Geomorphological Patterns of Modern and Buried Reefs in Two Insular Land-Locked Embayments (Lesvos Island, Greece): A Comparative Study

Manoutsoglou, E.; Lioupa, V., and Hasiotis, T., 2024. Geomorphological patterns of modern and buried reefs in two insular land-locked embayments (Lesvos Island, Greece): A comparative study. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 732-736. Charlotte (North Carolina), ISSN 0749-0208. The Gulfs of Gera and Kalloni are two neighboring semi-enclosed shallow embayments located on Lesvos Island. Multibeam bathymetry, side scan sonar imagery and subbottom information revealed numerous modern as well as buried reef structures. Surficial and core sampling coupled with ground-truthing from drop cameras, ROV and scuba dives showed that the reefs are colonized by benthic assemblages dominated by oysters. The reefs of Gera Gulf have a maximum height of 2.7 m, they are up to 780 m long and appear to have a concentric development, initiating from the center of the gulf. Kalloni Gulf reefs are up to 5.8 m in height, locally forming elongated structures (chains) up to 1100 m long often followed by shallow (0.5-1 m) depressions around their base and the largest concentrate mostly in the center of the gulf. The subbottom profiles revealed similar buried features, the distribution of which primarily aligns with the extent of the surficial structures. However, in the Gulf of Kalloni, the buried relief appears to be slightly increased. The buried reefs started to develop along a deeper-seated surface, related to the stratigraphic boundary, that flooded during the Holocene marine transgression and grew through the transgressive and highstand system tracts with periods of reef die-offs. The reefs thrive through a fine-grained matrix and this pattern appears to have persevered throughout Holocene. Also, other ecosystem engineers (i.e., Serpulidae worms) contributed to the development mainly of the larger reefs. The Kalloni and Gera Gulfs reefs constitute a unique finding in the Mediterranean region that deserves interdisciplinary research in order to explore the key factors guiding their growth and preservation but also the effect of environmental and climatic changes that altered their development during the Holocene.