Geology topics

E.M. Monroe

Publications and source records attributed to E.M. Monroe.

7 recordsLinked to original sources

USGS2019

Environmental DNA assays for invasive populations of the Black Carp, Mylopharyngodon piceus, in North America

The Black Carp, Mylopharyngodon piceus, is an increasingly widespread invasive species in North America that threatens freshwater mussel populations. We developed four qPCR assays for detecting environmental DNA (eDNA) from these Black Carp populations. Assays were designed to target four mitochondrial DNA loci and were based on 34 complete mitochondrial genome sequences, including 29 generated in this study from samples obtained in three countries. Assays were validated for taxon specificity with in silico comparisons against archived DNA sequences and with in vitro tests of 41 DNA samples from Black Carp, as well as DNA samples from 30 non‐target fish species, all from the Mississippi River Basin. All four assays were able to detect the DNA of all Black Carp samples and did not exhibit any positive results with DNA from other tested species. Tests conducted in round‐robin fashion among three different laboratories found that all four assays were able to detect DNA at very low template concentrations (limits of detection = 3 copies/qPCR, limits of quantification = 16‐64 copies/qPCR) and, as part of in situ validation, were successful in detecting eDNA from Black Carp in aquaculture ponds. Despite some challenges with other attempts at in situ validation, the assays were also effective in detecting Black Carp eDNA in water samples from a drainage ditch in the upper reaches of the species’ range that was known to contain juvenile Black Carp, as well as in water samples from the Missisippi River and a connected oxbow lake in the lower reaches of the species range.

Transactions of the American Fisheries Society↗

USGS2019

Refinement of eDNA as an early monitoring tool at the landscape-level: Study design considerations

Natural resource managers use data on the spatial range of species to guide management decisions. These data come from survey or monitoring efforts that use a wide variety of tools. Environmental DNA (eDNA) is a surveillance tool that uses genetic markers for detecting species and holds potential as a tool for large-scale monitoring programs. Two challenges of eDNA-based studies are uncertainties created by imperfect capture of eDNA in collection samples (e.g., water field samples) and imperfect detection of eDNA using molecular methods (e.g., quantitative PCR). Occurrence models can be used to address these challenges, thus we use an occurrence model to address two objectives: First, determine how many samples were required to detect species using eDNA; Second, examine when and where to take samples. We collected water samples from three different habitat types in the Upper Mississippi River when both Bighead Carp and Silver Carp were known to be present based on telemetry detections. Each habitat type (backwater, tributary, and impoundment) was sampled during April, May and November. Detections of eDNA for both species varied across sites and months, but were generally low, 0 - 19.3% of samples were positive for eDNA. Overall, we found that eDNA-based sampling holds promise to be a powerful monitoring tool for resource managers, however, limitations of eDNA-based sampling include different biological and ecological characteristics of target species such as seasonal habitat usage patterns as well as aspects of different physical environments that impact the implementation of these methods such as water temperature.

Ecological Applications↗

USGS2009

Characteristics of a refuge for native freshwater mussels (Bivalvia: Unionidae) in Lake St. Clair

The Lake St. Clair delta (??? 100??km 2 ) provides an important refuge for native freshwater mussels (Unionidae) wherein 22 of the ??? 35 historical species co-occur with invasive dreissenids. A total of 1875 live unionids representing 22 species were found during snorkeling surveys of 32 shallow (??? 1??m) sites throughout the delta. Richness and density of unionids and zebra mussel infestation rates varied among sites from 3 to 13 unionid species, 0.02 to 0.12 unionids/m 2 , and < 1 to 35 zebra mussels/unionid, respectively. Zebra mussel infestation of unionids in the delta appears to be mitigated by dominant offshore currents, which limit densities of zebra mussel veligers in nearshore compared to offshore waters (13,600 vs. 28,000/m 3 , respectively). Glycogen concentrations in the tissues of a common and widespread species in the delta (Lampsilis siliquoidea) suggest that zebra mussels may be adversely affecting physiological condition of unionids in a portion of the Lake St. Clair delta. Physiological condition and community structure of unionids within the delta may also be influenced by differences in food quantity and quality resulting from the uneven distribution of water flowing from the St. Clair River. The delta likely supports the largest living unionid community in the lower Great Lakes and includes several species that have been listed as Endangered or Threatened in Canada and/or the state of Michigan, making it an important refuge for the conservation of native unionids. Crown Copyright ?? 2009.

Journal of Great Lakes Research↗

USGS2004

Denitrification in the Upper Mississippi River: Rates, controls, and contribution to nitrate flux

We evaluated patterns of denitrification and factors effecting denitrification in the upper Mississippi River. Measurements were taken over 2 years, during which river discharge ranged from record flooding to base flow conditions. Over the period of study, average denitrification enzyme activity was highest in backwater lakes and lowest in the main channel. Throughout the study reach, highest denitrification enzyme activity occurred during fall and lowest occurred in winter. Rates during spring floods (2001) were only slightly higher than during the preceding winter. Mean unamended denitrification rates ranged from 0.02 (fall 2001 in backwaters) to 0.40 ??g N??cm -2??h-1 (spring 2001 in backwaters). Laboratory experiments showed that denitrification rates increased significantly with addition of NO3- regardless of sediment C content, while rates increased little with addition of labile C (glucose). Denitrification in this reach of the upper Mississippi River appears to be NO3- limited throughout the growing season and the delivery of NO 3- is strongly controlled by river discharge and hydrologie connectivity across the floodplain. We estimate that denitrification removes 6939 t N??year-1 or 6.9% of the total annual NO 3- input to the reach. Hydrologic connectivity and resultant NO3- delivery to high-C sediments is a critical determinant of reach-scale processing of N in this floodplain system.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2001

Seasonal variation in physiological condition of Amblema plicata in the Upper Mississippi River

Measures of physiological condition are being used as sub-lethal endpoints in studies with unionids exposed to a variety of stressors, yet the natural seasonal variation in these measures are largely undocumented. We measured concentrations of glycogen in foot and mantle tissue and a tissue condition index (TCI) in Amblema plicata (Say 1817), about monthly, for 2 years in mussels that were: (1) obtained directly from the Upper Mississippi River (riverine group); and (2) relocated from the river into an artificial pond (relocated group). In both groups, we observed significant seasonal variation in all physiological indicators. Seasonal variation in glycogen was 72% in mantle and 52% in foot tissue and paralleled reproductive activity in this short-term breeder. In the relocated group, most of the variation in glycogen occurred during the first six months after relocation, suggesting that handling stress may have been a contributing factor. The significant seasonal variation in the TCI paralleled glycogen in riverine mussels. We observed tissue-specific differences in glycogen in the riverine group, but not in the relocated group. These data suggest that an interaction of environmental and biological factors influence the energetic status of mussels in natural populations. A better understanding of this variation is needed to interpret changes in physiological condition due to stressors such as relocation.

Journal of Shellfish Research↗

USGS1999

Variation in glycogen concentrations within mantle and foot tissue in Amblema plicata plicata: Implications for tissue biopsy sampling

With the development of techniques to non-lethally biopsy tissue from unionids, a new method is available to measure changes in biochemical, contaminant, and genetic constituents in this imperiled faunal group. However, before its widespread application, information on the variability of biochemical components within and among tissues needs to be evaluated. We measured glycogen concentrations in foot and mantle tissue in Amblema plicata plicata (Say, 1817) to determine if glycogen was evenly distributed within and between tissues and to determine which tissue might be more responsive to the stress associated with relocating mussels. Glycogen was measured in two groups of mussels: those sampled from their native environment (undisturbed mussels) and quickly frozen for analysis and those relocated into an artificial pond (relocated mussels) for 24 months before analysis. In both undisturbed and relocated mussels, glycogen concentrations were evenly distributed within foot, but not within mantle tissue. In mantle tissue, concentrations of glycogen varied about 2-fold among sections. In addition, glycogen varied significantly between tissues in undisturbed mussels, but not in relocated mussels. Twenty-four months after relocation, glycogen concentrations had declined by 80% in mantle tissue and by 56% in foot tissue relative to the undisturbed mussels. These data indicate that representative biopsy samples can be obtained from foot tissue, but not mantle tissue. We hypothesize that mantle tissue could be more responsive to the stress of relocation due to its high metabolic activity associated with shell formation.

American Malacological Bulletin↗

USGS1998

Nonlethal evaluation of the physiological health of unionid mussels: Method for biopsy and glycogen analysis

In long-lived unionid mussels, many short-term measures of growth are of limited value. Changes in physiological condition may be an early indication of stress, because the increased energy demand associated with stress often results in a depletion of glycogen reserves, the principal storage form of carbohydrates in unionid mussels. Our goal was to nonlethally extract tissue from freshwater mussels and then to develop a rapid and dependable method for the analysis of glycogen in the tissue extracts. A biopsy technique was developed to remove between 5 and 10 mg of foot tissue in Amblema plicata plicata. The survival rate did not differ between biopsied and non-biopsied mussels during a 581-d observation period, demonstrating that the biopsy technique will allow nonlethal evaluation of the physiological condition of individual mussels through measurement of changes in contaminant, genetic, and biochemical indicators in tissue. We also modified the standard alkaline digestion and phenol-sulfuric acid analysis of glycogen for use on the small samples of biopsied tissue and to reduce analysis time and cost. We present quality control data, including method detection limits and estimates of precision and bias. The modified analytical method is rapid and accurate and has a method detection limit of 0.014 mg glycogen. Glycogen content in the biopsied samples was well above the method detection limit; it ranged from 0.09 to 0.36 mg, indicating that the method should be applicable to native mussels.

Journal of the North American Benthological Societ↗