402
M.C. Gambi and G. Cafiero
100
90
80
*70
of 60
.. S! 50
0
.g
'0 40
)(
41
"0
30
t::
20
10
o
a
OLa 22m
OLa 3 - 5m
m Ca 3-5m
.Ca 1m
Fig. la,b. a Seasonal trend of the
Index of borers (IB) in the studied stations. b Seasonal trend of
the number of individuals/m 2 in
the studied stations. (La, Laceo
Ameno Meadow; Ca, Castello
Meadow)
0&' ~o~' , }u' ')fl}<:- ' «-e?' ~t$- ' ~1-' ~fl}":;" ,)", <:-' ')So' ~"'C>.>' C:>~~' 0 0-'
Months/se a sons
300,-------------------------------------,
b
E 250
0.!!!.
~

200
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~ 150
.=
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E
~
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o
O La 22m
o La 3· 5m
r:lJ Ca 3-5m
• Ca1m
0&' ~o~' Q~(; ' ')fl}<:-' «-e?' ~r$- ' ~~<.. ' ~fl}":;" ,)",<:-' ')oS' ~"'C>.>. c:>~'Q ' 00-'
Months/seasons
1 m depth, boring polychaetes, when present,
were relatively abundant (e.g., in May and June)
due to the high shoot density recorded at this
site (mean = 919 shoots/m 2 ). At 3-5 m depth at
Castello polychaete abundances ranged between
18 (in August) and 98 (in March) individuals/m 2 ,
and showed a constant trend, increasing slightly
from February to May. In the Lacco meadow at 35 m depth borer abundances were higher than at
Castello at the same depth, and ranged between
29 (in March) and 115 (in December) individuals/m 2 (Fig. 2b). This may be due to the slightly
higher shoot density recorded at Lacco (mean =
375 shoots/m 2 ) with respect to Castello (mean=
358 shoots/m 2 ) at the same depth (3-5 m). Finally
at the deep stations off Lacco (22 m), despite the
relatively high values of the IB (Fig. 2a), the borer
abundances ranged from 34 (in April) to 69 (in
October) individuals/m 2 , probably related to the
relatively low density of the meadow at this