Planet WGSW-24010 User Manual page 60

Individual species per centage cover estimates
For all percentage cover estimates of scoring and non-scoring species, the whole survey area
surveyed equals 100%, ie the individual species percentage cover estimates are a percentage of
the whole survey area and NOT of the overall percentage cover estimated.
Estimate the percentage cover of each macrophyte species, then, depending on the percentage
cover scale chosen, allocate each macrophyte a Species Cover Value. Use the C scale for surveys
of 100m length and the A scale for surveys of 500m length.
The alternative Species Covers Value class scales are:-
Scale A
(for 500m survey)
A1
A2
A3
A4
A5
In the rare event that a percentage cover is estimated as being precisely on the border between
two categories and a judgement cannot be made than a value for the upper category should be
recorded, thus for example if exactly 1% then C3 is recorded.
When all species have been allocated a Species Cover Value add up the percentages, in the field,
to check that they correspond to the overall percentage cover estimated for that survey length
(however, see Quality Assurance note).
When assigning percentage cover to macrophyte species it is strongly recommended that a
systematic approach is adopted to make the process easier and more accurate. Use one of the
methods described in Boxes 7 and 8. As a double-check when estimating small areas of cover,
it may be useful to work out beforehand the area of pieces of survey equipment, and use these for
reference: for example, an A4 recording sheet (0.06 m
Sur vey ar eas choked with vegetation
At sites where macrophytes are very abundant the site may become choked with vegetation. For
surveys at these sites it is difficult to estimate percentage cover for individual species. The birds-
eye view method of recording cover should be taken. It may be necessary to use a grapnel and
underwater TV camera/glass-bottom bucket to search for submerged species which may be
surviving under other macrophytes. Record any species found from such searches and estimate
their abundance based on observations using the underwater camera or glass-bottom bucket.
Grapnel hauls should NOT be used as a means of estimating abundance (4.5.3).
R&D Technical Report E38
Scale C
(for 100m survey length)
<0.1% C1 <0.1%
0.1–1% C2 0.1–1%
1–5% C3 1–2.5%
C4 2.5–5%
5–10% C5 5–10%
>10% C6 10–25%
C7 25–50%
C8 50–75%
C9 >75%
2
) or the base of a glass-bottom bucket.
46