Indicators are effective tools for summarising and communicating key aspects of ecosystem state and have a long record of use in marine pollution and fisheries management. The application of biodiversity indicators to assess the status of species, habitats, and functional diversity in marine conservation and policy, however, is still developing and multiple indicator roles and features are emerging.

In June 2018, my colleagues and I convened a symposium and focus group entitled “From science to evidence – innovative uses of biodiversity indicators for effective marine policy and conservation” as part of the 5^th International Marine Conservation Congress (IMCC5) in Kuching, Malaysia. We used the sessions as an opportunity to form a community of practice for both users and developers of biodiversity indicators for marine policy and conservation, and to provide a forum to share successes and failures in developing and applying these indicators. Themes quickly emerged which are common across geographic regions and political scales and our new paper exploring these has just been published.

What do we mean by ‘biodiversity’ indicators?

We quickly realised that although indicators are commonly used in marine conservation and policy, the term ‘biodiversity’ means different things to different people. Some interpret ‘biodiversity’ broadly to mean all species and habitats in an ecosystem (as in the Convention on Biological Diversity) and others understand ‘biodiversity’ to mean simply the number of taxa. These different interpretations can lead to confusion among scientists and practitioners.

An analysis of > 2500 abstracts pulled from the Web of Science revealed a difference in treatment of the term ‘biodiversity indicator’ between academic scientists, marine policy-makers and managers (Fig 1). In publications on marine systems, ‘ecosystem indicator’ is used more commonly and synonymously with ‘biodiversity indicator’, though the use of ‘biodiversity indicator’ is increasing (see Fig. 1a). It also appears that the purpose, region, or policy context influences the interpretation of the term ‘biodiversity’. At times ‘biodiversity’ is indeed used for diversity indices such as species richness, dominance, or evenness, and these are useful metrics for describing some aspects of ecosystem change. However, ‘biodiversity’ is increasingly used to reflect a much broader ecosystem view. This broader definition includes trophic interactions, network structure and system stability, or resilience, is in line with the Convention on Biodiversity’s definition of ‘biodiversity’, above, and is often used by applied scientists, policy-makers, and managers. It is this second definition of ‘biodiversity’ that we adopted for our work, due to its frequency of use in conservation.

Like the terminology, the role of biodiversity indicators in marine conservation policy and management is also evolving. For example, some operational biodiversity indicators trigger management action when a threshold is reached, while others play an interpretive, or surveillance, role in informing management. For indicators to be used operationally, they should be responsive to environmental change, demonstrate a clear pressure-state relationship, and be linked to identified targets and thresholds. Where these criteria are not met, biodiversity indicators can deliver a valuable ‘surveillance’ role. Surveillance indicators are not assessable against quantitative thresholds, but can still provide contextual information on either wider ecosystem impacts of pressures or underlying environmental change (see also Bedford et al. 2018).

What do policy makers and managers need from biodiversity indicators?

Biodiversity indicator development and application is not a straightforward process. To be useful for policy or management, indicators must be linked clearly to policy or management objectives. Indicators, however, are often developed in academia, outside the policy process, and may therefore be suitable for monitoring change but not explicitly linked to objectives or practitioners may simply never find out about some indicators. A solution is to co-produce indicators, with scientists and stakeholders collaborating to ensure indicators are scientifically robust and meet policy or management needs.

Obtaining the right sort of data is also a challenge for managing marine biodiversity. Many marine biodiversity datasets are restricted in geographic area, usually focusing on coastal regions. Modelling or interpolation may be useful for filling in spatial gaps. Data are expensive to collect and it is therefore important to select or design indicators that allow the use of existing datasets; this is economical and also preserves and extends time-series. One solution is to combine or repurpose existing datasets to populate an indicator, revealing additional information for management without starting a new survey.  

For biodiversity indicators to be useful for management, they must measure progress toward policy goals. Identifying reference conditions against which to measure change and setting targets representing goal achievement can be difficult, however. Reference conditions can be constructed based on spatial or time-series data or using models allowing targets to be set at an acceptable distance from the reference conditions. Additionally, trend-based approaches to target setting can allow the measurement of change directionally, without the need reach a specified endpoint.

Strategies for communicating biodiversity indicators

No matter how scientifically robust a biodiversity indicator is, if that indicator cannot be effectively communicated policy makers or managers, it will not be useful in assessing the state of the ecosystem. The target audience must be identified so indicator communication can be tailored to its needs (Fig. 2). ‘Policy makers’ is a generic term for a diverse group of decision makers at multiple levels, including local councillors, environmental managers, civil servants, MPs and ministers. Each of these subgroups uses biodiversity indicators in different ways to support decisions and so requires information in various formats with different levels of detail and specificity. For example, an ‘on the ground’ manager requires more detail than a minister who only needs high level information. Regardless of the policy audience, biodiversity indicator communication must be clear, transparent, and easy to understand.

Conclusions

Biodiversity indicators are now an essential tool for effective marine conservation policy and management. We have identified challenges around their application as well as solutions to meeting those challenges. Some of these I’ve summarised here, but our paper contains further detail, analysis, and case study examples. IMCC5 presented a unique opportunity to discuss the state of the art of biodiversity indicator development and application among an international community of applied researchers and practitioners. As we approach the United Nations Decade of Ocean Science for Sustainable Development (2021-2030), we must develop strategies to address the UN’s Sustainable Development Goal 14 – to conserve and sustainably use the oceans, seas, and marine resources for sustainable development. Marine biodiversity indicators will be critical to meeting the targets associated with this ambitious goal.

Abigail, Plankton and Policy

Read more: McQuatters-Gollop, A., Mitchell, I., Vina-Herbon, C., Bedford, J., Addison, P.F.E., Lynam, C.P., Geetha, P.N., Vermeulan, E.A., Smit, K., Bayley, D.T.I., Morris-Webb, E., Niner, H.J. and Otto, S.A., (2019). From Science to Evidence – How Biodiversity Indicators Can Be Used for Effective Marine Conservation Policy and Management. Frontiers in Marine Science, 6. DOI: 10.3389/fmars.2019.00109