Management of recreational waters in relationship with harmful microalgae blooms (HAB) in the Mediterranean Sea

Transcription

1 EVK WORKSHOP Management of recreational waters in relationship with harmful microalgae blooms (HAB) in the Mediterranean Sea 25 26th October 2004 Hotel Don Antonio, Peguera- Calvià, Mallorca

2 A.M. P. di Tavolara Punta Coda Cavallo Town Council of Olbia Olbia Harbour Social and economical impacts of HAB Dott. Augusto Navone Advisor for H.A.B emergency in the town council of Olbia (SS)

3 Location of Olbia

4 mussel farming Olbia Gulf

5 After the earliest experiences in the first years of the twentieth century, in the last years mussel farming increased exponentially its production from about 1,200 tons during season to nearly 5,000 tons during the current season. Mussel farming uses the long-line technology, half-submerged systems with rows of different length ( m) and depth from 3 to 7 m. Each row is covered by a sock, which is a tubular net in polypropylene of different length and meshes of 4 cm, where mussels grow. In the farming, the harvest of mussels takes place throughout the year. The local produce is harvested from May to October; during the other months it comes from other places, then improved in the waters of the Gulf and immediately put on the market.

6 Fishing, harvesting and marketing of live bivalve mussels (LBM) are controlled by the D.L. 30 December 1992 no. 530, which adopts the EEC Directive 91/492. The decision of the Commission on 15 March 2002 no. 2002/225/EC introduced some changes concerning the highest level of algal bio-toxins.

7 Economical data: The staff of the mussel farming is currently composed of about 200 people, but this figure is nearly twice as many if the ground staff and the several marketing activities (e.g. shipment) are considered. Each hectare of a long-line system produces about 5 tons. (About) one operator is generally required to manage one hectare of long-line, except possible administration employees. Farmers of Olbia complain about the unsuitability of regulations concerning the mussel marketing, because they favour the imports rather than the national produce. They are forced to market frequently non-local products in order to beat the competition, which can rely on lower costs penalising the produce quality.

8 FARMING OF FISH SPECIES: In the Gulf of Olbia, fish species are farmed in floating cages (bass, gilthead, white sea bream, dentex). In the Gulf of Olbia, fish species are farmed in floating cages (bass, gilthead, white sea bream, dentex).

9 Filtering: Before being put on the market, mussels must be filtered in proper systems and never infected by coliforms, salmonella and other toxic agents.

10 Self-control: Each filtering system has a microbiology laboratory to carry out self-control tests on the produce. These controls aim to detect organic pathogenic agents.

11 The product is packed within the filtering system by proper machines. Label is stuck during this stage, by the health stamp certifying the filtering.

12 Anoxia and high summer temperatures affecting the farming placed in low depth areas of the Gulf can kill almost 100% of the farmed mussels. Another serious recent problem that threatens mussel farming in Olbia is posed by algal bio-toxins produced by microscopic algae caught by filtrating organisms and concentrated in the same. It is well know that bivalve mollusks and in particular mussels have the capacity to accumulate foreign substances at a concentration up to 1000 times that of that water in which they live. The consumption of mussels presenting high concentrations of these Bio-toxins, PSP (Paralytic Shellfish Poisoning) e DSP (Diarrhetic Shellfish Poisoning), can cause conditions ranching from gastroenteritis, to paralysis and even death.

13 Herbs instance (Harmful Algal Blooms) Predisposing factors: Low hydrodynamism High trophy Mussel farming activity

14 Instance outbreak PSP in Olbia in 2002: Formation of lasting cysts in sea sediments Vegetative forms (algal blooms) Toxin production Toxin accumulation in bivalve mussels Toxicity in mussels in 5 sampling sites

15 The Gulf of Olbia: PSP (2002) Seno cocciani Cala Saccaia Isola di Cavallo Mezzo cammino

16 Regional surveillance plan Ordinance of the Mayor Harvest is is prohibited till till the sanitary requirements provided for for by by the law will be be restored and, in in any case, for for at at least days from the latest unfavourable detection. In In case of of immediate risk for for the public health: Alerting the hospitals Communicating by by mass-media the high health risk

17 Surveillance and sanitary control of the system Intensifying the surveillance of of the Shipping Centre (check of of the origin of of the product) Intensifying the surveillance of of restaurants and markets Adoption of an intensive Sampling Plan Assessment of of algal toxins in in LBM: Sampling frequency of of water and LBM must be be increased Number of of sampling stations must be be increased

18 PSP TOXINS IN SAMPLES OF LIVE BIVALVE MOLLUSCS (Olbia, 2002) neg pos may june

19 Golfo di Olbia: PSP (2003) Seno cocciani Isola di Cavallo

20 PSP TOXINS IN SAMPLES OF LIVE BIVALVE MOLLUSCS (Olbia, 2003) neg pos april may june

21 Economic damages resulting from stopping the marketing of the produce: 2002 Standstill of 21 days Euro , Standstill of 27 days Euro ,00

22 Plan to reduce the damages by the outer areas of the Gulf of Olbia. Turn-over of the systems.

23 In 2004, data have remained under the threshold and the emergency plan has not become effective.