What is the Biodiversity Intactness Index, and why does it matter for conservation?

When we talk about biodiversity, we often think about the number of species found in a place. Birds, insects, plants, sharks, rays, corals, seagrasses, mammals, fungi, and all the living systems that make an ecosystem function.

But biodiversity is not only about whether a species is present.

It is also about whether that species is still there in healthy numbers, whether habitats still function properly, and whether the natural balance of an ecosystem has been maintained or slowly pushed out of place.

This is where the Biodiversity Intactness Index (BII), becomes useful.

The Biodiversity Intactness Index is a scientific measure that estimates how much of an area’s original biodiversity remains compared with an undisturbed or minimally disturbed natural baseline.

In simple terms, BII asks:

How intact is nature here compared with how it would be without major human pressure?

A BII score is usually expressed as a percentage.

A score close to 100% suggests that an ecosystem is still close to its natural state. Species are not only present, but many are still found in the kinds of numbers expected in a healthy, functioning habitat.

A lower score suggests that human pressures such as land conversion, pollution, overexploitation, urbanisation, intensive agriculture, coastal development, or habitat fragmentation have reduced the abundance of originally present species.

This makes BII more powerful than a simple species list. A species list may tell us what has been recorded. BII helps us understand how much ecological integrity remains.

For conservation, this distinction matters.

An area may still contain wildlife, but if most species are present only in very low numbers, or if sensitive species have disappeared and only disturbance-tolerant species remain, the ecosystem may no longer be functioning as it once did. BII helps translate this ecological change into a clear, comparable indicator.

At Merman Conservation Expeditions Ltd, we see BII as a valuable tool for connecting science, fieldwork, public engagement, and practical decision-making.

Our work already combines marine and terrestrial conservation, ecological research, environmental consulting, citizen science, education, and digital systems. Integrating BII into this work gives us a stronger framework for measuring not only where biodiversity exists, but how intact and resilient those ecosystems are.

For our conservation projects, BII can help us identify priority areas more clearly. By combining BII data with field surveys, species records, camera trap data, shark and ray sightings, habitat assessments, community observations, and local ecological knowledge, we can build a more complete picture of biodiversity conditions.

This can help us answer important questions:

• Which habitats are still relatively intact and need urgent protection before they are degraded?
• Which areas have already lost biodiversity but could recover through restoration?
• Where are human pressures increasing fastest?
• Which conservation actions are likely to deliver the greatest ecological benefit?
• How can we measure progress over time, instead of only reporting activity?

For marine and coastal work, BII can also support broader ecosystem thinking. Many of the species we care about, including sharks, rays, fish, seabirds, marine mammals, seagrasses, and coastal invertebrates, depend on connected and functioning habitats. A degraded coastline, damaged nursery area, polluted bay, or fragmented marine landscape does not affect one species alone. It affects the whole web of life.

By using BII alongside species-specific monitoring, we can better understand the condition of the wider ecosystem that supports those species.

This is especially important for projects such as shark and ray monitoring. Recording sightings is essential, but the next step is understanding the habitat and ecological context behind those records. Are sightings increasing because populations are recovering, because reporting is improving, or because animals are being displaced from other areas? Are key habitats still intact? Are coastal pressures reducing the long-term ability of ecosystems to support these species?

BII does not answer every question by itself, but it gives us a strong starting point for deeper investigation.

For our consulting work, BII can help organisations make better nature-related decisions.

Businesses, landowners, developers, tourism operators, supply chains, funders, and public bodies are increasingly expected to understand their impacts and dependencies on nature. Biodiversity is no longer just an environmental issue. It is becoming a planning, risk, compliance, investment, and reputation issue.

Through consulting, Merman Conservation can use BII as part of a wider biodiversity assessment process to help clients:

1. Map biodiversity risk across sites or project areas.
2. Understand whether activities are taking place in highly intact, degraded, or recovering ecosystems.
3. Screen projects before development decisions are made.
4. Identify where restoration, avoidance, mitigation, or biodiversity net gain actions are most needed.
5. Support reporting aligned with emerging nature-related frameworks.
6. Build practical biodiversity strategies that are grounded in evidence rather than vague commitments.

BII can also help make biodiversity communication clearer. Many people understand carbon because it can be measured, tracked, and reported. Biodiversity is more complex, but tools like BII help make the condition of nature easier to explain without oversimplifying the science.

For Merman Conservation, this is important because we believe conservation should be transparent, accessible, and useful. Good data should not stay locked away in technical reports. It should inform decisions, support communities, guide restoration, improve policy, and help people understand what is happening to the natural world around them.

By integrating BII into our work, we can achieve several important outcomes.

• We can improve conservation planning by identifying where action is most urgent.
• We can strengthen project design by linking activities to measurable biodiversity outcomes.
• We can support restoration by tracking whether the biodiversity condition is improving over time.
• We can help clients understand their nature-related risks and opportunities.
• We can make biodiversity reporting more credible, practical, and science-based.
• We can connect citizen science and professional ecological assessment into a stronger evidence base.
• Most importantly, we can move from simply describing biodiversity loss to actively measuring, managing, and reversing it.

BII is not a replacement for local ecological surveys, species monitoring, community knowledge, or expert fieldwork. Instead, it is a complementary tool. Its real value comes when it is combined with on-the-ground evidence, local context, and practical conservation action.
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That is the approach we want to take at Merman Conservation.

We want to use BII not just as a number, but as a decision-making tool.

A way to see where nature is still strong.

A way to identify where it is under pressure.

A way to measure whether our actions are making a real difference.

And a way to help communities, organisations, and partners work toward a future where biodiversity is not only protected on paper, but restored in the places that need it most.

Because conservation is not only about counting what remains.

​It is about understanding what has been lost, protecting what is still intact, and rebuilding the living systems that support both wildlife and people.