Changes in the Adriatic oceanographic properties induced by the Eastern Mediterranean Transient

[摘要] Long-term time series of physical and chemical parameters collected between1960 and 2010 along the Palagruža Sill transect, Middle Adriatic Sea,have been investigated in terms of average water properties and theirvariability. Nutrients, especially orthophosphates, reached rather highlevels of concentration below the euphotic zone between 1991 and 1998, thehighest levels in the investigated period. Simultaneously, the N:P ratio,which is normally higher than 25:1, decreased to values less than 16:1 inthe euphotic zone, indicating a switch from typical phosphorus to nitrogen-limited preconditioning for the primary production. Higher-than-usualnutrient levels peaking in the mid-1990s, coupled with lower-than-usualtemperature, salinity, dissolved oxygen and pH values, are presumablyrelated to the flow of the nutrient richer Western Mediterranean waters tothe Adriatic below the euphotic layer. These waters, which keep theirfootprint in the N:P ratio, enter the Adriatic during the anticyclonic phaseof the Bimodal Adriatic-Ionian Oscillation (BiOS), which has been uniquelystrengthened by the Eastern Mediterranean Transient occurring in the early1990s. This hypothesis should be confirmed through targeted research andmodelling exercises, as it is highly relevant for the biogeochemistry of theAdriatic Sea.

[学科分类] 地球化学与岩石