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"Marine algae as food Maine."
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Seaweed chronicles : a world at the water's edge
\"An ancient and vital part of the ecosystem, seaweed is now emerging as an increasingly important source of food in a world faced with diminishing natural resources. [This book] opens a window into the world of this ... plant by providing a look at life on the rugged shore of the Gulf of Maine, focusing not only on the plant life underwater, but also on the men and women who farm and harvest seaweed, and on the increasingly difficult task of protecting this critical natural resource against forces both natural and man-made\"-- Provided by publisher.
Book
Concise review of the red macroalga dulse, Palmaria palmata (L.) Weber & Mohr
Palmaria palmata, commonly referred to as dulse, is a well-known and highly valued red macroalga distributed along the North Atlantic shores within a latitude range of approximately 40 to 80 °N. It is a species of commercial importance with historical records of use as food dating back several centuries to the current harvesting of dulse by hand-picking on the foreshore in Western Europe as well as Canada (New Brunswick and Nova Scotia) and USA (Maine). Because the demand for P. palmata increases and future sustainable commercial developments cannot rely solely on wild-harvested biomass, significant efforts have been made by research and industrial actors to cultivate the species. The low rates of spore release and germination, high mortality and epibiont contaminations remain major bottlenecks and point towards the need for optimized hatchery methods to enable upscaling the biomass production. The present review summarizes the available knowledge related to the biology, including the unique life history of the species among the Rhodophyta, the ecology as well as the nutrient composition and quality of P. palmata as food. Recent advances in taxonomy and cultivation techniques are reported along with a status of regulations for the commercial harvest of wild populations. An outlook on future industrial perspectives using biomass of P. palmata is also given.
Journal Article
Invasive seaweeds transform habitat structure and increase biodiversity of associated species
1. The visual landscape of marine and terrestrial systems is changing as a result of anthropogenic factors. Often these shifts involve introduced species that are morphologically dissimilar to native species, creating a unique biogenic structure and habitat for associated species within the landscape. While community-level changes as a result of introduced species have been documented in both terrestrial and marine systems, it is still unclear how long-term shifts in species composition will affect habitat complexity or its potential to influence the biodiversity of species that occur at the base of the food web. 2. We analysed quadrat photos collected at several subtidal sites in the Gulf of Maine over a 30+ year period, and collected individual seaweed species to determine their complexity and the biodiversity of meso-invertebrates associated with each species. 3. By coupling the relationship of 30+ years of shifts in seaweed assemblages, morphological structure of the seaweed assemblage, and their meso-invertebrates, we determined introduced seaweeds have increased by up to 90%, corresponding to a rise in two-dimensional (2D) structure, and a decline in canopy height of subtidal rocky habitats. The highly complex two-dimensional habitat provided by introduced filamentous red seaweeds supports two to three times more meso-invertebrate individuals and species that form the base of the food web than simpler forms of morphological habitat. 4. Synthesis. The present study demonstrates a long-term shift in foundation species towards a dominance of invasive seaweeds that directly reduce canopy height and increase the 2D biogenic structure of the habitat. These introduced seaweeds harbour greater biodiversity of species found at the base of the food web than seaweeds with simpler forms such as the native kelp species. Such shifts in habitat structure will propagate to food webs by influencing the structure of lower trophic-level meso-invertebrates and indirectly upper trophic-level species that feed on these invertebrates and use the seaweed structure as refuge.
Journal Article
On the human consumption of the red seaweed dulse (Palmaria palmata (L.) Weber & Mohr)
The red seaweed dulse (Palmaria palmata) is one of the more popular seaweed species for human consumption in the Western world. With a documented historical use up to present days in Ireland, Brittany (France), Iceland, Maine (USA), and Nova Scotia (Canada), it has remained a snack, a food supplement, and an ingredient in various dishes. The trend towards more healthy and basic foodstuffs, together with an increasing interest among chefs for the seaweed cuisine, has posed the need for more quantitative knowledge about the chemical composition of dulse of relevance for human consumption. Here, we report on data for amino acid composition, fatty acid profile, vitamin K, iodine, kainic acid, inorganic arsenic, as well as for various heavy metals in samples from Denmark, Iceland, and Maine.
Journal Article
Effects of pre-freezing blanching procedures on the physicochemical properties and microbial quality of frozen sugar kelp
Global demand for seaweed is increasing, resulting in the rapid growth of the seaweed industry. To sustain and enhance the industry (seaweed growers and processors), it is essential to establish and optimize post-harvest food processing practices to extend the shelf life of the fresh, edible product. Blanching and freezing were applied in this study to offer longer-term storage to enable the distribution of sugar kelp (Saccharina latissima), farm-raised in Maine, USA. The objectives were to evaluate blanching, specifically the impacts of blanching method (direct immersion or vacuum packaged), temperature (80 or 100 °C) and time (5 or 30 s), kelp form (whole blade or shredded), and the effects of frozen storage on food product qualities including color, texture, drip loss, mineral content, total phenolic content, and the native microflora of sugar kelp after thawing. The fresh brown kelp developed a vivid green color immediately after blanching, especially with higher blanching temperature and longer blanching time. Drip loss was higher in blades than in shredded slaw, and vacuum packaged blanching produced higher moisture content, phenolic compounds, and antioxidant activity. Results substantiate the importance of the blanching method, temperature, and time on frozen kelp quality. Blanching prior to freezing resulted in relatively higher product quality than unblanched frozen kelp despite some losses in hardness and color. Frozen storage had minimal to no impact on texture, aerobic plate count, and psychrotrophic microorganisms. Higher temperature, longer time, and vacuum packaged blanching is suggested to extend the marketable shelf life of sugar kelp to at least 6 months at − 20 °C.
Journal Article
Assessment of bacterial pathogens on edible macroalgae in coastal waters
In the Northeast USA, the aquaculture of macroalgae is a rapidly growing industry. Within this region, there are no established regulations for farm siting or methods of pathogen detection on macroalgae cultivated or harvested for human consumption. Bacterial pathogens from natural and anthropogenic sources may persist in coastal waters and can potentially contaminate macroalgae. During the winter growing season, sugar kelp Saccharina latissima and adjacent water were sampled from three sites of kelp aquaculture located in adjacent bays of ME, USA. Membrane filtration onto selective media detected Escherichia coli, Vibrio parahaemolyticus, and Vibrio alginolyticus in kelp and water samples at all sites, however plate counts were very low. The foodborne pathogens Salmonella enterica ser. Typhimurium, V. parahaemolyticus, and enterohemorrhagic E. coli O157:H7 were detected on enriched kelp samples from 83%, 78%, and 56% of sampling events, respectively, using molecular methods. Even with low bacterial levels, this frequency of detection confirms the risk of foodborne pathogens present on kelp and recommends the development of best management practices to control microbial growth during kelp harvest and processing. Bacterial plate counts from kelp samples often varied from those of water, indicating the importance of sampling the kelp directly, and that the association between bacterial pathogens on kelp and in the surrounding water should be further investigated. This study provides the first food safety assessment of sea vegetables in this region with the goal of providing data to enable the expansion of its industry.
Journal Article
Effect of post-harvest processing methods on the microbial safety of edible seaweed
The American seaweed industry is growing, primarily into the edible sector, and more seaweed products are available for human consumption. It is necessary to evaluate the safety of industry’s current post-harvest storage and processing methods to ensure the risk of foodborne pathogens on edible seaweed remains low. We evaluated the pathogen load of edible kelp post-harvest under three different storage temperatures (4˚C, 10˚C, 20˚C) and two different drying methods (air- and freeze-drying). The focal pathogens for this research included: Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, pathogenic Escherichia coli, Vibrio vulnificus and Vibrio parahaemolyticus. We tested all six pathogens under each treatment condition on both sugar kelp (Saccharina latissima) and rockweed (Ascophyllum nodosum) as these are the most commonly farmed and wild-harvested species in Maine, respectively. We inoculated a known concentration of pathogen onto freshly harvested kelp, treated it under a storage temperature or drying method, and sampled it over time to determine the impact of treatment on pathogen load. Our results showed that storage at 20˚C can lead to replication while storage at 4˚C and 10˚C halted the replication of focal pathogens. Both air-drying and freeze-drying produced significant log scale reductions in surface pathogen load for all focal pathogens. Additionally, air-drying reduced pathogen load more than freeze-drying for a majority of pathogens and storing dried kelp for 6-weeks further reduced pathogen load across all cases. These results are promising for industry as they corroborate historical evidence that current post-harvest storage and processing conditions are producing products safe for human consumption.
Journal Article
Accelerating Trophic-Level Dysfunction in Kelp Forest Ecosystems of the Western North Atlantic
We use archaeological, historical, ecological, and fisheries data to identify three distinct and sequential phases in the trophic structure of kelp forests in the western North Atlantic's Gulf of Maine. Phase 1 is characterized by vertebrate apex predators such as Atlantic cod, haddock, and wolffish and persisted for more than 4,000 years. Phase 2 is characterized by herbivorous sea urchins and lasted from the 1970s to the 1990s. Phase 3 is dominated by invertebrate predators such as large crabs and has developed since 1995. Each phase change resulted directly or indirectly from fisheries-induced \"trophic-level dysfunction,\" in which populations of functionally important species at higher trophic levels fell below the densities necessary to limit prey populations at lower trophic levels. By using fractional trophic-level analysis, we found that phase changes occurred rapidly (over a few years to a few decades) as well as relatively recently (over the past half-century). Interphase durations have declined as fishing effects have accelerated in recent years. The naturally low species diversity of the kelp forest ecosystem we studied may facilitate rapid changes because the redundancy within each trophic level is low. If the biodiversity within controlling trophic levels is a buffer against trophic-level dysfunction, then our observations from Maine may be predictive of the fate of other, more diverse systems. If fishing successively targets most, or all, strong interactors at higher trophic levels, then as those population densities decline, the potential for trophic-level dysfunction and associated instabilities will increase.
Journal Article
Enrichment of marine productivity utilizing steelmaking slag: managing conflicting stakeholders’ interests in Taiwan
The restoration of the coastal environment can help to alleviate declining offshore fishery resources. When artificial fish reefs utilizing steelmaking slag are deployed on the seabed, they can improve algal growth to create habitats for fisheries enhancement. However, the use of slag reefs in the marine environment in Taiwan may draw public concerns about the compatibility of placing steel by-products in the marine environment and food safety issues. It is therefore likely that the further use of slag reefs for marine productivity enhancement (MPE) may encounter resistance and face uncertainty. In this study, controversial issues related to the application of slag reefs to the development of subsequent marine ranching were explored. Qualitative interviews with stakeholders were conducted, and their support or opposition for the application of steelmaking slag to the marine environment were discussed. The results of the interviews were analyzed based on grounded theory to establish conceptual models and clarify stakeholders’ policy opinions on the marine application of slag reefs. The results can inform policy for the further utilization and management of slag reefs, and may help the government to promote the circular economy and achieve its ultimate goal of sustainable ocean development.
Journal Article
What was Natural in the Coastal Oceans?
Humans transformed Western Atlantic coastal marine ecosystems before modern ecological investigations began. Paleoecological, archeological, and historical reconstructions demonstrate incredible losses of large vertebrates and oysters from the entire Atlantic coast. Untold millions of large fishes, sharks, sea turtles, and manatees were removed from the Caribbean in the 17th to 19th centuries. Recent collapses of reef corals and seagrasses are due ultimately to losses of these large consumers as much as to more recent changes in climate, eutrophication, or outbreaks of disease. Overfishing in the 19th century reduced vast beds of oysters in Chesapeake Bay and other estuaries to a few percent of pristine abundances and promoted eutrophication. Mechanized harvesting of bottom fishes like cod set off a series of trophic cascades that eliminated kelp forests and then brought them back again as fishers fished their way down food webs to small invertebrates. Lastly, but most pervasively, mechanized harvesting of the entire continental shelf decimated large, long-lived fishes and destroyed three-dimensional habitats built up by sessile corals, bryozoans, and sponges. The universal pattern of losses demonstrates that no coastal ecosystem is pristine and few wild fisheries are sustainable along the entire Western Atlantic coast. Reconstructions of ecosystems lost only a century or two ago demonstrate attainable goals of establishing large and effective marine reserves if society is willing to pay the costs. Historical reconstructions provide a new scientific framework for manipulative experiments at the ecosystem scale to explore the feasibility and benefits of protection of our living coastal resources.
Journal Article