Prevalence, Morpho-Histopathological Identification, Clinical Picture, and the Role of Lernanthropus kroyeri to Alleviate the Zinc Toxicity in Moron labrax

Abstract

The present context is the pioneer attempt to verify the ability of copepod, Lernanthropus kroyeri, L. kroyeri, to uptake and accumulate heavy metals. We primarily assess the prevalence of the parasite in various seasons, clinical signs, and post-mortem changes in sea bass (Moron labrax). Morphological features of the parasite using a light microscope, bioaccumulation of heavy metals in tissues of both L. kroyeri and M. labrax (gills, muscles) using Flame Atomic Absorption Spectrometry, and histopathological alterations were monitored. Fish (n = 200) were obtained from Ezbet Elborg and examined for the parasite, L. kroyeri. Results revealed that the total infection recorded 86%. The infested fish exhibited excessive mucous and ulceration at the site of attachment. The post-mortem lesion in gills was marbling appearance with destructed filaments. Various heavy metals (Zn, Co, Cu, and Cd) were detected in the tissues of L. kroyeri and M. labrax and surprisingly, L. kroyeri had the ability to uptake and accumulate a high amount of Zn in its tissues. Infested fish accumulated less concentration of Zn in their tissue compared to the non-infested ones. Within the host tissue, the accumulation of Zn was higher in gills compared to muscles. Histopathological findings demonstrated scattered parasitic elements with destruction of gill lamellae. Taken together, we clearly highlight the potential role of L. kroyeri to eliminate Zn and it can be utilized as a bio-indicator for metal monitoring studies for sustaining aquaculture.