Wild Seaweed Research Articles

Physicochemical properties of wild and cultivated Saccharina latissima macroalgae harvested in the Canadian boreal-subarctic transition zone

Saccharina latissima is a brown seaweed used as a food ingredient. The aim of this work was to study possible differences between S. latissima chemical composition, color, mode of cultivation, harvesting period and site and its environmental conditions. Water temperature, salinity, radiation, and fluorescence were monitored in each harvesting site. Chemical composition of S. latissima varied greatly with period and site, with a high content of carbohydrates and ash. Crude protein content varied from 3.7 % to 12.8 %, with a higher concentration observed in wild samples harvested in Bas-St. Laurent (11.1–12.8 %). Cultivated seaweed also presented a high crude protein (12.2 %) and ash (52 % against 27 % in wild samples) concentrations, but crude fiber and carbohydrates concentrations were lower, reaching up to 2.7 and 1.9-fold, respectively, than those in wild seaweeds. S. latissima presented a more intense yellow color in June. A trend of darker and more green-colored seaweeds when cultivated in the end of summer was confirmed. Our results suggest that variations in chemical components and chromaticity of this species are probably affected by complex interactions of environmental conditions.

Diverse Roles of Seaweed in the Blue Carbon Economy and Sustainable Development: A Comprehensive Review

The imperative to replace fossil fuels with renewable fuels, such as marine ecosystem-derived fuel and food, has spurred the development of a blue carbon economic model. Seaweed emerges as a pivotal element in this framework, demonstrating potential as a substantial carbon sink. Seaweed serves multiple purposes, encompassing climate change adaptation and mitigation and contributing to advancing a bioeconomy by reducing dependence on fossil fuels. Seaweed also holds promise as a source of human food, cattle feed, biofuels, renewable feedstocks, and other versatile applications. Numerous contemporary scientific publications, reputable organizations, and business resources offer illuminating insights and fresh perspectives on how seaweed can effectively contribute to the growing blue carbon economy, providing innovative tools for combating long-term climate change. This comprehensive review delves into the multifaceted potential of seaweed, concentrating on its contributions to carbon sequestration, its role as a blue carbon precursor, and the carbon-neutralization capabilities of both wild seaweeds and seaweed farming. Moreover, it explores the specific role of seaweed in the blue carbon economy, mainly as cattle feed in ruminant diets. In addition, seaweed cultivation has the potential to mitigate global climate change, promote economic development, and support sustainable livelihoods, offering a versatile solution to address pressing environmental and socioeconomic challenges.

Policy implications of wild seaweeds used in organic crop fertilizers

Policy implications of wild seaweeds used in organic crop fertilizers

Farming a wild seaweed and changes to its composition, bioactivity, and bioaccessibility: The Saccorhiza polyschides case study

Farming a wild seaweed and changes to its composition, bioactivity, and bioaccessibility: The Saccorhiza polyschides case study

Bed-scale impact and recovery of a commercially important intertidal seaweed

As the value of ecosystem-based management (EBM) approaches is increasingly recognized in marine ecosystems, it is critical that the impacts of resource harvest are assessed at various spatial scales. This is particularly true for habitat-forming resources, such as wild seaweeds, that act as foundation species by physically structuring ecosystems. The impacts of spatially heterogeneous harvest may change with scale, and have different management implications based on the ecosystem process or organism under consideration. Ascophyllum nodosum (hereafter rockweed) is a canopy-forming fucoid seaweed endemic to rocky coastlines in the North Atlantic Ocean that has been harvested for centuries. We conducted a Before-After Control-Impact study of commercial rockweed harvest at 38 sites across the coast of Maine (USA) from 2018 to 2020 in an effort to understand impact and one-year recovery of two rockweed bed structural characteristics, height and biomass, at a scale similar to a single harvest event. Our results indicate that rockweed harvest is spatially heterogeneous at the scale of the rockweed bed, and as a result, the effect sizes of harvest at this scale are smaller than those reported in previous studies that assessed smaller spatial scales. Mean rockweed biomass recovered to pre-harvest values after one year of recovery, but mean rockweed height remained lower at impacted sites. While post-harvest recovery was generally high in our study, sites that experienced higher intensities of harvest were less likely to fully recover height or biomass one year post-harvest. Our findings provide resource managers with a bed-scale perspective that can inform EBM approaches, particularly for population-level management of harvested resources and impacts of harvest on highly mobile organisms—such as birds and fish—that interact with these ecosystems at larger spatial scales.

Neutral Spores—An Easier Way to Cultivate Pyropia leucosticta (Thuret) Neefus & J.Brodie, 2011 (Bangiales, Rhodophyta) along the Romanian Black Sea Shore

Macroalgal cultures are currently of great interest worldwide. Although along the Romanian Black Sea coast, there is no tradition in this sense, currently, a major interest in developing this direction exists, taking into consideration that the overexploitation of wild seaweed resources involves the disturbance of the marine environment, with implications that can sometimes be irreversible. Porphyra and Pyropia species (also known as nori algae) are considered the world’s most valuable mariculture algal products due to their high nutritional value and multiple active principles, considered unique representatives of marine algae. Considering these aspects, attention was focused on the only nori species from the Romanian Black Sea coast, namely, Pyropia leucosticta. The species was cultivated in controlled laboratory conditions for 5.5 months by manipulating its reproductive elements. The aim was to establish a simple, low-cost method by avoiding the complicated conchocelis phase of the species; therefore, reproduction and further species development were achieved by collecting the released neutral spores and isolating them in culture vessels, ensuring, at the same time, proper nutrient conditions, using sterile enriched seawater and mimicking ambient conditions. At the end of the experiment, specimens of almost 80−90 mm were obtained, making this method suitable for obtaining ex situ P. leucosticta blades on the Romanian Black Sea shore.

Efficient spatial kelp biomass estimations using acoustic methods

Kelp forests are the largest vegetated marine ecosystem on earth, but vast areas of their distribution remain unmapped and unmonitored. Efficient and cost-effective methods for measuring the standing biomass of these ecosystems are urgently needed for coastal mapping, ocean accounting and sustainable management of wild harvest. Here we show how widely available acoustic equipment on vessels can be used to perform robust and large-scale (kilometer) quantifications of kelp biomass which can be used in assessments and monitoring programs. We demonstrate how to interpret echograms from acoustic systems into point estimates of standing biomass in order to create spatial maps of biomass distribution. We also explore what environmental conditions are suitable for acoustic measures. This has direct application for blue carbon accounting, coastal monitoring, management of wild seaweed harvest and the protection and conservation of marine habitats supporting high biodiversity.

Differences in Light Attenuation Patterns of Sargassum horneri Beds and Their Influences on Sebastiscus marmoratus Juveniles: A Case Study of Gouqi Island, Ma’an Archipelago, China

Sargassum beds ensure sustainable environmental, social, and economic benefits in the coastal areas around the world. They can provide shelter ground to different species of fish juveniles. To investigate these, we conducted field surveys in a peaking growth period of Sargassum horneri from May to June 2010 to evaluate them on Gouqi Island, Ma’an archipelago, China. The study indicated that the light attenuation rate inside the S. horneri beds was higher than that in the surrounding areas. The light attenuation rate was highest in Ganxie, the second highest in Huangshidong, and the lowest in Houtouwan. We found that the average length of Sebastiscus marmoratus corresponded to the average height of S. horneri. This study improves our understanding of the function of sheltering grounds provided by Sargassum beds. Additionally, this study is relevant to the development of the regulations and directives to ensure the sustainable exploitations and protection of wild seaweeds and the accompanying organisms resources.

Proximate Composition of Some Selected Seaweeds from Coastal Areas of Cox’s Bazar and the St. Martin’s Island, Bangladesh

The present study assesses the proximate composition of eight wild seaweed species viz. Hypnea sp., Enteromorpha sp., Sargassum sp., Hydroclathrus clathratus, Padina pavonica, Colpomenia sinuosa, Petalonia fascia and Dictyota ciliolata and one cultured species viz. Hypnea sp. collected from western coast of the St. Martin’s Island and Nunairchhara, Cox’s Bazar, respectively. Standard analytical methods were used to estimate moisture, ash, lipid, crude fiber and protein contents, while carbohydrates were measured by subtracting ash, fat, fiber and protein contents from 100 on a dry weight basis. Results showed average moisture content in different seaweed species ranged between 12.09% to 29.65% and varied from species to species. Maximum ash content was found in brown seaweed H. clathratus (61.98%), while the lowest was recorded in wild red algae Hypnea sp. (7.05%). This study showed mean lipid contents in all seaweed species were much lower than other contents of proximate composition. The highest crude fiber content was observed in P. fascia (10.08±0.07%), while the lowest was observed in Enteromorpha sp. (0.23±0.01%). The highest protein (23.64±1.44%) and carbohydrate content (46.71±0.54%) was found in Hypnea sp. This study showed that mean carbohydrate content was higher in Rhodophyta, Chlorophyta and Phaeophyta, whereas, lipid content was lower in the three groups. Proximate composition of ash, lipid, crude fiber and protein content within species varied due to habitat differences, changes of body structures or physiological alterations, changes in growth rates and photosynthetic function of seaweed species and geographical differences. The mean moisture and ash content were the highest in cultured Hypnea sp., whereas, lipid, crude fiber, protein and carbohydrate were formed to the highest in wild Hypnea sp. Results suggest wild Hypnea sp. was much nutritive because of having higher amount of protein, fiber, carbohydrate and lipid than cultured ones. The study indicates that seaweeds might be used as a potential source of protein, fiber and carbohydrate. The Dhaka University Journal of Earth and Environmental Sciences, Centennial Special Volume June 2022: 113-122

Enhancing anaerobic digestion of wild seaweed Gracilaria verrucosa by co-digestion with tofu dregs and washing pre-treatment

Marine biomass (such as wild seaweed Gracilaria verrucosa) is highly abundant in Indonesia and has been highlighted as a potential biomass resource for bioenergy production. Furthermore, agro-industrial waste (such as tofu dregs/TD which arises from large-scale production in the country) is rich in carbohydrates and proteins, and is therefore considered a viable feedstock for production of high-value added products. This study aimed to investigate the co-digestion of wild seaweed G. verrucosa (WGv) with TD and its impacts on biogas and methane production. The biochemical methane potential (BMP) test was operated for 28 days at temperature of 37 °C. The co-digestion of WGv with TD at 90:10 and 80:20 ratios significantly increased the specific methane potential (SMP), giving an average of 98 LCH4/kgVS and 120 L CH4/kgVS, respectively. Addition of co-digestion substrates promoted co-metabolism in the digesters, increasing the ability of the microorganism to effectively digest the organic matter present in the feedstock’s mixture. The washing pre-treatment reduced the concentration of inorganic compounds and salts within the wild seaweed G. verucosa, leading to an improvement in biogas and methane yield. The mass balance illustrated that this process configuration led to a reduction in the quantity of digestate to be managed (i.e. dewatering, transport, and land/soil application). This will subsequently reduce the cost and energy requirements for sludge management, estimated at 37%. Therefore, the co-digestion of WGv with TD and the application of a washing pre-treatment stage prior to AD can positively enhance biogas and methane production. In-depth investigation for optimal valorisation using AD technology is highly essential.

Evaluation of ecosystem services provided by farmed and wild seaweeds

Marine macroalgae provide a variety of ecosystem services in the environmental, social and economic spheres. This study presents a qualitative assessment of the ecosystem services offered by marine macroalgae (cultivated and natural populations). Furthermore, it provides a better understanding of the benefits of macroalgae cultivated in a case study (Gracilaria birdiae) in a tropical area in Brazil. For this, a literature review was carried out using articles available on the internet (Web of Science, Science Direct, Scopus, Scielo and Google Scholar) published between 2009 and 2020, which addressed the ecosystem services associated with macroalgae. A total of 1,428 articles were analyzed, of which 163 reported some type of ecosystem service. The most registered service was regulation (30.1%), followed by provision (28.4%), support (28.0%) and cultural (13.5%). In the case study, 12 services were identified, five of which belonged to support, three to cultural, two to provision and two to regulation. Thus, both cultivated macroalgae and natural populations offer diverse ecosystem services that contribute to environmental improvement and play a positive role in the preservation and conservation of the environment and human well-being. In addition, the ecosystem services provided by macroalgae are fully aligned with several Sustainable Development Goals, especially SDGs 2, 3, 5, 8, 10, 12, 13 and 14, which encompass the three pillars of sustainability (environmental, social and economic).

Biomass and height of Ascophyllum nodosum after two decades of continuous commercial harvesting in eastern Canada

With the increasing demand for seaweed resources worldwide, management must ensure that the harvest of wild seaweed stocks is sustainable. We evaluate the impact of over 25 years of commercial harvesting of Ascophyllum nodosum in eastern Canada by comparing the biomass and height of the seaweed in the late 1990s to the late 2010s over a broad spatial scale spanning the provinces of Nova Scotia and New Brunswick. There has been no significant decrease in the biomass of A. nodosum in either province, and biomass has increased in some regions of New Brunswick during that period. The average height of A. nodosum has decreased by 7.8 cm in Nova Scotia while it increased by 13.8 cm in New Brunswick. Biomass of A. nodosum in unharvested sectors was 7% higher than that in harvested sectors while height of A. nodosum in unharvested sectors in New Brunswick is similar to the values observed in harvested sectors. Over the same period, water temperature has increased in both provinces and, in recent years, has at times exceeded the optimal growing temperature for A. nodosum within bays in Nova Scotia. We conclude that the current management and harvest of A. nodosum in eastern Canada are sustainable and maintain the biomass and height of A. nodosum beds but that control sites are necessary to offer adequate comparisons as environmental conditions are changing.

The seaweed resources of Ireland: a twenty-first century perspective

The harvesting of wild seaweeds continues to play an important cultural and socioeconomic role for many coastal communities on Ireland’s Atlantic seaboard. Although Irish waters contain a diverse and substantial benthic seaweed flora, only a few species are exploited commercially. Historically in Ireland, seaweed was commercially used as a raw material in the production of high-volume, low-value commodities such as animal feed and raw material for alginate production. Recently, with increasing acceptance of seaweed as a sea vegetable and its ever-increasing role as a raw material in the cosmetic and pharmaceutical industries, there has been a renewed vigour in the Irish seaweed industry particularly with new entrants into the human nutrition and cosmetic markets producing high-quality, high-value products. Although many of Ireland’s native seaweed species can be sustainably exploited if well managed, the fucoid Ascophyllum nodosum maintained its prominent role in the Irish seaweed industry. The traditional harvesting of A. nodosum in Ireland continues, although the recent introduction of new harvesting techniques, along with the expected expansion of the Irish seaweed cultivation sector, undoubtedly marks a shift in the Irish seaweed seascape. We focus here on the seaweed resources in Irish waters and how the industry has changed in the last 20 years.

Co-culture ofUlvasp. andDicentrarchus labraxin Recirculating Aquaculture System: effects on growth, retention of nutrients and fatty acid profile

European sea bass andUlvasp. were co-cultured in different tanks of an indoor Recirculating Aquaculture System (Ulva-RAS) with bacterial biofilter, in an effort to optimize the efficiency of the system and to further decrease the waste effluent. A system with similar culture conditions, withoutUlva,was used as a control-RAS to elucidate integration effects on growth performance and chemical composition of sea bass. The role ofUlvaon N and P concentrations, gas (O2, CO2) and pH in water was also investigated. Fish were fed a diet of fish oil replacement (55%) with a mixture of rapeseed oil and palm oil (1:1). Our data showed thatUlvacould uptake N and P nutrients, but could also enrich sea water with phosphates. Sea bass reared inUlva-RAS exhibited isometric growth, while fish in control-RAS showed a positive allometric growth and an increased variance of body weight and length. In addition, sea bass inUlva-RAS demonstrated significantly higher levels of condition factor (K), feed intake, protein, lipid, P, EPA and DHA content (% wet weight of total body) and lipid productive value, compared to fish in control-RAS.Ulva,after bi-weekly culture, showed increased protein content (60%) compared to wild seaweed collected nearshore. CultivatedUlvaobtained dark green color, doubled chlorophyll concentrations, and exhibited lower levels of saturated and higher levels of certain monounsaturated and n-3 polyunsaturated fatty acids, indicating increased photosynthetic activity. Present results revealed the beneficial effects ofUlvaon sea bass growth and quality, which led to an improved response to the nutritional stress imposed by the fish oil replacement with vegetable oils, thus contributing to a sustainable aquaculture. Moreover, it was concluded thatUlvacould improve water quality by increasing pH and O2, reducing CO2and contribute to bioremediation of ammonia and nitrates from water in integrated aquaculture.

Ecosystem-based management of seaweed harvesting

Abstract Harvesting wild seaweeds has a long history and is still relevant today, even though aquaculture now supplies >96% of global seaweed production. Current wild harvests mostly target canopy-forming kelp, rockweed and red macroalgae that provide important ecosystem roles, including primary production, carbon storage, nutrient cycling, habitat provision, biodiversity and fisheries support. Harvest methods range from selective hand-cutting to bottom trawling. Resulting ecosystem impacts depend on extraction method and scale, ranging from changes in primary production to habitat disruption, fragmentation, food-web alterations and bycatch of non-target species. Current management often aims for sustainable harvesting in a single-species context, although some agencies acknowledge the wider ecosystem structure, functions and services seaweeds provide. We outline potential ecosystem-based management approaches that would help sustain productive and diverse seaweed-based ecosystems. These include maintaining high canopy biomass, recovery potential, habitat structure and connectivity, limiting bycatch and discards, while incorporating seasonal closures and harvest-exclusion zones into spatial management plans. Other sustainability considerations concern monitoring, enforcement and certification standards, a shift to aquaculture, and addressing cumulative human impacts, invasive species and climate change. Our review provides a concise overview on how to define and operationalize ecosystem-based management of seaweed harvesting that can inform ongoing management and conservation efforts.

Empty fruit bunch-seaweed biocomposite as potential soil erosion mitigation material for oil palm plantation

A composite prepared from oil palm empty fruit bunch (OPEFB) and abundantly available wild seaweed showed great potential as a soil stabilizer, which is attributed to its natural hydrophilic nature. The water absorption and thickness swelling percentages of the oil palm empty fruit bunch-seaweed composite (OPEFB-SW) were recorded at 117.2% (± 7.1) and 10.5% (± 1.7), respectively. The main objective of this study was to determine the effectiveness of the biocomposite in regulating runoff volume and water quality due to soil erosion from the experimental plots. Hence, the volume, turbidity, and total suspended solids (TSS) of the water runoff were investigated. A rainfall simulation test was conducted to test the effectiveness of the cover material (biocomposite) at different application levels (0 kg/m2 (T1), 3.0 kg/m2 (T2), 4.0 kg/m2 (T3), and 5.0 kg/m2 (T4)) of the composite in reducing soil erosion. Overall, the OPEFB-SW composite demonstrated its capability to absorb rainfall impact and therefore stabilize the soil structure. The runoff volume, turbidity, and TSS were reduced significantly to 49.1%, 94.6%, and 99.2%, respectively. In addition, the plot with 4.0 kg/m2 indicates the best treatment in regulating runoff volume, turbidity, and TSS.

Using internal transcribed spacers 2 (ITS2) to identify seaweed species from Tomini Bay and Banten Bay

Samples collected from two coastal areas by diving and using a boat. The fresh seaweed morphologically identified while the dried samples collected to be used for DNA testing. Previous research has been shown that there is an influence from environmental parameters on seaweed composition so that the water quality testing was carried out to determine the dominance of wild seaweed water. We conducted genomes extraction, PCR amplification, DNA sequencing testing, alignment with MEGA 7 application and made phylogeny tree, which are distributed at Tomini bay Dictyota sp., Halimeda sp., Padina sp., Polysiphonia sp., and Banten bay as Sargassum sp. This study evaluated the feasibility of using the ITS2 marker to identify some wild seaweed species, from Tomini Bay and Banten Bay waters. Five wild seaweed species collected from these waters were submitted for DNA barcoding. Currently available universal primers for ITS2 region amplification were sufficient to be successfully amplified and the result of DNA amplification continue to be sequenced. In conclusion, the data presented here indicates that ITS2 are useful markers for DNA barcoding of wild seaweed, with advantage for ITS2 due to the larger availability of analytical tools and reference barcodes deposited at databases for this marker.

Metal Concentrations in Wild-Harvested Phaeophyta Seaweed from the Atlantic Ocean (Canary Islands, Spain)

Seaweeds are being consumed more often worldwide and are a source of essential minerals, fiber, vitamins, amino acids, and various bioactive compounds that have many beneficial effects on human health. However, marine pollution and the high capacity of seaweed to absorb metals may mean this food can also be dangerous to human health. The concentrations of some trace elements (B, Ba, Fe, Ni, Li, and V) and toxic metals (Al, Cd, and Pb) were determined in various species of wild seaweeds in the Phaeophyta group of brown algae from the Atlantic Ocean. Inductively coupled plasma atomic emission spectrometry revealed high concentrations of Al (256 mg/kg dry weight), Pb (3.92 mg/kg dry weight), and Cd (0.20 mg/kg dry weight) in Padina pavonica. Pb contributed the most to the tolerable daily intake (TDI) of toxic metals in these samples; 57.2 and 45.3% of the TDI for Pb was found in 5 g of dehydrated P. pavonica and Halopteris scoparia, respectively. This percent contribution is half of the recommended TDI for this metal, which is 34.24 μg/day; therefore, high consumption of these species is discouraged. The maximum TDIs established by various institutions for the other metals were not exceeded from the daily consumption of 5 g of the other dehydrated seaweeds evaluated in this study.

Potency of Different Seaweeds as Diets for Developing Abalone (H. squamata) Culture in Nusa Penida Island, Bali

Nusa Penida island is one of center for seaweed culture in Bali province. Seaweed that cultured is Euchema spinosum and Euchema cottoni spread around coastal. There also found wild seaweed, such as Ulva sp and Gracillaria sp. Abalone (H. squamata) is one of kind Mollusca which high economic value, but abalone cultured is not yet develop in Nusa Penida island, although this island have high potency for developing abalone culture. Abalone culture needs seaweeds as a diet. The abundance of seaweeds as abalon diet is important for developing abalon culture in Nusa Penida Island in the future. The aim of this research was to asses the potency of seaweeds as diet for developing abalone culture in Nusa Penida island. Research was done in Batununggul village, Nusa Penida Island. Experimental design was used Completely Randomized Design (CRD) with 3 treatments and 3 replications. The treatments were used different seaweeds as diet for abalone culture: (DG=Diet Gracillaria sp, DS=Diet Spinosum sp. and DU=Diet Ulva sp.). Abalon were cultured for 4 months by feeding the diet at satiation. Data analysis was used analysis varian (Anova) with SPSS. 16. The result showed abalon fed with Gracillaria sp (DG) at 4.73 g was the highest growth by 4.73 g, followed DU by 3.93 g and DS by 3.43 g. Meanwhile the abalon shell length fed with Gracillaria sp (DG) was the highest growth by 6.55 mm, followed DU by 5.97 mm and DS by 5.60 mm. Based on variant analysis showed growth performance (length shell and weight) abalon, all treatments were not significantly different (P>0.05). The conclusion this research, the three species of seaweed can be used as diet for abalone culture. These seaweeds have same potency as diet for developing abalone culture in Nusa Penida Island

Comparison of bioethanol production from cultivated versus wild Gracilaria verrucosa and Gracilaria gigas

The seaweed genus Gracilaria is a potential candidate for the production of bioethanol due to its high carbohydrate content. Gracilaria is abundant throughout the world and can be found in both wild and cultivated forms. Differences in the ecological factors such as temperature, salinity, and light intensity affecting wild and cultivated specimens may influence the biochemical content of seaweeds, including the carbohydrate content. This study aimed to investigate the proximate composition and potential bioethanol production of wild and cultivated G. gigas and G. verrucosa. Bioethanol was produced using separate hydrolysis fermentation (SHF), employing a combination of enzymatic and acid hydrolysis, followed by fermentation with Saccharomyces cerevisiae ATCC 200062. The highest carbohydrate content was found in wild G. gigas. The highest galactose and glucose contents (20.21 ± 0.32 and 9.70 ± 0.49 g L−1, respectively), as well as the highest production of bioethanol (3.56 ± 0.02 g L−1), were also found in wild G. gigas. Thus, we conclude that wild G. gigas is the most promising candidate for bioethanol production. Further research is needed to optimize bioethanol production from wild G. gigas. Domestication of wild G. gigas is a promising challenge for aquaculture to avoid overexploitation of this wild seaweed resource.