# data[].attributes.headline
Environmental DNA in Conserving Freshwater Mussels

# data[].attributes.subject
Environmental DNA in Conserving Freshwater Mussels

# data[].attributes.body
Freshwater mussels are a diverse and threatened taxa, particularly in the United States (Haag and Williams, 2014).  As filter feeders they improve overall stream health, but are rapidly declining all across America (Haag and Williams). This document contains an overview of one method used to better understand where to focus conservation efforts.

# data[].attributes.body
All organisms, from single celled bacteria to complex humans, rely on genetic material in order to live, grow, and reproduce. In most living organism genetic material is in the form of deoxyribonucleic acid (DNA), seen in Figure 1. Components of DNA include four base pairs that create a genetic code. The information contained in this genetic code is specific to each living organism and can be used to determine what individual left behind their cells (Genetics Home Reference -NIH., 2020).

# data[].attributes.body
An example strand of DNA higlighting matching base pairs that make uniquee genetic codes (Genetics Home Reference -NIH., 2020)

# data[].attributes.body
Organism shed cells containing their DNA in skin, hair, feces, scales, mucus, gametes, saliva, and decaying bodies (Thomsen & Willerslev, 2014). When DNA is shed, it can mix with water, soil, or mud, becoming part of its habitat. The term environmental DNA (eDNA) is used to refer to this form of genetic information (Cho, Morris, Wilson, & Freeland, 2016). This eDNA can potentially be used to determine the presence or absence of organisms in particular areas, as can be seen in Figure 2 (Thomsen & Willerslev).

# data[].attributes.body
A visual of eDNA as a tool for discovering species in an environment (Holm, 2014).

# data[].attributes.body
Fresh water mussels typically bury into substrate and are difficult to find and count accurately.  To properly protect freshwater mussels monitoring populations and habitat is crucial  (Currier, Morris, Wilson, Freeland, 2017). Testing streams and rivers for eDNA left behind by freshwater mussels could help pinpoint areas of greatest diversity, lowest numbers, and areas for strict regulations and research.

# data[].attributes.body
Many studies are trying to improve this method of testing streams for sloughed cells of freshwater mussels. All studies use the same basic procedure: a test tube is interested into an assumed mussel habitat and then run through a PCR (polymerase chain reaction)* machine to amplify the amount of DNA. It is then run against known standard freshwater mussel DNA to determine what exactly is living in that habitat (Schill & Galbraith, 2018). Studies diverge in how they use results, either announcing presence, running stats on density, or narrowing an area for continued research.

*Polymerase chain reaction is a procedure in which multiple copies of a certain segment of DNA are made to streamline further research (Khan Academy, n.d.).

# data[].attributes.body
Gathering data is the most crucial step in truly understanding declining species. For freshwater mussels, knowing how many are in a certain space is the basis for implementing conservation action. The ability to calculate not only presence/absence, but also a population estimate by using only a water sample is a major step forward in the protection of many river species (Carraro et. al., 2018). This method of identifying species does not involve disturbing the mussels protecting them from possible stress and damage in human hands. It also can be more tine efficient than hunting for mussels in the sediment in rivers, saving time, resources, and energy.

# data[].attributes.body
While this method of uncovering organisms is growing, there are still holes in its success. For instance, it is difficult to have set standards for a wide variety of closely related invertebrates (Roussel ,Paillisson, Treguier & Petit, 2015). DNA must be run against known species DNA and many mussels are so closely related that it requires very precise comparisons (Schill & Galbraith, 2018). It is also still unclear how to calculate the abundance of a species, as well as exactly where upstream mussels may be located (Roussel,Paillisson, Treguier & Petit). These pitfalls however, are being investigated by many scientists and results could lead to more implementation of this method.

# data[].attributes.body
Conserving the diversity of freshwater mussels in the United States is a key priority for many people. A recent story by Nathan Rott (2019) discusses the scale of which freshwater mussels are declining. Knowing where to focus those efforts is key in gaining funding and passing legislation. The ability to use freshwater mussel DNA left in the environment could be a major player in saving this taxa from future decline.

# data[].attributes.body
Mussel diversity in the Clinch River (Virginia), an area of particular concern for scientists studying mussel conservation (Rott, 2019).

# data[].attributes.body
Carraro, L., Hartikainen, H., Jokela, J., Bertuzzo, E., & Rinaldo, A.  (2018). Estimating species distribution and abundance in river networks using environmental DNA. Proceedings of the National Academy of Sciences of the United States of America, 115(46), 11724–11729.

Cho, A., Morris, T., Wilson, C., & Freeland, J. (2016, May). Development of species-specific primers with potential for amplifying eDNA from imperilled freshwater unionid mussels. Genone, 59(12):1141-1149

Currier, C. A., Morris, T. J., Wilson, C. C., & Freeland, J. R. (2017). Validation of environmental DNA (eDNA) as a detection tool for at-risk freshwater pearly mussel species (Bivalvia: Unionidae). Aquatic Conservation-Matine and Freshwater Ecosystems, 28(3), 545-558

Genetics Home Reference -NIH. (2020, February 11). What is DNA? Retrieved from https://ghr.nlm.nih.gov/primer/basics/dna

Haag, W., & Williams, J. (2014). Biodiversity on the brink: an assessment of conservation strategies for North American freshwater mussels. Hydrobiologia, 735(1), 45–60.

Holm, L., (2014) In Thomsen, P. F., & Willerslev, E. (2014). Environmental DNA – An emerging tool in conservation for monitoring past and present biodiversity. Biological Conservation, 183, 4-18.

Khan Academy. (n.d.). Polymerase chain reaction (PCR) Retrieved from https://www.khanacademy.org/science/biology/biotech-dna-technology/dna-sequencing-pcr-electrophoresis/a/polymerase-chain-reaction-pcr

Rott, N. (Journalist) (2019, December 6). Natures Brita Filter Is Dying And Nobody Knows Why. Retrieved from https://www.npr.org/2019/12/06/784422726/natures-brita-filter-is-dying-and-nobody-knows-why

Roussel, J. M., Paillisson, J.M., Tréguier, A., & Petit, E. (2015, June 12). The downside of eDNA as a survey tool in water bodies. Journal of Applied Ecology.  52, 823-826

Schill, W. B., & Galbraith, H. S. (2018.). Detecting the undetectable: Characterization, optimization, and validation of an eDNA detection assay for the federally endangered dwarf wedgemussel, Alasmidonta heterodon (Bivalvia: Unionoida). Aquatic Conservation-Matine and Freshwater Ecosystems, 29(4), 603–611.

Thomsen, P. F., & Willerslev, E. (2014). Environmental DNA – An emerging tool in conservation for monitoring past and present biodiversity. Biological Conservation, 183, 4-18.