A review of the use of spores for the supply of high quality Kappaphycus alvarezii seedlings
Optimizing the seed production process is very important for the success of seaweed cultivation. Red seaweed can reproduce by spores. Spores are part of the seaweed life cycle; they are single-celled and function like the seeds of vascular plants. There are various potential advantages of using spores as seeds in the seaweed cultivation industry, especially in the red algae or Rodophyta. A series of studies on the effect of salinity, temperature, light colour, and type of artificial substrate on Kappaphycus alvarezii spore release and development were carried out in 2013 and 2014 at Hasanuddin University, followed in 2015 by experiments on growing spores into adult plants in the sea in Takalar Regency, South Sulawesi. Both temperature (optimal range 31-35 °C) and salinity (optimal range 30-35 ppt) had a significant effect on spore release, survival as well as plantlet growth and morphology, while green light proved unsuitable. In the sea, high quality thallus was produced in around 8 weeks. Predation by fish, crabs, and molluscs was a challenge. Once pest problems were overcome the seedlings grew well. They were densely branched with relatively large branch diameter and pointed tips, a turgid dense texture and a bright shiny colour, characteristic of good quality seaweed seeds. After 12 weeks of co-cultivation with seaweed farmers, the harvested yield of seaweed from spore-grown seeds was clearly superior to that from vegetative thallus cuttings in terms of quality (e.g. colour and branch morphology) as well as quantity. Spore-based culture shows great promise for K. alvarezii as well as other seaweeds, including Gracilaria sp.