Ultrastructural observation on the parasitic copepod, Lamproglena monodi Capart, 1944, infesting the gills of Sarotherodon galilaeus caught from the River Nile and Lake Manzala, Egypt, using the parasite as a bioindicator for pollution

The parasite Lamproglena monodi Capart, 1944 is a crustacean copepod infecting various Cichlid fish in Egypt. The parasites were collected between December 2022 and April 2023, from the gills of Sarotherodon galilaeus Linnaeus, 1758 caught from three different locations: Beni-Suif, El-Mansoura, and Lake Manzala. The prevalence values of L. monodi on S. galilaeus varied from site to site. The values of mean intensity of the parasite showed a narrow range of variations among the different study sites ranging from 1.7 at Lake Manzala to 2.3 at Beni-Suif. The highest values of prevalence (60%) and the mean intensity (2.3%) were recorded at Beni-Suif while the lowest ones, 1.3% and 1.7 respectively, were recorded at Lake Manzala. The parasite's distinctive morphological characteristics were illustrated using Scanning Electron Microscopy. Moreover, some heavy metals (Pb, Cd, Zn, Cu, and Fe) in water and parasites in different study sites were analyzed and the results showed that mean concentrations of Cd and Pb in collected water samples exceed the permissible limits according to The Egyptian drinking water standards and WHO in all study sites. Additionally, the findings revealed that all heavy metals were accumulated in parasite tissue more than water in all study sites. Also, this study investigated parasite dynamics as a bio-indicator of heavy metals pollution. The present results showed that Fe was the highest accumulated heavy metal in the parasite whereas Cu and Pb exhibited the lowest concentrations. Additionally, the findings revealed that the greatest values of heavy metal in the parasite were found in Beni-Suif and the lowest concentrations were in El-Mansoura. The present study suggests the use of L. monodi as bio-indicators responding well to changes in the environment's heavy metals