Basking sharks Cetorhinus maximus and oceanographic fronts: quantifying associations in the north-east Atlantic

Miller, PI; Scales, KL; Southall, EJ; Sims, DW. 2015 Basking sharks Cetorhinus maximus and oceanographic fronts: quantifying associations in the north-east Atlantic. Functional Ecology. (In Press)

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Abstract/Summary

Understanding the mechanisms linking oceanographic processes and marine vertebrate habitat use is critical to effective management of populations of conservation concern. The basking shark Cetorhinus maximus has been shown to associate with oceanographic fronts – physical interfaces at the transitions between water masses – to exploit foraging opportunities resulting from aggregation of zooplankton. However, the scale, significance and variability of these observed associations have not yet been established. Here, we quantify the influence of mesoscale (10s – 100s km) frontal activity on habitat use over timescales of weeks to months. We use animal-mounted archival tracking with composite front mapping via Earth Observation (EO) remote sensing to provide an oceanographic context to individual shark movements. We investigate levels of association with fronts occurring over two spatio-temporal scales, (i) broad-scale seasonally persistent frontal zones and (ii) contemporaneous mesoscale thermal and chl-a fronts. Using random walk simulations and logistic regression within an iterative generalised linear mixed modelling (GLMM) framework, we find that seasonal front frequency is a significant predictor of shark presence. Temporally-matched oceanographic metrics also indicate that sharks demonstrate a preference for productive regions, and associate with contemporaneous thermal and chl-a fronts more frequently than could be expected at random. Moreover, we highlight the importance of cross-frontal temperature change and persistence, which appear to interact to affect the degree of prey aggregation along thermal fronts. These insights have clear implications for understanding the preferred habitats of basking sharks in the context of anthropogenic threat management and marine spatial planning in the northeast Atlantic.

Item Type: Publication - Article
Additional Information. Not used in RCUK Gateway to Research.: Miller and Scales are joint first authors
Additional Keywords: animal tracking; biologging; remote sensing; front mapping; marine vertebrate; marine megavertebrate; habitat use; habitat preference
Subjects: Conservation
Earth Observation - Remote Sensing
Marine Sciences
Oceanography
Divisions: Marine Biological Association of the UK > Ecosystems and Environmental Change > Movement ecology, behaviour and population structure
Plymouth Marine Laboratory > Science Areas > Sea from Space
Depositing User: Dr Peter I Miller
Date made live: 09 Feb 2015 14:47
Last Modified: 06 Jun 2017 16:13
URI: http://plymsea.ac.uk/id/eprint/6324

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