Population Consequences of Disturbance

SMRU Consulting Europe – collaborating with a team of researchers at the University of St Andrews, led by Prof. John Harwood – have developed an implementation of the NRC (2005) Population Consequences of Disturbance (PCoD).

The basic PCoD approach was developed by an international group of experts in the US Office of Naval Research Working Group on the Population Consequences of Acoustic Disturbance US National Research Council’s Committee on Characterizing Biologically Significant Marine Mammal Behaviour in its 2005 report. Their work provided the foundation for the Interim PCoD framework, which was developed at a workshop on Assessing the Risks to Marine Mammal Populations from Renewable Energy Devices, which was jointly funded by Countryside Council for Wales (now Natural Resources Wales), the Joint Nature Conservation Committee and the Natural Environment Research Centre.

The Interim PCoD framework project was commissioned and jointly funded by The Crown Estate, Marine Scotland Science, the Joint Nature Conservation Committee, The Department for Energy & Climate Change, Natural Resources Wales, Natural England and Scottish Natural Heritage. Members of each regulatory and statutory nature conservation body, along with developer representatives, participated in a steering committee for the project to ensure that the model met their needs. The framework is underpinned by a study of The Sensitivity of UK Marine Mammal Populations to Marine Renewables Developments (Harwood & King 2014) that was funded by the Natural Environment Research Council as part of its Marine Renewable Energy Knowledge Exchange programme.

Interim Population Consequences of Disturbance

Anthropogenic activities such as offshore wind farm construction expose marine mammals to underwater noise that may alter their behaviour and physiology, with potential knock-on effects on survival and reproduction. The Population Consequences of Disturbance (PCoD) framework provides a conceptual and modelling structure to trace these effects from individual-level responses through to population-level outcomes. It was developed by an international group of experts in the US Office of Naval Research Working Group on the Population Consequences of Acoustic Disturbance US National Research Council’s Committee on Characterizing Biologically Significant Marine Mammal Behaviour in its 2005 report. The Interim Population Consequences of Disturbance framework (iPCoD) is an operational implementation of this concept, developed by researchers at the University of St Andrews and SMRU Consulting and funded by the Scottish Government and other UK and International partners (see funding at the bottom). It is designed to forecast the trajectory of a marine mammal population under user-specified disturbance scenarios — such as a multi-year piling programme, and any resulting disturbance and auditory injury in the form of permanent threshold shift (PTS) — and compare it against an equivalent undisturbed population, allowing regulators and developers to evaluate the potential population-level significance of a proposed activity. The inputs include information about the population size for a given species and the developments that could impact them (e.g. a calendar of days of activity, the numbers of animals impacted etc. – which come from external sources, such as impact assessments). The outputs provide the forecast of the population trajectory with and without the simulated disturbance and PTS.

It has been designed to use the kinds of information that are likely to be provided by developers in their Environmental Statements and Habitats Regulations Assessments. The package is developed for use in R, a free software environment for statistical computing and graphics.

 The iPCoD EE and DEB versions

There are now two different version of iPCoD model: the iPCOD EE 6.0 (five species) and the DEB 2.0 version (harbour porpoise only). The new versions of the models are now hosted and managed through GitHub:

https://github.com/SMRU-Consulting-Github/iPCoD-EE-DEB .

Please explore the full documentation, readme, license and model code at the above link.

The expert elicitation version of iPCoD (iPCoD EE) is available for five species: harbour porpoise, grey seal, harbour seal, bottlenose dolphin, and minke whale. The core of the model is a set of transfer functions that relate the number of days of disturbance and auditory injury experienced by an individual in a given year to its vital rates (survival and fecundity). The EE transfer functions for bottlenose dolphin and minke whales have not been significantly updated since the original release in 2013.

The Dynamic Energy Budget version if iPCoD (iPCoD DEB) is currently available for harbour porpoise only. It replaces the expert-elicited transfer function for disturbance with a mechanistic bioenergetics model — a Dynamic Energy Budget (DEB) model — that explicitly tracks the energy acquisition and expenditure of individual simulated females across their lifetimes. The effect of PTS is modelled the same way as in iPCoD EE using EE transfer functions.

We recommend potential users utilise the comprehensive information on the Github site to help them understand and use the models effectively.

Ongoing development

This model has been iteratively developed since funding from UK SNCBs, UK and Dutch government agencies and internal funding from SMRU Consulting. This model is shared openly as part of our research and commitment to advancing the field. While we’re pleased to make it freely available, our team does not receive ongoing funding for its maintenance. Users are encouraged to explore and apply the model at their own discretion.

We welcome reports of reproducible bugs or technical issues via the email below, which help us improve future versions. However, we’re unable to offer individual troubleshooting or interpretation assistance outside these cases. We appreciate your understanding and continued interest in our work.

To sustain ongoing development, we offer a limited number of paid custom support and integration services. If your project would benefit from direct collaboration, or alternatively If your use case needs deeper technical assistance or specialized development, our team can provide dedicated help — please contact info@smruconsulting.com to learn more.

A note from SNCBs

Upon the release of the iPCoD software in 2014, the iPCoD steering group released the following statement on the use of iPCoD:

“The statutory nature conservation bodies (SNCBs) and regulators participated in an Interim PCoD training workshop and are now considering the scope of the tool and how and when it might be used to inform EIA and HRA processes and consenting decisions for marine renewable energy projects. Therefore some of the messages that follow are preliminary.

1. To date, due to uncertainties about the consequences of disturbance on marine mammal individuals and populations, current consenting decisions have drawn upon expert opinion, but not always in a transparent, comparable and auditable way. Whilst Interim PCoD relies on some strong assumptions and on expert opinion, its strengths include being transparent, auditable and quantitative.

2. SNCBs consider the Interim PCoD a novel modelling tool with potential to increase our understanding of the effects of disturbance and collision on marine mammal populations, particularly in identifying those input parameters that may most influence the modelled outcomes, and as such support its use.

3. Developers should consult regulators and their advisers if they are considering using the Interim PCoD at an early stage i.e. before application stage.

4. Whilst SNCBs do not anticipate a need for the Interim PCoD to be used in the EIA/HRA processes for every single development, this tool may form a useful reference in standardising the type of data submitted in impact assessments which will help when assessing cumulative effects. For large-scale developments and clusters of developments the tool may also help standardise the process for population level assessments. Decisions on when PCoD might be a useful tool should be made on a case-by-case basis in discussion with the relevant SNCBs and Regulators.

5. One of the main strengths of the Interim PCoD may be at assessing the cumulative effect of several developments and SNCBs advise that this is better achieved at the strategic level (e.g. SEA, and/or as a result of a joint effort between regulators, their advisers and developers [e.g. regional monitoring groups]). We will be working to encourage this approach in the future.

6. SNCBs acknowledge that there will need to be a process in place to address matters related to the interpretation of model results (e.g. thresholds of acceptable change and time frames).

7. A joint effort involving government, regulators and industry is now needed to contribute to research on how disturbance influences life-history parameters. The outputs of this research would replace parameters in the model that have been quantified by the expert elicitation process with empirical values. There are some ongoing initiatives through NERC, ORJIP and industry led (e.g. DEPONS) but more is needed.

8. SNCBs would welcome feedback from developers on where and how they think this tool could add value to assessment processes.”

 PCoD Lite

As with the development of iPCoD, we collaborated with a team of researchers at the University of St Andrews, led by Prof. John Harwood – to explore how US Navy sonar might impact some of the marine mammal populations inhabiting ranges and whether PCoD frameworks could be used in assessments.

The potential risk of injury and/or disturbance to marine mammals during US Navy activities is assessed as part of standard environmental impact assessment processes. Possible consequences of exposure to underwater noise from US Navy sonar include; disturbance that could cause marine mammals to either move away or change behaviour, suffer temporary hearing damage or permanent physical injury. The interim PCOD model assesses what the longer term and larger scale impacts of these consequences are to the exposed group(s) of animals as a whole.

Such versions of the PCOD model are considered ‘interim’, because it was developed to help manage uncertainty within the current knowledge of marine mammals, where there are limited data available on some of the key information needed. For instance, relatively little is known about how changes in behaviour and hearing sensitivity caused by exposure to underwater noise affect the ability of individual marine mammals to survive and to reproduce (their ‘vital rates’). To combat this issue, SMRU Consulting received input from over 30 international marine mammal experts who delivered a range of opinions of how disturbance might impact on these vital rates of Blainville’s beaked whales and sperm whales.

You can read the main PCoD Lite report here, which details the overall approach, how we dealt with eliciting information from experts and how the outputs of PCoD might be tailored to the US regulatory system. We also produced a report applying the PCoD Lite model for the two species of interest on ranges in the Bahamas and Hawai’i. These are very much theoretical and speculative and we specifically note:

It should be recognised that the results presented in this report are not intended in any way as an assessment of the potential effects of Navy training and testing activities on beaked whale or sperm whale populations. Nor is it intended to influence regulatory policy or control over these activities. Rather, we have attempted to show how the Interim PCoD approach can be used with information that is routinely collected on some Navy ranges, such as AUTEC, or that is provided by the Navy Acoustics Effects Model to forecast these potential effects.

PCoD+

PCoD+ is a 3 year project (2016-2019) funded by the Office of Naval Research to build upon all the work done to date on exploring the Population Consequences of Disturbance (PCoD).

Since it’s initial development, the interim PCoD framework (for renewables) has been used for offshore wind and tidal energy projects in the UK, Netherlands, Germany, Denmark and most recently in North America, exploring the effects of US Navy sonar on Blainville’s beaked whales and sperm whales, shipping on killer whales and different noise sources on beluga whales. There are also researchers all over the world working on various elements of PCoD using different modelling approaches.

This new PCOD+ effort looks to build upon the extensive foundation of PCoD projects. However there is a lot of work to be done in this new applied field of marine mammal science. The overall objective of the PCoD+ project is to overcome the most important impediments that have limited the implementation of the PCoD framework.

The PCoD+ Team

We have assembled a project team with extensive experience of the development and application of PCoD models that will develop a widely-applicable and general approach for assessing the consequences of disturbance for marine mammal populations. The Principal Investigators for this project are:

• Dr. Cormac Booth – SMRU Consulting

• Prof. John Harwood – St Andrews University

• Dr. Catriona Harris – CREEM

• Dr. Rob Schick – CREEM

• Dr. Len Thomas – CREEM

• Dr. Leslie New – Washington State University

• Dr. Enrico Pirotta – Washington State University

• Prof. Dan Costa – University of California - Santa Cruz

• Dr. Lisa Schwarz – University of California - Santa Cruz

• Prof. Tony O’Hagan – Professor A O’Hagan Ltd

The team will be supported by an equally-experienced Scientific Advisory Panel, and will build on the activities of the PCoD working group and the ONR- and SERDP-funded behavioral response studies. We will do this in close collaboration with two projects that have been funded by the E&P Sound and Marine Life JIP: “A Bioenergetic Model to Estimate the Population Consequences of Disturbance” (PI Dan Costa) and “Updating the Southall et al. (2007) Marine Mammal Noise Exposure Criteria” (PI Brandon Southall).