ECOSTRIMED PROTOCOL: BIOASSESSMENT
TO DEFINE A RIVER'S ECOLOGICAL STATUS
Introduction: general procedure
The general procedure for rapid bioassessment to define a river’s
ecological status is as follows:
1. Selection of sampling sites
An appropriate series of sampling sites to be monitored must be
defined as a preliminary step, prior to beginning the study, using topographical
maps at a minimum scale of 1:50,000. Some considerations to take into account
for selecting sites are:
— The number of sampling sites will depend on the total
length of the main river, and also on the objectives of the study.
— The tributaries to the main river channel will be included
if we plan a very detailed network of sites. However, only the most important
tributaries or those which we can expect a priori to modify the characteristics
of the main channel will be chosen.
— The distance between sites should be between 1 and 10
kilometres. Shorter distances are suitable for local and detailed studies, while
longer ones are better for broader studies (one or more drainage basins).
— It is advisable for the subsequent interpretation of the
results to select sites before and after cities or towns, as well as
tributaries. The location should be at a certain distance from sewage inputs to
avoid local pollution effects.
— The first time a site is visited, a general examination of
the reach is recommended in order to determine the possible modifying factors of
water quality, which are impossible to predict or detect from a map.
— When necessary, the exact location of the sampling site can
be moved some metres up or downstream if this makes it more accessible or allows
the detection of elements causing possible changes not observed from map
— In studies with a large number of sites, we would consider
as suitable and efficient the sampling of at least 6 sites per day.
2. Sampling point identification
Each location should be identified (by name, code, etc.). The
date, time of sampling and weather should be noted on the field data sheet
provided in this protocol together with other observations which may be relevant
for the study.
3. Sampling procedure
The hydrological regime of Mediterranean rivers is
characterized by strong depletion of water discharge in summer, with the
formation of intermittent streams (with disconnected pools) or even entirely dry
channels. The discharge of the river or stream may modify the physical, chemical
and biological characteristics of the water, and can give us an idea of its
capacity to dilute runoff contaminants.
Temperature, conductivity, pH and dissolved oxygen may be
measured using field meters and recorded on the field data sheet. Remember to
calibrate the meter before sampling. If these field measurements cannot be
properly taken, a biological evaluation can still be done. On the other hand, if
there is the possibility of studying a complete data set of physicochemical
parameters in the field and in the laboratory, these can be useful for
interpreting data, although they are not strictly necessary for a biological
evaluation of water quality.
After the sampling, a preliminary field identification of the
animals found may be performed, and the results annotated on the field data
sheet (section 4), where the families present in Catalan rivers are listed. In
section 8 and annex 1 we provide some keys and a set of illustrations of each
family that should be useful in field recognition, but some previous knowledge
is necessary for correct family identification in the field. If no taxonomical
experience is available, the best alternative is to sort and identify the
animals in the laboratory, using a stereoscope. Each sample should be labelled
with the locality name and/or code and date of sampling.
environment study should be performed on a 100 m long stretch of the river
(although it can be shorter in small streams or when there are sudden changes in
the sampling area; a waterfall, for example).
4. Biological quality of the water and the status of the
If only lotic areas have been sampled, the FBILL
index will be calculated.
If all habitats have been included (riffles and pools) together
with different kinds of substrates (stones, macrophytes, plant litter, etc.), 'BMWP'
should be applied. The field sheet was designed for use with this index.
The riparian environment status is an important element for the
ecological assessment of Mediterranean rivers. The QBR
method has to be used.
5. Ecological status value
The ecological status is obtained following the instructions in
the ECOSTRIMED index and
using the values of the water biological index selected and the
Map with the sampling sites marked.
Field sheets (several copies, at least one per sampling site)
Field meters: to measure conductivity, solved oxygen (if
Distilled water to clean the meters.
Plastic tape-measure (minimum 10 m).
pH and disDepth meter consisting of a long stick with graduated
marks each centimeter.
Hand net with a mesh size of 250 mm, at least 30 cm in diameter
and 1 m long, to collect macroinvertebrates.
White tray measuring approximately 1 5 x 20 x 5 cm, to observe
the collected macroinvertebrates.
250 g plastic jars to transport the samples to the lab.
Plastic vials to collect and preserve animals not identified in
4% formalin or 70% ethanol to preserve the samples to be
transported to the laboratory.
Pencil, scissors, waterproof stickers and waterproof pens, to
label and mark the samples.
Paper labels to attach to the sample vials. They should be
written in pencil and contain the following information: code or name of the
sampling site, date, name of the collector, and the tentative taxonomical
Waders or boots.
Sun protection: hat, sun cream, etc.
Source: Diputació de Barcelona 2000
Developed by the Department of Ecology,
University of Barcelona, with the collaboration of the Department of Environment
of the Barcelona Council