Climate change: impacts and threats on freshwater aquaculture

This paper examines the major effects of climate charge on aquaculture, especially on the freshwater ecosytem. Aquaculture as established is not practiced evenly across the world. Therefore, the paper highlights the current aquaculture practices within the regions and across the different environments to ascertain the major effects of climate variations on the freshwater ecosystem and aquaculture practices in particular. The main elements of climate change that would impact on aquaculture produ ction, such as sea level and temperature rise, changes in monsoon patterns and extreme climatic events and water stress, among others were properly looked at and the reasons for their effects addressed. The different elements of climate change that are experienced in varying degrees can be either positive or negative or directly or indirectly, depending on the different culture systems that are practiced. It is in the process of our study that we brought out the complex attributes of climate change as it affects aquaculture productivity and the possible roles that the society can play to ameliorate the harsh effects of this ugly monstet; referred to as ”climate change and the consequent global warming trends

Effects of locust bean (Parkia bigtobosa) effluent on the histology of Clarias gariepinus juveniles (Burchell 1822)

The poor nature of most Agricultural processing practices in Nigeria have had adverse effect on our environment, and our aquatic resources are of no exception. This study was conducted to ascertain the median lethal concentration of the effluent within the 96 hours period and also to ascertain the extent of damage on some of the histological characteristics of the Clarias gariepinus juveniles. Juveniles of the Clarias gariepinus (mean weight 30g) were exposed to varied concentrations of the locust bean effluent under the standard laboratory conditions. Data on mortality corresponding to the various concentrations were subjected to the probit and logit transformations and used to calculate the LC50 graphically. The result shows the toxicity of the locust bean effluent to Clarias gariepinus juveniles as 0.089mg/L (treatment 4) during the period of study. Exposure to both the acute and subletheal concentrations resulted in a number of physiological dysfunction of the test fish. Observation of the fish under the tests revealed unbalanced swimming patterns loss of reflex, rapid opercular movements and gasping for air. Histopathological examination of the gill and liver of the treated fish showed signs of damage, ranging from Hypoxia, lesions, necrosis, fibrosis cell stasis and hyperplasia at the sublethal levels

Evaluation of rice-fish culture in south eastern Nigeria

A rice-fish culture trial was conduct in Umudike, Southeastern Nigeria, using FARO 44 rice variety Oreochromis niloticus and in six plots (198 m2 each'). Two treatments, sole rice and rice-fish culture were employed with each treatment replicated three times. Juveniles of O. niloticus with mean weight 12 g were stocked at the rate of 2/m2, four weeks after transplanting four- week -old rice seedlings using 20 cm inter and intra row spacing. Basal fertilizer (NPK 20:10:10) was applied at the rate of 300 kg per ha while 20 kg per ha urea was used as top dressing. Brewery spent grain was used as supplementary feed at the rate of 2% body weight of fish once daily. The fish and rice were harvested after 80 days of culture and 108 days after transplanting, respectively. The rice fish culture gave an average yield of 1125.25 kg per ha and 2433 kg per ha for fish and rice respectively. The sole rice treatment had an average yield of 2510 kg per ha. Since the integration of fish in the rice plots did not significantly (P<0.05) reduce rice production, adoption of this system will not only lead to increase in animal (fish) protein production but also generate additional income to farmers