POSTER SESSION 1
15:30–17:30, Monday, September 14
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ABSTRACT 1168 | POSTER 77
THE ROLE OF EMBAYMENTS AND ESTUARIES IN SECCHI DEPTH VARIABILITY ALONG A SALINITY GRADIENT IN THE SOUTHERN COASTAL BALTIC SEA: A 50-YEAR PERSPECTIVE
Coastal embayments and estuaries are optically complex environments where the simultaneous integration and transformation of signals from multiple optical and external drivers hinder a straightforward interpretation of Secchi depth variability across multiple timescales. Along a salinity gradient on the southwestern coast of Mecklenburg-Vorpommern (Germany), Secchi depth, temperature, and salinity have been monitored monthly since the 1970s at 83 stations shallower than 20 m. We assessed the seasonal, interannual, and decadal variability in Secchi depth across three embayments and related it to external forcing factors, including precipitation, wind speed and direction, storm frequency, and river runoff. A fourth region, characterized by stations representative of a more “open-ocean” environment, was defined for comparison. Our results showed that Secchi depth has been declining across all seasons in regions of higher salinity, as well as at open-ocean stations. This suggests a Baltic Sea-driven forcing on the optical properties of these waters. In contrast, embayments with limited influence from the Baltic Sea, and therefore, with lower salinity, exhibited no statistically significant trends in Secchi depth. We hypothesized that restricted circulation exchange with the Baltic Sea, in combination with local forcing, can account for the observed variability along the salinity gradient.
Helena Frazão, Leibniz Institute for Baltic Sea Research Warnemünde, [email protected], https://orcid.org/0000-0001-5477-1802
Mario von Weber, Landesamt für Umwelt, Naturschutz und Geologie Mecklenburg-Vorpommern (LUNG), [email protected]
Chandanlal Parida, Leibniz Institute for Baltic Sea Research Warnemünde, [email protected]
Ulf Gräwe, Leibniz Institute for Baltic Sea Research Warnemünde, [email protected]
Bronwyn Cahill, Leibniz Institute for Baltic Sea Research Warnemünde, [email protected]
Oliver Zielinski, Hereon Helmholtz Zentrum, [email protected]
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