Nutrient source, light availability, and a host of other environmental parameters will affect the physical and chemical characteristics of macroalgae. When macroalgae is being grown for a specific purpose (e.g. uptake nutrients in a settling pond, or making carrageenan), the environmental parameters of the culture system should be controlled, or at least monitored, as they affect the seaweed’s ability to provide the service or make the compound of interest.
To better understand how several species of tropical macroalgae react to different culture conditions, Ocean Era, Inc (OEI) undertook a series of experiments exposing four types of tropical macroalgae (Caulerpa lentilifera, Ulva lactuca, Halymenia hawaiiana, Gracilaria parvispora) to different sources of nutrients. The nutrient sources were either effluent water from a marine finfish aquaculture system (high in ammonia), or deep seawater (high in nitrite + nitrate). Growth rate, proximate analysis, and C:N ratios were analyzed to understand the effects of the conditions.
Macroalgae’s ability to “clean up” finfish effluent is well documented, but there is little information about the safety of that macroalgae for human consumption. To that end, OEI, and partners at the University of Hawai’i Mānoa explored the microbiome associated with seaweed grown in different conditions. Additionally, we examined how fish effluent water might affect levels of potentially pathogenic bacteria.
This presentation will provide an overview of the work that took place over 18 months, covering 10 separate trials, conducted at OEI’s facility in Kona, HI. Basic culture system information, performance metrics, resultant nutritional data, and microbial species data will be discussed.