Adverse Effects of Toxic Metal Pollution in Rivers on the Physiological Health of Fish

Abstract

Toxic metal pollution influences the lives of diverse aquatic organisms and humans who consume contaminated aquatic products. However, its potential impacts on aquatic organism health and, thus, ecological health, have been neglected in many regions. This research was carried out to contribute to filling that knowledge gap. Three freshwater fish species in the Nhue–Day River basin, Vietnam, have been chosen to study the bioaccumulation of metals (Zn, Cu, Pb, and Cd) in the tissues (livers, kidneys, gills) and their effects on fish physiological health (changes in the oxidative-GST activity, and physiological biomarkers-energy reserves, respectively) from 2013 to 2017. The extensive results revealed significant spatial and temporal variations in metal concentrations in tissues of common carp (Cyprinus carpio), silver carp (Hypothalmic molitrix), and tilapia (Oreochromis niloticus), and well correlated to their concentration in the water (p < 0.05). Fish bioaccumulated metals in the following order: Zn > Cu > Pb > Cd, with more in the kidneys and livers (spring and summer) than in other tissues. Metal accumulation in O. niloticus and C. carpio was higher than in H. molitrix. Biomarker responses (except for glycogen variation) were also higher during warm seasons. Changes in metal levels in water and fish tissues caused variations in biomarkers in the respective fish tissues, particularly in the livers, as demonstrated by significant correlations of metal concentrations in water and fish tissues to biochemical and physiological responses (p < 0.05). The findings suggest that metal pollution in the river basin adversely impacts the physiological health of both wild and cultured fish. Seasonal shifts in the levels of metal accumulation and biomarkers could be connected to species-specific differences in physiology and the levels of metals in environments. This biomarker set is simple but effective in assessing the impact of metal pollution on fish health and, hence, the aquatic ecosystem. This is one of the first biomonitoring studies to assist in designing better water management strategies for the Nhue–Day River basin.

Antioxidant Activity of Vitamin C and E Versus Oxidative Stress Induced by Heavy Metals in Common Carp (Cyprinus carpio)

“…Contaminated water causes not only morphological changes and damage to the function of gills but also biochemical changes. (Strzyzewska, 2016;Shah et al, 2020;Ngo et al, 2022) In this research, the level of proteins in all three organs decreased after exposure to heavy metals. Oxidative stress caused by heavy metals might have led to changes in protein metabolic processes, promoting protein catabolism.…”

“…These studies have reported that exposure to heavy metals is also manifested by changes in physiological and biochemical parameters in blood and also in fish tissues. Biochemical parameters such as total proteins and glucose levels, which were also investigated in the present study, are widely used as markers of water pollution (Ullah et al, 2021;Ngo et al, 2022). jms.mabjournal.com Malaysian Applied Biology…”

Responses of continuous cadmium exposure on some biological and physiological performance of cotton bollworm Helicoverpa armigera

“…tubules in S. exigua larvae at a dosage of 44 μg/g in the first generation had lower activity than control and then increased in the second generation (Kafel et al, 2003). One of the reasons for the high activity of GST can be the high accumulation of heavy metals, such as Cd (Ngo et al, 2022).…”

“…Similarly, the activity of GST in the midgut of fifth instar larvae and females of locusts of Aiolopus thalassinus (Orthoptera: Acrididae) collected from areas contaminated with heavy metals lead, cadmium, copper and zinc were considerably high (Abdelfattah et al, 2021), and also, GST enzyme in Malpighian tubules in S. exigua larvae at a dosage of 44 μg/g in the first generation had lower activity than control and then increased in the second generation (Kafel et al, 2003). One of the reasons for the high activity of GST can be the high accumulation of heavy metals, such as Cd (Ngo et al, 2022).…”

Ecological impact of heavy metals on aquatic environment with reference to fish and human health

“…Damage to the circulatory system and nervous tissue is also recorded in human due to chromium toxicity. Cr in the presence of other metals has been shown to increase glycogen levels in numerous organs that are stressed due to metal exposure (Ngo et al, 2022).…”