Investigation of some bioecological characteristics of invasive sea urchin (Diadema setosum) in the Kekova region of the Mediterranean coast of Turkey

In this research, some bioecological characteristics of the long-spined sea urchin Diadema setosum (Leske, 1778), defined invasive/alien, were investigated between June 2022 and June 2023 in the Kaş-Kekova Region. Sampling was carried out in monthly periods by SCUBA diving method. A total of 992 individuals were sampled at three stations and total weight, test diameter, test height, and gonad weight measurements were made from the samples. In addition, gonadosomatic index values, species' densities and biomass in the environment were estimated, and gonad food composition were analyzed. The reproductive period was determined by using gonadosomatic index value and histological results. Within the scope of the study, the surroundings of an islet with a surface area of 40 m in diameter and an average depth of 4 m, determined as a separate station, were first cleared of sea urchins and then the distribution of the species over time was observed.The average weight of the measured individuals was determined as 123.10±76.23 g, average test diameter as 64.46±15.59 mm, average test height as 33.38±8.67 mm. The highest gonadosomatic index value was calculated as 18.26 in July. The average protein, fat, moisture and ash contents of the gonads were calculated as 26.71%, 34.08%, 71.81% and 11.37%, respectively. The average density of the species in the environment during the sampling period was calculated as 0.75 individual/10m2, and its average biomass was calculated as 99 g/10m2. As a result, it was determined that D. setosum, a invasive species, had intensive reproduction activity in June and July in the Kaş-Kekova Region. It was determined that the density of the species decreased in the region during the study period and its spread rate was not very high. Considering the gonad-to-body weight ratio and gonad nutritional components of D. setosum, it is thought that it can be an important commercial product.