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| Titel |
The impact of inter-annual variability in hydrodynamic conditions on plaice settlement success |
| VerfasserIn |
Meinard Tiessen, Theo Gerkema, Piet Ruardij, Henk van der Veer |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092043
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| Publikation (Nr.) |
 EGU/EGU2014-6369.pdf |
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| Zusammenfassung |
| Using a hydrodynamic model coupled to a particle tracking routine, the impact of variability
in hydrodynamic conditions on drifting plaice eggs and larvae and their successful settlement
in nursery areas was studied.
The life cycle of many marine fish species consists of various life stages: Spawning
at open sea, pelagic egg and larval stages and often a juvenile stage bound to shallow water
nursery grounds. Numerous studies have demonstrated that pelagic stages appear to be the
most critical in determining ultimate year-class success, which holds true, for example, for
European plaice (Pleuronectes platessa). Plaice spawning grounds in the middle of the North
Sea and in the English Channel are connected to juvenile nursery areas (such as the Wadden
Sea) via (semi-)passive drift governed by residual currents. Field data from especially the
Balgzand nursery area have shown a strong variability in the number of plaice juveniles
settling there over the years. Changes to current patterns and water temperatures
are expected to strongly contribute to this inter-annual variability in settlement
success.
Here, we investigate these effects on pelagic plaice drift and settlement using a
coupled numerical model: A 3D hydrodynamic model (GETM) was used to produce
hydrodynamic data at a high spatial and temporal resolution, for the years 1994 - 2005. This
data was subsequently fed into a particle tracking routine (GITM), that computed the
trajectories for a million particles (representing pelagic plaice) for each year. In order to focus
on the physical processes, several biological contributions such as behaviour (vertical
migration) and mortality were excluded from the simulations. Spawning periods and
locations, drift durations, and settlement requirements were selected around known plaice
characteristics.
Results showed a strong inter-annual variability in the drift direction,
drift duration and settlement success of the particles, as well as in the absolute
number of settling particles and the relative importance of different nursery areas.
These results can be ascribed to changes in the dominant wind direction and water
temperature. Additionally, settlement in the western Wadden Sea showed seasonal
changes in the origin of settling particles: During winter, stronger currents and lower
temperatures result both in longer drift durations and larger displacements of particles. |
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