Canada occupies a special place among the world producers of seaweeds, mostly because it ranked first, from approximately 1950 to 1970, as a producer of the red alga Chondrus crispus (Irish moss), historically the first source of raw material for carrageenan extraction. However, seaweed harvesting along the coasts of the Maritimes is not a long-standing tradition, except in the case of Palmaria palmata (dulse), which has been harvested along the Bay of Fundy (especially on Grand Manan Island) for more than a century (even if the start of this cottage industry is difficult to date precisely). This chapter will focus on the seaweed industry on the Atlantic (East) Coast of Canada, the Pacific (West) Coast industry being treated in a separate chapter by S. Lindstrom. Along the East Coast, the emphasis will be on the Maritimes, which include the provinces of Prince Edward Island (PEI), Nova Scotia (NS) and New Brunswick (NB) (Fig. 1). The two provinces of Québec, and Newfoundland and Labrador are omitted, even though they have been the subject of numerous surveys, exploratory missions and reports, because no significant industry is presently operating there, except the sporadic harvesting of Laminaria sp. (kelp) in Québec (along the St. Lawrence Estuary and the Baie des Chaleurs) which was estimated at 500 wet tons (WT) in 1994 (Bodiguel 1995), and the harvesting of Ascophyllum nodosum (rockweed) and Laminaria sp. by a few small companies in Newfoundland.
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Integrated multi-trophic aquaculture (IMTA) is discussed.
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The National Oceanic and Atmospheric Administration (NOAA) National Sea Grant College Program has been funding marine aquaculture projects since the inception of the program in 1968. Early funding emphasis was on disciplinary studies such as nutrition, pathology, genetics, systems engineering, and life history studies of promising candidate species for aquaculture.
In the early 1990s, additional focus was placed on developing production systems that had the best potential for application in the environmentally conscious United States. These aquaculture technologies included recirculation system technologies, offshore aquaculture, and marine fisheries enhancement. Sea Grant funded several symposia on these subjects and proposed increases in funding through the NOAA budget process and this helped to further focus the research efforts for the NOAA based program.
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As Tornabene1,2 has already discussed in this and in an earlier volume, many microorganisms — photosynthetic or not — are capable of producing hydrocarbons which can account for up to 1% of the dry mass (see tables I–V in ref. 1). At the moment, it seems that there is only 1 exception described in the literature which produces a larger proportion: the unicellular green alga Botryococcus braunii.
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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 tons 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 tons 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 tons 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.
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The oceans cover 70% of Earth yet they yield only 1.5% (117 million metric tons (mt)) of the 7.6 billion mt of food that we produce each year. Can we make more productive use of them? If so, how and, in light of challenges now faced by global agriculture, should we try? This paper addresses these questions by looking at seaweed farming and the idea that a parallel, photosynthetically driven system of food production, a 'Marine Agronomy', could be developed at sea to supplement the food we grow on land.
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Current conventional wisdom argues that human-induced excesses in nutrient loadings to estuaries often stimulate ‘excess’ algal production leading to hypoxia, via bacterial pathways, and subsequent reduced recruitment/survival of finfish and shellfish. Why wouldn’t such elevated production stimulate more animal production, rather than less? In a three-year study of Long Island Sound, U.S.A., a multitude of variables were quantified along a west to east gradient, to address the above question via the hypothesis that different successes among planktonic species experiencing eutrophication alter planktonic food web structure away from traditional pathways to microbial loop dominated ones. Variables studied included: nutrient concentrations and ratios (i.e. NO2, NO3, NH4, DON, PON, PO4, Silicate, N/P and N/Si), phytoplankton, protozooplanktonic ciliate, zooplankton, heterotrophic nanoplankton (HNAN), photosynthetic nanoplankton (PNAN), size-fractionated chlorophyll, larval fish and bacterial concentrations and/or species composition, and bacterial growth rates (as frequency of dividing cells, FDC). Results indicated that although current nitrogen and other nutrient loadings into the estuary are much higher than past inputs (especially in western waters), the average concentration of dissolved inorganic nutrients is similar (though slightly higher) to past values. Relative proportioning among chemical species does vary from west to east, with NH4 and dissolved organic nitrogen (DON) at times more prevalent in the west, especially in bottom waters. Excess loadings of nitrogen and other nutrients into the estuary are converted to elevated biomass of both small (< 10 µm), and large (>20 µm) phytoplankton in the west. Slightly enhanced bacterial densities and growth rates shadow the elevated chlorophyll levels, with distinctive Sound-wide seasonal patterns that follow not total chlorophyll, but rather PNAN concentrations. HNAN concentrations also are elevated in the west, and likely influence bacterial dynamics. Species composition of phytoplankton routinely differ west to east. Inorganic N/P are routinely low (i.e. below Redfield ratios), especially in the west, while total dissolved N/P (i.e. including DON) are similar among stations and typically are significantly higher than Redfield ratios. Associated with bacterial and <10 µm chlorophyll enhancements to an elevated diversity of ciliate species in the west. Copepod biomass is extremely enhanced in the west, indicating that while stimulating the microbial loop, eutrophication is also enhancing the secondary production preferred by larval fish and gelatinous zooplankton. Larval fish diversity is down relative to the past, but shows little contemporaneous west/east variations. So, if adult fish populations are down, but larvae are not food limited, possibly toxicity, overfishing, and/or habitat destruction which prevent a healthy, normal system response to eutrophication are culpable. It is suggested that recipients of the excess copepod production are likely gelatinous zooplankton and benthic sediments, and that unused copepod ‘excess’ biomass likely significantly contributes to hypoxia. New conventional wisdom: Excess nitrogen stimulates microbial loop and net phytoplankton biomass and production, which in turn stimulates microcrustasean biomass and production and fecal release, and both significantly fuel hypoxia and likely stimulate gelatinous zooplankton production.
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Mass culture of benthic macroalgae under rough offshore conditions in the North Sea requires rigid culture support systems that cannot only withstand rough weather conditions but can also be effectively handled while at the same time retain the cultured species. Various carrier constructions and different mooring systems were tested. Laminaria saccharina grew on all of these carriers with initially high (up to 14.5% per day) and later decreasing length increments. Longlines, ladder and grid systems had certain disadvantages and these are discussed. The study results led to a new ring carrier (patent pending), first used in 1994/1995, which was gradually improved until 2002. This system now emerges as being superior, since it resists not only rough weather conditions (2 m s−1 current velocity, 6 m wave height) but also permits ease of handling when compared to other constructions. The ring allows various operational modes and can be equipped with culture lines that can be collected offshore or transported to shore facilities for harvesting. The modular nature of the tested ring system lends itself for future use in integrated aquaculture systems located in or attached to offshore wind farms.
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This paper presents the concept of raising seaweeds and other valuable organisms with the aid of huge structures ('ocean farms') emplaced in the surface waters of the open oceans. Potential advantages from and difficulties to be expected in realizing the associated technologies are briefly set forth. Much of the published literature pertaining to the concept is referenced and summarized. Wave-powered upwelling of cool, nutrient-rich waters through vertical pipes extending to depths of 100-300 m is indicated as desirable. Technologies are outlined for using the harvested seaweeds to create foods and other valuable products such as animal feeds, fertilizers, fibers, plastics, synthetic natural gas (methane), and alcohol and gasoline fuels. Results from site selection studies and economic analyses are given. It appears that dynamically positioned farms orbiting with the surface current patterns typically found on the ocean will be most cost-effective. The general conclusion is stated that open ocean farming will become economically more feasible as the cheaper fossil fuels and food producing lands of the earth become increasingly consumed in the course of the next century.
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Worldwide, biodiversity is declining and the marine environment is no exception, with increasing sea surface temperatures leading to drastic alterations in marine populations, communities and ecosystems. Of particular concern is the potential for loss of macroalgae, which function as ecological engineers, primary producers, habitat and structure providers, nutrient cyclers, keystone species, food and nursery grounds for invertebrates and pelagic organisms, and shoreline buffers from storms. Furthermore, macroalgae are a (U.S.) $11 billion industry as food, animal feed and fertilizers.
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
Contact: Marine.Agronomy.Group@gmail.com
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