Download Phytoplankton-Meth.16-12

PHYTOPLANKTON I N THE WATER
FRAMEWORK DIRECTIVE
Presented by Caridad de Hoyos
CEDEX (Spain)
ANALYSIS OF PHYTOPLANKTON
• Sampling
(The same samples places, depths and dates that in the case of chlorophyll).
• Preservation
• Microscopical examination of samples
• Sedimentation
• Species composition
• Counting procedure
PRESERVATION
• For meso- and oligotrophic waters: 2ml of Lugol´s solution per liter
• Samples should be kept in brown glass bottles
• Samples should be kept stored in the dark
• Samples should be kept cooled not higher than 10 ºC
MICROSCOPICAL EXAMINATION OF SAMPLES
• Quantitative
analyses
must be done under an
inverted microscope with
magnitudes of e.g. 100 x,
400x, and 1000 x.
•One eyepiece should be
equipped with a calibrated
ocular micrometer.
SEDIMENTATION
• An Utermöhl chambre must be used, which is composed by a bottom
counting chamber and a chamber cylinder
•The samples must be adapted to room temperature before they are set up
for sedimentation.
•Then, they have to be mixed by turning the bottle upside-down
approximately 100 times.
• Sedimentation time is depending on the volume of the subsample. For
oligotrophic and mesotrophic water is usually used 50 ml chambers. In this
case, the sedimentation time is 24 h.
Figures: bottom counting
chamber and chamber
cylinder set up for
sedimentation
SPECIES COMPOSITION
• A taxon list should be compiled before the quantitative analysis
of the sample starts, in order to provide an overview of
phytoplankton composition prior to detailed quantitative
analysis.
• If we are going to analyse phytoplankton composition based on
indicator species, drawings or digital photos of taxa observed
should be made and retained as reference collection and interand intra- laboratory comparison test should be performed to
avoid/minimize identification differences between analysts
• If we are going to analyse phytoplankton composition based on
taxonomic groups of algae, it is not necessary to identify to
species level. The different taxa should be named using running
names (e.g. Anabaena 1, Anabaena 2).
COUNTING PROCEDURE
• Each taxa of the taxon list should be counted separately.
• For species less than 50 m a number of randomly-selected counting field
must be counted with high magnification (magnitudes of 1000 x or 600 x) until
the total number of observation of the most common species have reached a
certain value (e.g. 100). Depend on the level of precision one wants.
•For species larger than 50 m with low densities the whole chamber must be
counted at low magnification (100 x or 200 x)
• The number of algal objects counted is converted to give a concentration per
unit volume of sample as follows:
N = X*(A*d/a*v)
N - number per unit volume
X - mean number per field or the total count for the whole chamber)
A - total effective area of the chamber
V - is the volume of the sub-sample in the chamber
a - area of the field (= A is the count is of the whole chamber)
D - dilution or concentration factor, if applicable.
• The individual cell of colonies should always be counted separately as well
as number of colonies. The cell number of large colonies must be estimated
from the colony size and filamentous forms, with no clearly differentiated cells,
counted as number of filaments and each of the filament should be measured.
BIOVOLUME CALCULATION
•The specific volume of different species is calculated by using the
measurements of cell dimensions and subsequently the geometric formulas.
•The number of measured cells varies from 5 to 10.
• There are some bibliographic references with biovolume data of some species
and recommendations about the formula to apply in some species
•Biological data base with mean volumes of taxa is used in some countries for
phytoplankton monitoring data.
Rott, 1981
Elder, 1979
CEN TC 230/WG 2/TG 3/N83
Water quality- Guidance standard for the routine analysis of phytoplankton
abundance and composition using inverted microscopy (Utermöhl
technique)
Working draft stage. (The most recent version)