Aquaponics: closing the cycle on limited water, land and nutrient resources

Hydroponics initially developed in arid regions in response to freshwater shortages, while in areas with poor soil, it was viewed as an opportunity to increase productivity with fewer fertilizer inputs. In the 1950s, recirculating aquaculture also emerged in response to similar water limitations in arid regions in order to make better use of available water resources and better contain wastes. However, disposal of sludge from such systems remained problematic, thus leading to the advent of aquaponics, wherein the recycling of nutrients produced by fish as fertilizer for plants proved to be an innovative solution to waste discharge that also had economic advantages by producing a second marketable product. Aquaponics was also shown to be an adaptable and cost-effective technology given that farms could be situated in areas that are otherwise unsuitable for agriculture, for instance, on rooftops and on unused, derelict factory sites. A wide range of cost savings could be achieved through strategic placement of aquaponics sites to reduce land acquisition costs, and by also allowing farming closer to suburban and urban areas, thus reducing transportation costs to markets and hence also the fossil fuel and CO2 footprints of production

Determination of salinity tolerance limits of tilapia, Oreochromis mossambicus, for use in tuna line fishery

Assignment (MPhil)--Stellenbosch University, 2003.ENGLISH ABSTRACT: Many species of tilapia such as Oreochromis mossambicus are euryhaline, able to adapt to different salinity waters. Their ability to withstand high salinity levels has given rise to the possibility of using tilapia as baitfish for tuna line fishery. The purpose of the study was to determine the survival rate of tilapia O. mossambicus during direct transfer from freshwater to the salinity levels of 0, 15, 20, 22.5, 25, 27.5, 30, 32.5, and 35 ppt. The data was analysed through means of univariate ANOVAand regression analysis. O. mossambicus showed no mortality to all salinity regimes up to 25 ppt. Mortality was observed at 27.5 ppt, with 100% mortality at 35 ppt. LC 50 and LC 90 were found to be 30.5 and 34.2 ppt, respectively. The results indicate that tilapia (0. mossambicus) will survive a direct transfer to salinities up to 25 ppt. acclimation will be required in the event of transfer to salinity levels above 25 ppt, in order to prevent significant levels of mortalities.AFRIKAANSE OPSOMMING: Meeste van die tilapia spesies soos Oreochremis mossambicus het die vermoë om by water van verskillende soutgehaltes aantepas. Dit is hierdie vermoë om hoë sout vlakke te weerstaan wat die moontlikheid vir gebruik as lewende aas in die tuna langlyn visvangbedryf moontlik maak. Die doel van hierdie studie was om die oorlewingsvlak van tilapia, O. mossambicus te bepaal by die oorplasing van varswater direk na soutwater by vlakke van 0, 15, 20, 22.5, 25, 27.5, 30, 32.5, en 35 dele per duisend. Die data is verwerk deur gebruik te maak van eenvariant ANOVAen regressie analises. O. mossambicus het geen mortaliteite tot gevolg gehad by al die oorplasings van vlakke tot en met 25 dele per duisend sout nie. Mortaliteite is wel gevind vanaf 27.5 dele per duisend, met 100 % mortaliteite by 35 dele per duisend. LC 50 en LC90 was gewees 30.5 en 34.2 dele per duisend onderskeidelik. Die resultate toon aan dat tilapia (0. mossambicus) sal oorleef by direkte oorplasing na soutwater by vlakke van tot en met 25 dele per duisend. Tilapia wat na hoër vlakke as 25 dele per duisend oorgeplaas wil word, sal eers geleidelik moet akklimatiseer om mortaliteite te beperk

Life cycle assessment of food products

Life Cycle Assessment (LCA) provides a rigorous framework to assess a product against a range of environmental impact categories from the ‘cradle to the grave’. LCA sets out a clear method for analysis, including goal and scope definition, Life Cycle Inventory (LCI) development, Life Cycle Impact Assessment (LCIA) and interpretation. This article provides an overview of each of these LCA phases, with a specific focus on food and agriculture. We provide a summary of LCAs applied to food and agriculture, as well as insights into LCA’s function in providing a more food secure future.</p