Cape sea urchin Parechinus angulosus faeces as a functional feed for hatchery-produced Haliotis midae abalone

The Cape sea urchin Parechinus angulosus offers shelter, food and possibly microorganisms to juvenile abalone Haliotis midae along the South African coastline. To assess whether sea urchin faeces benefit hatchery-produced H. midae performance, a two-month experiment was conducted at a commercial abalone farm. The trial consisted of two sets of three tanks, where juvenile abalone were fed a mixed diet of diatoms, formulated feed, Ulva and Gracilaria, with one set of tanks supplemented with sea urchin faecal matter and the other not (control). Metagenomic samples (n = 75) included incoming seawater (500 mL) that was collected on filters, sea urchin intestines and faecal matter, abalone intestines and faecal matter, as well as each of the feeds.