Dataset Information

Strange attractor of a narwhal (Monodon monoceros).

ABSTRACT: Detecting structures within the continuous diving behavior of marine animals is challenging, and no universal framework is available. We captured such diverse structures using chaos theory. By applying time-delay embedding to exceptionally long dive records (83 d) from the narwhal, we reconstructed the state-space portrait. Using measures of chaos, we detected a diurnal pattern and its seasonal modulation, classified data, and found how sea-ice appearance shifts time budgets. There is more near-surface rest but deeper dives at solar noon, and more intense diving during twilight and at night but to shallower depths (likely following squid); sea-ice appearance reduces rest. The introduced geometrical approach is simple to implement and potentially helpful for mapping and labeling long-term behavioral data, identifying differences between individual animals and species, and detecting perturbations.

SUBMITTER: Podolskiy EA

PROVIDER: S-EPMC9498936 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature

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Publications

Strange attractor of a narwhal (Monodon monoceros).

Podolskiy Evgeny A EA Heide-Jørgensen Mads Peter MP

PLoS computational biology 20220922 9

Detecting structures within the continuous diving behavior of marine animals is challenging, and no universal framework is available. We captured such diverse structures using chaos theory. By applying time-delay embedding to exceptionally long dive records (83 d) from the narwhal, we reconstructed the state-space portrait. Using measures of chaos, we detected a diurnal pattern and its seasonal modulation, classified data, and found how sea-ice appearance shifts time budgets. There is more near- ...[more]

PMID: 36136974

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Project description:Animal-borne telemetry devices have become a popular and valuable means for studying the cryptic lives of cetaceans. Evaluating the effect of capture, handling and tagging procedures remains largely unassessed across species. Here, we examine the effect of capture, handling and tagging activities on an iconic Arctic cetacean, the narwhal (Monodon monoceros), which has previously been shown to exhibit an extreme response to extended capture and handling. Using accelerometry-derived metrics of behaviour, including activity level, energy expenditure and swimming activity, we quantify the post-release responses and time to recovery of 19 individuals following capture and tagging activities considering the intrinsic covariates of sex and individual size and the extrinsic covariates of handling time and presence of a 'bolt-on' satellite telemetry device. From accelerometer-derived behaviour, most narwhals appeared to return to mean baseline behaviour (recovery) within 24 hours after release, which was supported by longer-term measures of diving data. None of the covariates measured, however, had an effect on the time individuals took to recover following release. Using generalized additive models to describe changes in behaviour over time, we found handling time to be a significant predictor of activity levels, energy expenditure and swimming behaviour following release. Individuals held for the longest period (>40 min) were found to display the largest effect in behaviour immediately following release with respect to swimming behaviour and activity levels. We also found some support for relationships between activity levels, energy expenditure and swimming activity and two other covariates: sex and the attachment of a bolt-on configuration satellite tags. Our results indicate that narwhals recover relatively quickly following capture, handling and tagging procedures, but we suggest that researchers should minimize handling time and further investigation is needed on how to mitigate potential effects of bolt-on satellite tags in these sensitive species.

Project description:Narwhals and belugas are toothed whales belonging to the Monodontidae. Belugas have a circumpolar Arctic and sub-Artic distribution while narwhals are restricted to the Atlantic Arctic. Their geographical ranges overlap during winter migrations in the Baffin Bay area (Canada/West Greenland) and successful interbreeding may occur. Here, we employed geometric morphometrics on museum specimens to explore the cranium and mandible morphology of a known hybrid (NHMD MCE 1356) and the cranium morphology of a putative hybrid (NHMD 1963.44.1.4) relative to skull morphological variation in the parental species. Specifically, we used 3D models of skulls from 69 belugas, 86 narwhals, and the two known/putative hybrids and 2D left hemi-mandibles from 20 belugas, 64 narwhals and the known hybrid. Skull shape analyses allowed clear discrimination between species. Narwhals are characterised by a relatively short rostrum and wide neurocranium while belugas show a more elongated and narrower cranium. Sexual size dimorphism was detected in narwhals, with males larger than females, but no sexual shape dimorphism was detected in either species (excluding presence/absence of tusks in narwhals). Morphological skull variation was also dependent on different allometric slopes between species and sexes in narwhals. Our analyses showed that the cranium of the known hybrid was phenotypically close to belugas but its 2D hemi-mandible had a narwhal shape and size morphology. Both cranium and mandible were strongly correlated, with the pattern of covariation being similar to belugas. The putative hybrid was a pure male narwhal with extruded teeth. Comparison of genomic DNA supported this result, and stable carbon and nitrogen isotope values suggested that the putative hybrid had a more benthic foraging strategy compared to narwhals. This work demonstrates that although the known hybrid could be discriminated from narwhals and belugas, detection of its affinities with these parental species was dependent on the part of the skull analysed.

Dataset Information

Strange attractor of a narwhal (Monodon monoceros).

Publications

Strange attractor of a narwhal (Monodon monoceros).

Similar Datasets

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