MASTS Open Forum Session - From Strandings to Population Consequences: Understanding Cetacean Health and Multiple Stressors

The Marine Mammal and Aquatic Stressors research forums from MASTS are pleased to host a joint open forum session with speakers: Dr Enrico Pirotta (University of St Andrews) and Rachel Lennon (University of Glasgow).

Understanding the combined effects of multiple stressors on marine mammals – A synthesis of the Population Consequences of Multiple Stressors (PCoMS) project - Enrico Pirotta (University of St Andrews)

Assessing the combined effects of stressors on marine mammal populations is required in many jurisdictions, but neither scientific theory nor available data are adequate to meet regulatory requirements. The Population Consequences of Multiple Stressors (PCoMS) project aimed to advance the understanding of the cumulative risk posed by multiple stressors to marine mammals through an interdisciplinary working group and a series of case studies (on North Atlantic right whales Eubalaena glacialis, common bottlenose dolphins Tursiops truncatus, and northern elephant seals Mirounga angustirostris). Our conceptual framework uses health indicators to integrate short-term, non-lethal effects and to predict their impact on survival and reproduction. The case studies provide a roadmap for future research and highlight critical data needs, including long-term monitoring, spatiotemporal measures of stressor exposure, and individual health indicators (e.g., using epigenetics, respiratory microbiomes, and photogrammetry). The project developed new theory, measures, and data, which will inform the assessment and management of the impact of human activities on marine mammal populations exposed to a wide range of stressors.

The Dead Do Tell Tales: Using Stranding Data to Understand Cetacean Health - Rachel Lennon (University of Glasgow)

As top predators, cetaceans are considered sentinels for environmental change in the ocean, whilst also being particularly vulnerable to stressors and their cumulative impacts. These effects are notoriously difficult to quantify but modelling changes in health presents a valuable tool for understanding how species are being impacted both individually and at the population level. Using 349 necropsy records of harbour porpoise stranded on the Scottish coastline as a case study, we developed a structured pathology database suitable for statistical analysis. Application of unsupervised and supervised machine learning techniques revealed underlying patterns in harbour porpoise pathology and showed that necropsy data may provide a more comprehensive insight into health than traditional methods. Patterns in the data revealed three typical pathological profiles of Scottish harbour porpoise, notably highlighting underlying compromised health in adult harbour porpoises. Our approach demonstrates how pathology data from necropsy reports can be used to derive population level health insights, offering a tool for monitoring the impacts of environmental and anthropogenic pressures on wildlife populations.

The session with be chaired by Emily Hague (UHI - Shetland) and Catriona Harris (University of St Andrews). Q&A will take place after both talks.