Modelling the Northeast Atlantic circulation: implications for the spring invasion of shelf regions by Calanus finmarchicus

Citation
Jh. Harms et al., Modelling the Northeast Atlantic circulation: implications for the spring invasion of shelf regions by Calanus finmarchicus, ICES J MAR, 57(6), 2000, pp. 1694-1707
Citations number
33
Categorie Soggetti
Aquatic Sciences
Journal title
ICES JOURNAL OF MARINE SCIENCE
ISSN journal
10543139 → ACNP
Volume
57
Issue
6
Year of publication
2000
Pages
1694 - 1707
Database
ISI
SICI code
1054-3139(200012)57:6<1694:MTNACI>2.0.ZU;2-F
Abstract
The appearance in spring of the copepod Calanus finmarchicus in continental shelf waters of the northeastern Atlantic has been hypothesized to be main ly attributable to invasion from across the continental slope rather than i n situ overwintering. This paper describes the application of a hydrodynami c circulation model and a particle-tracking model to Northeast Atlantic wat ers in order to assess the influence of the flow field and ascent migration parameters on the spring invasion of C. finmarchicus. For hydrodynamic mod elling, the Hamburg Shelf-Ocean Model(HAMSOM) was applied to the North Atla ntic and Nordic Seas and forced with daily mean atmospheric data. Simulated flow fields from HAMSOM serve as forcing functions for a particle-tracking model of the same region. The robustness of the simulated shelf invasion i n three target boxes of the Northeast Atlantic Shelf was assessed by means of a sensitivity analysis with respect to variations in four key migration parameters: overwintering depth, ascent rate. ascent timing, and depth duri ng residence in upper layers. The invasion of the northern North Sea and No rwegian Shelf waters is more sensitive to ascent migration parameters than invasion of the Faroese Shelf. The main reason for enhanced sensitivity of the North Sea invasion is the time and space-dependent flow structure in th e Faroe-Shetland Channel. Dense aggregations of overwintering C. finmarchic us are found in the Channel, but because of the complex Row field only a pr oportion of the overwintering stock has the capacity to reach the North Sea . (C) 2000 International Council for the Exploration of the Sea.