Annual assessment of the sea urchin (Paracentrotus lividus) humoral innate immune status: Tales from the north Portuguese coast.

Abstract Innate immune status of the sea urchin Paracentrotus lividus population from two different rocky shore beaches in the northern Portuguese coast was evaluated for a period of one year. Although some ecological studies regarding the effect of toxics on the immune parameters of the sea urchin were made in Portuguese waters, there is a current lack of knowledge concerning their immune status all over the year. In perspective of a changing ecosystem in these waters due to global warming and colonization of new species, it is important to assess the status of the major species living in the area. In this way, immune parameters such as total protein content, nitric oxide concentration, haemolytic activity, protease activity, lysozyme concentration and bactericidal activity were evaluated in the perivisceral coelomic fluid, and were correlated with the gonadal index of the population and water parameters. Also, the spawning period can upset some immune status parameters, and others such as haemolytic activity and bactericidal activity against Vibrio anguillarum, showed a clear correlation with the gonad maturation status. The knowledge of the basal immune status of the species could serve as ecological indicator of some stress agent or contaminant into the field; also, coelomic fluid is suggested as good quality marker to assess the immune status of sea urchins. Highlights • Annual survey of the humoral innate system of Paracentrotus lividus. • Decrease of innate immune parameters due to spawning period. • Positive correlation of haemolytic activity and bactericidal activity with gonad maturation. • Small differences recorded between sampling sites; good status of the northern Portuguese coast population. • Perivisceral coelomic fluid suggested as a good quality marker for assessing health of sea urchins. [ABSTRACT FROM AUTHOR]