Culture of Hypnea musciformis (Rhodophyta, Gigartinales) on artificial substrates attached to linear ropes

Abstract

Hypnea musciformis is the only species so far exploited in Brazil as raw material for the production of k-carrageenan. Due to the erratic production in space and time, increasing harvest and transportation costs, experiments have been performed in order to assess the viability of H. musciformis mariculture.

In nature the species occurs as an epiphyte, and so mariculture using artificial substrates that simulated the natural host of the species was tried. These substrates were attached, at regular intervals, to linear ropes. In the sea, these ropes were stretched between cement blocks.

Seeding occurs naturally, by means of spores, or detached pieces of H. musciformis scattered in the water column that get entangled on the ropes. The best yields (0.54 wet kg m⁻¹ month⁻¹) were obtained with unthreaded rope substrates maintained in a vertical position by small rafts. Production is highest in the first 18 m off the rocky shore (0–2.1 m deep), at the highest substrate density utilized (10 m⁻¹), 2–3 months after installing the ropes in seawater. The main factor controlling seasonal production is water movement.