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THE EFFECT OF SUB-LETHAL DOSES OF CYPERMETHRIN ON THE HISTOPATHOLOGY AND HAEMATOLOGY OF CLARIAS GARIEPINUS
In urban aquatic environments, fish may be exposed to myriad of substances at the same time produced by different kinds of anthropogenic activities. Biological changes in fish that are related to the exposure or to the effect of contaminants are called biomarkers and their use has led to good results on environmental risk assessment (Vander Oost et al., 2003).
Water is an important determinant of the socio-economic development (El-Nagger et al., 2016). It is the supreme fluids that promotes the human health and maintain the integrity of natural ecosystem. Water stimulates the biochemical processes of living organism and reduces the toxic effects of a broad spectrum of pollutant (Majumder and Dulta, 2014; Singh, 2014, El-Naggar, 2016). To function properly, water needs to be of adequate quality and free from harmful substances.
Addition of unwanted substances into the water bodies cause changes in the physical, chemical and biological characteristics of the aquatic system which lead to ecological imbalance.Industrialeffluents contribute a lot to water pollution forming a threat to aquatic plants and animals (Ramona et al., 2001). A greater part of the pollutants exhibit biomagnification and bioaccumulation capabilities with a broad spectrum of impacts, and stresses on aquatic organisms (Censi et al., 2006).
The pollution leads to a steady decline in the aquatic flora and fauna, particularly fishes. Wedemeyer (1996) reported that the fishes are more susceptible to stress than many other animals because of their intimate dependence upon their surrounding environment.
Industries are major sources of pollution in all environments. Based on the type of industry, various kinds of pollutants can be discharged directly or indirectly into the environment (Tilt, 2013). Waste water from industry may include sanitary waste of employees, processing waste from manufacturing plants, water emanating from washing the factory floor as well as those utilized in various cooling systems (Awaleh and Soubaneh, 2014). This may vary widely depending on the size of the industry and what is being produced.
The use of physiological and biochemical parameters as indicators of water quality has recently been developed to detect sub-lethal impacts of pollutants. Prominent among these biomarkers according to Lohneret al., (2001) and Cazenaveet al., (2005), are haematological data and physiological variables, such as plasma levels of metabolites as documented by Digiulioet al., (1995) and ions (Engelhardt et al., 1996; Martinez and souza, 2002), levels of hormones like cortisol (Hontela et al.,, 1996; Barton et al., 1998; Hontela, 1998; Benguira and Hontela, 2000) and biochemical variables such as detoxifying enzyme activities (Paris – palacioset al., 2000; Teleset al., 2003).
Increased indiscriminate disposal of pollutants or toxicants such as fertilizers, herbicides, pesticides, insecticides, among others into water bodies in recent times, calls for serious concern by regulatory authorities (Warren, 1977). IPIECA (1991) documented that in most countries, pollutants are constantly allowed to drain into the aquatic environments with little or no treatment given to reduce toxicity. These could possibly contribute to additional stress on the environment and the aquatic biota (Das, 2003; Fakayode, 2005).
As a result of high water solubility; low persistence and extensive usage of the insecticide in the environment, exposure to non-target aquatic organisms is a source of concern (Odo et al., 2017). Leilan et al. (2017) suggested that indiscriminate or misuse of the insecticide or discharge of untreated effluents into natural water ways, have harmful effect on the fish population and other aquatic organisms and may contribute to long term ecotoxicological effect in resident aquatic organisms. As noted by Food and Agricultural Organization, FAO (1984), the proper management of natural water bodies’ demands that, water of suitable quality and condition be provided for use by man and animals.
Essien-Ibok et al., (2019) reported that toxicity expresses the degree to which a substance is poisonous, destructive or generally harmful to life. Poisons or toxicant are chemicals which have harmful or adverse effect on living organisms and the study of toxic substances is known as toxicology (Essien-Ibok et al., 2019). After exposure to pollution or toxicant, fish may exhibit alterations in metabolism and biochemical processes (Ajani and Awogbade, 2012). Histopathological analysis has already been tested and proposed as an efficient and sensitive tools to the monitoring of fish health and environmental pollution in natural water bodies (Gaber et al., 2013; Coasta et al., 2009).
Blood is the most essential and abundant body fluid and is a vehicle for quick mobilizing defense against trauma and ailment (Bamidele et al., 2018). Its composition often reflects the overall physiological disorder and extensively used in Ichthyology research, aquaculture research as well as toxicology and biological monitoring (Adedeji et al., 2008; Adeyemo, 2008). Changes in haematology also aid in diagnosing the structural and functional status of faunas exposed to the toxicants (Suvetha et al., 2010; Chaudhary et al., 2015; Prasad et al., 2015).
Bamidele et al. (2018) also reported that the significant decrease in PCV may be described to gills damage osmoregulation leading to anaemia haemadillution. The decline in RBCs might be attributed to decline erythropoietic activity (Gluszak et al., 2006).Many studies have shown that hematological parameters can provide satisfactory information on physiological parameters of fish to environmental stressors and presence of contaminants, for example exposure to metals; for two major reasons namely, the close association of the circulatory system with the external environment and the ease of availability of fish blood (Cazenave et al., 2005, Li et al., 2011 and Gaber et al., 2013).
Hematology as well as biochemical parameters are important biomarkers for assessing the health status of animals (Iheanacho et al., 2018; Yaji et al., 2018). Nwani et al. (2015) reported that negative heath conditions such as disease, physiological and metabolic dysfunctions including stress can be assessed via hematological and biochemical indices.
Histopathological analysis has already been tested and proposed as an efficient and sensitive tool to the monitoring of fish health and environmental pollution in natural water bodies (Gaber et al., 2013). Vander Oost et al. (2003) also recognized histopathological analysis has reliable biomarkers of stress in fish (Vander Oost et al., 2003, Elahee and Bhagwant, 2007).
Study revealed that when the aquatic quality is affected by contaminants, any physiological variation will be revealed in value of one or more haematological parameters of aquatic animals (Akinrotimi et al., 2007; Gabriel et al., Bamidele et al., 2018).
The hematological studies in fishes have assumed greater importance because these parameters were used as an efficient and sensitive index to monitor the physiological and pathological changes induced by natural or anthropogenic factors such as bacterial or fungal infection or pollution of water resources (Barcarolli et al., 2004). Blood parameters therefore considered as a useful tool in diagnosing the functional status of the body in response to various stressors (Omar et al., 2014). The toxicants are stressors which are accumulated in the fish through the food chain or absorption through the general body surface and severely affect the life supporting system at molecular and biochemical levels. The Pollutantsgenerally produce relatively quick changes in hematological characteristics of fish (Johansen et al., 1994; and Rizkallaet al.,1999).
Histological studies have been considered as the tool for evaluating the toxic effects in target organs of fish in laboratory experiments and in the field experiments (Wester and Canton,1991; Schwaigeret al., 1992 and Dutta, 1996). Gills are the primary site for oxygen uptake in fishes and these delicateorgans are in contact with chemicaltoxins that cause stress exacerbated. Similarly, liver, the detoxification site and the intestine through which all the toxicants pass through, can produce histopathological changes in fish.
1.1 Statement of Problem
The world is presently faced with challenge of feeding ever growing human population. The high demand for food has necessitated extensive use of agrochemicals (fertilizers, pesticides and herbicides) to boost food production, in order to meet demand. These chemicals when applied boost agricultural productivity with improved crop and animal production through pests and insects elimination.
Cypermethrin is a synthetic pyrethroid used for the control of ectoparasites which infest cattle, sheep, poultry and some companion of animals. Cypermethrin has become one of the most important insecticides in wide scale used (Boxaspen and Holm, 2001 & Treasurer and Wadsworth, 2004). It has widely use recently in control insects in cotton, cereals, vegetables and cotton, cereals and vegetables and fruits, for food storage in public health and animal husbandry. Unfortunately due to extensive use and/or misapplication, Cypermethrincan diffuse into aquatic ecosystem through surface run-offs. On reaching water bodies, these toxicants are easily absorbed by organism through consumption, respiration and skin (Asuwaju et al., 2014). Studies shows that organisms exposed to Cypermethrin exhibit deleterious behavioral, physiological, immunological, histological and haematological changes and later lead to cell damage (Omitoyin et al., 2006). And indirectly through consumption affect human being.
1.2 Description of Test Organisms
The species, Clariasgariepinus belong to the phylum chordate, the family of clarridae and is one of the most widely cultured catfish in Nigeria (Essien-Ibok et al., 2019; Ariweriokuma et al., 2011). They are found throughout Africa and Middle East, and live in fresh water lakes, rivers, and swamps, as well as human-made inhabitants, such as oxidation ponds or even urban sewage systems. They have the ability to grow on wide range of artificial and natural foods, with good feed conversion efficiency (Akinrotimi et al., 2007. They are hardy and tolerant to low dissolved oxygen and other adverse culture conditions. It feed on living, as well as dead animal matter. Because of its wide mouth, it is able to swallow relatively large prey whole. It has been known to take large water birds such as the crawl on dry period time, between raining season. They are hardy and tolerant to low dissolve oxygen and other adverse culture conditions. Its body colouration varies from Olive green to brown and black with the flanks often uniform grey to olive-yellow with dark slate or greenish brown black. Other parts are pale olive to white and are mottled irregular with dark brownish green or uniform silvery olive. It is a heavy boned, flat headed fish with premaxilla and lower Joar pointed teeth arranged in several rows and four pairs of long trailing sensory organs known as ‘barbells’ around it mouth giving it a similar appearance to a cat, hence the name catfish. The African catfish is dominant freshwater fish. It can grow to a range between 1.4 and 2m long and can weigh anything from 8kgs to 59kgs. The South African angling record is 35kgs; however 58.9kg specimen was caught in the Vaal River. Spawning of catfish takes place mostly at night in the shallow, inundated areas of the rivers, lakes and streams (Anoop et al., 2009). Courtship is preceded by highly encounters between males. Courtship and mating takes place in shallow waters between isolated pairs of males and females. The male lies in a U-shape curved around the head of the female, held for several seconds. A batch of milk and eggs is released followed by a vigorous swish of the female’s tail to distribute the eggs over wide area. The pair usually rest after mating (from seconds up to several minutes) and then resume mating (FAO, 1984 &Adebayo and Daramola, 2013).
The term pesticide is composite term that includes all chemicals that are used to kill or control pest. In agriculture, these include herbicides (weed), insecticides (insects), fungicides (fungi), nematocides(nematode), and rodenticides (vertebratepoison). While agricultural use of chemical s is restricted to a limited number of compound s, agriculture is one of the few activities where chemicals are intentionally release into environment to eliminateagricultural pests, Over 98% of sprayed insecticides and 95% herbicides reach a destination other than their target species both in the land and in water(Miller, 2004). Pesticidescontaminates land and water when its escape from production sites and storage tanks, whenits runs off from field, when discarded, when sprayed aerially and when sprayed into water to kill algae (Tashkent, 1998). Some pesticides contribute to global warming and depletion of ozone layer (Rynolds, 2007).