Suspended culture of Ostrea edulis in the Calich lagoon (North western Sardinia, Italy): preliminary results

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 Linné, 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<0.01) were also found in final mean oyster width (28.4±3.1mm at station 1 vs 27.5±2.8mm at station 2) and weight (F=4.00; p<0.05) values (91.4±16.7g at station 1 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

Suspended culture of <i>Ostrea edulis</i> in the Calich lagoon (North western Sardinia, Italy): preliminary results

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 Linné, 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&lt;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&lt;0.01) were also found in final mean oyster width (28.4±3.1mm at station 1 vs 27.5±2.8mm at station 2) and weight (F=4.00; p&lt;0.05) values (91.4±16.7g at station 1 vs 87.7±18.3g at station 2). Moreover, chi-square test revealed a significantly different survival rate (χ2=10.04; p&lt;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

Marine benthic forms of the Marine Protected Area Capo Caccia-Isola Piana (Sardinia, Italy)

The great ecological and economic value of the biocenoses of Marine Protected Area 'Capo Caccia-Isola Piana' (MPA) requires a constant monitoring. For this reason, a continuous study of the area producing overlapping maps useful to control in real time the evolution of the biocenoses is necessary. The integrated use of several methodologies, such as Side Scan Sonar, Remote Operating Vehicle and Drone, has allowed us to realize a very detailed map. This paper presents the marine benthic map of the MPA and compares the present situation with that recorded in 2008

Morphometric relationships and annual gonad index of the edible Sea urchin <i>Paracentrotus lividus</i> from North Western Sardinia = Relazioni morfometriche e indice gonadico annuale del riccio di mare commestibile <i>Paracentrotus lividus</i> nel nord ovest Sardegna

Weight/diameter, weight/height and height/diameter morphometric relationships were calculated for a shallow rocky Paracentrotus lividus population sampled monthly near Alghero (Italy) from November 2004 to October 2005. Gonad index (GI) of the sea urchins was also evaluated. Statistical analyses showed significant differences of GI between 2 distinct periods of the year: late fall-winter and spring-late summer

An Alternative suspended culture method for the Mediterranean carpet clam, <i>Tapes decussatus</i> (L.), in the Calich Lagoon (North Western Sardinia) = Un Metodo alternativo di allevamento in sospensione della vongola verace mediterranea, <i>Tapes decussatus</i> (L.), nello stagno di Calich (Sardegna nord occidentale)

Tapes decussatus seed was grown in two distinct groups of six suspended modules each placed at two different sites of the Calich lagoon from January to July 2004. Each module was composed of three stacked plastic baskets filled with coarse sand to prevent shell deformities. Statistical analyses showed significant differences in carpet clam survival at the two sites, while no differences in growth were detected

Accrescimento in long-line di <i>Mytilus galloprovincialis</i> Lmk. nello stagno di Calich (Sardegna nord-occidentale) = Growth of long-line cultured <i>Mytilus galloprovincialls</i> Lmk. in the Calich Lagoon (North-Western Sardinia)

The Mediterranean mussel Mytilus galloprovincialis (Bivalvia, Mytilidae) was long-line cultured in two different areas of the Calich Lagoon (NW Sardinia, Italy). Several physical and chemical water parameters, chlorophyll a and sedimentation rate were measured in the two culture stations and in a third considered as a control. Mussel growth rate was similar in the two stations. It was positively affected by the increase of water temperature and chlorophyll a concentration and negatively by oxygen depletion

Distribuzione di <i>Caulerpa racemosa</i> nel Golfo dell'Asinara (Sardegna settentrionale) = Distribution of <i>Caulerpa racemosa</i> in the Gulf of Asinara (NW Sardinia)

Caulerpa racemosa (Chlorophyta), a non indigenous green alga from the Indo-Pacific, has been detected and mapped in the gulf of Asinara (NW Sardinia, Italy), to a depth of 30 m. The total covered area, mostly on "dead matte", is 776 ha and the interested coastline amounts to 13 km (44% of the total coastline investigated)

Common Bottlenose Dolphin Protection and Sustainable Boating: Species Distribution Modeling for Effective Coastal Planning

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Principali avversità biotiche dell'eucalipto in Sardegna

Il genere Eucalyptus (fam. Mirtaceae) è originario dell'Oceania e include oltre 600 specie di alberi e arbusti sempreverdi. Nell'Italia centro meridionale la specie più diffusa è l'Eucalyptus camaldulensis Dhenh. La grave diffusione di fenomeni di deperimento e di moria di piante nei popolamenti di eucalipto della Sardegna ha richiesto indagini di carattere entomologico e patologico, condotte in 12 aree dell'Isola