The study of estuarine ecosystems is essential for protecting and reestablishing their threatened biota. In this research the spatio-temporal variations in the distribution patterns of foraminifera, ostracods and molluscs are analyzed in surficial sediments sampled in 2012/13 at six low-tide estuaries of the southeastern Mediterranean coast. Live assemblages are studied using multivariate statistical analyses to determine their ecological preferences and seasonal dynamics whereas the dead assemblages are used to establish a reference baseline for future paleoenvironmental reconstruction.The statistical analysis indicates that salinity, TOC and % carbonate are the main environmental factors explaining 60% of the cumulative variance and controlling the distribution pattern of the different brackish taxa encountered in these estuaries. The foraminifera Ammonia tepida and some miliolids (Quinqueloculina and Varidentella) inhabit most estuaries during summer when salinities of 13-18 psu and temperatures of 26-34 °C occur. At the Naaman stream the agglutinated species Birsteiniolla macrostoma and Trichohyalus aguayoi dominate the assemblage during autumn and winter, respectively when salinities of 3-7 psu and temperature of 18-24 °C prevail. High abundance of the monospecific assemblage of the ostracod Cyprideis torosa was encountered at the Tanninim year round in oligohaline water. The gastropod Heleobia phaeniciaca prefers living at the Naaman and Tanninim streams while Pyrgophorus sp., an invasive and low salinity species, continue colonizing more stream reaches along the Israeli coast.The dead assemblages are composed of high numbers of local and transported species. It includes post storm-surge sediments containing high numbers of inland fresh and brackish water species transported by the floods. Those are mixed with inner to mid-shelf benthic and planktonic foraminifera, ostracods and molluscs. Transportation of the marine organisms a few hundred of meters inland via the estuaries indicates that the coastal areas are prone to storm surge events that are preserved clearly on the coast.The present study demonstrates that the combined use of different multi-proxy faunal records enhances significantly the understanding of the dynamics of low-tide estuaries. This can be applied also to other low-tide estuaries worldwide and facilitate better management of these threatened environments. Additionally, it enables understanding of the post-mortem processes that control the transition from the living to the death assemblages and by that improve paleoenvironmental reconstruction of the lower reaches of low-tide estuaries.
Bibliographical noteFunding Information:
This study was carried out with the support of the Ministry of Science and Technology and of the Ministry of Energy and Water Resources (Grant nos. 3-7818 and 212-17-022 respectively). We gratefully acknowledge the technical assistance received from M. Kitin and C. Netzer-Cohen of the Geological Survey of Israel and A. Yurman and M. Bachar from the RIMS diving workshop, of the Department of Maritime Civilizations and the Leon Recanati Institute for Maritime Studies, Haifa University. H. K. Mienis, of the National Mollusks Collection in Tel Aviv University and S. Mischke, of the Faculty of Earth Sciences in the University of Iceland are highly appreciated for their contribution in the identification of molluscs and ostracods, respectively. Many thanks are also due to Darvasi Yaniv of the Institute of Earth Sciences at the Hebrew University of Jerusalem for the graphics. Two anonymous reviewers are thanked for their help in improving many aspects of the manuscript.
© 2015 Elsevier B.V.
- Live and dead assemblages
- Low-tide estuaries
- Southeastern Mediterranean
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science