Geology topics

Christopher M. Barnhart

Publications and source records attributed to Christopher M. Barnhart.

3 recordsLinked to original sources

USGS2025

The complete mitochondrial genomes of the freshwater mussel Ortmanniana ligamentina (Lamarck, 1819): male and female mitotypes

Freshwater mussels of the Unionida order are important to freshwater ecosystems but are highly imperiled worldwide. Improving our understanding of these species is crucial to their continued conservation. Some Unionid mussels exhibit double uniparental inheritance (DUI) in which individuals have two mitochondrial genomes. Of those species with DUI, sequences of the female mitotype are most prevalent in genetic databases. Here, we demonstrate the ability to recover both mitotypes of Ortmanniana ligamentina (Lamarck, 1819) from a non-lethal collection method coupled with high-throughput sequencing. Increased male mitotype sequence representation facilitates understanding Unionid genetic diversity and development of molecular tools for species detection.

Missouri, Pennsylvania↗

USGS2023

Impacts of acute and chronic suspended solids exposure on juvenile freshwater mussels

Construction activities may affect adjacent water systems by introducing increased levels of suspended solids into the water body and may subsequently affect the survival and growth of freshwater mussels. We tested three sediment types from sites in Missouri, including Spring River sediment (SRS), Osage River bank clay soil (ORC), and quarried limestone from Columbia (LMT). We prepared series of suspensions of each sediment with total suspended solids concentrations ranging from 0 to 5000 mg/L. Juveniles from three mussel species, Fatmucket ( Lampsilis siliquoidea ), Arkansas Brokenray ( Lampsilis reeveiana ), and Washboard ( Megalonaias nervosa ) were exposed to these suspensions in both acute (96-h) and chronic (28-d) tests. No clear impact on survival was observed from the acute or chronic exposures, but chronic test showed that juvenile mussels' growth was strongly affected. Interestingly, growth was enhanced at lower levels of SRS and ORC (≤500 mg/L, p < 0.05), and the juvenile mussels exposed to 500 mg/L SRS exhibited approximately 60 % more dry weight than those reared in the control. LMT did not enhance growth. Growth was slowed by high concentrations (>1000 mg/L) of all three sediments, implying that high suspended solids levels could reduce survival in the long term. Our findings may help to inform regulations and guidelines for construction activities to minimize adverse effects on juvenile mussels.

Science of the Total Environment↗

USGS2023

Survival and growth of juvenile mussels in an outdoor pond after 28-day laboratory exposure to aqueous zinc

The extent to which effects seen in chronic toxicity studies in the laboratory affect mussel fitness later in life is poorly known. We examined juvenile Fatmucket ( Lampsilis siliquoidea ) survival and growth for 56 d following exposure to Zn in a laboratory bioassay. We conducted a 28-d chronic toxicity bioassay with 6-wk-old juvenile mussels exposed to a control and two Zn treatments (120 and 240 µg/L). We then transferred surviving mussels into a grow-out pond and monitored their survival and growth for 56 d. Survival and shell length were lower in both Zn treatments than in the control after the 28-d toxicity bioassay. After the 56-d grow-out period, survival did not differ among treatments, but shell length was lower in the 240-µg/L treatment than in the control and mass was lower in both Zn treatments than in the control. Mussel length was lower throughout the experiment in both Zn treatments than in the control, but there was weak support for a difference in the slopes, suggesting that Zn-exposed mussels may fall farther behind in size over time. Persistence of reduced size following Zn exposure could result in delayed sexual maturation and lowered fecundity, which could have long-term population-level effects.

Freshwater Mollusk Biology and Conservation↗