Planet WGSW-24010 User Manual page 56

clarity of the water will determine the number of times it is necessary to lower and rotate the
camera lens so that 360 degrees can be observed. If necessary a small weight (see manufacturers
guidelines) can be attached to the base of the camera to ensure greater stability and upright
orientation. In silty/muddy sites avoid contact with the base of the river channel so no
disturbance of the bed occurs leading to reduced visibility.
Gr apnel
A grapnel may be used to retrieve submerged macrophytes for identification from areas of deep
water. It is recommended, however, that the grapnel is NOT used to 'search' for macrophytes
as a substitute for visual observation, due to the following problems:
· fine-leaved and deeply rooted macrophytes will not be found unless a direct hit is made,
and therefore will either be missed entirely or under-represented;
· 'bushy' species such as Elodea will easily be collected by grapnel and their abundance
may therefore be over-estimated.
Use of a grapnel alone will lead to high levels of inaccuracy in both the records of submerged
species and the estimation of overall percentage cover.
Grapnel hauls should only be used when necessary, to retrieve macrophytes for identification or
determine if macrophytes are present, as they can damage or uproot macrophytes. Particular care
should be taken in an area with high conservation or aesthetic value.
4.5.4 Identification of macr ophyte species
Identification should be to species level where possible. Take a field identification guide, which
gives distinguishing features and shows which species are easily confused, into the field. Recent
synonyms are listed in Appendix 5 (Table A1). It may also be useful to take into the field a copy
of the survey sheets/results from the previous survey(s), as this may minimise gross identification
errors and help ensure sparely-distributed plants are not overlooked. Previous results must be
used with care, however, as the macrophyte community may have changed and/or the results may
contain errors — they should only be used in a final check, and not as a first point of reference.
Certain species can only be identified when fruiting bodies or flowering parts are present; and
even then only with difficulty. If identification to species cannot be achieved, for example due
to absence of seasonal diagnostic features, and all other routes to identification fail (see below),
then record only to the level to which you are confident (eg genus), even if this then renders the
specimen 'non-scoring'.
Macrophyte species identified in the field should be checked for positive identification features.
This takes an experienced surveyor very little time, ensures that rarer species are not overlooked
and recorded as their more common counterparts, and reduces the likelihood of macrophyte
species with superficially similar features being incorrectly identified.
Macrophyte species positively identified in the field should be recorded on the standard record
sheet. When a species unfamiliar to a surveyor is found it should be identified in the field if
possible but a representative sample should also be taken back to the laboratory for confirmation
of the identification. A small, representative sample should be taken and placed in a plastic bag
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