary food item consumed by nearshore game fishes such as young-of-the-year (YOY) yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris). We propose that those breakwaters that harbor abundant Hemimysis constitute novel ecosystems (ecosystems that include both native and non-native biota) that might benefit harbor fisheries if well-managed. This project demonstrated how a low-cost design modification could be applied during the repair of rubble-mound, breakwater structures to achieve benefits beyond safe navigation. Integr Environ Assess Manag 2022;18:49-62. Published 2021. This article is a US Government work and is in the public domain in the USA.

Summary Tested was the hypothesis that juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) would exhibit no response in short-term survival or swimming performance when exposed to varying concentrations of suspended sediment simulating dredge plumes in waterways where this species may be impacted by dredging operations. Sediment collected from Savannah Harbor, South Carolina, USA was used to simulate a worst-case scenario. Juvenile sturgeon were contained for a 3-day period in flow-through aquaria, with limited opportunity for movement, in sediment of varying concentrations (100, 250 and 500 mg L−1 total suspended solids [TSS]) mimicking prolonged exposure to suspended sediment plumes near an operating dredge. Of the 90 fish exposed, 86 (96%) survived the test. Of the four fish that died, one was exposed to 250 TSS and three to 500 TSS. Swimming performance results indicated that nearly all fish were positively rheotactic. Critical swim speeds (Ucrits) were moderate, whether measured as absolute values (21–31 cm s−1) or as relative values (1.4–2.1 body lengths s−1), with no significant differences among treatments (F

Bottom sediments are resuspended into the water column during dredging operations. These resuspended sediments are an often cited concern used to justify restrictions applied to dredging schedules in many areas of the USA. One example of a temporal restriction, commonly referred to as an environmental window, involves dredging schedules in the James River, Virginia, because of potential impacts on the eastern oyster (Crassostrea virginica Gmelin). Yet, effects’ data are lacking to understand the effects of suspended sediments to C. virginica. To address this data gap, we performed a laboratory study mimicking sediment resuspension during annual dredging operations in the James River. Field-collected oysters were exposed for 7 days under flow-through conditions to 0, 100, 250, and 500-mg/L total suspended solids (TSS) in a unique exposure system where oyster movements could be electronically monitored. Endpoints analyzed were survival, percent of time open, total number of shell movements, weight change, and condition index. Data indicated no significant effects of suspended sediment on these endpoints after 7 days of exposure. Weight change in oysters attached vertically to monitor their movements was significantly less than in oysters not monitored in every treatment. No significant differences in condition index, an indicator of oyster growth sensitive to environmental pollutants, were observed among treatments measured 30 days postexposure. Correlations performed for each treatment among monitored oyster endpoints found significant negative associations between number of movements and percent open in the 100, 250, and 500-mg/L TSS treatments and in all treatments combined. These data will help reduce the uncertainty surrounding the effects of suspended sediments on C. virginica.

The resuspension of sediments caused by activities, such as dredging operations, is a concern in Great Lakes harbors where multiple fish species spawn. To address such concerns, smallmouth bass (Micropterus dolomieu) were exposed to uncontaminated suspended sediment (nominally 0, 100, 250, and 500 mg/L) continuously for 72 h to determine the effects on egg-hatching success and swim-up fry survival and growth. The test sediments were collected from two harbors: (1) fine-grained sediment in Grand Haven Harbor, Lake Michigan, and (2) coarser-grained sediment in Fairport Harbor, Lake Erie. Eggs exposed to total suspended solids (TSS) concentrations >100 mg/L resulted in decreased survival of post-hatch larval fish. Fry survival was >90 % at the highest exposure concentration (500 mg/L), but growth was decreased when the exposure concentration was >100 mg/L. Growth and survival of swim-up fry held for a 7- and 26-day post-exposure the grow-out period was variable suggesting that the sediment grain size and strain of fish may influence lingering effects after the cessation of exposure. The results suggest that exposed eggs hatched normally; however, newly hatched larvae, which are temporarily immobile, are more vulnerable to the effects of suspended sediment. The swim-up fry were found to be more sensitive to high TSS concentrations in sandy relative to silty sediment. These data represent a conservative exposure scenario that can be extrapolated to high-energy systems in the field to inform management decisions regarding the necessity for dredging windows or need to implement controls to protect M. dolomieu.

Purpose: This document summarizes the design features used to create a nesting area for the Common Tern (Sterna hirundo) that was incorporated as part of the maintenance repairs to the harbor breakwater located in Ashtabula, OH. The purpose of the tern nesting project was to demonstrate an option that can be used during such maintenance activities for increasing infrastructure benefits as part of the Engineering With Nature initiative (Bridges 2012). The U.S. Environmental Protection Agency’s Great Lakes Restoration Initiative (GLRI) and the U.S. Army Corps of Engineers’ Dredging Operations and Environmental Research (DOER) Program sponsored the development of the nesting habitat site. The project was developed in consultation with the The Nature Conservancy and the Ohio Department of Natural Resources.

Background Chemical bioavailability is an important dose metric in environmental risk assessment. Although many approaches have been used to evaluate bioavailability, not a single approach is free from limitations. Previously, we developed a new genomics-based approach that integrated microarray technology and regression modeling for predicting bioavailability (tissue residue) of explosives compounds in exposed earthworms. In the present study, we further compared 18 different regression models and performed variable selection simultaneously with parameter estimation. Results This refined approach was applied to both previously collected and newly acquired earthworm microarray gene expression datasets for three explosive compounds. Our results demonstrate that a prediction accuracy of R2 = 0.71–0.82 was achievable at a relatively low model complexity with as few as 3–10 predictor genes per model. These results are much more encouraging than our previous ones. Conclusion This study has demonstrated that our approach is promising for bioavailability measurement, which warrants further studies of mixed contamination scenarios in field settings Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2541-5) contains supplementary material, which is available to authorized users.

In recent years, a significant number of environmental studies have been conducted in New Orleans, LA and surrounding Gulf Coast areas due in part to the occurrence of hurricanes Katrina and Rita. Data collected from studies in the New Orleans area indicate that inorganic contaminants including arsenic (As), iron (Fe), lead (Pb), and vanadium (V); high concentration of bioaerosols, particularly Cladosporium and Aspergillus, and several organic pollutants (PAHs, pesticides, and volatiles) may pose a risk to human health in New Orleans. While many of these results resemble historical data, a current quantitative exposure assessment has not been conducted. We engaged in one such assessment for lead (Pb) contamination in surface soils. We used Pb concentrations in surface soils ( μg/day to 102 μg/day for our study area within urbanNew Orleans. These data are concerning because children exposed to >33.5 μg/d Pb may cause their blood-Pb levels to exceed the Centers for Disease Control and Prevention (CDC) threshold for blood-Pb of 10 μg/dL. It has generally been accepted that a more protective blood Pb concentration threshold of 6 - μg/dL is warranted. Using the 6-μg/dL threshold puts children exposed to as little as 20.2 μg/day Pb at risk.

Sediments collected at various field locations may have chemical and physical constituents that influence test results and may contain organisms that cannot be readily removed. Thus, reference sediments are needed that can be formulated to match diverse freshwater and estuarine sediments encountered in comprehensive testing programs. This research evaluated formulated reference sediments in terms of (a) their ability to match field-collected sediments both chemically and physically; (b) their suitability as habitant (survival and reproduction) for typical invertebrate toxicity testing species (Hyalella azteca Saussure, Chironomus tentans Fabricius, and Daphnia magna Straus) during chronic exposures; and (c) their suitability as a substrate for Hyalella azteca, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia Richard, and Pimephales promelas Rafinesque in 14-d whole-sediment exposures. Formulated reference sediments were prepared to match naturally occurring sediments with respect to particle-size distribution, organic matter, organic carbon, pH, solids, CEC, but not redox potential. After preparation, a conditioning period of at least 7 d was required for pH stabilization of formulated reference sediments. In culture experiments, formulated reference sediments was suitable for Hyalella azteca, Chironomus tentans, and Daphnia magna survival and reproduction for 56,40, and 28 d, respectively. Hyalella azteca, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia and Pimephales promelas survival more » was [>=] 88% in 14-d exposures to formulated reference sediment. Formulated reference sediments may reduce some unexplained physical, chemical, or biological toxicity'' of field-collected sediments (e.g., organic matter) that may influence toxicity testing results. « less

The effects of five di-ortho polychlorinated biphenyl (PCB) congeners on survival, growth, and reproduction in the fathead minnow. Pimephales promelas, were determined. Fish were exposed to one of two nominal concentrations of each congener for a total of 13 weeks (7-week prespawning period plus 6-week spawning period) under flow-through conditions using methanol as a carrier solvent. At termination, P. promelas survival was high in all PCB congener treatments. PCB congeners had no significant sublethal effects on reproductive success within the concentration range examined. The total number of eggs, clutch size, number of clutches, percent hatchability, and presence of terata in offspring were not significantly affected. Reproductive success was slightly but not significantly enhanced in the solvent control and high treatment concentrations for congeners 52, 101, 138, and 153. Growth expressed as wet weight was not affected for both adult males or females. Male lengths were not significantly affected but female lengths were significantly reduced when exposed to congeners 101, 138, 153, and 180. Pimephales promelas accumulated substantial amounts of all PCBs, with tissue concentrations ranging from 13 to 183 mg/kg wet weight at termination in PCB-exposed fish. These tissue residues are one to several orders of magnitude greater than thosemore » reported for these congeners in aquatic biota previously collected in industrial waterways of the Great Lakes. Several di-ortho PCB congeners frequently found in aquatic biota showed minimal adverse effects on fathead minnow survival, growth, and reproduction even though bioaccumulation of these congeners was substantial.« less

The equilibrium partitioning approach for developing numerical sediment-quality criteria was tested in the laboratory using a mixture of chlorinated ethers/alcohols sorbed to sediments. The sorption behavior of the principal component of the mixture, tetrachloropropyl ether (TCPE), was determined on sediments with organic carbon contents ranging from 0.3 to 5.2%. Sorption was found to be a strong function of organic carbon with a log(Koc) of 2.9. Predictions of log(Koc) using Kow correlations and molecular connectivity indexes ranged from 2.9 to 3.3. Toxicity tests were then conducted on sediments spiked with the chlorinated ether mixture using the amphipod Hyalella azteca, the midge Chironomus tentans, and the water flea Daphnia magna. Sediment toxicity was highly dependent on the sediment organic carbon content, but there were differences in toxicity that could not be explained by differences in organic carbon. Interstitial water concentrations of total chloroether did not compare with effects between different sediments for either of the two sediment-dwelling organisms, with LC50 values ranging from 1.6 to 10.5 mg dissolved chloroether per liter for Hyalella azteca and 1.5 to 9.3 mg dissolved chloroether per liter for Chironomus tentans. The effect of other sediment properties on the sensitivity of these two organisms may account for this difference. For Daphnia magna, there was a much closer correlation between interstitial water concentrations and effects, with the aqueous LC50 having a range of only 0.9 to 2.0 mg/L.

To examine equilibrium-partitioning model predictions of interstitial water concentrations of fluoranthene as part of the equilibrium-partitioning (EqP) approach to sediment quality criteria development, the bioavailability (toxicity) of fluoranthene-amended sediment (a nonpolar organic compound) to Hyalella azteca, Daphnia magna, and Chironomus tentans was determined. Fluoranthene was added to three freshwater sediments with similar organic carbon content (0.44-0.50%). Although sediments were from divergent sources (Water Research Field Station [WRFS], Trinity River [TR], and Lake Fork [LF]), sediment physical and chemical characteristics did not vary appreciably, leading us to hypothesize (based on EqP theory) that fluoranthene-amended sediment toxicity would not vary between sediments. Predicted interstitial water concentrations from the equilibrium-partitioning model were similar to measured interstitial water concentrations for WRFS and TR sediment, but the model underpredicted measured values for LF sediment by a factor of two. EC50s for Daphnia magna, Hyalella azteca, and Chironomus tentans in interstitial water were a factor of two to five greater for LF than for WRFS and TR sediments. Factors other than organic carbon content of sediments (e.g., dissolved organic carbon content in interstitial water) probably contributed to the variability in bioavailability of fluoranthene. Based on 10-d sediment toxicity tests with Hyalella azteca, Daphnia magna, and Chironomus tentans, organic carbon-normalized sediment concentrations were better predictors of toxicity than interstitial water and bulk sediment fluoranthene concentrations. In 10-d aqueous-phase tests with fluoranthene, Chironomus tentans and Hyalella azteca were twice as sensitive as Daphnia magna. The response of freshwater organisms to fluoranthene-amended sediment was similar to that of marine organisms exposed to fluoranthene in other studies. The EqP approach for sediment-quality criteria accurately predicted sediment toxicity for WRFS and TR sediments but not for LF sediment, indicating the model may be overly protective for some bottom sediments. Factors other than organic carbon content may be important in affecting neutral organic compound bioavailability.

Increased global trade and modern intercontinental transportation have made invasive species an increasingly prominent stressor of freshwater ecosystems. Invasive species risk assessments, which range from simple screening protocols that focus on species attributes and ecological requirements to rigorous analyses of infestation, have become an important component of environmental impact assessment. In this paper we present two recent case studies in which risk and decision methods were applied to non-toxicological environmental issues that are central to many aquatic ecosystem management programs. The first example reviews potential infestation by the zebra mussel, Dreissena polymorpha, on Bayou Bartholomew, located in southeast Arkansas, as a result of the proposed augmentation of low flow conditions by pumping water from the nearby and much larger Arkansas River. The second example presents a retrospective analysis of the results of transplanting fat pocketbook pearly mussels, Potamilus capax, from an approximately 6-km reach of a drainage ditch in eastern Arkansas. The two examples presented herein indicate the potential for improving environmental decision-making in the face of uncertainty-but in the presence of substantial information. As more rigorous attempts are made to widen and enhance applications of risk and decision methods to environmental decision-making, ecosystem management is likely to further improve.