A Senior Capstone Experience by Mirabelle White

Submitted to the Department of Environmental Science and Studies and the Department of Biology

Advised by Dr. Rebecca Fox and Dr. Jennifer Wanat

Contributor Biography: Mirabelle White graduated from Washington College in 2024 with majors in Environmental Science and Biology.

Description: Freshwater ecosystems, especially lotic systems (streams and rivers), hold important value as a resource. Despite the small area they cover on Earth’s surface, they are hotspots for biodiversity. However, they also have higher species extinction rates than those of marine and terrestrial ecosystems due to invasive species, habitat destruction, and chemical pollution; and are often neglected from aquatic biodiversity conservation. If lotic biodiversity continues to decline, it can impact the ability of these ecosystems to provide goods and services for future generations, as well as lead to ecosystem collapse. Adequate monitoring techniques are imperative to assessing biodiversity threats. Current methods include kick-netting, gillnetting, and electrofishing. However, they require a tremendous amount of time and energy to be implemented, and can result in unwanted habitat destruction and species mortality. A new method was recently developed, known as environmental DNA (eDNA), which references the genetic material from organisms left behind in the environment. It is extracted from water, sediment, and gas samples, and is then amplified using a polymerase chain reaction (PCR), to sequence the DNA, and identify its source. This determines community composition, therefore biodiversity levels, which could also be used to infer chemical impact, such as in ecological risk assessments. Numerous studies have compared the ability of eDNA to traditional methods in measuring biodiversity, and eDNA was found to yield similar or clearer results. eDNA was also found to detect community composition changes in response to contaminant presence and absence. However, the technique is still being developed and has issues that need to be addressed before replacing traditional methods. eDNA shows promise as an additional conservation and ecotoxicity assessment method, but for now it should be used alongside traditional monitoring methods and lab assessments before fully replace them.

Read Mirabelle’s SCE here: