Holistic biodiversity monitoring: Combining bioacoustics and eDNA to deepen our understanding of marine life

Tackling the global biodiversity crisis: How innovative monitoring helps us protect our ocean

Biodiversity is in steep decline. Every year, more species, habitats, and natural resilience are lost, deepening a global biodiversity crisis that demands action. The world has responded with ambitious commitments. The United Nations Convention on Biological Diversity sets a clear vision: “By 2050, biodiversity is valued, conserved, restored, and wisely used, maintaining ecosystem services, sustaining a healthy planet, and delivering benefits essential for all people.” To move towards that goal, the 2022 Kunming-Montreal Biodiversity Framework introduced 23 global targets, including the protection of 30% of Earth’s land and ocean by 2030.

Across the EU, this ambition is taking shape through the Nature Restoration Law. Member states are translating these targets into national legislation, supported by international frameworks such as the Marine Strategy Framework Directive (MSFD) which strengthens the tools used to assess environmental status and human impacts.

In the UK, a similar shift is underway. Biodiversity Net Gain, mandated by the Environment Act 2021, requires most developments in England and Wales to leave nature in a measurably better state than before. Scotland and Northern Ireland are shaping comparable policy, while countries such as Australia are adopting net-benefit principles for coastal and marine projects. Marine Net Gain is also under consultation, signalling its likely influence on future consenting for major infrastructure.

Across all these initiatives, the message is simple: we need clearer insights into what is present in the marine environment, how many there are, and how this is changing over time. Meeting that need requires new approaches to biodiversity monitoring.

Why biodiversity monitoring needs to change

Accurately assessing biodiversity has always been challenging, particularly offshore. The marine environment is dynamic, remote, and often difficult to access. Traditional surveys rely on periodic visual observations and manual sampling. While essential, these methods are limited by weather, cost, and spatial or temporal gaps.

But biodiversity doesn’t stand still – species move, spawn, migrate, and respond to human activity on timelines that traditional surveys can miss. As expectations for environmental accountability rise, monitoring methods must capture a more complete picture. One that is non-invasive, scalable, and capable of supporting both sustainable development and healthy ecosystems.

Bioacoustics: Listening to the ocean’s hidden conversations

The ocean is far from silent. Waves, currents, and vessels all contribute to the soundscape, but beneath these layers lies the acoustic activity of marine species. Sound travels nearly five times faster underwater than it does in air, making it a vital communication tool. Many aquatic animals rely on sound to find mates, coordinate groups, defend territory, and navigate environments where visibility is limited.

Bioacoustics offer a window into this world. Using passive acoustic monitoring (PAM), hydrophones record the underwater soundscape continuously across a wide range of frequencies. This gives insights into:

• Which species are present

• How their behaviour changes over time

• How they respond to offshore activity

• When key biological events, like spawning, take place.

Bioacoustics is non-invasive, long-term, and automated, which reduces survey disturbance while improving ecological resolution. The natural acoustic signatures of marine mammals, fish, and some invertebrates allow analysts to map habitat use, track seasonal patterns, and understand ecosystem dynamics across large areas. Continuous data also provides valuable insights during all stages of offshore operations, helping developers avoid ecological disruption by adjusting activity during sensitive periods.

eDNA: Tracing the genetic footprints of marine life

Every marine organism leaves behind microscopic traces of genetic material in the environment such as skin, slime, scales, and other fragments. eDNA captures these traces. Through metabarcoding, analysts can identify which taxa are present in a sample and build a snapshot of biodiversity at a specific time and place.

eDNA offers several advantages:

• Detection of elusive or fast-moving species

• Broad taxonomic coverage from a single sample

• The ability to track change across hours, days, or seasons.

As eDNA is probabilistic rather than quantitative, careful interpretation is essential. Field controls, replicates, and robust analytics improve confidence. eDNA is especially powerful for tracking change and for filling gaps left by traditional visual or acoustic surveys as part of a monitoring programme.

Automated eDNA sampling systems are now emerging that can operate independently or integrate with other autonomous technologies, enabling scalable and scientifically effective holistic biodiversity monitoring.

Seeing the full picture: A holistic approach to marine biodiversity

Bioacoustics and eDNA each offer distinctive strengths, but their value increases when used together. Traditional visual and geophysical surveys answer the question of “where?”, by mapping habitats and species distribution. Bioacoustics captures the “when?”, revealing seasonal cues and behavioural patterns. eDNA uncovers the “who?”, identifying a wider spectrum of species, including those rarely observed.

A combined approach can help:

• Build stronger environmental baselines

• Detect change more quickly and reliably

• Strengthen biodiversity net gain and marine net gain strategies

• Improve marine spatial planning and impact assessments

• Align monitoring with international biodiversity expectations.

Integrated programmes – such as those delivered through SEAWATCH® - bring these methods together. They combine continuous soundscape monitoring with genetic, video, and geophysical insights. This creates long-term, high-quality datasets. These datasets give a more complete view of how marine ecosystems behave. They help developers understand environmental dynamics and gain the confidence to assess risks and plan for sustainable operations.

These approaches also support regulatory frameworks such as the MSFD and the Kunming-Montreal targets, which depends on high quality environmental evidence. 

How this helps you make sustainable decisions

Teams planning or managing marine infrastructure face growing expectations for transparency and environmental responsibility. Reliable evidence is essential to understand how activities interact with biodiversity.

A combined bioacoustics and eDNA approach offers the clarity needed to:

• Identify sensitive species and life stages

• Understand how marine life uses an area

• Time operations to minimise disturbance

• Track biodiversity net gain commitments across a project life cycle

• Build trust with regulators and communities

• Demonstrate a meaningful contribution to global biodiversity goals.

As these methods are scalable and non-invasive, they reduce operational disruption while improving insight and decision-making.

A smarter way to protect marine biodiversity

The biodiversity crisis is urgent, and the need for informed action has never been clearer. By bringing bioacoustics and eDNA together with established survey capability, clients gain a deeper, more meaningful understanding of their marine environment.

This isn’t just about compliance. It’s about enabling decisions that leave the ocean in better condition than before – ensuring that marine development supports long term ecological resilience and global biodiversity ambitions.