Methodology - PLANKTON
Phytoplankton & microplankton Water column Phytoplankton (microplankton) is collected with the use of perplex glass bottle of 5dm3 volume with closing device (Niskin Bottle or similar design). Samples are collected from the depths delimited after the light measurement (usually at surface, 50%, 10% and 1% of surface irradiance), in the absence of light meter the samples are collected from 0, 2, 5,10 and 50m depth. Water sample onboard is placed into 250cm3 jar, fixed with Lugol solutiona and 3% formaldehyde. Samples are analysed in the lab under the inverted microscope, after the sedimentation in 1ml chambers. Phytoplankton is counted under the 200x magnitude , and as minimum 1000 objects are identified and counted from each sample. |
 Conical
net of 20 µm mesh size for qualiatative phytoplankton
sampling |
 Cascade filtering
device with two different filters mounted; upper
filter with 10 µm, lower with 0.4 µm mesh size |
 Niskin
bottles, 5 and 15 l volume |
Mesozooplankton Sampling WP2 net with 57cm diameter, 180um gauze, closing device and flow meter is the standard net used for vertical hauls. Routinely three water strata are sampled, delimited after CTD measurements (usually: surface water - 0-20m, intermediate layer - 20-50m, below picnokline - 50-200m). Vertical sampling in layers thinner than 10m is not practical. Once retrieved, the net is being washed externally with the hose with seawater onboard, what allows flushing down the plankton attached to the net column. Then the collector is removed and emptied into the small plastic bucket. The collector's walls are rinsed gently to remove all remaining plankton and the sample is poured into the jar of 250ml volume. Excess water is being filtered out through the same gauze. The sample is preserved with 37% formaldehyde buffered with borax, to obtain 4% formalin solution in the plankton sample. Second standard device is multinet sampler (Hydrobios-Kiel) with 0,25 m2 opening, equipped with 5 nets with 180um mesh size and flow meters. Net is hauled vertically through the five discrete water layers, established after the CTD profiling. The sample treatment is the same as described above. Sorting In the laboratory, the jar with zooplankton sample is placed under the ventilation funnel. The sample is gently rinsed with tap water on the 180um gauze sieve to remove the formalin. If needed sample is poured into the splitter and divided into equal parts before analysis. Washed sample is placed into100-200ml glass. All the conspicuous and large specimens are removed first and identified. From the remaining plankton, series of five subsamples are taken by 2 ml pipette and put into the glass or plastic Petri dishes with an mm grid on the bottom. Organisms from each sub- sample are identified, counted, and measured under the stereomicroscope. At least 1000 small sized specimens are identified from the sample. The rest of is looked through to check for the large individuals, rare species and macroplankton. Finally, the number of specimens counted is recalculated to the original sample volume. After the identification, plankton is placed back into the original jar. |
 Multinet |
 Multinet -
main part of the gear, before mounting the nets |
|
 Multinet -
colectors are numbered and placed in safe box that prevent falling
down |
 Messenger with
safety wire, type used for water casts and plankton nets with closing
device |
|
 WP2 mesozooplankton
net before lowering |
 WP2 -
closing device mounted on WP2 net |
|
 WP2 -
plankton is being gently washed from the gauze into sample jar |
