Investigating the Exoparasites Infecting the Lessepsian fish Hardyhead silverside (Atherinomorus lacunosus) in the Syrian marine waters and the effect of some physicochemical water properties on the infection

Abstract

Infestation with parasites is one of the most common stressors in fish, and with the migration of some fish species from the Red Sea through the Suez Canal, the parasites have been transferred with them. No previous study has been conducted in Syrian marine waters on the migratory trout (Therinomorus lacunosus), So, this research aims to investigate the external parasites infecting the Trout (Atherinomorus lacunosus) in Syrian marine waters off the coast of Latakia Governorate. It also examines the effect of certain physicochemical water properties, such as temperature, pH, and dissolved oxygen levels, on the severity of infestation. To achieve this, 60 fish were collected and examined from the area between the coast of Al-Basit and the coast of Jableh, passing through Ras Ibn Hani, during the period from June 2022 to August 2024. The examination included a detailed inspection of the body, fins, gills, and oral cavity.

The study resulted in the isolation of two isopod species. The first, from the genus Livoneca (family Cymothoidae), was found in the gills of 34 fish, registering an infestation rate of 56.67% with a severity of 1.74 parasites per fish. The second parasite, from the genus Gnathia (family Gnathiidae), was isolated from the gills of 28 fish, showing an infection rate of 46.67% with a severity of 1.68 parasites per fish. The severity of the infection was found to increase during the summer months.

Simple correlation analysis revealed a strong and significant positive correlation between the infection rates of both parasites and both temperature and pH, while a strong negative correlation was found with dissolved oxygen concentration.