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Fish assemblages in sicilian areas invaded by �aulerpa spp. 589
At each of the three above mentioned locations we performed three censuses, at
3-5 m depth range, for a total of 27 underwater surveys. These locations con-
sisted of a soft bottom covered mainly by a continuous meadow of Caulerpa spp.
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(average of upright fronds ± standard deviation 450 ± 130 m ) with patches of
posidonia oceanica (L.). Data were analysed by non-metric multidimensional scal-
ing (nMDS), using Bray-�urtis distance index on untransformed data. We used
analysis of similarity (ANOSIM) to examine differences among Caulerpa beds in
each of the three sampling times (PRIMER, 6.1, Plymouth Marine Laboratory).
Results
A total of 28 fish species, representing 8 families, for a total of 1298 indivi-
duals, were recorded. The most frequent species at all locations were Coris julis
(Linneo 1758) (14±2.3 SE), symphodus tinca (Linneo 1758) (7.3±1.8 SE), oblada
melanura (Linneo 1758) (5.7±3.6 SE), diplodus vulgaris (E. Geoffroy St. Hilaire
This study was funded by the M.A.T.T. (Ministero dell’Ambiente e Difesa del Territorio) research project to GRE
1817) (4.6±0.6 SE) e diplodus sargus (Linneo 1758) (4.0±0.49 SE). Species richness
(Gruppi Ricerca Ecologica).
and eveness were not conspicuously high at any Caulerpa bed, but the fish assem-
blage observed in June on C. taxifolia showed the highest diversity and evenness
values, 2.08 and 0.90 respectively, than in those collected on C. racemosa and �.
prolifera. The nMDS ordination (Fig. 1) showed that fish assemblages present on
Fig. 1 - nMDS ordination of fish assemblages from the locations affected by C. prolifera (Pro), C. taxifolia (Tax)
C. taxifolia, C. racemosa and C. prolifera constituted two distinct groups. Accor-
and C. racemosa (Rac) sampled in June (G), July (L) and August (A) 2004.
Ordinamento nMDS dei popolamenti ittici presenti nelle tre località colonizzate da C. prolifera (Pro), C. taxifolia
ding to ANOSIM test, the fish assemblage of the site colonized by C. taxifolia
(Tax) e C. racemosa (Rac) campionate a giugno (G), luglio (L) ed agosto (A) 2004.
significantly differed from those covered by C. racemosa and C. prolifera (Global
R= 0.6, significance level %=0.1; pairwise tests: C. tax vs C. prol **; C. tax vs C.
rac ** and C. rac vs C. prol*).
Stress: 0.14
ProG Pro L
Pro A Tax G
Tax L Tax A
Rac G RAc L
Rac A
Fig. 1 - nMDS ordination of fish assemblages from the locations affected by C. prolifera (Pro),
C. taxifolia (Tax) and C. racemosa (Rac) sampled in June (G), July (L) and August
(A) 2004.
ordinamento nMds dei popolamenti ittici presenti nelle tre località colonizzate da �. prolifera (pro),
�. taxifolia (tax) e �. racemosa (rac) campionate a giugno (G), luglio (l) ed agosto (a) 2004.