The water quality and algal diversity of the stocked and unstocked ponds and the dam reservoir at Gesedaddo farms, Yola, Adamawa State, Nigeria, were assessed for ten months. Meteorological data were accessed from Modibbo Adama University of Technology, Yola. Physico-chemical parameters such as temperature, pH, transparency, conductivity dissolved oxygen, total dissolved solids (TDS),biochemical oxygen demand (BOD), magnesium, potassium, sodium, nitrates, sulphates, phosphates,and some trace elements (iron, copper, and zinc) were determined using standard methods.Thedrop count method was employed in algal microscopy. Algal diversityand species richness were determined using Margarlef and Shannon-Wiener indices. A total of forty algal taxa belonging to four divisions were found. They are Cyanophyta (26.47%), Chlorophyta (44.53%), Bacillariophyta (24.80%) and Euglenophyta (4.20%). All data were subjected to statistical analysis using Analysis of variance ANOVA, Duncan Multiple Range Test DMRT and Correlation coefficient. Tests of significance were done at P < 0.05 and P < 0.01 confidence levels. Water temperatures correlated positively with air temperatures, PO4, NO3, Fe, Na and Cu. Total hardness correlated negatively with pH, K, Mn and Zn. Air and water temperatures correlated positively with Navicula and Nitzschia spp. and negatively with Eudorina elegans and Trachelomonas spp.Seasonal variation of algal population revealed that Microcystis species a toxin producing blue-green alga was not recorded in wet season but were recorded in dry season. However, Micrasterias anindicator of clean water was recorded in the un-stocked fish pond. Phacus, Euglena, and Trachelomonas, indicators of organically polluted environment were recorded in dry season in the fish ponds but absent in dry season in the dam reservoir. The seasonal presence and absence of algal species in particular locations with the ambient physico-chemical parameters make them potential bioindicators for biomonitoring of the fish ponds. Anthropogenic activities in the catchment area affected the concentrations of chemicals in the dam reservoir and stocked fish pond. Chlorophycean indices were 0.96, 0.873 and 1.57 for the stocked fish pond, unstocked fish pond and the dam reservoir respectively, while the Myxophycean indices were 1.0, 0.839 and 1.80for the three locations respectively.These values suggest that fish ponds were oligotrophic and the dam reservoir eutrophic. The study recommends qualitative and quantitative studies of water quality for early signals of pollution for timely intervention.
Pond water is considered as one of the major sources of water for fisheries (Ekpenyong and Adeniyi, 1996; Mustapha, 2006; Chowdhury and Almamun, 2006). Pond fishery is practiced in the north-eastern part of Nigeria on a large scale for better augmentation of fish products and hence makes an interesting biotope for physico-chemical and biological studies.
The anthropogenic inputs of complex mixtures from neighboring communities and agricultural wastes, such as runoff of manures and fertilizers could lead to alteration of water quality (Mustapha, 2006; Garget al., 2009). Of primary concern of these anthropogenic activities is their effects on the water quality and aquatic life, hence water quality monitoring is of immense importance in the use of water bodies for the management of fisheries (Mustapha, 2006; Nweze, 2009a).
The practice of using cow dungand inorganic fertilizers to encourage algal growth in fish ponds is wide spread in pisciculture in Nigeria (Nweze, 2009b). The algae serve as food for zooplankton, fish fry, benthic vertebrate and other primary consumers that serve as food for fish (Ezenwaji, 2004). Excess nutrients cause the water body to become choked with organic substances exceeding the capacity of micro-organisms that recycle them. It ultimately leads to eutrophication and encourages rapid growth or blooms of algae (Chukwu and Odunze, 2006; Okebukola and Akpan, 2008; Akanet al., 2010).
Phytoplankton are of great ecological significance, since they comprise the major portion of primary producers in the aquatic environment (Nweze,2003;Barinova et al.,2008, Bellinger and Sigee, 2010). Human activities such as pond fertilization, fertilizers, pesticides and herbicides application as cultural practices of farm management;obnoxious fishing practices, effluent discharges, washing and bathing with detergent and soda soaps stimulate growth of algae.Some of these are thecommonest sources of human-induced water pollution that bring about eutrophication, hypoxia, fish kill, disruption of food web and changes in the community ecosystem (Mustapha, 2002, 2006; Krantz and Kifferstein, 2005; Garg et al., 2006a, Chia et al., 2011a).
Algae can equally be harmful as some species aretoxins producing, in particular the genera Microcystis,Oscillatoria,Aphanizomenon and Anabaena which cause serious problemsin aquaculture (Nweze 2009b). Some harmful algae in Nigerian waters had been discussed byKadiri (2000).
Man is currently harnessing phytoplankton forms for augmentation of food supply in fish ponds, nitrogen fixation in rice growing, pharmaceuticals, direct in food and food supplement, bioremediation and biomonitoring (USEPA, 1976; Borowitzka, 1995; Nweze, 2009a, andb; Kadiri, 2010). Knowledge of the algal diversity of the Nigerian aquatic environment is pertinent to meeting up of such demands.
Phycological information on Nigerian lotic and lentic systems is still scarce. The study of phytoplankton distribution in the Nigerian environmenthas been hindered by taxonomic difficulties, and more importantly, inadequate facilities for the relevant studies (Ekpenyong and Adeniyi, 1996; Opute, 2003; Kadiri, 2007).Despite these challenges, there is the need to track the trends that threaten our aquatic ecosystems, specifically pond habitats, and assess the influence of physico-chemical parameters on the algal diversity for stable aquatic ecosystem.
1.1 AIM AND OBJECTIVES OF THE STUDY
The aims and objectives of the study are to access and determine the water quality and algal diversity of fish ponds and Dam reservoir in Gesedaddo farms, Yola, Nigeria.
The specific objectives are to:
- Assess the water quality (physico-chemical parameters) of Gesedaddo farm’s fish ponds (stocked and unstocked) and dam reservoir;
- Identify the algae present in the ponds and dam reservoir;
- Determine the influence of season on algal diversity in the ponds and dam reservoir.
- Identify indicators for monitoring the water quality of the ponds and dam reservoir;
- Correlate the physico-chemical parameters with algal population of the various ponds and dam reservoir;
- Determine the trophic status of the ponds and the dam reservoir.
- Compare flora and physico-chemical (water quality) of the three locations.