INTRODUCTION AND LITERATURE REVIEW
Fisheries serve as an important source of food, income, employment, and recreation in the world (Allison, 2001). Appreciation of aquatic ecosystems has been accompanied by concern about the effects of increasing human populations and activity on aquatic life and the quality of water (Liouset al., 1996). Fish farming is of high importance contributing to the sustenance of man through its products like crustaceans, fishes, molluscs. Williams, 1996 reported that it is the cheapest source of protein. Man-made toxic chemical are released into aquatic environment during production, utilization and transportation, hence pose a threat to living biota. Therefore the assessment of environmental hazard due to toxic substances is an important challenge to toxicologist and eco-toxicologist.
Water is an abundant natural resource that is important to human activities, comprising of 70% of earth surface that is essential to all forms of life and makes up 50-97% of the weight of all animals and plants(Allan, 1990). The significance of water to plant and animal cannot be over emphasized. Despite its importance, water is one of the most misused resources in the world (Chutte, 1998). Water quality is closely linked to water use and to the state of economic development (Chennakrishnanet al., 2008). There are numerous economic and scientific facts thatwater shortage or its pollution can cause decrease in productivity and deaths of living species.
Pollution also means the discharge of unwanted material into the environment (air, water or land). Pollutants are substances which causes pollution. It is also the release of harmful substance into the environment that can cause discomfort, instability and disorder to the system and organism that lives therein. They could occur in natural or unnatural substances released into the environment by
human activities. The growth of human population, industrial and agricultural practices is the major causes of pollution. The aquatic environment where aquatic organisms and fishes live is subjected to different types of pollution hence introducing stress to aquatic creatures. Stress reaction includes alteration in blood composition and immune mechanisms, decreased growth, decreased mobility, low productivity, disease outbreaks and mortality in aquaculture. Water pollution occurs when unwanted materials with potentials to threaten human and other natural systems find their ways into rivers, lakes, wells, streams, boreholes or even reserved fresh water in homes and industries.
Effluents are waste water, unwanted fluids and chemical in liquid forms that are discharged as industrial waste. Textile effluents are known toxicants, which inflict acute disorders in aquatic organisms. Textile industries utilize substantial volumes of water and chemicals for wet-processing of textiles. These chemicals, ranging from inorganic compounds and elements to polymers and organic products are used for desiring, scouring, bleaching, dyeing, printing, and finishing [Rajamohan and Karthikeyan, 2004]. There are more than 8,000 chemical products associated with the dyeing process listed in the Colour Index, including several structural varieties of dyes, such as acidic, reactive, basic, disperse, azo, diazo, anthraquinone based and metal-complex dyes [Melvin, 2006]. The bio-accumulation of organic and inorganic toxicants depends on availability and persistence of the contaminants in water, food and physiological properties of the toxicants. The aquatic vertebrates such as fish live in an intimate contact with the environment through the gills making them susceptible to aquatic pollutants. Gills are the primary organs for the respiration, ionic and osmoregulation and acid base balance. Due to this environment the function of these organs may cause homeostatic disorders. Some physiological functions may breakdown compensatory responses to maintain homeostasis, at least overall life performance of animal. Since most of these dyes are toxic in nature, their presence in industrial effluents is of major environmental concern because they are usually very recalcitrant to microbial degradation [Ugoji and Aboaba, 2004).
A highly toxic substance with low toxicity generally require large dose to produce mild symptoms. Toxicity could either be chronic or acute (Heath, 1991). Normal physiological processes are affected long before death of an organism hence the need for physiological and biochemical indicators of health and sub-lethal toxicant effect (Nusseyet al., 1998). Acute toxicity is the ability of a substance to cause adverse health effects resulting from long term exposure to the substance. Fishes have the ability to metabolize most of these pollutants in their blood, livers and gills, where uptake of these pollutants may cause disease and interrupt the normal physiological functions. These changes may affect respiration, swimming performance, gill, gut, decrease in heartbeat rate, habit alteration, and tissue damage (Borden, 1982, Tanternet al., 1997).
Citrus fruit peel is a rich wellspring of flavonoid,coumarins, glycosides and volatile oils which could efficiently be used as drugs or food supplements. Most of the chemicals are known to have some disease preventive properties and hence, they offer protections against pathogens and serves as antibacterial.
Fish species serves as a major test organism in eco-toxicological assessment because of their link to man in the food chain. They are useful in assessing waterborne and sediment deposited toxins where they provide warning of the potential danger of chemicals and the possibility of environmental pollution. Heteroclariasis a species of the Catfish family Claridae with fast growth rate (Kamastra and Ending, 2001).Comprise the most commonly cultivated fishes in Nigeria. The growth of aquaculture in Nigeria now is likely being boosted by a steady rise in catfish culture. Inadequate availability of seed for stocking and feed used to be major problems. Their ability to pond conditions, tolerate crowded conditions, accept artificial feeds and possess high quality flesh have enabled it to gain tremendous population as a cultured fish.
Fish haematology is of great importance in fish culture because of its importance in monitoring the health status of fish since they are sensitive to stress.Haematological parameters are those parameters related to the blood and blood forming organs. They range from giving the level of the blood to detecting health disorders through them. Gorgen and Levene (2003) reported that biochemical changes as a result of toxins have effect on haematological parameters. Fish blood comprises of two main types; erythrocyte (RBC) and leucocyte (WBC) which both develop from haematoblast precursor cell and mature after getting into the blood stream. Erythrocytes are most abundant in fish blood containing haemoglobin that aids oxygen transfer to various parts of the body since blood is the most abundant in the body. Haematological variables remain an important tool in determining the sub-lethal concentration of pollutants in fish. The most common haematological variables measured during stress include red and white blood cells count, haemoglobin content, haematocrit value and red blood cells indices.
Yakeenet al., (2011) reported a significant reduction in red blood cell and haemoglobin exposed to DDT within a period of 60days using four sub-lethal concentrations (0.0005, 0.0010, 0.0025 and 0.0050 ppm), variations in values of MCH,MCV and MCHC was observed. Impact of textile industry effluent onPoeciliarecticula causes abnormal behavior including erratic swimming, rapid opercular movement and thick mucus secretion (Selverajet al., 2015). Also a study was conducted on the impact of textile dye effluent on some haematological parameters of freshwater fish Oreochromis mossambicus (Ante and Mhaskar, (2015).A review of literature on fish showed that little work had been done on the alteration of blood constitutions following exposures of fish to dye effluent. The harmful effect of dye effluent pollution on fish haematology may depend on the duration of exposure (chronic or acute). However, information on the use of orange peel in the amelioration of t effect caused by dye effluent on heteroclarias juvenile is not immense hence, this work is aimed at experimenting the amelioration level of orange peel on the effect of dye effluent on Heteroclarias.
OBJECTIVE OF THE WORK
The aim of the research work is to evaluate the haematological effects from acute and chronic exposure of Heteroclarias (hybrid catfish) to different concentrations of dye effluent hence, deducing the tolerance level and the ameliorative effect of orange peel on the haematological parameter of juvenile Heteroclariasspecies.