Sub-surface hotspots in shallow seas

fine-scale limited locations of top predator foraging habitat indicated by tidal mixing and sub-surface chlorophyll

B. E. Scott*, J. Sharples, O. N. Ross, J. Wang, G. J. Pierce, C. J. Camphuysen

*Corresponding author for this work

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

The foraging habitats of 7 species of marine apex predators were observed simultaneously in a shallow sea, with continuous measurements taken of the detailed bio-physical water column characteristics to determine habitat preferences. We found the occurrence of small scale ‘hotspots’, where 50% of all animals were actively foraging in less than 5% of the 1000 km of transects surveyed. By investigating a contrasting range of foraging strategies across a variety of fish-eating seabirds and marine mammals, we determined which habitat characteristics were consistently important across species. A static habitat variable, tidal mixing, log10(h/U3) (h = water depth, U = tidal current amplitude), was found to be the best indicator of the probability of presence and abundance of individual species. All 7 mobile top-predators preferentially foraged within habitats with small-scale (2 – 10 km) patches having high concentrations of chlorophyll in the sub-surface chlorophyll maximum (CHLmax) and high variance in bottom topography, with different species preferring to forage in different locations within these habitats. Patchiness of CHLmax was not associated with the locations of strong horizontal temperature gradients (fronts) or high surface chlorophyll values, but instead maybe related to areas of high sub-surface primary production due to locally increased vertical mixing. These small-scale areas represent a newly identified class of spatially important location that may play a critical role in the trophic coupling of shallow seas. Such sub-surface hotspots may represent the limited locations where the majority of predator-prey interactions occur, despite making up only a small percentage of the marine environment.
Original languageEnglish
Pages (from-to)207-226
Number of pages20
JournalMarine Ecology Progress Series
Volume408
Issue number-
Early online date3 Jun 2010
DOIs
Publication statusPublished - 3 Jun 2010

Keywords

  • biological hotspots
  • foraging habitats
  • marine top predators
  • predator-prey interactions
  • shallow sea
  • sub-surface chlorophyll maximum
  • tidal mixing
  • topography
  • Eastern Tropical Pacific
  • bottle-nosed dolphins
  • harbor porpoises
  • British-Isles
  • Georges Bank
  • fish larvae
  • North-Sea
  • Irish Sea
  • front
  • seabirds

Cite this

Sub-surface hotspots in shallow seas : fine-scale limited locations of top predator foraging habitat indicated by tidal mixing and sub-surface chlorophyll. / Scott, B. E.; Sharples, J.; Ross, O. N.; Wang, J.; Pierce, G. J.; Camphuysen, C. J.

In: Marine Ecology Progress Series, Vol. 408, No. -, 03.06.2010, p. 207-226.

Research output: Contribution to journalArticle

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KW - fish larvae

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