The Role of Hydrodynamics on the Sustainable Mussels’ Culture Activity. The Case of the Chalastra Basin (NW Gulf of Thessaloniki)

In line with the framework of strategic guidelines for marine aquacultures, mussel cultures have to be operated in Areas of Organized Aquaculture Development (AOAD). Forty per cent of the national mussel culture production, which is based in Chalastra (NW Gulf of Thessaloniki, part of the Thermaikos Gulf), uses pole and longline systems. Due to legislative changes, both farmers and the authorities are in the process of reforming the existing units and planning processes based on the principles of sustainability, as defined in AOAD. The aim of this study is to estimate the appropriate orientation lines on which the mussel socks are to be placed in the mussel culturing units, in relation to the direction of sea currents for optimum water circulation in AOAD. The hydro-dynamics of the Chalastra basin is mainly wind driven and affected by prevailing northerly and southerly winds during winter and summer periods, respectively. When placed perpendicular to sea currents, the socks in the mussel production lines form an obstacle. Thus, the appropriate orientation of pole and longline units based on natural current directions can comprise a useful tool for sustainable mussel cultures. The benefits arising from the application of the proposed scheme are twofold: (a) productivity through the appropriate circulation and regeneration of nutrients can be maximized and (b) the environmental impacts of mussel culture activity can be minimized, as byproducts can more easily be dispersed of and biodegraded. In the present study, two basic schemes are proposed: (a) the division of AOAD is being researched into three sub-areas for pole and long-line units respectively and (b) the placement of the shortest possible length of production lines parallel to sea currents.

Green mussel (Perna viridis) culture on the central coast of Vietnam.

Grow-out culture of green mussels is currently being developed in some estuaries and lagoons in central Vietnam such as Lang Co lagoon in Thua Thien Hue province, Nha Phu lagoon in Khanh Hoa province, O Loan lagoon in Phu Yen province, and Nai lagoon in Ninh Thuan province. Green mussels attach to substrates such as wooden stakes, cement block stakes and plates, rope strings, net bags and baskets. Mussel seed is collected from the wild or transported from different places. Culture duration ranges from 6 months to 2 years depending on seed size. The commercial size is 10-15 individuals kg-1, with a shell size of 10-12 cm. The price ranges from VND 5,000 to 15,000 kg-1 depending on the local market. Minimal labour is needed for green mussel culture, although the stakes need to be consolidated in the monsoon season, substrates need to be cleaned of barnacles, mud, rubbish and predators (crabs, swimming crabs), and security must be provided.

Implanted byssal hairs on postlarval shells of Mytilus edulis platensis (Bivalvia: Mytilidae) from Patagonia

This communication describes the first records of byssal hairs on the postlarvae shells of Mytilusedulisplatensis d’Orbigny, 1842. The postlarvae used in this study were sampled on artificial collectors used for mussel culture in San Jorge Gulf, Sudoccidental Atlantic Ocean. A general description of the hairs is made as well as an exploratory analysis of their spatial distribution on the shell surface. The presence of these byssal hairs is suggested as a criterion to differentiate M.edulisplatensis from other mytilids.

Site selection for new green mussel culture area expansion in Buguey estuary, Cagayan, Philippines.

Currently, there is limited data on the suitability of estuaries in Cagayan province, Philippines for aquaculture. In this brief report, we discuss the overall assessment score of Buguey estuary in the municipality of Buguey, Cagayan as potential spot for the culture of green mussel (Perna viridis), locally known in the Philippines as "tahong". The score is mainly based on salinity and water temperature. We also present the condition of dissolved oxygen and pH levels in the estuary but these factors do not have major effect on mussel growth compared to salinity and water temperature. The reference ideal values for a suitable culture site are 27 to 35 psu for salinity; 27 to 30°C for water temperature; >5 mg/L for dissolved oxygen; and 7.7 to 8.4 for pH. Based on this reference values, areas in Buguey estuary have acceptable possibility of success for green mussel culture, which is qualitatively equivalent to having "good" suitability. This translates to a production estimate of 81% to 90% of cultured mussels will have a marketable size. However, these ratings may vary due to competition with existing oyster farming, water depth of the chosen site (since several areas in Buguey estuary are shallow), and other factors.