Biological and inorganic factors in the destruction of limestone coasts

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Investigations were conducted along the northern Adriatic coast near Rovinj, with findings compared to locations in Bermuda, Florida, and Marseille. The study explains limestone coast destruction through a complex interplay of biological and inorganic factors. Physical and chemical parameters of tidal- and rock-pool waters were measured over 24-hour periods, revealing that these waters cannot dissolve the carbonate substrate inorganically and remain oversaturated with respect to CaCO3. Variations in alkalinity are partly biologically driven, as cyanophytes can assimilate bicarbonate, challenging the assumption that alkalinity changes directly indicate CaCO3 dissolution or precipitation in biologically productive environments. Rock-pool floors are rich in epi- and endolithic algae, fungi, and lichens, which limit direct water-substrate exchange and inhibit inorganic dissolution, playing a minor role in coastal destruction. The coastal profile displays distinct color zones, with morphological and biological zonations aligning accordingly. Endolithic and epilithic organisms corrode rock through etching, while grazing gastropods remove microflora and rock particles. This biological corrosion and abrasion, termed biokarst, contributes to sedimentation in the subtidal zone, with preliminary estimates indicating that limestone coast destruction accounts for about 15% of total sedimentation in the northeastern Adriatic, averaging a de