Development of an indoor seagrass nursery in the United Arab Emirates: mastering the cultivation methods of the seagrass species living in the hottest sea on Earth.

Despite the extreme environmental conditions of the Arabian Gulf, three species of seagrass are observed in its coastal waters, Halodule uninervis, Halophila stipulacea and H. ovalis. These species are forming large seagrass beds representing up to 6% of the worldwide meadows. The Gulf’s seagrass meadows are supporting the World second largest population of dugongs, Dugong dugon. They are also playing a vital role in this vegetation-scarce region as blue carbon ecosystems, alongside the mangrove forests. Based on all these reasons, scientific interest is growing rapidly to understand the mechanisms behind their resilience to heat as well as to develop large scale effective restoration methodologies.

An aquaculture system has been designed to support the development of optimum indoor cultivation methodologies of the local seagrass species. The Recirculatory Aquaculture System is based on aquaponic principles with water from large fish tanks feeding into the seagrass raceways. Temperature and salinity are controlled in the fish tanks while lighting, water depth and currents are adjustable in the raceways. The current trials are aiming to define the optimum cultivation conditions focusing on the light intensitya and spectrum, the sediments characteristics and the nutrient inputs.

Samples from mixed meadows of H. uninervis and H. ovalis have been successfully maintained in this aquaculture system since their collection in winter time.The ability to control the water quality, the photoperiod as well as the light spectrum and intensity distributed over the seagrass raceways is critical to define the species growth optimums.

As little knowledge is existing about these seagrass species’ sexual reproduction in the Gulf, subsequent trials will be developped to pinpoint environmental conditions that could trigger their flowering in this indoor cultivation setting. The aim of the overall project is to enable the production of seeds that would support large-scale restoration programs in the Gulf region.