SAMMIE ALEXANDER

Recent George Mason University Environmental Science and Policy M.S. graduate. Thesis work investigated fish passage use in Potomac River tributaries by regional Species of Concern, Blueback Herring (Alosa aestivalis) and Alewife (Alosa pseudoharengus), with future investigations focused on incorporating the evaluation of passage use by two regionally invasive species, Blue Catfish (Ictalurus furcatus) and Northern Snakehead (Channa argus).

 

Thesis work utilized environmental DNA (eDNA) sampling methods in combination with habitat and water quality assessments to evaluate factors contributing to the movement of aquatic organisms through human-made structures (e.g., bridges and culverts). My research aimed to generate knowledge to inform management strategies that ensure the persistence of Virginia's living resources.

Graduated: December 2020

This blog began as a living journal of my research experiences as an undergraduate and continued to be a place of reflection as I navigated graduate school. I hope to continue this blog as I begin my journey as an environmental science professional.

RECENT VENTURES

Recent manuscript published in Environmental Biology of Fishes

Recent manuscript published in Environmental Biology of Fishes

Read my latest research stemming from an undergraduate research scholars program study, published with Springer Nature in Environmental Biology of Fishes.

qPCR plate prepared for 20 samples

qPCR plate prepared for 20 samples

Once all DNA has been extracted from the filters, the DNA must then be amplified using a river herring specific probe and quantitative polymerase chain reaction (qPCR). Each sample is run in triplicate (i.e., 3 wells/holes on the plate are used), with a fourth well to test for inhibition (i.e., a known concentration of river herring DNA is added to a forth well containing the sample DNA to see if the probe will fluoresce). Horn Point Laboratory - Cambridge, MD. Fall 2019.

DNA Extractions

DNA Extractions

Before we can determine which organisms' DNA are present in our water samples, we must extract the DNA from the filter and corresponding particles. Each 2 mL vile is what is left of the original 1 liter sample collected in the spring. Horn Point Laboratory - Cambridge, MD. Fall 2019.

eDNA filtration

eDNA filtration

Once samples are collected, we return to the lab to filter particles out of the water. The particle-containing filters are later used to extract and amplify the DNA captured on the filters.

Fish Passage

Fish Passage

An example of a fish passage, in this case a round metal culvert in Dumfries, VA. Spring 2018.

Fish Passage Assessment

Fish Passage Assessment

An example of a fish passage, in this case, a bridge below a road crossing at Prince William Forest Park in Triangle, VA. Spring 2018. We collect 1 liter water samples to detect the presence of various fish species by utilizing the DNA they have shed into the water.

First eDNA sampling day

First eDNA sampling day

First eDNA sampling day for my master's thesis at GMU. Looking for traces of Alewife, Blueback Herring, Northern Snakehead, and Blue Catfish DNA in water samples above and below road crossings to assess fish passage usage in NOVA. Hiking through the woods to a sampling location in Prince William Forest Part in Triangle, VA. Spring 2018.

Fish Passage

Fish Passage

An example of a fish passage, in this case a square concrete culvert, below a road crossing at Prince William Forest Park in Triangle, VA. Spring 2018.

First eDNA sampling day

First eDNA sampling day

First eDNA sampling day for my master's thesis at GMU. Looking for traces of Alewife, Blueback Herring, Northern Snakehead, and Blue Catfish DNA in water samples above and below road crossings to assess fish passage usage in NOVA. Hiking through the woods to a sampling location in Prince William Forest Part in Triangle, VA. Spring 2018.

The Science & 

Mathematics University

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