Kelp Farming Research Articles

A highly prevalent filamentous algal endophyte in natural populations of the sugar kelp Saccharina latissima is not detected during cultivation in Northern Brittany

The sugar kelp Saccharina latissima is cultivated in Europe for food, feed and ultimately the production of chemical commodities and bioenergy. Being cultivated in the open sea, S. latissima is exposed to potentially harmful organisms, such as Laminarionema elsbetiae, a filamentous brown algal endophyte with a very high prevalence in wild populations of European S. latissima. As it was shown previously that S. latissima sporophytes get infected by L. elsbetiae very early in their life, seeding the spores on collectors and keeping them under controlled conditions during the critical time of a possible infection with filamentous endophytes could be advantageous over direct seeding techniques, where the ropes are deployed within days after seeding. We used a qPCR-assay to assess the prevalence of the endophyte L. elsbetiae in S. latissima cultivated during winter in Northern Brittany, comparing individuals from direct-seeded ropes and collector-seeded lines that were kept in laboratory conditions for different time spans. No DNA of the endophyte was detected in the samples, suggesting that either the kelps were not infected or the amount of endophytic filaments were below the detection rate of the qPCR assay. Furthermore, L. elsbetiae could not be detected in the seawater surrounding the kelp farm, indicating that L. elsbetiae is not fertile or disperses at a very small scale in Northern Brittany during the deployment time of young kelps. Our results suggest that infections of cultivated S. latissima with the endophyte L. elsbetiae might be a minor problem in kelp farms in Northern Brittany if the seeding production is kept under controlled conditions without external contamination.

The Potential for Upscaling Kelp (Saccharina latissima) Cultivation in Salmon-Driven Integrated Multi-Trophic Aquaculture (IMTA)

Integrated multi-trophic aquaculture (IMTA) has the potential of reducing open-cage fish farming impacts on the environment while also introducing new value chains. The aim of this study was to investigate the growth and composition of the kelp Saccharina latissima in salmon-driven IMTA, and to assess the spatial extent of the influence of salmon derived nitrogen in order to evaluate the upscaling potential for IMTA. S. latissima was cultivated 100, 200 and 1,000 m east and 1,000 m west of a 5,000 tonnes salmon farm in Western Norway from February to September 2013. The proportion of salmon derived nitrogen available for the kelp showed a clear decline with distance from the farm. Accordingly, the kelp cultivated near the salmon cages grew faster during the spring season, and growth rate decreased with increasing distance from the farm. A spatially explicit numerical model system (SINMOD), including compartments for dissolved nutrients and kelp growth, was tuned to the field data and used to investigate the potential for upscaling IMTA production. The model was used to introduce a new metric – the impacted area IA - for the areal effects of IMTA in terms of the increase in production by IMTA. The model showed that a 25 hectare kelp farm in the vicinity of the studied salmon farm could take up 1.6 of the 13.5 tonnes of dissolved inorganic nitrogen released during kelp cultivation, amounting to almost 12 % of the ammonia released during the cultivation period from February to June. The 25 hectare kelp farm would have a production yield of 1,125 tonnes fresh weight (FW), being 60 % more than that of a non-IMTA kelp farm, while a 20 % increase of kelp FW could be obtained over a 110 hectar area in salmon-driven IMTA. To achieve an even mass balance, an area of approximately 220 ha-1 would be needed to cultivate enough kelp to fix an equivalent of the nitrogen released by the fish.

Ecological priming of artificial aquaculture structures: kelp farms as an example

AbstractThe continued development of the aquaculture industry is contributing to the proliferation of artificial structures in the marine environment. Observations of seaweed farms (infrastructure and biomass) suggest they act as a habitat for associated species. Seaweed farms differ from other forms of artificial infrastructure as the material deployed already has marine organisms (i.e. culture species) growing on it. This ‘priming’ of ropes with juvenile sporophytes may affect future development of communities by facilitating colonizing species or suppressing competitors. We call this process ‘ecological priming’: the provision of a biological platform that influences the successional development of specific communities. The communities that developed on ropes primed with Alaria esculenta individuals were compared with unprimed ropes to assess the ecological priming effect, at a commercial kelp farm in south-west Ireland. Species richness increased over two cultivation seasons and species composition was consistent between years, with distinct communities developing on primed and unprimed treatments. Timing of species occurrence on primed ropes was predictable with no predictable pattern occurring on unprimed ropes. Multivariate tests indicated distinct communities between treatments, with suppression of other algal species and potential facilitation of some species that have a particular association with A. esculenta on primed ropes. Communities from primed holdfasts contained a lower diversity of algal species compared with unprimed communities. Cultivated kelp holdfasts represent a habitat for distinct assemblages that reflect ecological priming of the substratum.

Monitoring of macroalgae (kelp) farms with autonomous underwater vehicle-based split-beam sonar

The long-term goal of ARPA-E's MARINER (Macroalgae Research Inspiring Novel Energy Resources) program is to increase the scale of offshore kelp aquaculture so that biofuel may be derived from macroalgae. An autonomous underwater vehicle (AUV) system including acoustic, optic, and environmental sensors has been developed for the purposes of monitoring these large-scale kelp farms. The primary sensor for observing farm infrastructure such as horizontal longlines (from which the kelp grows) as well as kelp growth is a broadband split-beam sonar system. Structural information, such as droop in the longlines, is available from time-of-flight of the acoustic echoes. Growth of kelp is quantified from both time-of-flight and volume backscattering echo data. Experimental results from ocean measurements taken with the REMUS 100 AUV on longlines are presented, along with preliminary processing techniques for estimating longline position and macroalgae extent for vehicle control and farm mapping purposes [work supported by ARPA-E.]

Investigation of broad scale implementation of integrated multitrophic aquaculture using a 3D model of an estuary

A 3D ecosystem model was used to quantify changes in water quality brought about by salmon aquaculture in the D'Entrecasteaux Channel and Huon Estuary in southeast Tasmania. Macroalgae-based integrated multitrophic aquaculture (IMTA) was simulated and showed that IMTA is capable of reducing the increased chlorophyll concentration attributable to fish farming by up to 10–15% in large areas of the region, during the season of highest production. Kelp farms (Macrocystis pyrifera) recovered between 6 and 11% of the dissolved inorganic nitrogen (DIN) input by salmon aquaculture over a nine month period, with DIN remediation increasing linearly with farm size. Under a ten-fold increase in aquaculture to very high loads, a much lower remediation effect was found for both chlorophyll and DIN. Model results indicate that IMTA could have an important impact on reducing negative effects of finfish aquaculture on water quality providing that stocking rates are not too high.

The effects of intensive aquaculture on nutrient residence time and transport in a coastal embayment

Aquaculture in many countries around the world has become the biggest source of seafood for human consumption. While it alleviates the pressure on wild capture fisheries, the long-term impacts of large-scale, intensive aquaculture on natural coastal systems need to be better understood. In particular, aquaculture may alter habitat and exceed the carrying capacity of coastal marine ecosystems. In this paper, we develop a high-resolution numerical model for Sanggou Bay, one of the largest kelp and shellfish aquaculture sites in Northern China, to investigate the effects of aquaculture on nutrient transport and residence time in the bay. Drag from aquaculture is parameterized for surface infrastructure, kelp canopies, and bivalve cages. A model for dissolved inorganic nitrogen (DIN) includes transport, vertical turbulent mixing, sediment and bivalve sources, and a sink due to kelp uptake. Test cases show that, due to drag from the dense aquaculture and thus a reduction of horizontal transport, kelp production is limited because DIN from the Yellow Sea is consumed before reaching the interior of the kelp farms. Aquaculture drag also causes an increase in the nutrient residence time from an average of 5 to 10 days in the middle of Sanggou Bay, and from 25 to 40 days in the shallow inner bay. Low exchange rates and a lack of DIN uptake by kelp make these regions more susceptible to phytoplankton blooms due to high nutrient retention. The risk is further increased when DIN concentrations rise due to river inflows.

Marine spatial planning makes room for offshore aquaculture in crowded coastal waters

Marine spatial planning (MSP) seeks to reduce conflicts and environmental impacts, and promote sustainable use of marine ecosystems. Existing MSP approaches have successfully determined how to achieve target levels of ocean area for particular uses while minimizing costs and impacts, but they do not provide a framework that derives analytical solutions in order to co-ordinate siting of multiple uses while balancing the effects of planning on each sector in the system. We develop such a framework for guiding offshore aquaculture (bivalve, finfish, and kelp farming) development in relation to existing sectors and environmental concerns (wild-capture fisheries, viewshed quality, benthic pollution, and disease spread) in California, USA. We identify > 250,000 MSP solutions that generate significant seafood supply and billions of dollars in revenue with minimal impacts (often < 1%) on existing sectors and the environment. We filter solutions to identify candidate locations for high-value, low-impact aquaculture development. Finally, we confirm the expectation of substantial value of our framework over conventional planning focused on maximizing individual objectives.

A survey of epiphytic organisms in cultured kelp Saccharina japonica in Korea

A survey was conducted to investigate the presence of epiphytic organisms in four kelp Saccharina japonica farms in the coastal area of Korea from 2014 to 2015. Of 740 kelp samples that were taken, 208 exhibited six kinds of epiphytic organisms, including hydroid (detection rate: 11.6%), bryozoan (6.4%), polychaete (3.4%), algae (3.2%), caprellid (3%), and oyster (0.5%). The infestation rate for hydroid, bryozoan, and polychaete was significantly higher in the Wando farm, Busan farm, and Pohang farm, respectively. Epiphytic organisms were generally observed during May to September and not January to April, indicating that their infestation was significantly higher when the water had a higher temperature. The histopathogical examination revealed that hydroid and bryozoan organisms were attached on the cuticula of the thallus while some algae were attached on the cuticula of the thallus or had penetrated the epidermis. These results indicate that hydroid and bryozoan were the most predominant epiphytic organisms in Korean kelp farms, even though the infested thallus had not been broken.

Responses of mesozooplankton communities to different anthropogenic activities in a subtropical semi-enclosed bay

To evaluate the effects of different anthropogenic activities on zooplankton and the pelagic ecosystem, we conducted seasonal cruises in 2010 to assess spatial heterogeneity among the mesozooplankton communities of Xiangshan Bay, a subtropical semi-enclosed bay in China. The evaluation included five different areas: a kelp farm, an oyster farm, a fish farm, the thermal discharge area of a power plant, and an artificial reef, and we aimed to identify whether anthropogenic activities dominated spatial variation in the mesozooplankton communities. The results demonstrated clear spatial heterogeneity among the mesozooplankton communities of the studied areas, dominantly driven by natural hydrographic properties, except in the area near the thermal discharge outlet of the power station. In the outlet area, thermal shock caused by the discharge influenced the mesozooplankton community by decreasing abundance and biomass throughout the four seasons, even causing a shift in the dominant species near the outlet during summer fromAcartia pacificato eurythermal and warm water taxa. Unique features of the mesozooplankton community in the oyster farm may be due to the combined effects of oyster culture and the natural environment in the branch harbour. However, kelp and fish culture, and the construction of an artificial reef did not exert any obvious influence on the mesozooplankton communities up to 2010, probably because of the small scale of the aquaculture and a time lag in the rehabilitation effects of the artificial reef. Thus, our results suggested that the dominant factors influencing spatial variations of mesozooplankton communities in Xiangshan Bay were still the natural hydrographic properties, but the thermal discharge was an anthropogenic activity that changed the pelagic ecosystem, and should be supervised.

Macrocystis pyrifera aquafarming: Production optimization of rope-seeded juvenile sporophytes

The use of kelp in different human activities has increased over recent decades and this demand is increasing the demand for cost-effective farming technologies. In the case of the giant kelp (Macrocystis pyrifera) there is a large accumulation of knowledge concerning the relevant information required for aquafarming that allowed the installation of a 20ha pilot culture farm 5years ago in southern Chile. However, this experience indicated that to achieve a production level above 200tons per hectare per year it is necessary to optimize all the protocols starting from the hatchery level through to the growing phase in order to be cost effective. In this study we present information on optimizing the hatchery phase of M. pyrifera culture. The results show that it is possible to obtain 4 to 5mm long M. pyrifera juvenile sporophytes attached to seeded rope in less than 45days. To obtain this result, temperature should be 12°C with a photon irradiance of 12μmolm−2s−1 and a photoperiod of 16:8, L:D. In addition, macro and micronutrient concentrations should be maintained as the traditional Provasoli culture medium indicates, and with aeration of 414Lh−1 to maintain water movement in the culture system. Statement of relevanceCommercially hatchery kelp farming protocol development is presented.

Scaling up bioethanol production from the farmed brown macroalga Macrocystis pyrifera in Chile

AbstractInterest in third‐generation biomass such as macroalgae has increased due to their high biomass yield, absence of lignin in their tissues, lower competition for land and fresh water, no fertilization requirements, and efficient CO2 capture in coastal ecosystems. However, several challenges still exist in the development of cost‐effective technologies for processing large amounts of macroalgae. Recently, genetically modified micro‐organisms able to convert brown macroalgae carbohydrates into bioethanol were developed, but still no attempt to scale up production has been proposed. Based on a giant kelp (Macrocystis pyrifera) farming and bioethanol production program carried out in Chile, we were able to test and adapt this technology as a first attempt to scale up this process using a 75 L fermentation of genetically modified Escherichia coli. Laboratory fermentation tests results showed that although biomass growth and yield are not greatly affected by the alginate:mannitol ratio, ethanol yield showed a clear maximum around a 5:8 alginate:mannitol ratio. In M. pyrifera, a much greater proportion of alginate and lower mannitol abundance is found. In order to make the most of the carbohydrates available for fermentation, we developed a four‐stage process model for scaling up, including acid leaching, depolymerization, saccharification, and fermentation steps. Using this process, we obtained 0.213 Kg ethanol Kg−1 dry macroalgae, equivalent to 9.6 m3 of ethanol hectare−1 year−1, reaching 64% of the maximum theoretical ethanol yield. We propose strategies to increase this yield, including synthetic biology pathway engineering approaches and process optimization targets. © 2016 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

A model for the growth of mariculture kelp Saccharina japonica in Sanggou Bay, China

The kelp Saccharina japonica is one of the most important mariculture species in China. To predict kelp growth and provide a component for a general multitrophic ecosystem model, a dynamic individual growth model was developed to evaluate environmental effects on kelp growth. This model was calibrated and validated using data from 2 annual mariculture cycles (2008−2009, 2011−2012) from Sanggou Bay, China. Gross growth of S. japonica was described as functions of temperature, light and nutrient contents in plant tissues (internal nutrients), and nitrogen (N) and phosphorus (P) in seawater. Net growth was defined as gross growth minus respiration. The simulation results showed that nutrients were the key limiting factor for growth throughout the kelp growth cycle, whereas both temperature and light only limited kelp growth during simulation days 60−120, i.e. from 1 January to the end of February. Scenario simulations showed that fertilizing with nitrogen could improve kelp growth by as much as 4.4 times. The model also predicted that individual dry weight of S. japonica would increase by 18% when lifting the culture ropes up to the surface. Sensitivity analysis indicates that the empirical coefficient of respiration (r), maximum growth rate (μmax) and minimum internal quota for nitrogen (Nimin) were among the most sensitive parameters. This model shows that the introduction of culture methods such as cage culture, which allows more effective fertilization and depth control, would result in more effective kelp farming.

Use of sugar kelp aquaculture in Long Island Sound and the Bronx River Estuary for nutrient extraction

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 531:155-166 (2015) - DOI: https://doi.org/10.3354/meps11331 Use of sugar kelp aquaculture in Long Island Sound and the Bronx River Estuary for nutrient extraction Jang K. Kim1,*, George P. Kraemer2, Charles Yarish3 1Department of Marine Sciences, University of Connecticut, 1 University Place, Stamford, CT 06901, USA 2Department of Environmental Studies, Purchase College, 735 Anderson Hill Road, Purchase, NY 10577, USA 3Department of Ecology and Evolutionary Biology, University of Connecticut, 1 University Place, Stamford, CT 06901, USA *Corresponding author: jang.kim@uconn.edu ABSTRACT: We previously demonstrated the suitability of seaweed aquaculture as a nutrient management tool, using the warm temperate rhodophyte Gracilaria tikvahiae McLachlan. The present follow-up study revealed an even higher nutrient bioextraction capacity in the cold-water species Saccharina latissima at 3 sites—the mouth of the Bronx River Estuary (Bronx, NY; BRE), western Long Island Sound (Fairfield, CT; WLIS) and central Long Island Sound (Branford, CT; CLIS), during winter and spring of the 2012-2013 growing season. These sites differ in temperature (BRE > CLIS > WIS), salinity (BRE < WLIS = CLIS) and nutrients (BRE >> WLIS = CLIS). We estimated that S. latissima could remove up to 180, 67 and 38 kg N ha-1 at BRE, WLIS and CLIS respectively, in a hypothetical kelp farm system with 1.5 m spacing between longlines. In the same hypothetical kelp farm system, the estimated carbon sequestration values are 1350 (BRE), 1800 (WLIS) and 1100 (CLIS) kg C ha-1. The potential monetary values of N sequestration by the sugar kelp are up to $1600 (BRE), $760 (WLIS) and $430 (CLIS) ha-1, if incorporated in the State of Connecticut Nitrogen Credit Trading Program and a carbon-pricing scheme. The potential economic values of C sequestration are $30-300 (BRE), $40-400 WLIS), and $24-240 (CLIS) ha-1. These results suggest that seaweed aquaculture is a useful technique for nutrient bioextraction in urbanized coastal waters, such as LIS and BRE. Alternation of the warm- and cold-water species would maximize nutrient bioextraction and augment other ecosystem services, producing economic benefits for the region while helping to manage non-source eutrophication. KEY WORDS: Nutrient bioextraction · Kelp aquaculture · Saccharina latissima · Estuary Full text in pdf format PreviousNextCite this article as: Kim JK, Kraemer GP, Yarish C (2015) Use of sugar kelp aquaculture in Long Island Sound and the Bronx River Estuary for nutrient extraction. Mar Ecol Prog Ser 531:155-166. https://doi.org/10.3354/meps11331 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 531. Online publication date: July 02, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Intraspecific crossing of Saccharina japonica using distantly related unialgal gametophytes benefits kelp farming by improving blade quality and productivity at Sanggou Bay, China

When cultivating the kelp, Saccharina japonica, in China, one of the causes leading to degeneration in blade quality and productivity has been thought to be inbreeding caused by the use of limited numbers of sorus-bearing individuals that are continuously used over generations to produce large numbers of offspring. One of the effective solutions is to use intraspecific hybrid vigor to produce new cultivars or to recreate the original agronomic features of the older cultivars. This study produced a sporophytic B013 (cultivar code) by crossing a pair of distantly related unialgal male and female gametophyte clones. The male was isolated from an individual collected from a farmed population at Rongcheng, China, while the female came from a Korean wild individual sporophyte. In comparison with four controls, the B013 sporophytic offspring demonstrated excellent blade quality (entirely dark green in the dried product), high alginate (29.7-32.9 %) and iodine (0.29-0.31 mg g(-1)) contents in the dried product, the lowest fresh weight/sun-dried weight (FW/DW) ratio and the smallest coefficients of variation for total length (7.4 %), width (6.9 %), and biomass output (14.6 %). In addition, this cultivar remained in a vegetative state from June to August, greatly reducing the biomass loss during the hot summer season. In comparison with seeding zoospores for seedling production, seeding a selected pair of unialgal gametophytes had apparent advantages in effectively preventing inbreeding depression, which gave rise to a uniformed product and provided new cultivars for large-scale farming.

Estimation of Kelp Farming Working Time in a Case of Fukushima, Hokkaido

Estimation of Kelp Farming Working Time in a Case of Fukushima, Hokkaido

Production and economic assessment of giant kelpMacrocystis pyriferacultivation for abalone feed in the south of Chile

Kelp biomass availability for mass abalone cultivation remains a critical issue in Chile. The technical and economic feasibility of a commercial scale kelp farming activity has not been established. This study describes the production and economic results of a pilot scale unit installed in southern Chile. Our results show 25 kg m−1 of production over a 9-month spring-summer period, and 16.2 kg m−1 during the autumn-winter period. These values indicate that a total biomass production of 41.3 kg (wet) m−1 year−1 can be obtained by placing the culture lines at 4 m intervals. High quality animal food-grade plants with a 9% protein content, over 5 m in length were harvested. Sensitivity analysis showed that by cultivating 30–50 ha with a market value of US$ 78 ton−1, a return on investment can be made after the first year.

Mathematical model ofLaminaria production near a British Columbian salmon sea cage farm

The technical and economical feasibility of farmingLaminaria saccharina for a food base product near a salmon sea cage farm was evaluated. Suitability of kelp for nutrient removal was also analyzed. A computer model of a conceptualized system was developed in order to make the assessments. Kelp growth was modelled as a linear function of temperature and background dissolved inorganic nitrogen concentration, and it was partially experimentally validated. Based on model simulations, aLaminaria farm containing 10,60 m ropes on each end of a salmon sea cage farm is fertilized by the salmon farm and yields annually 1600 kg of dried kelp. The payback period for the initial investment of $61 × 103 is 6 years after which an annual net profit of 20 × 103 Canadian dollars ($16.68 × 103 US) can be achieved. The net present worth of the kelp farm was positive for a rate of return up to 25%. Kelp production on multiple salmon farms or at a higher kelp density could increase the overall revenue.

Effect of Particle Size on Desalting and Bioconversion of Kelp to Methane

ABSTRACT LARGE ocean kelp farms can potentially produce a significant amount of fuel gas, feed and food. Grinding probably would precede either bioconversion of kelp to methane or mechanical dejuicing of kelp for reduction of bulk and salt content. Grinding energy consumption varied from about 2 W-h/kg of kelp to produce material where 70% (w/w) would pass a 4.3 mm aperture (dyo = 4.3 mm) to about 6 W-h/kg for material with dyo of 1.4 mm. This equals 1-3% of the energy obtained by bioconversion of kelp to methane. In a limited test, particle sizes in the range of chopped (ca. 75 mm) to dyo of 2.1 mm had little, if any, effect on methane yield. Decreasing particle size produced relatively small decreases in salt content of pressed CaCl2-heat treated kelp, not enough in most cases to offset the increased loss of organic matter. In general, there appear to be no processing advantages to grinding to a size smaller than that needed for material handling.

In situ rates of nitrate uptake by giant kelp, Macrocystis Pyrifera (L.) C. Agardh: Tissue differences, environmental effects, and predictions of nitrogen-limited growth

NO − 3 uptake rates were measured in situ for seven types of tissue of adult sporophytes of Macrocystis pyrifera (L.) C. Agardh. Uptake by mature blades of canopy fronds followed saturation kinetics. At near-saturation concentrations, mean rates of uptake by different tissues ranged from 0.1 to 2.1 μg-at.· g wet wt −1 · h −1 (7–68 ng-at. · cm −2· h −1). Different tissues incubated under similar environmental conditions took up NO − 3 at different rates, indicating physiological differences. Uptake rates showed no apparent relation to tissue age or nutritional history, but were influenced by certain environmental factors: uptake was 44–48% slower in dark than at ambient mid-day light levels, and dark uptake was 40% slower by blades incubated at 12m depth than by blades incubated at the surface. These physiological and environmental differences resulted in generally rapid uptake by tissues located at or just below the surface and slower uptake by tissues deeper in the water column. Daily NO − 3 uptake by M. pyrifera populations was predicted using a model based on in situ NO − 3 uptake rates. According to predictions of the model, NO − 3 concentrations of 1–2 μM throughout the water column are required to support kelp growth at the 4% · day −1 (wet wt) rate typical of inshore populations. Vertical stratification, with high NO − 3 concentrations only at near-bottom depths, would result in severe nitrogen-limitation of growth. Seasonal changes in frond size distribution do not greatly affect nitrogen-limited growth rate. The model was also used to evaluate potential fertilizing methods and problems in management of offshore kelp farms.

A SUBJECTIVE ANALYSIS OF ALTERNATE APPROACHES TO THE MASS CULTURING OF SEAWEEDS

ABSTRACTFour different approaches to the mass commercial culturing of seaweeds are explored in terms of their major characteristics and current state‐of‐the‐art. This includes lagoon culturing, as practiced commercially in the Pacific, and the possibility of large open ocean kelp farms. Presented for possible development is an intensive seaweed culturing concept that promises significant savings in capital and operating costs in comparison with the more conventional raceway approach. In addition, these approaches axe compared as to their potential performance, costs, risks and relative advantages. Identified are technological areas where improvements promise high leverage towards achieving greater economic viability for mass commercial seaweed culturing systems.