Abiodun Falade1, Peter Britz1, Clifford Jones1
1Rhodes University, South Africa
Abalone aquaculture in South Africa is land-based with much dependence on nutrient-enriched formulated feed. This production process generates large volume of dissolved and particulate waste nutrients capable of creating environmental pressure. In this context, a recommendation to mitigate the potential environmental impacts caused by abalone waste would be using and recycling these waste nutrients considered as pollutants, in an eco-efficient way, with methods such as the IMTA. This system integrates the culturing of organisms with different and complementary ecosystem functions. This study which forms a part of the European Union H2020 Aquavitae project aimed at examining the bioremediation potential and growth of the green seaweed, Ulva lacinulata cultured in an IMTA system with abalone and sea cucumber. For such, two systems were set up: (1) Ulva cultivated with abalone, (2) Ulva cultured with abalone and sea cucumber. Significantly the same growth rates of Ulva (20.56 – 20.02 % d-1) were recorded for both production systems (Student’s t-test = 2.56, p = 0.06). The daily biomass yield of Ulva farmed in abalone effluent was significantly higher than the yield of Ulva cultured in abalone-sea cucumber effluent (Student’s t-test = 2.97, p = 0.04). The TAN removal efficiency by Ulva cultured in abalone effluent (85.6%) was similar to that of Ulva (95%) cultured in abalone-sea cucumber (Student’s t-test = 1.59, p = 0.19). Likewise, phosphate uptake efficiency (50.01 – 52.78 %) of Ulva was similar for the two systems (Mann–Whitney U = 3.00, n1 = n2 =3, p = 0.66). This study shows that Ulva lacinulata is very efficient in restoring water quality of abalone effluent and useful in alleviating the environmental impact derived from the high load of nutrients contained in abalone effluents.