SPATIAL AND TEMPORAL VARIABILITY OF TRANSPARENCY IN THE EASTERN ADRIATIC SEA

摘要

Simple for use and cheap, transparency measurements with the Secchi disk are probably a unique marine parameter of unchanged methodology since 1860 and still interesting, especially from its long-term prospective. In this paper, we present long-term series of transparency for the eastern Adriatic Sea. Three stations in its northern part, ten stations from the middle and three stations from the South Adriatic area were investigated. Many of these stations were sampled monthly. The stations encompass the least transparent shallow coastal bays, moderately transparent channels and the most transparent open sea areas. The oldest records are from the Najade expedition (1911-1914). The ANOVA tests were performed and annual trends of presented data were shown. Seasonal signals indicate mainly late summer as the most transparent season, and mainly winter as the least transparent period. Diverse behavior of transparency was noticed among the areas, from no trends to decreasing or increasing trends for different seasons or periods. High spatial variability of transparency rises from variable influences of natural or anthropogenic factors. The causes of spatial differences, temporal variability and trends were taken into consideration.