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Equipment for laboratory work
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Whatmann GF/C filters (47 mm) for Chl a, if not filtered in the field.
Alu foil
Small plastic tubes for Chl a filters
Zipper bags.
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2.6.2 Parameters to be monitored every 5 year
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Fish (taxonomic groups, population and for isotopes)
Macroinvertebrates (taxonomic groups, abundance and for isotopes)
Phytoplankton and zooplankton for isotopes
Sediment (paleo analyses of chironomids, diatoms and cladocerans).
Fish
In each lake a maximum of 9 (1.5 m deep) sinking Lundgren biological
multi mesh gill nets are used for approx 16-18 hours. Gill nets are set in
the littoral and in the pelagic (in the middle of the water column) and at
the bottom (benthic nets) in the late afternoon. Nets are taken the following morning. The catch is treated per net and per net type (littoral, pelagic, benthic). Each fish is given a number, identified to species and sex,
and length and weight is measured.
a. Tissue samples for isotope analyses (liver and dorsal muscle): For
each species, samples are taken from approx 20 fish per lake considering all size classes of fish. The tissue samples are frozen in plastic
vials and marked with lake name, date, fish number (same as above)
and content.
b. From the above mentioned fish, stomach content is taken as well.
Stomachs are preserved in 96% ethanol in vials or 100, 200 or 300 ml
jars, depending on the size of the stomach. The container is marked
with lake name, date, fish number (same as above) and content.
c. From the above mentioned fish, otoliths are taken as well. These are
kept in paper and marked with lake name, date, fish number (same
as above) and content.
Benthic invertebrates
8 sediment cores are sampled randomly from the profundal zone of the
lake (depth between 70% and 90% of maximum depth) using the kajak
sampler. A visual characteristic of the sediment colour is recorded (light
grey / dark grey / brown / black / layered / plant material). Each core
is emptied into a small bucket in the dinghy (before taking the next).
Samples are kept separate (8 buckets). Based on the content of the
bucket, a visual characteristic of the sediment type is recorded (silt/clay
(< 0.06 mm), fine sand (0.06-0.6 mm), course sand (> 0.6 mm)). Samples
are brought to the laboratory. The following day they are filtered as
much as possible on a 212 µm sieve, gravel and plant remains are removed. If animals are not counted at that time, the sample must be preserved in 96% ethanol to a final concentration of 70%. Samples are kept
separate.
Sediment/paleo samples
1) 5 sediment cores are sampled from the deepest part of the lake (depth
> 80% of maximum depth) using the kajak sampler. Be careful not to disturb the sediment cores when unscrewing the core form the sampler.
When the cores are taken in board there must be a sharp threshold be-
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