Aquaculture Africa 2023

November 13 - 16, 2023

Lusaka, Zambia

SHORE BASED IMTA OF ABALONE, SEAWEED AND SEA CUCUMBER IN SOUTH AFRICA

  Peter J Britz , Clifford Jones, Emmanuel Falade and Heleen Senekal

 Department of Ichthyology and Fisheries Science

 Rhodes University, Grahamstown 6140 , South Africa

 p.britz@ru.ac.za

 



Improved integrated multitrophic aquaculture technology for co-culturing abalone (Haliotis midae ), seaweed (Ulva lacunilata ) and an indigenous sea cucumber (Neostichopus grammatus ) was developed on the Wild Coast Abalone farm in South Africa. The research formed part of the European Union H2020 ‘Aquavitae ’ programme to develop technology for the culture of low trophic species in the Atlantic Ocean region. A baseline assessment of energy and nutrient utilization efficiency was undertaken on the existing abalone –  effluent  Ulva culture system which provided fresh seaweed feed for the abalone. A series of trials  to improve the IMTA system were  undertaken  to  1) introduce a high value sea cucumber species to remove solid abalone tank waste, 2) improve the nutrient uptake efficiency of the culture  Ulva  and 3) evaluate the performance of the IMTA  Ulva  in a formulated abalone pellet.  The culture of seaweed in abalone effluent significantly reduced the demand for mineral fertilisers at Wild Coast Abalone as the dissolved nutrients in abalone wastewater provided (34-38%) of the nutrients required by IMTA seaweed .  The  Ulva  growth rate, yield and nutrient utilization efficiency was substantially improved by substituting 50% of the applied inorganic fertilizer with a live microbial fertiliser. Wild-collected sea cucumbers adapted well to captive conditions, readily consuming solid abalone waste and coming into spawning condition in early summer. The sea cucumbers performed best when provided with a sandy substrate.  Overall the results demonstrated that the IMTA technology can improve economic performance and reduce environmental impacts in respect of effluent nutrient discharge and carbon footprint.