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8.3 Sur vey methodology
_
Check equipment list before departure to field sites and follow health and safety guidelines
at all times.
û
Do not survey during or after periods of high flow, flooding or management operations, nor
in windy conditions, turbid water (unless normal) or periods when boat traffic is heavy.
_
Check that the survey length is correctly located and paced measurements are accurate.
_
Cross the survey length every 2.5m in a zig-zag manner, surveying the whole river width if
possible.
û
Do not guess percentage cover estimates. Estimate on the basis of observation, using one
of the methods of estimation recommended in this manual.
_
Use a grapnel, glass-bottomed bucket and/or an underwater TV camera where appropriate,
to aid observation and identification of macrophytes. Take particular care to look for small
patches of macrophytes.
û
Do not use grapnel samples to estimate percentage cover: only record percentage cover based
on observation of plants in situ.
_
Identify macrophytes to species level where possible. Take representative specimens of
'difficult' species back to the laboratory for confirmation of identification. Maintain a
herbarium.
û
Do not record macrophytes overhanging, but neither attached nor rooted in the channel.
_
Record physical variables, make a sketch map and take a photograph.
_
Fill in all the details on the survey sheet at the time of the survey, except for the SCV total,
CVS total, MTR score and data-archiving details. Assign a measure of confidence in the
survey (A, B or C) and in the physical comparability of sites (I, II or III) before leaving the
site or shortly afterwards.
û
Apply extreme caution to MTR results assigned a suffix of confidence of 'C' and/or 'III'.
8.4 Data analysis
_
Calculate MTR to one decimal place, using scoring species only.
_
Assign a measure of confidence in the MTR score, based on the number of highlighted
species.
û
Do not use surveys with a suffix of confidence of 'III' and/or 'C' to interpret trophic status.
R&D Technical Report E38
99
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