Population biology and threats of Arbacia lixula, Paracentrotus lividus, and Sphaerechinus granularis (Echinodermata: Echinoidea) on the coast of Gran Canaria Island, Spain

Abstract

Sea urchins are marine invertebrates that play a key role in marine coastal ecosystems because of their control over algal coverage by limiting their abundance and distribution, primarily through grazing. While sea urchins have been the subject of extensive research globally, studies on their populations in the Canary Islands remain scarce. Furthermore, the limited available literature has predominantly concentrated on the species Diadema africanum, due to the behavior producing barrens and the recent mass mortalities. There are three common species in the coastal rocky shores of the Canary Islands: Arbacia lixula (LINNAEUS 1758) and Paracentrotus lividus (LAMARCK 1816), usually found over the rock with different food preferences and behavior; and, in some locations, it is possible to find other species, Sphaerechinus granularis (LAMARCK 1816), in the interface between the rocky substrate and the sand bottom. The sea urchin populations in coastal areas have been affected by human activities, such as overfishing and contamination, resulting in negative effects like mass mortality, diseases, and, in most cases, the collapse of fishery activities and an imbalance in ecosystems. In addition, it is well known that threats such as pollution can modify the reproduction, density, settlement, and population structure of the sea urchins, but in some species is poorly understood. Regarding the lack of information on the sea urchin species status in Gran Canaria Island and all the threats that affect the sea urchin population, this thesis aims to contribute to the knowledge of the reproductive cycle, population structure, and the threats faced by Paracentrotus lividus, Arbacia lixula, and Sphaerechinus granularis in the rocky coastal areas of the island. [...]