BS/EN 17204-2019 pdf download.Water quality – Guidance on analysis of mesozooplankton from marine and brackish waters.
The following chemicals may be useful for analysis of zooplankton samples:
6.5 1-Hexadecanol (Cetyl alcohol, CH3(CH2)14CH20H) to reduce the surface tension (few drops per
100 ml).
6.6 Eosin Y, for staining of animals in phytoplankton rich samples (few drops per 100 ml).
6.7 Observation fluid, for example Steedmans observation fluid; 5 ml [l 1-phenoxypropan-2-ol (C9H1202) and 45 ml I-i propane-1-2-diol (C3H802) in demineralized water.
7 Procedure
7.1 Sample and sub-sample preparation
For sampling and storage of zooplankton samples from marine waters, see EN 172 18:2019. All samples should be retained in storage until the subsequent investigation is completed.
To remove the formaldehyde from the sample before the microscopic investigation the sample should be filtered through a sieve and rinsed with filtered or sieved tap water. The mesh size of the sieves shall be considerably smaller than the mesh size of the plankton net used for sampling. All activities should occur under a fume hood to deflect the formaldehyde fume.
The formaldehyde should be collected in the sample vessel and reused to preserve the zooplankton organisms after completion of the microscopic analysis.
The zooplankton should be transferred under careful rinsing from the sieve with filtered tap water into a glass vessel and refilled to a certain volume depending of the density of organisms. The whole zooplankton sample should be filled in a counting chamber or divided in case organisms are too densely concentrated. Depending on the splitting device, the sample should be concentrated by sieving or diluted with tap water as necessary.
Before filling the splitter the volume of the total sample shall be measured in a graduated glass or plastic cylinder. The volume shall be noted in the protocol.
If the sample contains large clumps of plankton (e.g. by gelatinous organisms or Cercopagis) or macroalgac. these shall be carefully removed and placed on a very large mesh. The clump should be gently rinsed with water or seawater while pulling at the clumps with forceps to free trapped organisms, which are returned to the sample before splitting or analysis. All the organisms still attached to the clump shall be identified, counted and recorded.
To divide the sample into defined subsamples a calibrated Plunger sampling pipette according to Hensen. a Folsom plankton sample divider (splits Into two subsamples), a Motoda box splitter or a Kott splitter (splits into eight subsample’s) is recommended, see E.2.
NOTE 1 Non-random distribution in the sample during sub-sampling is the most important source of en-or.
NOTE 2 The Kott Splitter, which produces eight sub samples. is somewhat better in precision, but Is more time- consuming to handle, while the Folsom sample divider splits samples into halves.
The counting chambers should be cleaned with tap water immediately alter finishing the analysis to avoid adhesion of dried organisms.
For routine counting of larger zooptankton taxa a stereomicroscope should be used, which allows manipulation of the specimens during identification. For smaller organisms, an inverted microscope should be used. For special investigations during identification, a compound microscope should be used.
7.2 Species identification and counting
7.2.1 General
Species identification and counting are the basis of all zooplankton community analysis. Depending on the aim of the investigation all taxa appearing in the sample are to be determined or only dominant organisms and groups.
If possible, the complete sample shall be analysed. At least 100 individuals shall be counted. With higher abundance, representative subsamples shall be analysed.
A hierarchical counting technique should be used to obtain density estimates for all taxa. This procedure consists of first identifying all specimens (adults and development stages) and counting at least 100 individuals of the occurring dominating taxonomic groups. excluding nauplil. rotifers and tintinnids. If these minimum counts are not achieved in one subsample, additional subsamples shall be counted. The taxonomic group(s) that reached 100 inthviduals in the previous subsample(s), do not need to be counted in the next subsample(s). The precision of calculated abundance for organisms of the fIrst three groups, that will be counted up to 100 specimens, amounts to 20 % LI 1J. The estimation of abundance for other groups (tail”) will be less precise 1101.
All individuals should be counted to avoid heterogeneities due to splitting. While counting the settlement of all organisms to the bottom shall be ensured. It is possible to sink floating Microcrustacea by gently pressing them down using the microprobe or by adding a drop of dilute laboratory detergent (e.g. Cetyl alcohol). If a sample cannot be completely analysed and archived within 2 days, the sample should be kept in the refrigerator and preservative added to prevent the degradation of the sample.
For the quantitative analysis of microzooplankton organisms of particular interest (e.g. tintinnids or naupliar stages) abundance can be estimated semiquantitatively from the first subsample. For the quantitative analysis of macrozooplankton organisms and rare species of particular interest (e.g. non- indigenous species) the whole sample shall be scanned through.BS/EN 17204-2019 pdf download.