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564 F. Cubadda et al. / Chemosphere 45 (2001) 561±569
Table 2
Weight-adjusted means and ranges of metal concentrations (lg gÀ1 dry wt) in M. turbinata and M. mutabilis
Sampling station Cd Cr Cu Pb Zn
M. turbinata (n 50)a 13.8
(10.1±18.5)
1 1.59 0.24 5.0 0.37 37.4
(33.1±46.1)
(0.70±5.20) (0.11±0.55) (3.1±10.8) (0.22±0.87) 37.8
(20.0±61.2)
2 1.78 0.12 8.4 0.13 53.7
(42.0±60.5)
(1.07±4.14) (0.07±0.33) (5.1±23.9) (0.10±0.29)
18.9
4 0.68 0.41 16.9 0.14 (10.7±29.7)
23.2
(0.10±1.84) (0.10±0.74) (8.9±25.7) (0.06±0.56) (17.7±40.4)
5 2.93 0.30 18.5 0.47
(1.47±5.89) (0.10±0.48) (7.9±28.3) (0.10±0.87)
M. mutabilis (n 60)a
1 1.29 0.35 9.9 0.15
(0.96±3.05) (0.13±0.74) (6.0±16.6) (0.08±0.30)
0.12 18.2 0.12
2 1.64 (0.08±0.15) (8.5±34.7) (0.06±0.22)
(0.28±4.11)
a Total number of individuals analysed.
Table 3
Weight-adjusted means and ranges of metal concentrations (lg gÀ1 dry wt) in P. caerulea and P. lusitanica
Sampling station Cd Cr Cu Pb Zn
P. caerulea (n 70)a 3.9
(2.2±5.8)
1 3.5 0.19 1.67 0.10 6.2
(3.4±11.9)
(1.7±11.8) (0.10±0.66) (1.00±3.21) (0.06±0.20) 4.1
(2.5±7.9)
2 4.8 0.20 1.51 0.33 6.3
(4.1±10.1)
(2.1±9.5) (0.11±0.52) (1.04±2.65) (0.14±0.48) 18.2
(10.3±19.1)
3 4.1 0.42 1.27 0.20
8.4
(2.4±11.5) (0.23±1.01) (0.95±3.79) (0.16±0.51) (5.8±9.0)
9.4
4 4.1 0.35 1.50 0.18 (6.0±22.8)
17.6
(2.1±7.2) (0.15±0.84) (1.02±3.11) (0.11±0.30) (14.4±21.3)
5 8.8 0.37 2.02 1.42
(2.3±10.2) (0.14±0.58) (0.47±2.50) (1.00±2.18)
P. lusitanica (n 30)a
2 3.0 0.16 2.51 0.14
(2.3±4.1) (0.10±0.25) (1.94±2.83) (0.10±0.22)
0.29 2.08 0.30
4 2.1 (0.22±0.90) (1.42±3.85) (0.20±0.95)
(2.0±4.6) 0.37 2.80 0.71
(0.24±0.49) (2.07±3.90) (0.38±1.02)
5 4.9
(2.1±6.6)
a Total number of individuals analysed.
concentrations and body weight were observed. This (station 5). On the other hand, the species of the genus
means that, in the four species examined here, the Patella exhibit similar slopes for Zn and, in some
largest individuals contain the highest levels of met- stations, for Cr.
als. A partial exception is represented by zinc in the
species M. mutabilis and, to a smaller extent, Table 5 reports the ANCOVA results, expressed as
M. turbinata. In these latter cases the slope of the re- percentage of the total sum of squares explained by the
gression line is near zero and therefore Zn concentra- factor location (sampling station) or by the covariate
tions are almost size-independent. The species of the (log-transformed body weight). These two eects explain
genus Monodonta also shows similar slopes for Cd, Cu a signi®cant proportion of the observed variability and
and Pb, with the exception of the very high value this is consistent with the very high ratios obtained in the
observed for Pb in M. turbinata from the local harbour F -statistic (10 < Flocation < 6682, always P < 0:001; 88 <
Fbw < 1077, always P < 0:001).
