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On the front line: ocean front metrics for understanding marine predator habitat use
On the front line: ocean front metrics for understanding marine predator habitat use
Submitted on 18 Feb 2014

Kylie L. Scales, Peter I. Miller, Stephen C. Votier, Simon N. Ingram, David W. Sims
Plymouth Marine Laboratory
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Poster Abstract
Oceanographic fronts are interfaces between water masses, manifesting at the surface as enhanced horizontal gradients in temperature, salinity, density, turbidity or colour. Bio-physical coupling along fronts can drive the formation of pelagic foraging hotspots. Several, taxonomically diverse marine predators are known to associate with fronts, yet understanding of these associations remains incomplete. Using novel remote sensing techniques coupled with animal tracking technologies, we aim to elucidate the influence of fronts as physical drivers of marine predator habitat use. Composite front mapping enables objective detection of mesoscale (10s – 100s kms) thermal and chlorophyll-a fronts (Miller, 2009). From composites, we can derive metrics that allow us to quantify associations and explore the effects of spatial scale and temporal persistence. Analyses have revealed that northern gannets Morus bassanus breeding in the Celtic Sea target search effort within spatially predictable, persistent frontal zones, but behavioural responses to contemporaneous fronts vary. Oceanic-foraging loggerhead turtles Caretta caretta from Cape Verde associate with mesoscale thermal fronts in the Northwest African upwelling, presumably foraging on aggregated prey. Composite front mapping can identify potentially critical at-sea habitats for marine predators, locating priority conservation areas in the open oceans.

Miller P. Composite front maps for improved visibility of dynamic sea-surface features on cloudy SeaWiFS and AVHRR data. Journal of Marine Systems. 2009;78(3):327-36.

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