1. Select a river stretch that has not been flooded
recently.
Samples should be taken in the central areas or at the edges at
depths greater than 0.2 m.
2. Divide the river stretch into different areas
according to the different substrates present:
With high current speed and hard substrate (1)
Lentic with hard substrates (2)
Among the submerged portion of the emergent vegetation of the river edges
(3)
Among submerged macrophytes or macroalgae (4)
With sand, gravel or mud (5)
It is very important to select a river stretch that has the
maximum number of different substrates in order to obtain all the
macroinvertebrate biodiversity.
3. Sample once at each habitat following the appropriate
methodology.
In habitats (1) and (2)
Remove the large stones from an area of 2 m˛.
If the stones are less than 10 cm in diameter in diameter, kick an
equivalent area and collect all the material disturbed, holding the net against
the flow of the river.
In habitats (3) and (4)
Use the net to collect organisms present among the vegetation, submerged
roots and macrophytes.
In habitat (5)
Kick the bed and collect the suspended material with the net.
In all cases sampling should continue until no new families
appear in the successive samples for each habitat.
As the sampling is qualitative, a representative sample should
be obtained. An exhaustive search for macroinvertebrates is not necessary.
Remember that the net should have a mesh of 250 µm and the
opening should have a diameter of at least 30 cm.
The net should be carefully cleaned between two consecutive
sampling stations in order to prevent the presence of animals from the previous
sampling.
4.Sorting, identification and counting
This stage is performed mostly in the field, with the following
steps:
Place the sample in a white tray with some water
Identify the animals to family level, directly with the naked eye or using a
magnifying glass.
Identification should proceed until no new families are detected.
If the macroinvertebrates cannot be properly identified in the field, the
animals should be kept in vials and taken to the laboratory for correct
identification under a stereoscope.
The following abundance code should be used:
1
2 or fewer individuals
2
3 - 10 individuals
3
11 - 100 individuals
4
more than 100
In the event of the observer having little experience in taxonomy, the whole
sample (all the habitats together or separately) should be preserved and sorted
later at the laboratory following the steps used in the FBILL
methodology.
Caution should be taken if the tray is full of litter. In this
case the sample should be divided into several parts and each of them carefully
examined for macroinvertebrates.
Source: Diputació de Barcelona 2000 (Copyright)
Developed by the Department of Ecology, University of
Barcelona, with the collaboration of the Department of Environment of the
Barcelona Council
