Browsing by Author "Rayment W"

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A contribution to the anatomy of two rare cetacean species: The hourglass dolphin (Cephalorhynchus cruciger) and the spectacled porpoise (Phocoena dioptrica)
(Wiley Periodicals LLC on behalf of American Association for Anatomy, 2025-10-22) Graïc J-M; Gerussi T; Cozzi B; Boys RM; Kot BCW; Perrott MR; Fleury K; Chung TYT; Tsui HCL; Burns E; Webster T; Hunter S; Betty EL; Howarth O; Loch C; White S; Dawson S; Rayment W; Cole R; Cox D; Waterhouse T; Hendriks H; van Helden A; Johnstone M; Stewart RO; Fordyce RE; Stockin KA
The anatomical description of the hourglass dolphin (Cephalorhynchus cruciger) and the spectacled porpoise (Phocoena dioptrica) remains largely unexplored, due to limited specimen availability and preservation challenges. This study employed digital imaging techniques, conventional histology, and computed tomography to provide visualization of anatomical structures for a detailed analysis. We present a comprehensive analysis of the gross macroscopical and microscopical morphology of two hourglass dolphins and four spectacled porpoises. Morphometric measurements and skeletal characteristics aligned with the literature, while internal anatomy (organs and systems) was similar to other odontocetes. Precise and consistent lung measurements were challenging; qualitative assessments indicated relatively large lungs with respect to body size. The spectacled porpoise dorsal fin was uniquely large with a well-developed blood supply; this is hypothesized to act as a thermoregulatory window, though it may also play a role in sexual display in the case of males. Overall, this study provides new data on the anatomy of the hourglass dolphin and spectacled porpoise, contributing insights that may influence future research on these rare species. The findings highlight the importance of anatomical studies as a basis for explaining evolutionary relationships within cetaceans and their ecological roles in the Southern Ocean ecosystems.
A contribution to the anatomy of two rare cetacean species: the hourglass dolphin (Lagenorhynchus cruciger) and the spectacled porpoise (Phocoena dioptrica)
(2025-03-26) Graïc J-M; Gerussi T; Cozzi B; Boys RM; Kot BCW; Perrott MR; Fleury K; Chung TYT; Tsui HCL; Burns E; Webster T; Hunter S; Betty EL; Howarth O; Loch C; White S; Dawson S; Rayment W; Cole R; Cox D; Waterhouse T; Hendriks H; van Helden A; Johnstone M; Stewart RO; Fordyce RE; Stockin KA
Leveraging Synteny to Generate Reference Genomes for Conservation: Assembling the Genomes of Hector's and Māui Dolphins
(John Wiley and Sons Ltd, 2025-04-04) Alvarez-Costes S; Baker CS; Constantine R; Carroll EL; Guhlin J; Dutoit L; Ferreira S; Heimeier D; Gemmell NJ; Gillum J; Hamner RM; Rayment W; Roe W; Te Aikā B; Urban L; Alexander A; DeWoody A
Escalating concern regarding the impacts of reduced genetic diversity on the conservation of endangered species has spurred efforts to obtain chromosome-level genomes through consortia such as the Vertebrate Genomes Project. However, assembling reference genomes for many threatened species remains challenging due to difficulties obtaining optimal input samples (e.g., fresh tissue, cell lines) that can characterise long-term conservation collections. Here, we present a pipeline that leverages genome synteny to construct high-quality genomes for species of conservation concern despite less-than-optimal samples and/or sequencing data, demonstrating its use on Hector's and Māui dolphins. These endemic New Zealand dolphins are threatened by human activities due to their coastal habitat and small population sizes. Hector's dolphins are classified as endangered by the IUCN, while the Māui dolphin is among the most critically endangered marine mammals. To assemble reference genomes for these dolphins, we created a pipeline combining de novo assembly tools with reference-guided techniques, utilising chromosome-level genomes of closely related species. The pipeline assembled highly contiguous chromosome-level genomes (scaffold N50: 110 MB, scaffold L50: 9, miniBUSCO completeness scores > 96.35%), despite non-optimal input tissue samples. We demonstrate that these genomes can provide insights relevant for conservation, including historical demography revealing long-term small population sizes, with subspecies divergence occurring ~20 kya, potentially linked to the Last Glacial Maximum. Māui dolphin heterozygosity was 40% lower than Hector's and comparable to other cetacean species noted for reduced genetic diversity. Through these exemplar genomes, we demonstrate that our pipeline can provide high-quality genomic resources to facilitate ongoing conservation genomics research.
Looking Back to Move Forward: Lessons From Three Decades of Research and Management of Cetacean Tourism in New Zealand
(Frontiers Media S.A., 2021-02-11) Fumagalli M; Guerra M; Brough T; Carome W; Constantine R; Higham J; Rayment W; Slooten E; Stockin K; Dawson S; Pacheco AS
Cetacean tourism in Aotearoa New Zealand is now over 30 years old and has experienced substantial growth in visitor numbers and operations. The industry is remarkably diverse, targeting several dolphin and whale species, and encompassing varied habitats in coastal waters, fiords and submarine canyons. The knowledge and experience collected over these past 30 years has both advanced the global understanding of cetacean tourism, and influenced scientific practices for its study and management. Here we review the approaches taken in quantifying the impact of cetacean tourism in New Zealand, and critically assess the efficacy of the research and management strategies adopted. We place particular focus on the Bay of Islands, Hauraki Gulf, Kaikoura, Akaroa and Fiordland, areas that include the oldest, and longest studied industries nationally. We propose a set of best research practices, expose the most notable knowledge gaps and identify emerging research questions. Drawing on perspectives from the natural and social sciences, we outline the key determinants of failure and success in protecting cetacean populations from the detrimental impact of tourism. We suggest four golden rules for future management efforts: (1) acknowledge cetacean tourism as a sub-lethal anthropogenic stressor to be managed with precaution, (2) apply integrated and adaptive site- and species-specific approaches, (3) fully conceptualize tourism within its broader social and ecological contexts, and (4) establish authentic collaborations and engagement with the local community. Lastly, we forecast upcoming challenges and opportunities for research and management of this industry in the context of global climate change. Despite New Zealand's early establishment of precautionary legislation and advanced tourism research and management approaches, we detected flaws in current schemes, and emphasize the need for more adaptive and comprehensive strategies. Cetacean tourism remains an ongoing challenge in New Zealand and globally.