Which technique is commonly used to assess freshwater biodiversity?

Environmental DNA (eDNA) analysis is a powerful technique for assessing freshwater biodiversity due to its ability to detect genetic material shed by organisms into the environment, such as in water samples. This method allows researchers to identify species present in a given area without the need for direct observation or capture of the organisms. It is particularly effective because it can detect both well-known and cryptic or rare species, providing a comprehensive view of the biodiversity within a freshwater ecosystem.

eDNA analysis is often more efficient and less invasive than traditional methods, such as netting or trapping, and can help monitor biodiversity changes over time, assess the impacts of human activities, and identify populations of species that are difficult to observe. This technique has revolutionized biological monitoring by enabling large-scale assessments of freshwater habitats with relatively minimal effort.

Other techniques mentioned, such as photographic documentation, have limitations in the number of species they can reliably record, and techniques like radiometric dating are not directly related to assessing biodiversity but rather to determining the age of geological formations or environmental changes. Satellite imaging can provide general information on habitats but lacks the specificity needed for species-level assessments.