Monitoring
Abundance of Five Sympatric Stream Dwelling Mussels Varies with Physical Habitat
Abstract -
Freshwater mussel species regularly co-occur in streams forming assemblages, but the extent of shared versus unique instream habitat features that contribute to their distribution and abundance is poorly understood. In Massachusetts, a rare species, Alasmidonta varicosa, is often found with four other species: Alasmidonta undulata, Strophitus undulatus, Margaritifera margaritifera, and Elliptio complanata, yet variation in species composition within assemblages raises questions of potential species-specific habitat associations. Identifying species-level habitat information is critical at a spatial scale that malacologists can use to identify translocation or restoration areas. 1) This study investigated whether species abundance varied by mesohabitat type (riffle, run, dam pool, scour pool), instream habitat characteristics, and within-reach location (centre versus edge). From 2016 to 2019, freshwater mussel surveys were conducted in nine streams across Massachusetts and associated habitat information was collected. 2) Species abundances were similar across mesohabitat types. Elliptio complanata was the exception, whereby higher abundances occurred in runs and dammed pools than in riffles. Unique species relationships with habitat existed for M. margaritifera with macroalgae and emergent vegetation, and A. varicosa with heterogeneous substrate. Flow transitions, such as depositional areas that create heterogeneous substrates, may provide habitats for A. varicosa. 3) Most mussel species were distributed with higher abundance in the river centre than the edge; E. complanata was the only species with a higher abundance at the river edge. Locations with high abundance varied based on unique relationships with pebble heterogeneity (A. varicosa), depth (A. undulata), large wood (A. undulata), and canopy closure (E. complanata). Including physical characteristics in a holistic assessment of habitat that incorporates fish and landscape attributes may further an understanding of river reaches that best support translocated and propagated freshwater mussels.
Standard Operating Protocol for Mark and Recapture Monitoring of Brook Floater in Streams
The objective of this protocol is to develop a coordinated, standardized, monitoring approach for Brook Floater to estimate population status and trends and demographic rates that allow for comparisons among populations throughout its range. As part of the Brook Floater SWG, we aimed to collect data to compare demographic data among locations with different densities and habitat conditions and understand why there may be differences in demographic stability. As such, the protocol includes methods for collecting ancillary data for assessing detection and addressing questions about habitat. This protocol may also be adapted to address a variety of research questions that require population and demographic data (e.g., population size, emigration, survival, etc.) and supplemental habitat or water quality data that may be collected to address additional hypotheses about the species’ sensitivity to environmental stressors. Furthermore, while this protocol was developed for Brook Floater, many aspects of this monitoring approach are likely applicable to mark and recapture of other stream-dwelling freshwater mussel species.
Photos courtesy of Sterrett et. al 2022.
Photos courtesy of Sterrett et. al 2018.
Brook Floater Rapid Assessment and Long-term Monitoring Survey
Monitoring for conservation can provide snapshots or long-term trends of wildlife population distribution and demography. One objective of the BFWG is to develop rapid assessment and long-term monitoring protocols for state partners to employ across the range of the Brook Floater. Our rapid assessment protocol, which uses an Occupancy framework, has been published in 2018 and will be implemented in the summer of 2017 it order to:
1. Estimate the occupancy (percent area occupied; PAO) of Brook Floater within watershed that are recently (<20 years) known to have Brook Floaters present as evident by state element occurrence records
2. Estimate the effects of reach- and watershed-scale habitat features on Brook Floater occurrence
3. Understand how survey covariates influence detection of Brook Floater (and improve survey efficiency)
Brook Floater Restoration in Massachusetts
Ayla Skorupa recently defended her dissertation 'Developing a restoration strategy for Brook Floater (Alasmidonta varicosa) at University of Massachusetts Amherst. One portion of her dissertation examined the impact of water quality on mussel growth and survival prior to stocking. Ayla also created a reintroduction framework that used species distribution models and modeled streamflow metrics to identify initial sites. This process is not used to identify sites for potential reintroduction in Massachusetts.
Photos courtesy of Ayla Skorupa.
Future Plans
Moving forward, we plan to monitor habitat change, mussel densities, and mussel demographic responses to stressors. These actions include:
1. Assess mussel habitat responses to dam removal
2. Perform rapid mussel and habitat assessment surveys at historic and new locations using established monitoring protocols
3. Evaluate survey protocols for distribution of mussel species co-occurring with Brook Floater
4. Collect genetic samples to support ongoing USFWS population genetic efforts
Continued Work:
* Assessing the mussel and habitat response to a dam removal in prep.
* Monitoring beaver activity near a Brook Floater Site in Massachusetts
* Mussel translocation monitoring plan for a dam removal in Massachusetts