Geology topics

Nicholas Sievert

Publications and source records attributed to Nicholas Sievert.

5 recordsLinked to original sources

USGS2026

Tissue metal concentrations and toxicity in wild turkeys following chronic exposure to mining-contaminated soils in southeast Missouri, USA

The Big River watershed in southeast Missouri (SEMO) is a Superfund site with an extensive history of lead (Pb) and zinc (Zn) mining; cadmium (Cd) and other metals also occur in the ore and waste materials. We examined whether SEMO wild turkeys ( Meleagris gallopavo ) exposed to mining-contaminated floodplain soils and food resources in the Big River watershed had elevated metal concentrations in their tissues, indicating Pb poisoning and associated toxic effects. Compared to reference birds ( n = 15) harvested in northern Missouri, SEMO turkeys ( n = 23) had significantly elevated Pb concentrations in ventricular content, liver, kidney, bone and contour feathers. Liver and kidney from SEMO turkeys also contained significantly elevated Cd concentrations compared to reference birds. Grit (2.8–5.6 mm) from turkeys ( n = 1 reference; n = 6 SEMO) was within the size range of coarse sediments reported to contain toxic metal concentrations, and 63% of turkeys harvested within 4 km of the Big River floodplain had tissue concentrations that exceeded avian thresholds for Pb poisoning. Tissue concentrations of Pb were significant predictors of keel hemorrhage as well as reductions in testis weight and bone Zn concentration. These sublethal endpoints suggest that chronic metal exposure in SEMO turkeys may be inducing toxic effects at lower tissue metal concentrations than would be estimated by current avian toxicity thresholds. These findings highlight the need for decision makers to consider how metal contamination may affect local turkey health and abundance, and the need for data-driven guidance for the safe consumption of wild foods harvested in SEMO and other mining-affected sites.

Missouri↗

USGS2025

A flexible conservation and connectivity tool to inform stream conservation prioritization

Healthy stream networks rely on diverse fish assemblages and the mobility of fish between habitats to maintain ecosystem structure and function. Anthropogenic structures that impede fish movement (e.g., roads, dams) disrupt life cycles of migratory fishes and isolate fish populations making them more sensitive to environmental stressors. Growing interest in barrier removal is driven by the recognition that restoring fish passage improves ecosystem health and resilience at multiple trophic levels, but identifying which streams should be reconnected and which barriers to remove remains an unresolved issue. Using the state of Missouri (USA) stream network, we developed an interactive decision support tool designed to help natural resource managers identify a shortlist of stream reaches to prioritize for reconnection, barrier removal, and habitat restoration. Our aquatic connectivity decision support tool, which we call AquaConn, is aimed at managers seeking to improve connectivity within and between existing conservation areas, particularly in wadeable streams. AquaConn provides a flexible platform that allows managers to consider entire assemblages of fish or individual species across local or more regional spatial scales. While AquaConn ( https://bit.ly/4kQgXK8 ) was built for the state of Missouri, our approach and framework can be replicated in any geographical region that has adequate fish assemblage data.

Missouri↗

USGS2025

Disentangling the historical impacts of warming and fishing on exploited freshwater fish populations

Worldwide, exploited fish populations are increasingly affected by the combined effects of warming and fishing. Disentangling the relative effects of these factors is challenging yet crucial for designing management strategies. We used a temperature-dependent population dynamics model to assess the impacts of lake warming and fishing on 521 freshwater fish populations in the Midwestern United States—a transitional zone between cold- and warmwater species. Overall, most warmwater species (65% of populations) exhibited increases in productivity from warming, while slightly more than half of the cool-/cold-water species (53% of populations) experienced reduced productivity. Populations closer to their carrying capacity showed greater resilience to warming. For the majority of populations (92%), fishing had a more pronounced effect on population dynamics than warming during the time period examined. Therefore, while warming is likely to increasingly threaten many fish populations, effective local fishery management remains a key lever to mitigate these impacts.

Minnesota, Wisconsin↗

USGS2022

Projected stream fish community risk to climate impacts in the Northeastern and Midwestern United States

Climate change is expected to alter stream fish habitat potentially leading to changes in the composition and distribution of fish communities. In the Northeastern and Midwestern United States we identified the distribution and characteristics of those fish communities most and least at risk of experiencing changes in climate which deviate from the climate they are associated with. We classified stream fish communities based on a suite of climate and environmental variables with multivariate regression trees under both recent and future conditions based on eight climate models. Our findings showed that some areas, such as the majority of the Illinois, Wisconsin, and Iowa), have high levels of risk of change in stream class, while much of Kentucky, West Virginia, Virginia, Pennsylvania, Eastern Ohio, Southern Michigan, and the Atlantic Coast are at relatively low risk. Stream class shifts ranged from over 75% of segments lost (associated with cooler temperatures) to gains of over 40% (associated with warmer temperatures). Common warmwater species such as green sunfish ( Lepomis cyanellus ), bluegill ( Lepomis macrochirus ) and largemouth bass ( Micropterus salmoides ) are expected to have the largest net gains in associated stream classes, while species associated with cooler streams such as Southern redbelly dace ( Chrosomus erythrogaster ), slimy sculpin ( Cottus cognatus ), and Eastern blacknose dace ( Rhinichthys atratulus ) were expected to experience the largest proportional losses. By pairing our climate risk predictions with other stressors such anthropogenic land use, habitat fragmentation, and water quality impairment, we identified opportunities for preservation (low risk due to all threats), restoration (low risk due to climate, high risk due to other stressors), and adaptation (high climate risk with low risk from other stressors). Understanding which communities are at risk due to climate change will aid in developing adaptation strategies to help sustain them in the future.

Connecticut, Delaware, Illinois, Indiana, Iowa, Ke↗

USGS2020

Incorporating established conservation networks into freshwater conservation planning results in more workable prioritizations

Resources for addressing stream fish conservation issues are often limited and the stressors impacting fish continue to increase, so decision makers often rely on tools to prioritize locations for conservation actions. Because conservation networks already exist in many areas, incorporating these into the planning process can increase the ability of decision makers to carry out management actions. In this study we aim to identify priority areas within established networks to provide an approach which allows managers to focus efforts on the most valuable areas they control, while identifying areas outside of the network, which support species with minimal representation within the network, for acquisition or conservation partnerships. The goal of this approach is to prioritize sites to achieve high levels of species representation while also developing workable solutions. We applied a methodology incorporating established networks into a systematic conservation planning process for fish in temperate wadeable streams located in Missouri, USA. We compared how well species were represented in our approach with two commonly used alternatives: A blank slate approach which used the same systematic conservation planning technique but did not incorporate established networks, and a habitat integrity approach based solely on anthropogenic threat data. Relative to the blank slate approach, our approach required 210% more segments for representation of all species, and contained an average of 0.5 additional occurrences for the least well-represented species. Although the blank slate solution was more efficient in achieving species representation, 77% of segments in this solution were not already protected. This would likely pose a challenge for implementing conservation actions. Relative to habitat integrity-based priorities, our approach required only 38% of the number of stream segments to achieve representation of all species and contained an average of 5 additional occurrences of the least represented species, representing a substantial gain in representation. Incorporating established networks may allow managers to focus resources on areas with the greatest conservation value within established networks and to identify the most valuable areas complementary to the established networks, resulting in priorities which may be more actionable and effective than those developed by alternative approaches.

Missouri↗