Introduction
S hellfish culture is traditionally supported by the collection of wild juveniles. For Ostrea edulis , however, this practice is inefficient given the scarcity of biological material available in the lagoon. T he productive recovery of native species requires strengthening the production capacity of existing hatcheries. However, the production increases should not adversely affect the environment and ecosystem in which these are grown , especially when they are located in fragile areas but of high cultural, landscape and natural value. The o bjective of the present study is to evaluate new technologies and solutions to improve the productivity and environmental sustainability of hatcheries for pre-growing of Ostrea e. for their productive recovery.
Experimental
The study can be divided into three main steps:
Results
Long-term tests were performed to verify the stability of the response of the sensors placed in the closed-circuit tanks of the hatchery. The purpose of the tests was to verify the accuracy of the data provided by the sensors (pH, salinity, dissolved oxygen, temperature, chlorophyll, ammonium, and nitrate) and to establish the timing required for their maintenance (cleaning and calibration) in order to ensure their optimal operation and the reliability of the results obtained. The survival rate of specimens divided by size class of Ostrea edulis in tanks controlled with sensor and non-sensor systems were monitored.
2. Synthesis of feed for oysters from macroalgae
Average composition of the main nutritional constituents of algae (Ulva lactuca and Gracilaria) undergoes some significant variation in relation to seasonality. The two seaweed species studied differ significantly in ash and lipid content. Ulva lactuca shows a higher content of both. Since the uses and health benefits of unsaturated lipids contained in many marine animal and plant species are known, the lipid profile of seaweeds was studied. In addition, the suitability of microalgae extracts for use as feed ingredient for oysters. In particular, the organic and inorganic micropollutants were determined. The algae-based material was encapsulated using a mixture of lipids and alginate to produce small droplets. The encapsulated feed was tested on bivalve mollusc larvae. The results obtained showed that the optimal growth rate of the larvae was achieved by using a mixture of encapsulated feed and 50% phytoplankton.
3. Biofilters from waste (shells)
A wastewater filter system was installed at Naturedulis (Figure 1), consisting of a cylinder filled with a mixture of adsorbent materials obtained from shells.The efficiency of the proposed system in the relevant environment was tested. Water samples were taken before and after the filter treatment, which are subjected to chemical analysis. The data obtained shows that the filter system removes more than 50% of the heavy metal in water.
Acknowledgment
The authors thanks PO FEAMP Priorità 2 – Obiettivo tematico 3, Misura 2.47 – “Innovazione in Acquacoltura” Art. 47 Reg. (UE) n. 508/2014 for financial support.