In the Northern Adriatic Sea, tuberculate abalone (green ormer) (Haliotis tuberculata L.) are particularly threatened by bottom trawling and seafood disturbance , and their populations face a decline. A low average depth of 30 m, and a weak bathymetric gradient characterizes the Northern Adriatic . The most important oceanographic factors in the Adriatic are seasonal salinity, the concentration of nutrients, light intensity, currents and temperature. Seasonal changes of oceanographic factors, including temperature, algae and wave motion, greatly affect the growth and physiology of green ormers. For this reason, the Northern Adriatic green ormer tissues were studied over the main seasonal periods for their microanatomical structure, biochemical and antioxidant defense properties.
Tissue concentrations of glucose (GLU), triglyceride (TRIG) and cholesterol (CHOL) were determined as the main energy sources for metabolic demands. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), total antioxidant status (TAS) were evaluated as parameters for antioxidant capacity and lipid peroxidation. Tissue magnesium (Mg) and calcium (Ca) were investigated as formative shell elements, crucial for ionic homeostasis and reproduction control. S ignificant differences were found between spring/summer and winter samples for TAS, with peaks in June. GPx had the highest activities in fall samples, just as SOD, CHOL, GLU, TRIG, Mg and Ca parameters. Differences in green ormer tissue biochemical and antioxidant defense properties over seasons are shown in the figure as a log10-based scale. Data were grouped tightly in ormer tissues in spring/summer and winter, having unsymmetrical interquartile ranges.
Long-term temperatures between 8.5 and 9.0°C are the lethal limit for ormers, and at low temperatures, they are limited in their ability to absorb food and grow. W inter low temperatures thus contributed to lower TAS and SOD concentrations.
Not only antioxidant capacity, but also tissue Mg, Ca and GLU were on the decreased levels in ormers in winter. However, in fall a number of parameters had their yearly peaks, such as Mg, Ca, SOD, GPx, TRIG, CHOL and GLU.
Interestingly, in this work ormers had elevated total antioxidant status in the warmer period, which can be attributed to the availability of food containing antioxidant compounds.
During the spring/summer season, gonads were at the mid-maturation stage, and in fall, the ripe and spawned stages were recorded.