Electrosensing in cetaceans: anatomy and implications

Mynett, Natasha Savanna (2022) Electrosensing in cetaceans: anatomy and implications. Masters by Research thesis (MSc), Manchester Metropolitan University.

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Abstract

Offshore wind developments are increasing the amount of artificial electromagnetic fields (EMFs) in the ocean, and these are known to have behavioural and physiological impacts on many marine species. A previous investigation on a cetacean (Guiana dolphin, Sotalia guianensis) found that an individual was able to electrosense accredited to their vibrissal follicles. However, it is not known whether this sensory modality is present in other cetaceans, or if they are affected by artificial EMFs. Therefore, the aim of this thesis is to evaluate the potential and impact of electrosensing in cetaceans by i) identifying potential electrosensory organs, ii) identifying cetacean species that may be able to detect electric and magnetic fields from ecological characteristics and phylogeny, and iii) reviewing the data on movement and interactions of cetaceans around windfarms. The vibrissal follicles of three species of foetal cetaceans were characterised here for the first time. Vibrissal follicles in two species, the harbour porpoise (Phoconea phocoena) and minke whale (Balaenoptera acutorostrata), displayed follicles like that of mechanosensory hair follicles observed in mysticetes. In contrast, the Atlantic white-sided dolphin (Lagenorhynchus acutus) had follicles that were closer to the electrosensing Guiana and the bottlenose dolphin (Tursiops truncatus). These delphinid species had follicles that had a characteristic innervation pattern around the base and sides of the follicle. Members of the Delphinidae are therefore of great interest to further study the effects of EMFs. Around the UK, sighting data are available for several species of cetacean. However, these records do not overlap with the dates and positions of windfarm sites, and it is therefore not possible to infer the effects of EMFs on cetacean distribution and behaviour in situ. Future work would need to survey cetacean distribution and behaviour at windfarm sites over the long-term. Anatomical studies and psychophysical studies of captive animals will complement the data in this study and provide a greater understanding of electrosensory form, function and sensitivity in cetaceans. Although the ability of both magneto- and electrosensing in cetaceans is not fully understood, these sensory modalities may be crucial in relation to detecting the increasing levels of EMFs from the increasing developments of offshore windfarms. Therefore, more information is needed to characterise the possible impacts of EMFs on cetacean physiology and behaviour.