Cichlidogyrus Sclerosus (Monogenea: Ancyrocephalinae) and Its Host, the Nile Tilapia (Oreochromis Niloticus), as Bioindicators of Chemical Pollution

Abstract

Experimental results showed that the gill monogenean Cichlidogyrus sclerosus and its host, the Nile tilapia Oreochromis niloticus, exhibited significant numerical and physiological responses after exposure to sediments polluted with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and heavy metals in comparison with control fishes. After 15 days of exposure, C. sclerosus abundance significantly increased in treatments with low to fairly high sediment pollutant concentrations, but declined at high sediment pollutant concentrations. Hypertrophy and hyperplasia in secondary gill lamellae and the spleen melanomacrophage centers were significantly higher at extremely high sediment pollutant concentrations compared with the controls. Spleen lymphocyte and monocyte counts were significantly lower at extremely high sediment pollutant concentrations and were significantly correlated with high fluorescent aromatic compound concentrations measured as PAH exposure indicators. A multivariate redundancy analysis showed significant statistical association between sediment pollutant concentration, C. sclerosus abundance, and tilapia physiological variables. The polluted sediments negatively affected monogenean abundance and induced immunosuppression in hosts, consequently increasing histological damage in hosts and allowing persistent C. sclerosus infection. This study documents evidence suggesting that C. sclerosus and its host are indeed excellent models to test environmental quality in tropical freshwater ecosystems.

Parasites of native Cichlidae populations and invasive Oreochromis niloticus (Linnaeus, 1758) in tributary of Amazonas River (Brazil)

“…were also low due to the occurrence in some months of the year (RANZANI-PAIVA et al, 2005). Sanchez-Ramirez et al (2004) reported that in O. niloticus kept experimentally in polluted environment, the abundance of C. sclerosus decreased, but the infection was chronic. Therefore, C. tilapiae may be sensitive to environmental eutrophication and may have seasonal infection pattern, this is why it was not found parasitizing this invasive fish in the main channel of the natural investigated ecosystem.…”

Aspects of the ecology ofCichlidogyrus philandercollected fromPseudocrenilabrus philander philanderfrom the Padda Dam, Gauteng, South Africa

“…Dorovskikh & Matrokhina (1987) recorded that the oxygen saturation of the water leads to a change in the occurrence of Dactylogyrus amphibothrium on ruffe Gymnocephalus cernua and a decrease in their abundance. Sanchez-Ramirez et al (2007) found that the abundance of Cichlidogyrus sclerosus increased significantly in low to fairly high sediment pollutant concentrations, but in high sediment pollutant concentrations the abundance declined and higher levels of hypertrophy and hyperplasia of the secondary gill lamellae was found (SanchezRamirez et al 2007).…”

Environmental Parasitology. Interactions between parasites and pollutants in the aquatic environment

“…This is most likely attributable to the fact that "Environmental Parasitology" is an interdisciplinary field which relies on simultaneous expertise from toxicology, environmental chemistry and parasitology (see e.g. Sanchez-Ramírez et al, 2007). However, the results published so far clearly show that it is worth to combine these expertises.…”