Full life cycle cultivation of three local kelp species (Ecklonia maxima, Laminaria pallida and Macrocystis pyrifera) in an aquaculture setting in Small Bay of Saldanha Bay, South Africa

Abstract

Seaweed farming is a growing global industry with significant potential for environmental and economic benefits. While East and Southeast Asian countries dominate current production, interest and investment in kelp farming are expanding to other regions, including Africa. In South Africa limited information is available on the cultivation potential of the three local west coast kelp species Ecklonia maxima, Laminaria pallida and Macrocystis pyrifera. This study was conducted as part of the South African Kelp Farming Project (SA KFP) and is the first full life cycle cultivation of the three species in an aquaculture setting over the same 8-month period in Africa. All three kelp species were grown in the hatchery/nursery to ~ 1 cm in 49 days (at 15 ℃, a 16 h L:8 h D photoperiod, GeO2 in the first two weeks, half strength PES from the second week onward, spore concentration of 2000 spores mL−1 for E. maxima and L. pallida, and 5000 spores mL−1 for M. pyrifera). To overcome sedimentation and biofouling pressure at the grow-out site, an at-sea weaning step was introduced where juvenile sporophytes were grown for ~ 2 weeks to 2.0–2.5 cm. Results of the 6-month grow-out period demonstrated that all three species can be cultivated in an aquaculture setting but that a good understanding of the spatiotemporal variations in environmental and biological factors at any particular site is critical before full-scale operations are attempted. The methodologies used in this study provide a foundation from which a kelp farming industry in South Africa could potentially develop and improve on.