Contribution to the knowledge of main abiotic and biotic factors in Boka Kotorska Bay from the aspects of rearing of edible shells
Abstract
This study comprises the results gained by investigations of basic abiotic (temperature, salinity, phosphorous P-PO4, sea currents) and biotic factors (production of phytoplancton) in the Boka Kotorska Bay from the viewpoint of possibility for commercial farming of edible shells-fish (Mytilus galloprovincialis LAMK., Ostrea edulis L., Crassostrea gigas THUNBERG).
This analyses are related to the possibility of exploatation of Bay aquatory for farming, by the way of systems of parks (50X5 m).
Location of Bay in Adriatic, orographic structure, jagged coastline and specific abiotic characteristics make this Bay a specific biotip so that life conditions differ from those in open part of Adriatic.
Relief and petrographic composition make Boka Kotorska Bay very complex area. In the sea bottom relief of the Bay there are two levels: strand and shelf. The bottom is partialy coverred with tick stratum of fine mud terigen by origin.
Generally taking the Boka Kotarska Bay, especially investigated areas (coves Kukoljina and Krtole in Tivat’s Bay; areas in Risan’s and Kotor’s Bay — P. 1), are protected from strong winds and stormy sea what is that most favorable condition for successful farming.
Surface of Bay aquatory is 87,334 km2, what makes 0,06% of total Adriatic aquatory. Surface of investigated aquatory, most favorable for stationary farming, totals 711,5 ha from what 659,2 ha goes to areas in Tivat Bay (coves Kukoljina and Krtole).
Currents of sea masses in Bay are very irregular. Direction and power of currents are influenced by tides, winds, changes of air pressure and influx of fresh water. Currents are weak in the summer (0,7 Knots on hour) and during fall, winter and spring season they are very strong (2,5—3 Knots on hour). Vertical currents from bottom to the surface, are present, especially in inside part of the Bay, during the reany periods.
The presence of forests results in bringing considerable quantity of nutritious salts and higher level of production (average two-year values of phosphorous P-PO4 on all three investigated localities is 5,468 mg/t).
As a result of fresh water influx Bay is characterised with great production of zooplancton and phytoplancton. Consequently, the water of the Bay has green colour and its transparency is very weak.
The fresh water influx influence constantly decreased salinity of water masses with high concentration of nutritious salts, what is most important for successful farming of edible shell-fish. This occurrence is present during whole year with culmination during reany periods (XI—V).
