Environmental DNA

Environmental DNA (eDNA) is genetic material recovered from environmental samples such as water, soil, or air, rather than directly from an organism. It can reveal which organisms are present without capturing or observing them.

DNA shedding: The release of cells, tissue, or other biological material containing DNA from an organism. Organisms shed the material that supplies most eDNA samples.
Aquatic invasive species: Non-native organisms that establish and spread in aquatic environments, often causing ecological or economic harm. eDNA surveys can detect newly arrived invaders before conventional observation finds them.
DNA: A molecule that stores hereditary information in most living organisms. Environmental samples contain fragments of this molecule shed by organisms.
False positive rate: The proportion of negative cases incorrectly classified as positive by a test. Contamination and mistaken sequence assignments can make eDNA indicate a species that is absent.
DNA degradation: The chemical and biological breakdown of DNA into smaller fragments. Degradation limits how long eDNA remains detectable after organisms leave.
Environmental DNA biomonitoring: The use of environmental DNA measurements to assess species presence or ecological conditions over time. Repeated eDNA sampling can track biodiversity and ecosystem change.
DNA barcoding: Species identification using short, standardized DNA sequences as genetic markers. Reference barcode sequences help assign eDNA reads to species.
False negative rate: The proportion of positive cases incorrectly classified as negative by a test. Sparse shedding or poor sampling can hide species that are present.
Polymerase chain reaction: A laboratory method that amplifies selected DNA sequences through repeated cycles of copying. PCR can amplify scarce target DNA recovered from environmental samples.
Marine biodiversity: The variety of genes, species, and ecosystems in the world's seas and oceans. Water samples can reveal marine species that are difficult to observe directly.

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