Biophysical Properties of Waste Water From Fish Pond
Chapter One
OBJECTIVES OF THE STUDY
The objectives of the study are:
- To determine the physicochemical characteristics of fishpond effluents.
- To determine the microbiological properties of a fishpond effluent
- To alert fishpond farmers in Imo State on the need to stick to stipulated environmental guidelines and standards.
CHAPTER TWO
LITERATURE REVIEW
ENVIRONMENTAL IMPACTS OF FISH POND EFFLUENTS
Feed, unconsumed feed and metabolic waste products such as faeces, pseudo-faeces and excreta in intensive culture provide the largest source of nutrients that cause pollution (Seymour and Bergheim, 1992). Bergheim et al., (1994) reported that fishpond exist with suspended solid levels ranging from 1 to 100mg/1 during ‘normal’ operation but between 30 to 5800mg/1 during cleaning of ponds. Tsutsumi et al., (1992) reported that approximately 90% the feed given to fish results in discharge into the environment. In Thialand, it has been reported that 77.5% of nitrogen and 86% of phosphorus added to intensive ponds were lost to the environment (Macintosh and Philips, 1992). However, there is lack of data on the specific amount and quality of effluents loading from fishponds as well as to related ecological effects on receiving water bodies (Barg, 2014). Nevertheless, (Macintosh and Philips 1996), were able to identify the primary and second day effects from waste materials from semi-intensive and intensive fish culture systems.
Eutrophication of coastal water due to the discharge of effluent from fish farm which contains large load of organic matter nitrogen and phosphorus is well documented. Based on 10 current annual fish production of 150,000 ton and feed conversion ratio (FCR) of 1.5, the waste released from fish feed is estimated to be 131,250 tons organic matter, 8,400 tons of nitrogen and 3,150 tones of phosphors (Lin, 2012).
Ecological impact of eutrophication, as a result of excessive primary production may lead to lower biological diversity and highly imbalance trophic structure of biota in the system. Finally, the highly polluted environment resulting from continuous nutrient influx would make the water quality unsuitable as a source of water for fishpond. (Macintosh and Philips, 1992). According to SRAC (2015), the potential environmental effects of water discharged from aquaculture ponds include:
Organic matter in the effluent which may increase the oxygen demand of water downstream from the discharge. Nitrogen and phosphorus in the effluent may stimulate algal blooms in the receiving body of water. Solids in the effluent may settle in downstream from the point of discharge.
The effect on receiving waters will depend largely upon the volume and strength of effluents in relation of the volume of the receiving water body, as well as on the aquatic species present in the receiving water body. (SRAC,2015).
ENVIRONMENTAL IMPACTS FROM CHEMICALS
It has been discovered that the use of chemicals in aquaculture is widespread because no legal registration has been required for their use (Lin, 1998). Because of their importance in fish industry, various drugs and antibiotics were dumped into culture systems. Savas (1992) noted that, in southeast Asia, fish culture indulge in the overuse and abuse of the antibiotics and other drugs, to avoid massive mortality in culture ponds.
CHAPTER THREE
MATERIALS AND METHODS
SAMPLE LOCATION
Effluent samples were collected from fishponds located in Owerri Municipal area of Imo State.
SAMPLE COLLECTION
Two different water samples in duplicates from different levels were collected from the fishpond. The two were 0.3meters from the surface and another two samples were collected approximately 0.3 meters above the bottom with a manually operated water sampling machine-and were transferred to sterile water sampling bottles (SRAC, 2015).
MEDIA USED
The media used include; Sabourand Dextrose agar, MacConkey agar, Nutrient agar and Salmonella-Shigella Agar, for culturing and preparation of standard cultures as described by Cruickshank et al (1992).
CHAPTER FOUR
RESULTS
MICROBIAL LOAD OF FISH POND WASTE WATER SAMPLES ANALYZED.
The results on the microbial load of fishpond waste water samples analyzed are shown in Table 3.1. The result showed that the total heterotrophic bacteria count (cfu/ml) for the surface effluent and bottom effluent are 3.6 x 104 and 4.1 x 104 respectively. The result for total coliform count (cfu/ml) for surface effluent sample and bottom effluent sample are 8.6 x 103 and 1.3 x 103 respectively. The result for total fungi count (cfu/ml). for the surface effluent and bottom effluent are 1.8 x 103 and 1.3 x 103 respectively.
CHAPTER FIVE
DISCUSSIONS, CONCLUSIONS AND RECOMENDERTION
DISCUSSION
PHYSIO CHEMISTRY OF THE FISHPOND EFFLUENT
The results of physic chemical parameters were all with WHO standards which showed that the effluent quality will not significantly impact negatively on the environment. All the parameters analyzed were all present in both the surface and bottom sample. (SRAC, 1998).
The unobjectionable and repulsive odours were indication of purification and decaying of organic substances by microorganisms is the surface and bottom effluents (Aqua CRSP, 2005) according to Henry-Silva, (2006), the nitrates, sulphates and phosphate present in the effluent samples can increase the quantity of suspended solids and promote the enrichment of nitrogen, phosphorus and sulphate in aquatic systems and soil.
Thus, the potential impact of agriculture on the receiving water is eutrophication of the receiving water rather than a direct toxic effluent on animal or plant health downtrend from the discharge. (SRAC, 1998).
The high turbidity of the bottom effluent sample is due to loose particles present in the discharge and can be removed from the pond bottom around the pipe intake. (Soak et al, 1995). The main input of energy in intensive agriculture is fish feed, partly transformed into fish biomass and partly released into the water as suspended organic solids, carbon dioxide, ammonia, phosphates and other compounds (Boyd, 2003; True, et al., 2004; Baccarin and Camargo, 2005). The variation of nitrate from the surface effluent to the bottom effluent (0.8-mg/1), the insignificant variations might be due to the shallowness of the fishponds.
Though the effluent samples do not have high BODs values (1.5 and 1.60) mg/1, were not significantly high, the increase in the suspended solids and dissolved organic nutrients might be responsible (SRAC, 1998) the presence of heavy metals iron (1.20-2.65) and copper (1.34-2.80) are indication of conditions from feeds and pesticides added in the fish pond might increase in toxicity in the environment at higher concentrations.
MICROBIOLOGY OF FISH POND EFFLUENT
The bacteriology of fish pond effluent includes the isolated of bacteria genera; Klebsiella sp., Enterobacter sp., Shigella sp., Salmonella sp., E. coli sp., Yersinia sp., Citrobacter sp., Proteus sp., and Pseudomonnas sp., while the fungal isolate includes Aspergillus sp., Rhizopus sp., Absidia sp., Mucor sp., and Sporotrichum schenckii sp.
These genera of bacteria are not uncommon to aquatic environment and have been isolated by other workers from culture system (Ogbulie, 1995; Austin and Ausyin, 1987; Okafor and Nzeako 1985; Holt, 1984). The large consortium of bacteria isolated from the pond effluents potray the extent of food chain, intra specific independency and the nutrient levels (trophic states) of the pond, since these organisms may not grow in sterile water free from extraneous nutrients. This corroborates the work of Ogbulie (1995). Furthermore, the isolation of E coli is an evidence of past and present pollution of the culture systems with feacal pollutions, whereas the fungi isolated could be formed spent grain and other wet starch based fermenting feed supplement. These organisms have been reported in one form or another as fish pathogens (Austin and Austin, 1987). Thus, the presence of these organisms under a stressful rearing condition can cause a devastating loss of fish as a result of bacterial disease of fish.
Among these bacterial genera isolated from fishpond effluent, the genus Pseudomonas contains three species P. chloraphis, p anguslliseptic and p. fluorescence which have been reported to cause devastating diseases of rainbow, trouts, carp, eels and other fishes in Japan, Scotland and other parts of the world (Ellis et al., 1983; Ogbulie 1995) Staphylococcus sp., has been reported by Sugiyama and Kusuda (1981) as an important pathogens of fresh and marine fish species. Numerous other report also centered on the pathogenic role of other gram negative bacteria, especially the pigmented rod groups (Allen et al., 1983; Ogbulie, 1995). The gram negative rods have been credited with gill disease saddle-like lesion, culmunaries, fin rot and other disease conditions.
The conclusively elucidate the sources of these organisms, the feed and other supplements might be responsible for bacterial and fungal load (populations) other than incoming water to the fish pond. The association of these organisms of public health concern with feed supplements corroborates the work of Ward (1989). These organisms amongst other bacteria have been implicated in human enteric disease. According to the works of Ogbulie (1995), the spent grain, polluted and unpolluted feed samples had comparable microbial load with more fungi and yeast occurring in the spent grain than other blend of fish feed. The diversity of organism according to Ogbulie (1995) could be as a result of poor storage facilities, which may have lead to the contamination of the different blends of fish feed. Furthermore, the isolation of diverse group of bacteria from these blends of fish is as expected since these or other carbohydrates base, blood meal, chicken, pig/cow excreta, shells of mollusks and bone as source of calcium (Dupree and Hurner, 2013).
CONCLUSION
The results of the analysis of the biophysical quality of the fish pond effluents has shown that though the effluent might not pollute the environment significantly with physiochemical quality, it might increase the fertility of the soil by the addition of nutrients to the soil environment. The presence of heavy metals is an indication of toxic potential of the effluent to both the aquatic and soil environment and should be closely monitored to avoid devastating consequences.
RECOMMENDATION
The presence of microorganisms of public health importance and pathogenic to fish (responsible for fish diseases) is an indication that the water is contaminated with fish disease causing organisms. The fish feeds have been implicated and proper management of fish feeds should be utmost and uppermost in the management of fishponds to avoid disastrous consequences of colossal fish deaths and other related consequences. The feed quality should be properly checked before use and the feed should be kept away from moisture, exposure to contamination and should not be applied to the fishpond by the use of already contaminated mechanical systems. The fishpond water should not only be devoid of contamination before addition to ponds but should be of the proper quality. Extraneous materials should not be allowed to enter the fish pond because this could cause disease out breaks, the water should be changed, the fishpond properly flushed and antibiotics should be added to help in the elimination of pathogenic organisms.
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