Geology topics

Angelique D. Dahlberg

Publications and source records attributed to Angelique D. Dahlberg.

4 recordsLinked to original sources

USGS2026

Assessing low-dose copper treatment for dreissenid mussels: Effects on nontarget organisms

Zebra mussels ( Dreissena polymorpha ), an invasive dreissenid mussel, have been established and caused considerable effects in many North American aquatic ecosystems. In response, copper-based pesticides have been used to manage zebra mussel populations. We evaluated the effects of a low-dose (60 µg Cu/L for 10 d) copper-based molluscicide for zebra mussel suppression on nontarget species in Lake Minnetonka (Minnesota, USA). Specifically, we assessed changes in four fish species, a native mussel species, adult zebra mussels, chlorophyll-a concentrations (as a proxy for phytoplankton productivity), the zooplankton community, and the benthic invertebrate community before and after treatment. Chlorophyll- a concentration increased in both the treated and reference bays 1 and 4 d posttreatment. Non-target zooplankton community composition changed in both bays over the course of this study; zooplankton abundance and diversity initially decreased in the treated bay but gradually recovered and was back to pretreatment and reference bay levels after one year. We observed no significant differences in non-target benthic invertebrate abundance or diversity between the treated and reference bays, although abundance and diversity estimates were dynamic and uncertain. Among caged non-target organisms, copper bioaccumulation was higher in both mussel species than in fish, and among fish, was highest in fathead minnow ( Pimephales promelas ). These findings contribute to our understanding of the potential effects of copper-based pesticides on aquatic ecosystems and provide insights for zebra mussel management.

Minnesota↗

USGS2026

Assessing a low-dose copper treatment for dreissenid mussels: Effects on zebra mussel (Dreissena polymorpha) population

We conducted and evaluated a low-dose copper treatment (applied as EarthTec QZ) to suppress zebra mussel ( Dreissena polymorpha Pallas 1771) veliger abundance and settlement in a 66.3 ha bay in Lake Minnetonka (Hennepin County, MN) over a 3-y period. We maintained a mean (standard deviation [SD]) concentration of 83.0 (10.3) µg/L as copper over the 10-d treatment period, much lower than the maximum allowable 1 mg/L as copper. Veliger density was reduced from 6.0 veligers/L before treatment to 0.3 veligers/L following the treatment period. Posttreatment zebra mussel settlement was 1900 times lower in the treated bay compared to an untreated bay days after the treatment despite similar pretreatment veliger densities. Veliger density and settlement remained suppressed nearly 2 y following the treatment. Sampling for adult zebra mussels within the treated bay returned variable results but survival of caged adult zebra mussels indicated ~30% treatment-related mortality. Copper in surface waters returned to near pretreatment concentrations 90 d after treatment. Our study demonstrates that low-dose applications of a copper molluscicide can effectively reduce zebra mussel veliger densities and settlement.

Minnesota↗

USGS2025

Using bioavailability modeling to refine copper treatments for zebra mussel control and better understanding risks to non-target species

Copper can be toxic to aquatic organisms at high concentrations and has been previously used successfully to control zebra mussels ( Dreissena polymorpha ). Because copper’s toxicity changes with water chemistry, using the same copper concentration in different waterbodies could yield different outcomes. We demonstrate how measuring water chemistry parameters and using the Biotic Ligand Model (BLM) and multiple linear regression (MLR) models can predict a suitable, site-specific copper concentration for management. We exposed zebra mussel adults and non-target organisms to varying concentrations of copper over 10 d in a mobile laboratory. We found that one non-target species, Daphnia magna , had a 50% chance of survival at 9.50 µg Cu/L (i.e., the 50% lethal concentration, LC 50 ), within our BLM-predicted range of 3.38–16.95 µg Cu/L LC 50 values. In the future, managers could make similar predictions and tailor their copper concentrations to their management goals. We also measured zebra mussel larvae mortality at copper concentrations ranging from 0 to 191 µg Cu/L. While those results were inconclusive, we present the results of this work as a foundation for future projects. Our study underscores the importance of developing site-specific copper concentration recommendations and demonstrates the potential utility of the BLM and MLR approaches for informing those recommendations.

Minnesota↗

USGS2023

Open water dreissenid mussel control projects: Lessons learned from a retrospective analysis

Dreissenid mussels are one of the most problematic aquatic invasive species (AIS) in North America, causing substantial ecological and economic effects. To date, dreissenid mussel control efforts in open water have included physical, biological, and chemical methods. The feasibility of successful dreissenid mussel management or eradication in lakes is relatively undocumented in the freshwater management literature. This review presents information on 33 open water dreissenid mussel control projects in 23 North America lakes. We reviewed data from past dreissenid mussel control projects and identified patterns and knowledge gaps to help inform adaptive management strategies. The three key lessons learned include (1) pre- and post-treatment survey methods that are designed to meet management objectives are beneficial, e.g., by sampling for all life stages and taking into account that no survey method is completely comprehensive; (2) defining the treatment area—particularly ensuring it is sufficiently large to capture all life stages present—is critical to meeting management objectives; and (3) control projects provide an opportunity to collect water chemistry, effects on non-target organisms, and other efficacy-related data that can inform safe and effective adaptive management.

Scientific Reports↗