Water is an important driver of economic and social growth, as well as a critical component in sustaining the natural environment's integrity. Various dangerous contaminants have had a tremendous impact on the environment in general and water in particular over the last few decades, particularly heavy metals, which has become one of the most serious environmental challenges (Wang and Chen 2006). Metal contamination is a serious environmental hazard in aquatic environments, particularly river systems. Not only does this form of pollution degrade water quality, but it also has an impact on all living organisms in the system (Van Dyk 2003). Metals' ecological significance stems from their overall toxicity, as well as the fact that they are nonbiodegradable and extremely persistent, causing them to accumulate in the environment (Coetzee et al. 2002).
Metals are released into the environment through natural processes or as a result of human actions. Natural and anthropogenic inputs may be of the same order for some metals (Zn), but for others (Pb), anthropogenic inputs dwarf natural inputs (Clark 2001). The most important metal contaminants from human activities are Pb, Zn, As, Cd, and Cu. In this study, the biological responses of (Lanistes carinatus) were estimated, as growth rate is a fundamental indicator of physiological fitness/performance and one of the most sensitive indices of stress in organisms, heavy metal bioaccumulation, and genotoxicity. Biomagnification and bioaccumulation in biological creatures and human bodies can result in unwelcome significant health consequences such as cancer, kidney and liver damage, and even death at high levels of exposure (Paul 2017).
According to Egyptian law 48 (1982) for the protection of the River Nile and its tributaries from pollution, the concentration of zinc (Zn) in water must be less than 1 mg/l, the concentration of lead (Pb) must be less than 0.001 mg/l, the concentration of iron (Fe) must be less than 0.5 mg/l, and the concentration of manganese (Mn) must be less than 0.2 mg/l., but in this study revealed that the concentration of zinc (Zn) in water measured during sampling was more than the permissible limit in site 2 in Edfu city. This probably may be due to the influence of sewage, industrialand agricultural discharge and due to the deposition of these metals from the atmosphere (Malhat and Nasr 2012).
By studying heavy metal deposition in the water, sediment and Lanistes carinatus tissue, the study was able to quantify the amount of Nile River water pollution in selected Egyptian streams in Edfu city, Aswan Governorate. The study used integrated biochemical and molecular biomarkers to measure the ability of heavy metals uptake and tolerance in both natural and laboratory environments.
The exhaust of automobiles that run on leaded fuel appears to be the primary source of Pb pollutants in the marine environment. Rain and windblown particles also bring lead into the maritime environment (Castro and Huber 1997). The concentration of lead (Pb) in water measured during sampling in site 2 and site 1 was higher than the allowed limit in this study.
The concentration of iron (Fe) in water recorded during sampling in site 2 and site 1 was higher than the allowed limit in this study. This may be due to ferrosilicon factory, the floating ships and maintenance work of floating ships. The most common metals found in nature are iron and manganese. The kind and amount of dissolved organic matter, as well as the pH of the water, all influence iron concentration in fresh water (Vuori 1995). Fe concentrations exceeded the limits set by aquatic life (CCME 2007), but the study revealed that the concentration of manganese (Mn) in water measured during sampling was lower than the permissible limit in site 2in Edfu city and site 1. According to the USEPA1994, Fe and Mn are regulated as a secondary drinking water contaminant in public water sources that may create objectionable taste, odour, colour corrosion, or staining issues. In general, industrial effluents have a significant impact on the distribution of these metals in the study area
Smelting, fertilizers, and pesticides used in agriculture, soil erosion due to rainfall, fossil fuels, and land development activities are the main sources of Zn (Higgins et al. 2007). The manufacturing of nonferrous pyrometallurgical metals, steel, iron, coal combustion, cement production, and the accumulation of sewage sludge are all sources of lead waste. Lead is also found in a wide range of electronic devices. An estimated 96 percent of lead emissions come from human-made sources (Awalina 2011). The high concentrations of Fe found in the sediments may be mainly result from the natural deposits and industry (Laxon 1985).
Mn is involved in a variety of physiological processes in humans and other living beings. It's a crucial part of enzymes (Crossgrove and Zheng 2004). Mn, which has a metallic taste and staining qualities, can be a nuisance if present in large concentrations (Jung and Vahter 2007). Mn generally affects the brain and central nervous system, causing symptoms such as decreased neurological and neuromuscular coordination (Agency for Toxic Substances and Disease Registry 2015). The present study revealed that increasing of zinc (Zn), Lead (Pb), Iron (Fe) and manganese (Mn) concentrations in sediment measured during sampling in site 2.This demonstrates the water way sediment was marginally contaminated by Zn, Pb, Fe and Mn in the study area.
Gastropods play a critical role in the aquatic system's metal cycles. They are eaten as food by some birds and fish, who are then eaten by humans as part of the food chain. In numerous freshwater Mollusca species, soft tissues were more successful in accumulating Fe, Mn, Zn, and Pb; this observation corresponds with (Gundacker 2000; De Wolf et al. 2001; Yap et al. 2003;Cravo et al. 2004). Metal concentrations in gastropods vary by species due to each species' unique ability to regulate or accumulate these elements (Christopher et al. 2010). The species-specific digestive physiology and metal absorption rate across gut epithelium could explain the inter-specific differences in metal assimilation efficiencies (Lee and Lee 2005). For a long time, gastropods have been thought of as bio-indicators and bio-monitoring objects. They are extremely resistant to a variety of contaminants, particularly heavy metals (Waykar and Petare 2016).
According to the current data, heavy metal concentration varies depending on the type of heavy metal, the species and the presence of metal in the natural ecosystem. In general, increases in metal levels in Mollusca tissue may be attributed to body size, reproductive period growth, physiological fitness, and metabolic rate changes. These are in agreement with (Suryawansh 2017).
The current study's findings revealed a wide range of BAF values based on the metal type and organism. This is due to mollusks' ability to tolerate persistent harmful substances, such as metals, to a larger extent than other creatures, and their ability to function as good biomonitors or indicators (Rehman et al. 2016). These findings matched those of Kowalczyk and Czepiel (2013) and Rehman et al. (2016), who investigated the accumulation of several heavy metals in soft body mass. BAF shows the contamination of the fresh water and sediment with heavy metals this agree with (Karlsson et al. 2002)
Acute toxicity studies are short-term assessments of the effects of chemical exposure at relatively high concentrations. In most cases, the measurement endpoint represents the degree of lethality. Deaths that occur during a specific time period, usually (24 to 96) hours, are recorded. By comparing the % mortality of organisms exposed to site media to the percent mortality of organisms exposed to uncontaminated medium, the results can be examined.LC50: estimate the concentration of the medium at which 50 percent of the organisms died (United States Environmental Protection Agency 1994). One hundred percent of control animals maintained in dechlorinated tap water survived throughout the experiment for Lanistes carinatus.
A few studies had reported on the acute toxicity of metals to fresh water Mollusca, showed that 96 h-LC50 of Pb were 6.82 mg/l (Shuhaimi-Othman 2012), 14.0 mg/l (Cairns et al. 1976), 2.54 mg/l (Gadkari and Marathe1983)., Zn were 3.90mg/l (Shuhaimi-Othmanet al.2012), 10.49 mg/l (Khangarot et al. 1982), 0.64 mg/l (Gupta et al.1981)., Fe were8.49 mg/l (Shuhaimi-Othman et al.2012),12.09 mg/l (Birge et al. 1985), 76.0 mg/l (Nishiuchi and Yoshida 1972). Mn were 45.59mg/l (Shuhaimi-Othman et al. 2012), 100.0 mg/l (Tomasik, et al. 1995).
In comparison with other taxa, to Lanistes carinatus show less sensitivity to metals. Other studies show different results of toxicity with different snails. According to Luoma and Rainbow (2008) the order of toxicity of metals will vary between organisms. Khangarot and Ray (1987), showed that the order of toxicity was Cd > Ni > Zn; with Viviparus bengalensis, Gupta et al. (1981) and Gadkari and Marathe (1983); Nebeker et al. (1986). found that the order of toxicity was Zn > Cd > Pb > Ni.
Bioconcentration of Zn, Pb, Fe, and Mn in surviving Lanistes carinatus data obtained from live snails increases with increasing concentration exposure. Similar results were reported by Moolman et al. (2007) on Cd and Zn accumulation by two freshwater gastropods (M. tuberculata and Helisomaduryi). These results are in agreement with the statement of Luoma and Rainbow (2008) who state that the uptake of trace metals from solution by an aquatic organism is primarily concentration dependent. The higher the trace metals dissolved content, the greater the metal's absorption from solution into the organism, until the uptake mechanism becomes saturated. Cu, Pb, and Cd were the most abundant metals in freshwater snail tissues in dams and rivers in southwest Nigeria, according to Adewunmi et al. (1996). This is in line with the findings of the current investigation, which revealed that Cu was the most hazardous to the snail. However, a comparison of the uptake rate in aquatic organisms showed that in general the order of the uptake rate constant is Ag > Zn > Cd > Cu > Co > Cr > Se (Luoma and Rainbow 2008).
Invertebrates' metal-accumulation techniques differ interspecifically for the same metal in closely related organisms (Rainbow and Dallinger 1993). This study indicates that Lanistes carinatus could be a potential bioindicator organism of metals pollution and in toxicity testing. In ecological risk assessments of aquatic environments, biomarkers that use enzyme activity measurements to detect sublethal levels of pollution are becoming more common. These biomarkers have the ability to detect the occurrence of contaminated exposure (Berra et al. 2002). The stimulation of detoxifying enzymes capable of digesting the xenobiotic or the reduction in activity of enzymes sensitive to xenobiotic inhibition are examples of biochemical alterations (Callaghan et al. 2002).
ROS generate new radical species, resulting in chain oxidation. All of the cell's biomolecules (nucleic acids, lipids, proteins, and polysaccharides) are potential ROS substrates (Manduzio, et al. 2018). For the deactivation and elimination of AOS, living organisms contain a variety of biochemical defense systems. The hydroxyl radical is the most common cause of LPO. It is the most reactive type of oxygen species that results from oxygen reduction. It is formed when chemical compounds (electron donors) interact with oxygen in the atmosphere (Bartosz 2003). Other mollusk field and experimental research have shown that a decrease in antioxidant enzyme activity and peroxidase pool induces an increase in LPO (Choi et al. 2001), which agree with our study.
The antioxidant catalase's efficiency changes based on the organism, the type of stressor, and the length of exposure, and it's utilized as an oxidative stress biomarker (Halliwell and Gutteridge 2007). The highest CAT activity, implying that this enzyme protects against oxidative damage. GST is the main enzyme involved in xenobiotic detoxification (Bukowska 2005). GST activity has long been recognized as a biomarker of pollution in aquatic settings in many biomonitoring studies (Cajaraville et al. 2000). While GST inhibition has been suggested to be a more particular response to a chemical challenge (Pennec and Pennec 2003). Metals can establish covalent interactions with the enzyme's molecular structure, rendering the enzyme inactive for the substrate (Walker et al. 2001). GPX is the most essential peroxidase for hydroperoxide detoxification. It is one of the most important antioxidant enzymes for protecting organisms from the harmful effects of oxyradical generation (Orbea et al. 2000). SOD is usually an organism's first line of defense against reactive oxygen species, and it plays an important role in protecting cells from oxidative damage. This enzyme converts a highly reactive radical, hydrogen peroxide, into a less reactive form of oxygen, molecular oxygen (Bafana et al. 2011).
The results of certain biochemical markers (LPO, GPx, GST, SOD, and CAT) assessed in the soft tissue of Lanistes carinatus, a good environmental sentinel, are reported in this work. As a result, changes and differences in biomarker levels in toxicity tests between the four sites and the treatment groups may be connected to the severity and duration of the stress exposure. In Lanistes carinatus, statistical analysis (LSD) of enzyme activity revealed variations between treated groups and different sites. This demonstrates the impact of stress exposure intensity and duration on (LPO, GPx, GST, SOD, and CAT)
For species classification, genomic mapping, and phylogenetic analysis, the RAPD approach is already widely utilized. Furthermore, its application in examining genomic DNA for evidence of various types of DNA damage and mutation suggests that RAPD-PCR could be used as a biomarker for detecting damage and mutational events in bacteria, plants, and mammals. It is used in genotoxicity, carcinogenesis investigations, and environmental toxicology study as a useful inquiry method. The comparison of profiles generated from control and treatment DNA is used to detect genotoxic effects using RAPD. The genomic template stability is determined by RAPD and is related to the extent of DNA damage (Pal 2016). Kore and Aras (2011) employed the RAPD test to track DNA alterations caused by heavy metals like lead, cadmium, and copper. Cr, Ni, Cu, Zn, Cd, Pb, Hg, and as are among the most harmful environmental heavy metals and metalloids (Barakat 2011). In the present study, the RAPD-PCR technique was used to determine the potential acute (4 days) Zn, Pb, Fe and Mn genotoxicity in Lanistes carinatus.
In the RAPD-PCR analysis for Lanistes carinatus genome band did not appear in control and some other treated group due to primer mismatch or relative sequence abundance (Williams et al. 1990). on the other hand, Lee et al. (2007) found same intensities for band patterns were identified for most 10-mer primers, when analyzing DNA damage caused by arsenite this agree with Mona et al. (2013). Alterations in primer binding sites, as well as structural variations caused by heavy metals exposure, can cause changes in RAPD patterns in the treated groups. These DNA impacts are likely attributable to an increase in free radical activity or free radical life span in organisms exposed to heavy metals, and Reactive Oxygen Species could impair the antioxidant defense mechanism. (Guier et al. 2006). Different and distinctive finger pattern were obtained from Lanistes carinatus DNA under investigation. Primers used in Lanistes carinatus DNA exposed to Zn, Pb, Fe, Mn yielded RAPD patterns differ from the control samples. This indicated that DNA from samples exposed to Zn, Pb, Fe, Mn created polymorphic regions in Lanistes carinatus genome this agrees with Abumourad et al.2012.
Kumari and Thakur (2014), revealed that the changes in band intensity could represent the efficiency of amplification of certain regions, with a direct relationship between copy numbers and band intensity. Cytotoxic and nucleic acid damage, as well as DNA band breaks, are caused by reactive oxygen species (ROS).