TUBULAR NETS- AN INNOVATIVE TECHNIQUE OF PRODUCING THE HIGHER VALUED SEAWEED Kappaphycus FOR COASTAL COMMUNITIES IN TANZANIA  

Kappaphycus production in Tanzania has decreased in the last fifteen years because of its vulnerability to environmental changes when cultivated using the traditional shallow water off-bottom method. A new innovative technique -the tubular net technique - was studied for one year to test its viability as a novel method of cultivating Kappaphycus in deeper waters (1 - 3 meters at low tides) in Zanzibar, Tanzania.

Results showed that tubular nets can be used effectively to cultivate Kappaphycus with monthly average specific growth rate (sgr) of 2.1±0.1 d^-1 recorded in July 2015 to 12.6±4.7 % d-1 recorded in September 2014. In the off-bottom, sgr was 2.0±0.2 % d^-1 to 10.3±4.5 % d^-1. Water temperature averaged 29.0±0.4 - 32.7±0.4 ⁰C in the deep water and 29.0±0 - 34.0±1.1 ⁰C in the shallow water depending on the season. Salinity averaged 26±0 - 35±0 ‰ in both cases.  

Nutrient concentrations (ammonia, phosphate, and nitrate) maximised at 5.5, 0.9, and were higher in the shallow than deeper water (Table 1). Breakage of the seaweed was 30% in the deeper water compared with up to 80% in the shallow water, depicting the suitability of the tubular net method in cultivating Kappapphycus in Tanzania.