engleski

Holocene ostracod assemblage from Lake Velo Blato on the Island of Pag: a new paleolimnological record along the Croatian coast

Lake Velo Blato is a shallow (ca. 3 m deep) coastal lake situated on Pag Island on the Eastern Adriatic Coast (EAC). A 568 cm long sediment core (VB-2) was drilled in the central part of the lake and was analysed by a multiproxy approach. This contribution is focused on the ostracod analysis. In total, 19 species were recognised, belonging to 16 genera. The most abundant species are Cyprideis torosa, Candona angulata, Limnocythere inopinata, Darwinula stevensoni, Cypridopsis vidua, and Cypria ophtalmica. Subordinated species are Paralimnocythere psammophila, Pseudocandona marchica, Herpetocypris sp., Ilyocypris sp., Metacypris cordata, Cypris bispinosa, and Hungarocypris madaraszi. Changes in ostracods assemblages reflect environmental changes for the last 8100 cal yrs BP, specifically paleosalinity and paleohydrology driven by the Holocene sea- level rise. The most evident environmental transition was recorded in the Middle Holocene (at ca. 7100 cal yr BP) and is marked by changes from typical freshwater (Cypridopsis vidua, Paralimnocythere psammophila, Ilyocypris sp., Cypris bispinosa) to brackish (Cyprideis torosa, Candona angulata) associations. This transition is followed by an increase in the Sr/Ca ratio and the occurrence of authigenic Mg-calcite. However, relatively high abundances of L. inopinata and D. stevensoni suggest transition to moderately (oligohaline) brackish conditions, which lasted throughout the Holocene. Salinity increase results from saltwater intrusion through the karstic underground due to the sea-level rise and thus represents a new index point along the EAC for the sea-level curve. However, significant variations in ostracod assemblages during the Late Holocene were observed (e.g. abrupt changes in Cyprideis torosa abundances and valve morphology), which could be related to Holocene climatic variability. Further ostracod analyses (species identification, statistics, and valve geochemistry), coupled with stable isotope geochemistry, will provide more information about Holocene environmental changes in Dalmatia along the Croatian coast.

Ostracods, karst lakes, paleolimnology, Holocene

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