How Environmental DNA Is Revolutionizing Marine Mammal Science in the North Atlantic
For centuries, studying marine mammals meant braving treacherous seas for fleeting glimpses of surfacing whales or elusive porpoises. Today, scientists are tracking these ocean giants using something invisible: the genetic breadcrumbs they leave behind.
The North Atlantic is a dynamic theater of marine life, where whales, dolphins, and porpoises navigate vast distances amid warming waters and human pressures. Traditional monitoring methods—aerial surveys, acoustic buoys, or physical captures—are labor-intensive, costly, and often miss rare or deep-diving species. Enter environmental DNA (eDNA), a revolutionary tool that detects genetic traces shed from skin, mucus, feces, or decomposing tissue into seawater. A single water sample can reveal biodiversity patterns across entire ecosystems, transforming how we study marine mammals in this rapidly changing ocean 1 4 .
Genetic material collected from environmental samples like water, soil, or air without first isolating target organisms.
A critical habitat for 30+ marine mammal species facing climate change and human impacts.
Environmental DNA refers to genetic material freely circulating in marine environments. As marine mammals swim, they constantly shed DNA through:
Scientists collect this eDNA by filtering hundreds of liters of seawater. The trapped genetic material is then analyzed using:
| Method | Limitations | eDNA Advantages |
|---|---|---|
| Visual Surveys | Weather-dependent; misses cryptic species | Detects species day/night, any depth |
| Acoustic Monitoring | Species-specific; limited by noise | Broad biodiversity screening |
| Physical Captures | Invasive; stressful for animals | Non-invasive; minimal ecosystem disturbance |
eDNA excels in the North Atlantic's remote, deep habitats—like fjords or seamounts—where marine mammals are logistically challenging to observe 8 .
Harbor porpoises (Phocoena phocoena) in the Baltic Sea face critical endangerment, with only ~500 individuals remaining. Conflicting evidence suggested they might belong to the same population as North Sea porpoises, complicating conservation efforts. To resolve this, researchers deployed a genome-wide eDNA approach 6 .
| Region | Sub-Region | Samples |
|---|---|---|
| North Atlantic | Iceland (ICE) | 3 |
| North Sea (NOS) | – | 6 |
| Baltic Sea | Skagerrak (SK1) | 5 |
| Inner Baltic (IBS) | 10 |
| Population Pair | FST (SNPs) | FST (Microsatellites) |
|---|---|---|
| North Sea vs. IBS | 0.08 | 0.02 |
| BES2 vs. IBS | 0.12 | 0.03 |
| Tool/Reagent | Function | Example Use Case |
|---|---|---|
| Autonomous Gliders | Collects water samples at depth | Tracking deep-diving beaked whales 1 |
| Drifting Acoustic Recorders | Paired with eDNA sampling; detects vocalizations | Correlating sperm whale calls with eDNA 1 |
| Smith-Root eDNA Sampler | Self-preserving filter; inhibits degradation | Remote fjord surveys 8 |
| eDNAjoint R Package | Bayesian model integrating eDNA/traditional data | Reduces false positives in tidewater goby studies 3 |
| Metabarcoding Primers | Amplifies DNA "barcodes" for species ID | Detecting 91 seabird species from seawater 1 |
Collect eDNA samples at precise depths without human intervention
Stabilize DNA during transport from remote locations
Advanced algorithms analyze complex genetic mixtures
Innovations are expanding eDNA's reach:
Environmental DNA has turned the ocean into an open book. By decoding genetic whispers in water—or even air—scientists are mapping marine mammal highways, pinpointing climate refugees like northward-moving sei whales 1 , and safeguarding critical populations like the Baltic's harbor porpoises. As this technology matures, it promises not just to observe the ocean's hidden stories, but to rewrite how we protect them.
Dr. David Duffy (UF Whitney Lab) captures it best: "It seems like science fiction, but it's becoming science fact. The technology is finally matching the scale of environmental problems" 5 .