Suspended culture of Ostrea edulis in the Calich lagoon (North western Sardinia, Italy): preliminary results
2010
Suspended culture is a widespread farming method used for many bivalve species such as mussels, oysters and
scallops. In the Mediterranean, this technique is mainly practised in lagoons or in sheltered coastal areas using
floating lines from which molluscs are suspended in several ways. In this study, the European flat oyster ( Ostrea
edulis Linne, 1758) was grown in suspended lantern nets in the Calich lagoon (Sardinia, Mediterranean Sea) from
March 2004 to March 2005. Two distinct groups of 6 lanterns each were hung to longline ropes near the mouth (station
1) and in the central portion of the lagoon (station 2). In each lantern (diameter=50cm; height=30cm), 90 O.
edulis specimens were grown and, in order to ensure good water circulation inside the lantern net, fouling organisms
were removed every month. Overall mortality, shell length (anterior-posterior axis), shell width (maximum
distance on the lateral axis, between both valves of the closed shell) and total wet weight of a 180 specimen oyster
sample (30 from each lantern) were recorded every 2 months at each site. In addition, water temperature, salinity,
dissolved oxygen, and pH were monitored monthly by means of a multi-parametric probe at both sites (between
10a.m. and 12p.m.). One-way ANOVA was used to test for differences in oyster final mean morphometric characters
recorded at the 2 growing stations. Chi-square test (with Yates correction for continuity) was performed to compare
survival rates at the end of the trial. From an initial mean shell length of 49.5±4.6mm, O. edulis growth rate
showed a similar trend at both the stations. Nevertheless, ANOVA detected significant differences (F=7.10; p<0.01)
in final mean oyster length values (83.7±6.5mm at station 1 vs 81.7±7.6mm at station 2). Significant differences
(F=9.74; p vs 27.5±2.8mm at station 2)
and weight (F=4.00; p vs 87.7±18.3g at station 2). Moreover, chi-square test
revealed a significantly different survival rate (χ2=10.04; p<0.01) between the 2 groups (57.4% at station 1 vs 47.6%
at station 2).Water temperature, salinity, dissolved oxygen, and pH monthly values recorded at the 2 growing stations
were almost identical. Thus, the observed differences in oyster growth and survival seemed not to be due to
the hydrological variables considered. Instead, they could probably be related to mechanical and chemical effects of
water renewal by coastal waters, which may have led to different seasonal seston food supplies at the 2 sites. The
suspended culture of the European flat oyster described in this paper can increase the mollusc production of the
Calich lagoon by growing a valuable bivalve species which is naturally scarce in this biotope. In fact, our preliminary
results showed good survival and growth rates of O. edulis especially near the mouth of the lagoon.
Furthermore, this farming technique could be a possible source of economic benefits for local fishermen and, above
all, a low impact aquacultural activity compatible with the environment.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
3
Citations
NaN
KQI