Higher trophic levels in the Southern North Sea
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Research within TROPHOS will focus on processes structuring the higher trophic levels in the North Sea ecosystem. Special attention will be given to:

The output foreseen to result from this research project is listed under expected results and deliverables. To get an idea of the status of the project, take a look at the activities.

Food web interactions:

This task will be executed by RUG-Marine Biology Section and NIOO-CEME and is focussed on meiobenthos. Monthly sampling of two stations, showing a clearly different food web structure, will allow for describing changes in the composition and densities of the meiobenthos when changes in the primary production in the water column will occur. The primary production will sink to the sea floor and acts as an important food source for the benthos. Possible consumption of phytoplankton can be studied by comparing the natural occurring stable isotopes of the meiobenthos with those present in the phytoplankton. Changes in bacterial diversity will be assessed by means of Denaturing Gradient Gel Electrophoresis (DGGE). The benthic response to the sedimentation of the spring phytoplankton bloom will be evaluated trough experiments with enriched and labelled (stable isotopes 13C and 15N) phytoplankton. Benthic food web flows and the benthic contribution to the metabolism of the ecosystem will be inferred from inverse modelling.

Dispersal mechanisms of key species:

This part of TROPHOS will be performed by KUL, RUG and MUMM. Larvae and post larvae of fish, sole and gobies and Mysidacea, of the genus MesoSPSDpsis, will be sampled using the appropriate sampling gear. Population-specific life history characteristics (e.g. fertility, survival, growth…) will be collected. Genotyping will be done with at least 8 DNA microsatellites per fish (KUL) or with SSCP combined with sequencing of variable nuclear and mitochondrial loci (MesoSPSDpsis (RUG) and Gyrodactylus (KUL)). The behaviour of the planktonic stages of the fishes and MesoSPSDpsis will be modelled with a combined 3-D hydrodynamic and particle tracking model by MUMM.

Coastal and sea birds:

This part of TROPHOS will be a combined effort of RUG and IN. Pelagic fish will be collected monthly at 7 locations on the BCS by means of a MIC-net at the surface and near the bottom. Frequency of sampling will be diminished towards the end of the project. Species composition, length distribution, abundance, zooplankton density and a number of environmental variables will be measured.
Distribution patterns of Common Tern, Sandwich Tern, Auk, Common Guillemot and Great Crested Grebe will be compared with the horizontal distribution of their prey fish. Stomach contents analysis will be performed on fresh corpses of Guillemot, Auk and Great Crested Grebes found during beach bird surveys along the coast and birds accidentally caught in fishing nets. Population size of seabirds nesting in Zeebrugge will be determined. Laying date, clutch size, predation rate, hatching success, chick growth and survival will be measured. Nest attendance and prey specific foraging time will be established. Food intake and diet composition of Sandwich and Common Tern chicks will be measured from a hide. Food composition of adult terns will be identified by means of otholits and other food remains found in faeces and pellets. Variation in food composition will be compared to fluctuations in food availability. Reading of ringed Sandwich Tern, Common Tern, Herring Gull and Lesser Black-backed Gull will be analysed and migration between colonies will be assessed.

Expected results and deliverables:

Supported by
the Belgian Federal Science Policy Office

General coordination: Magda Vincx, Jan Vanaverbeke
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