Biology subjects

Marshall, N. T.

Publications and source records attributed to Marshall, N. T..

4 recordsLinked to original sources

bioRxiv2026

Seasonal patterns of environmental DNA detection for freshwater unionid mussels

Environmental DNA (eDNA) provides a powerful non-invasive tool for monitoring freshwater mussel assemblages, yet detection probabilities can be influenced by reproductive behaviors, seasonal vertical migration, and hydrological conditions. This study assessed eDNA detection from April through October across two diverse mussel beds in Ohio, encompassing species with both tachytictic (short-term brooders) and bradytictic (long-term brooders) reproductive strategies. Mussel DNA was consistently detected across seasons, with detection patterns generally aligning with species observed through a visual tactile survey. Overall, the eDNA sequence abundance was positively correlated with tactile mussel counts, however congruence between the two surveys was strongest during low discharge and when the surveys occurred in close temporal proximity to one another. This study finds that eDNA sampling for freshwater mussels performs adequately within the currently prescribed survey window for visual surveys. However, seasonal factors such as endobenthic burial behavior and high discharge events may have reduced detection efficiency, particularly in Killbuck Creek, where species richness was lowest during periods of high flow in early spring. Therefore, decisions made regarding the timing of eDNA surveys should consider local environmental conditions (e.g., temperature and flow) to achieve optimal results.

ecology↗

bioRxiv2026

A conservation planning assessment of basin wide Unionid mussel assemblages using environmental DNA

Conservation planning for rare, threatened, and endangered species requires basic information for distribution and abundance. Often this information is lacking due to the nature of traditional survey methods which can be time and labor intensive and thus costly. Environmental DNA (eDNA) metabarcoding offers a promising approach for monitoring freshwater mussel assemblages, a taxonomic group that is both highly imperiled and difficult to survey using traditional methods. We evaluated the performance of eDNA metabarcoding across 30 km of Fish Creek, in Ohio and Indiana, U.S.. We compared results to visual surveys conducted at the same sites. eDNA detected 25 mussel species, including four species not observed alive visually, while visual surveys detected 22 live species. Both methods confirmed the presence of three federally protected species, and eDNA uniquely detected Simpsonaias ambigua, a species rarely encountered in conventional surveys. Incorporating detection repeatability improved congruence between methods: high-repeatability detections strongly aligned with visual presence, whereas moderate and low repeatability detections likely represented reach-scale occupancy. Overall, eDNA metabarcoding offers an efficient and sensitive tool for assessing mussel assemblages and can substantially enhance monitoring programs when integrated with species ecology and hydrological context.

ecology↗

bioRxiv2026

Assessment of Environmental DNA Surveys for the Cryptic Salamander Mussel (Simpsonaias ambigua)

Simpsonaias ambigua (Salamander Mussel), is a small and thin shelled freshwater mussel often found in difficult to survey habitats, such as beneath slab stones, in the crevices of rock walls, or buried within roots of emergent vegetation and in undercuts of banks. The use of environmental DNA (eDNA - genetic material released from urine, waste, mucus, or sloughed cells) sampling may improve detection and assessment of presence / absence for this rare mussel in comparison to visual tactile techniques. This study completed side by side comparisons of traditional mussel searches and eDNA for a direct assessment of mussel detection efficiencies. Surveying was conducted in several waterbodies of different habitat characteristics with varying abundances of S. ambigua. Additionally, a broad assessment of S. ambigua presence was conducted throughout the proposed critical habitat reach of the Blanchard River in northwest Ohio, to assess if the species remained extant. All eDNA samples were also assessed for the presence of Necturus maculosus (Mudpuppy), the obligate host species for S. ambigua. The eDNA sampling successfully detected S. ambigua from multiple sites and watersheds where it was found with visual surveys. In some cases, eDNA detections occurred in locations where over 16 hours of search yielded only a single individual or fresh dead shells, supporting the sensitivity of eDNA for detection of rare species. Furthermore, probability of detection analysis suggests eDNA sampling can provide high detection efficiency with relatively low effort in comparison to visual searches. The development and validation of an eDNA protocol for the simultaneous detection of S. ambigua and its host salamander increases survey efficiency, reduces field costs, and can support future conservation efforts for listing drainages of extant populations and monitoring conservation goals.

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bioRxiv2022

Detecting bat environmental DNA from water-filled road-ruts in upland forest

Declines in population and diversity of North American bats are rapidly occurring due to habitat loss, incidental take from various industry projects, and lethal White-nose Syndrome disease. It is critical to accurately census habitat for appropriate conservation measures, yet traditional sampling methodology, such as mist netting and acoustic recordings, can be time-intensive and biased. Instead, a passive sampling tool that does not rely on the a priori knowledge of bat roosts may provide crucial information on bat communities. In the water-limited habitats of forested uplands of the Appalachian Plateau, water-filled road-ruts are important resources for bats. Therefore, we developed an environmental DNA (eDNA) protocol to sample isolated road-ruts that may have the presence of sloughed cellular material from actively drinking bats. The detection of bat eDNA was investigated from a positive control experiment, and across 47 water samples collected in Kentucky and Ohio. Water samples were analyzed using both species-specific quantitative polymerase chain reaction (qPCR) and community metabarcoding methodologies. Using qPCR analysis, we detected eDNA from big brown bat (Eptesicus fuscus) and eastern red bat (Lasiurus borealis) from water-filled road-ruts. While the community metabarcoding approach failed to detect any bat eDNA, many non-target amphibians, birds, and mammals were identified. These results suggest eDNA found within road-ruts provides an additional detection tool for surveying biodiversity across upland forests. Additionally, the use of qPCR increased the detection of rare eDNA targets, which will be crucial for properly implementing future eDNA applications for improving bat conservation efforts across the landscape. Article impact statementEnvironmental DNA provides detection of bats from drinking sources offering a novel survey method for management and conservation efforts

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