Performing Department
(N/A)
Non Technical Summary
Current Issue and Opportunity. Seaweeds are large, plant-like algae that grow in the ocean. Nearly 30% of global annual aquaculture production on a mass basis comes from seaweed, mainly from brown and red seaweeds. In 2019, over 35 million wet tons of seaweed were produced globally through aquaculture, mainly by Asian countries including China, Indonesia, Japan, and Korea. Unfortunately, the U.S. contributed less than 0.1% of this total. Gracilaria, a red seaweed, merits consideration as a priority emerging candidate for aquaculture development in the United States. Gracilaria species are rich in proteins, carbohydrates, and a diverse array of bioactive compounds including antioxidants. They are a quality source of food, food ingredients, and value-added products such phycocolloids used as thickeners in a variety of consumer products. G. pacifica is used as aquaculture feed for abalone, and Gracilaria species can also be integrated into multi-trophic aquaculture (IMTA) systems that contribute to restorative aquaculture practices.A critical barrier to red seaweed aquaculture development in the US is that the practices used in Asian countries to achieve scale and low cost cannot be duplicated in US coastal regions. For example, Gracilaria species in Asia are cultivated through manually-intensive inoculation and cultivation, and harvesting practices in the nearshore marine environment, such as planting in shallow ponds where seaweed plantlets are manually tied to rope lines. Although these operations have low productivity, they are economically feasible in many countries because labor costs are relatively low, environmental standards are relaxed, and the nearshore environment is made available for mass cultivation However, in the US marine coastal waters, more environmental regulation and natural resource policy factors come into play, and a low-cost manual labor pool is not readily available. Therefore, to work around these issues, this project will focus on land-based cultivation of red seaweeds, using engineered approaches that automate and intensify the productivity of the grow-out process.Methods and Approaches. The proposed research will support the development of sustainable aquaculture systems for intensified production of commercially-significant red seaweed in land-based cultivation systems. As described above, Gracilaria species are a source food as well as plant-based proteins and industrial phyco-colloids, which together constitute nearly 90% of biomass dry organic weight. The biomass is produced using non-potable seawater, carbon dioxide from air or waste combustion gases, and sunlight. This proposed project will address the USDA Aquaculture Program Area Priority relevant to the design of environmentally and economically sustainable commercial aquaculture production systems, focusing on the commercially-significant red seaweed Gracilaria as model system.The proposed research will focus on the combination of biological and engineering approaches to automate and intensify the grow out processes in land-based recirculating tanks, resulting in increased productivity and labor-saving production technologies designed to reduce risk for advancing the nascent red seaweed aquaculture enterprise in the United States. As part of this effort, robust cultivars for Gracilaria species of emerging commercial significance, G. pacifica and G. parvispora will be established, and scalable processes to grow these Gracilaria strains on modular mesh panels will be developed. These Gracilaria panels will be tested relevant industrial environments in collaboration with our private partner Oregon Seaweed to assess productivity and product quality. Based on the test results, economic analyses will be performed to estimate costs and target technical improvements for further cost reduction.The project includes extension and outreach efforts to support and promote the nascent red seaweed aquaculture enterprise in the Pacific Northwest region, including the initiation of a Red Seaweed Aquaculture Learning Group and a delivery of a workshop focused on land-based aquaculture of red seaweeds.Ultimate Goal. The ultimate goal of this project is to establish land-based cultivation of commercially-significant red seaweeds as a technically and economically viable agricultural enterprise for the United States. If successful, these processes will create jobs, particularly in rural coastal regions, and provide a steady supply of plant-based proteins for feeding a healthy population.
Animal Health Component
25%
Research Effort Categories
Basic
50%
Applied
25%
Developmental
25%
Goals / Objectives
Project Goal. The proposed research will support the development of environmentally and commercially sustainable aquaculture systems for intensified production of commercially significant red seaweed in land-based cultivation systems. In particular, Gracilaria species are a source of plant-based protein and industrial phyco-colloids, which together constitute nearly 90% of the ash-free dry weight of the biomass. The biomass is produced using non-potable seawater, CO2 from air or waste combustion gases, and sunlight. The research will focus on integration of biological and bioprocess engineering approaches to automate and intensify the inoculation and grow out processes in land-based cultivation systems, resulting in increased productivity and labor-saving production technologies designed to reduce risk for advancing the nascent red seaweed aquaculture enterprise in the United States.Project Objectives. This proposed project will integrate biological and engineering approaches to develop new propagation and intensified cultivations strategies for commercially-significant red seaweed within genus Gracilaria, and test these new strategies in land-based, scalable environments. The Project Objectives are to:1) Establish and maintain clonal strains for two Gracilaria species of emerging commercial significance, G. pacifica and G. parvispora;2) Develop scalable processes to inoculate Gracilaria onto a porous mesh support using a mechanical blending and fluidic injection process;3) Test inoculated Gracilaria panels in relevant scalable environments in collaboration with our private partner Oregon Seaweed;4) Develop extension programming to support and promote red seaweed aquaculture in the US Pacific region.
Project Methods
The Methods are organized around the Project Objectives.Objective 1: Establish and maintain clonal strains for Gracilaria species of emerging commercial significance by adapting techniques developed for Gracilaria vermiculophyllaTask 1-1. Establish new clonal strains. Previously, we developed procedures for establishing clean, clonal strains of G. vermiculophylla from field-collected plants adapted to both cold and warm waters through stepwise tissue surface decontamination, apical explant selection and growth under vigorous mixing to promote branching, and temperature acclimation. We will extend these methods to two Gracilaria species of emerging commercial significance for food and plant proteins: G. pacifica (California Ogo) and G. parvispora (Ogo).Task 1-2. Maintenance of clonal cultures. Clonal plantlets established under Task 1-1 will be maintained in 450 mL bubbler flasks within a temperature-controlled cold room with f/2 enriched artificial seawater medium to clean conditions for the progenitor stocks at 16 C. An array of aerated tanks (4 L, 20 L, 40 L) as well as 100 L raceway tanks will be used to generate inoculum at the 0.20 to 2.0 kilogram scale for use in activities described under Objectives 2 and 3.Objective 2: Develop scalable processes to inoculate Gracilaria onto a porous mesh support using a mechanical blending and fluidic injection processTask 2-1: Determine optimal conditions for fluidic injection of thallus tissue fragments onto porous mesh supports. Fluidic injection procedures recently developed in the OSU PI's laboratory for G. vermiculophylla will be adapted to G. pacifica or G. parvispora clonal cultures. Biodegradable, semi-rigid, mesh materials based on polybutylene succinate, which have a lifetime of up to 24 months in an open ocean environment before being microbially degraded will also be tested. Combinations of mesh opening size (e.g. 3 mm), fluid burst velocity (e.g. 10 m/sec, set by injection pressure) and burst duration (e.g. 0.5 sec) are tested until the blended fragments remain attached to the mesh. We will use a statistical design of experiments approaches to manage permutations of testing variables, and data will be statistically correlated (e.g. multi-variate ANOVA) to identify optimal parameters. Task 2-2: Fabricate and test scalable inoculation platform. To automate the inoculation process and facilitate scaling, a system that combines tissue blending and multiport injection onto a large mesh panels will be developed, tested, and used for scale-up studies under Objective 4. It will be designed to inoculate "panel elements" of 20 x 20 cm and 20 x 80 cm size at inoculation densities of 5-20 g FW per m2 panel area.Objective 3: Test inoculated Gracilaria panels in relevant scalable environments in collaboration with our private partner Oregon SeaweedTask 3-1: Cultivation of Gracilaria panels in re-circulating raceway. In the recirculating raceway cultivation system, seawater medium flows around the red seaweed panels, eliminating the need to use costly aeration to suspend the biomass. There are two unknown factors that must be addressed to reduce the technical risk for potential adopters of this technology: the effects of fluid velocity and panel spacing. Higher velocities will reduce boundary layer resistance and promote nutrient and dissolved carbon flux resulting in higher growth rates, but will require higher power consumption, increasing operating costs. Decreasing the spacing between rows of panels will increase areal density, but may result in light shading effects that reduce growth rate as the frond tissues are crowded closer together. Existing raceway systems will be used to characterize the effects of fluid velocity on the areal productivity for G. vermiculophylla panel arrays at 6.5 cm (dense) and 15 cm (open) spacing. Biomass accumulation on each panel will be measured with time and converted to areal productivity as detailed in our previous work, and photographs of panels will be used to assess effects of hydrodynamics on thallus morphology. Multi-variate ANOVA will be used to assess spatial variations in biomass accumulation, and Tukey's analysis will determine the statistical dependence of cumulative areal productivity on fluid velocity.Task 3-2: Cultivation of Gracilaria panels in open tanks at Oregon Seaweed. The Oregon Seaweed Garibaldi site presently has twenty 6000 L cylindrical tanks with nominal diameter of 3 m and liquid depth of 1.0 m. We will test the growth performance of Gracilaria on mesh panels at the Oregon Seaweed Garibaldi site, which is a two-hour drive from OSU-Corvallis. Clonal cultures of Gracilaria will be inoculated onto mesh supports (Task 3-2) at OSU and transported to the Oregon Seaweed site in Garibaldi, Oregon and placed into one of the 6000 L aerated tanks at their tank farm. Biomass growth on the panels will be measured weekly over a six-week grow out period by Oregon Seaweed personnel as part of the in-kind contribution to this project. Ash, total carbohydrate, pigment, and protein/amino acid (AA) content will be assayed at OSU. The presence of epiphytes (diatoms, filamentous algae, grazers) on thallus tissue will be assessed microscopically. bTests will be carried out in triplicate during fall, winter, spring, and summer grow out periods at a seawater exchange rate of 1-2 culture volumes per day. Nitrate in the effluent, a limiting nutrient, will be assessed weekly to determine if supplemental macronutrients (N,P via Proline f/2 Algae Food) are needed. In the test tank, the aeration rate, currently at nearly 0.1 vvm, will be reduced to below 0.02 vvm since with panel cultivation it is no longer necessary to use aeration to suspend the biomass. Average specific growth rate (% per day), areal productivity (g AFDW/m2-day in active zone), and total protein/amino acid content will be correlated to season by ANOVA. Water temperature, salinity, daily solar irradiance, pH, and aeration rate will also be monitored continuously by a Vernier Logger pro system.Task 3-3: Analytical procedures. Thallus morphology and extent of pigment formation will be assessed by microscopic image analysis using ImageJ. Standard techniques will be used to assay thallus tissue for total protein content, phycobiliprotein (R-phycoerythrin, phycocyanin) and chlorophyll a/carotenoid content, ash-free dry biomass, and C/N content. Amino acid profiles will be assayed by HPLC using facilities at the OSU Linus Pauling Institute Analytical Services Core. From the amino acid (AA) analysis, the PDCAAS score, a measure of protein digestibility corrected for essential AA content, will be determined. Carbohydrates will be profiled by HPLC available in the PI's laboratory.Task 3-4: Preliminary Techno-economic Analysis (TEA). The PI will assist Oregon Seaweed with preliminary TEA of the cultivation process, focusing estimation of operating and capital costs (OP/CAPX) for a hypothetical 1000 wet ton per year Gracilaria aquaculture facility that includes panel inoculation, grow-out, and monthly harvest. The analysis will be summarized in a spreadsheet model, a version of which will be made publicly available through our proposed Learning Group. We will compare outcomes, normalized to $ per ton, for cultivation of Gracilaria panels in aerated tanks vs. raceway technology using biomass productivity data obtained over the course of this proposed project. Cost sensitivity to nutrient addition, supplemental CO2 addition (e.g. a waste or combustion gas source), aeration rate, and current velocity will be assessed.