Reproduction, intracapsular development and carryover effect of the Mediterranean gastropod after long-term exposure to low pH

Spawning performance, intracapsular development and carryover effect of the banded dye murex (Hexaplex trunculus) were investigated following long-term exposure (>250 days) to a range of pHs. Gastropods were collected in Bistrina Bay, part of the Mali Ston Bay in the Southeastern Adriatic Sea (42°52'19.1 N 17°42'02.3 E). Experiment was performed in Laboratory for Mariculture, University of Dubrovnik, located ion the Bistrina Bay. Details of the experiment setting and carbonate chemistry measurements are available in PANAGEA datasets Grđan et al. 2024 & Grđan et al. 2025. After 250 days of exposure marked females were separated into individual containers. Until the start of spawning, females were fed Mediterranean mussel, Mytilus galloprovincialis. The start and duration of spawning were recorded for each female. The number of females spawning was recorded for each pH treatment. Immediately after spawning, ten randomly selected capsules from each spawn were measured with a digital caliper (precision 0.01 mm) for length (cl, mm), width (cw, mm) and thickness (ct, mm), with the length being the greatest distance between the basal membrane and the apex, width the greatest distance between lateral edges at right angles to length, and thickness the greatest distance from convex side to concave side at right angles to length and width (D'Asaro, 1986). Five capsules were carefully opened with a scalpel; eggs were emptied onto a microscope slide and counted under a stereo microscope (Olympus SZ40).