LIFECO: Effects of Frontal Processes in the plankton: resource controls and trophic interactions

This work package is part of the LIFECO
programmme: LInking hydrographic Frontal
activity to ECOsystem dynamics is the North
Sea and Skagerrak - Importance to fish stock
recruitment

This package considers the effects of frontal
processes on resource utilization (bottom up
processes) in the plankton and assembles
information on the specific trophic interactions
and controlling mechanisms at this level. The
package is designed to:

1) estimate production of key phytoplankton
and zooplankton species in relation to quantity
and quality of available nutrients and food
resources in different frontal areas.
2) estimate growth rates and nutritional
status of fish larvae and early juvenile fish
in relation to the production of suitable
zooplankton prey species/stages and sizes
3)quantify trophic transfer rates among the
abundant planktonic and micronektonic organisms
in different hydrographic regimes
4) compare estimates of predation and
production rates of key zooplankton species
and the impact of variability in these processes
on growth and nutritional status of fish larval
and early juvenile life stages
5) examine the distinctness of frontal
plankton and micronekton communities and assess
the influence of trophic and physical processes
in the separation of specific communities in the
frontal zone.

We will collect samples of the abundant and
for the ecosystem, important organisms and
analyze the herbivores for lipid composition
and the planktonic carnivores for gut contents.
Further, we will carry out analysis of
production and growth of selected species.
For algae we will use the C14 method and for
copepods the egg production and stage
composition method. Growth and nutritional
condition of ichthyoplankton and micronektonic
fish will be investigated by otolith
microstructures (ring count and ring width
measurements) and storage lipid contents.
The effort will be concentrated within specific
cross-frontal sections, covered in different
seasons characterised by varying frontal
activity and we will use concurrent sampling
of all organisms to ensure the comparability
among data.