Imagine being able to study marine life without disturbing it or even seeing it. That’s what environmental DNA, or eDNA, allows scientists to do. eDNA is a groundbreaking tool that helps us learn more about the creatures living in our oceans, from the tiniest bacteria to the largest fish, without ever needing to lay eyes on them.
What is eDNA?
Environmental DNA, or eDNA, refers to the genetic material shed by organisms into their surroundings. In aquatic environments, this means DNA that is left behind in the water by marine organisms. Think of it like a biological fingerprint—every time an organism sheds a piece of tissue, releases waste, or sheds mucus, it leaves traces of DNA. By collecting and analyzing these samples, scientists can gather a wealth of information about the organisms present in that particular area of water.
How Do Scientists Collect eDNA?
Collecting eDNA involves a few steps, starting with water sampling. Scientists use special tools, like a Niskin bottle, to collect water samples from different depths and locations. These bottles can be attached to various devices, such as remotely operated vehicles, which can dive deep into the ocean. The collected samples are carefully labeled with information like the exact location (latitude and longitude), depth, water temperature, salinity, and the type of filter material used.
Once the water is collected, it goes through a filtration process using a special cellulose nitrate membrane that captures the eDNA. The DNA is then either frozen or preserved in a solution that prevents it from degrading over time. This step is crucial because it allows scientists to store the DNA samples for years, making it possible to revisit the samples if a new species is discovered in the future.
What Happens After Collection?
Once the samples are safely stored, they are sent to a laboratory for DNA sequencing. DNA is made up of four building blocks known as bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Every living organism has a unique pattern of these bases. By reading the sequence of these bases in eDNA, scientists can identify which species the DNA came from.
This process, known as “metabarcoding,” involves labeling the DNA sequences and comparing them to a vast database of known sequences. This comparison helps scientists determine which species are present in the water sample, often identifying them down to their family, genus, or even species.
Why Use eDNA?
eDNA is becoming an increasingly popular tool because it provides a non-invasive way to study marine ecosystems. Traditional methods of studying marine life often require physically capturing organisms, which can be stressful for the animals and disruptive to their habitat. In contrast, eDNA allows researchers to gather valuable information without directly interacting with the creatures.
This method is particularly useful for studying species that are hard to observe, such as those that are small, elusive, or live in deep or otherwise inaccessible parts of the ocean. For example, some organisms avoid the lights of underwater robots or cameras, making them difficult to capture on video. However, they still leave behind their DNA, which can be detected by eDNA sampling.
eDNA is also incredibly versatile. It can detect a wide range of organisms—from tiny bacteria to large vertebrates—giving scientists a fuller picture of the biodiversity in a given area. This technology has even helped researchers link larvae to their adult forms, clarifying misunderstandings about species that were previously thought to be different due to their varying appearances at different life stages.
The Future of eDNA
eDNA represents a significant leap forward in our ability to study and understand marine ecosystems. By providing a non-invasive, efficient, and comprehensive method for detecting marine life, it complements traditional sampling methods and expands the scope of ocean exploration. As this technology continues to develop, it will undoubtedly play an even more crucial role in marine conservation, research, and resource management, helping us to better protect our oceans for future generations.
Image by GrumpyBeere from Pixabay
