Seaweed Cultivation Research Articles

Beyond the Win–Win Discourse: Designing Seaweed Farming for Long‐Term Success

ABSTRACTCommunication about seaweed aquaculture has so far been dominated by its many socio‐economic and ecological advantages. A key risk of this ‘hype’ is the potential loss of support from communities affected by seaweed cultivation if reality fails to live up to expectations. This could have justice and equity implications for impacted communities, and undermine potential benefits for those communities, as well as affecting the long‐term success of emerging industries. This paper highlights experiences from other marine sectors in which a similar emphasis on benefits has drowned out discussion of potential costs, often leading to initial success but long‐term failure. We highlight the importance of clearly communicating possible negative impacts, and meaningfully engaging stakeholders to shape marine interventions. Finally, we recommend further research into the social dimensions of seaweed farming in geographies where this practice is nascent, and increased attention to the potential trade‐offs of scaling up seaweed cultivation.

Understanding and estimating the role of large-scale seaweed cultivation for carbon sequestration on a global scale over the past two decades

Seaweeds, as marine photosynthetic organisms, are harvested by humans from the wild or through cultivation for various production purposes and to provide a range of marine ecosystem services, including nutrient removal, oxygen production, and carbon sequestration. The potential use of cultivated seaweed in mitigating carbon dioxide (CO2) has been extensively proposed in conjunction with commercial seaweed production worldwide. This study aims to assess the annual potential and benefits of cultivated seaweed in reducing and fixing anthropogenic CO2. Over the past two decades (2000–2019), global seaweed production has seen significant growth. The total output of cultivated seaweed reached 407.4 × 107 tons (t), with coastal mariculture removing 4.26 × 107 t of carbon annually and wild capture removing 2.24 × 106 t. The recalcitrant dissolved organic carbon (RDOC, 549.88–621.60 × 104 t) plays a significant role in the carbon sinks of seaweed cultivation. The substantial benefits of carbon sink resulting from the formation of RDOC from seaweed make up a considerable proportion in the calculation of carbon sequestration and sink enhancement benefits in large-scale seaweed cultivation. The sizable carbon sink base of seaweed cultivation (8631.90–9567.37 × 104 t) results in significant carbon fixation benefits. The total economic value of carbon sequestration and oxygen production was estimated at $70.36 ± 1.52 billion, with an annual average benefit of $3.52 ± 1.70 billion. Increasing the area and yield available for cultivated seaweed has the potential to enhance biomass production, carbon accumulation, and CO2 drawdown. It is crucial to emphasize the need for improved communication regarding the essential criteria for the feasibility of CO2 removal (CDR), with a focus on conducting life cycle assessments (LCA) when utilizing marine processes in the present and future work. The sustainable development of the seaweed cultivation industry not only ensures that Asian-Pacific countries remain leaders in this field but also provides an effective yet overlooked solution to excessive CO2 emissions worldwide.

White Rot Disease Occurs on Wild Individuals of the Economically Important Red Seaweed Halymenia durvillei (Rhodophyta)

Seaweed diseases have been reported in both wild and cultivated seaweed species worldwide. However, reports on tropical seaweed diseases are uncommon and are often focused on farmed species. In the Philippines, seaweed diseases have been reported in economically important species such as Eucheuma, Kappaphycus, and Halymenia. Regarding Halymenia, the occurrence of white rot disease has been reported on laboratory-reared and open sea-outplanted individuals. Here, I report for the first time the occurrence of white rot disease on Halymenia durvillei as observed in the wild. While the disease may have detrimental effects, I hypothesize that the disease and the subsequent breaking of branches may play a role in the dispersal and reproductive success of H. durvillei. Nonetheless, studies on the bio-ecology of its pathogen and the impacts of the disease should be conducted considering the commercial potential of H. durvillei farming.

Sustainable seaweed aquaculture and climate change in the North Atlantic: challenges and opportunities

Seaweed aquaculture is gaining traction globally as a solution to many climate issues. However, seaweeds themselves are also under threat of anthropogenically driven climate change. Here, we summarize climate-related challenges to the seaweed aquaculture industry, with a focus on the developing trade in the North Atlantic. Specifically, we summarize three main challenges: i) abiotic change; ii) extreme events; and iii) disease & herbivory. Abiotic change includes negative effects of ocean warming and acidification, as well as altered seasonality due to ocean warming. This can lower biomass yield and change biochemical composition of the seaweeds. Extreme events can cause considerable damage and loss to seaweed farms, particularly due to marine heatwaves, storms and freshwater inputs. Seaweed diseases have a higher chance of proliferating under environmentally stressful conditions such as ocean warming and decreased salinity. Herbivory causes loss of biomass but is not well researched in relation to seaweed aquaculture in the North Atlantic. Despite challenges, opportunities exist to improve resilience to climate change, summarized in three sections: i) future proof site selection; ii) advances in breeding and microbiome manipulation; and iii) restorative aquaculture. We present a case study where we use predictive modelling to illustrate suitable habitat for seaweed cultivation in the North Atlantic under future ocean warming. Notably, there was a large loss of suitable habitat for cultivating Alaria esculenta and Laminaria digitata. We show how selection and priming and microbe inoculates may be a cost-effective and scalable solution to improve disease- and thermal tolerance. Co-cultivation of seaweeds may increase both yield and biodiversity co-benefits. Finally, we show that aquaculture and restoration can benefit from collaborating on nursery techniques and push for improved legislation.

Sea Vegetables: An Alternative Food Source: A Review

Seaweeds or sea vegetables are the non-traditional vegetables largely produced and consumed by China, Japan, Korea, Indonesia, Philippines, Malaysia, Vietnam and other island countries. They are rich in essential nutrients, including minerals, vitamins, amino acids etc. making them a valuable addition to a balanced diet. Moreover, they have low caloric content and are free from cholesterol, essential for weight management and heart-healthy diets. Additionally, sea vegetables contain unique bioactive compounds such as polysaccharides, polyphenols and omega-3 fatty acids, which have antioxidant, anti-inflammatory and anti-cancer properties. Globally the demand for seaweed as vegetables along with its several value-added products are increasing day by day. The cultivation of seaweed is cost effective as it does not require seeds, fertilizers, pesticides, no freshwater and arable land. Sea vegetables can serve as bio filters by absorbing excess nutrients from aquatic ecosystems, thus promoting environmental sustainability in coastal aquatic system. To combat hunger, achieve food security and protect the environment, it is crucial to create public awareness on the health benefits and nutritional value of sea vegetables. More in-depth research and developments are required to commercialize, explore the diversity of sea vegetables, develop innovative culinary applications and establishment of quality and safety standards. The present review works highlights a comprehensive overview of seaweed diversity, nutritional composition, health benefits, diverse uses, cultivation methods and potential for developing processed products for food and agricultural industry.

PEMETAAN TEMATIK KESESUAIAN LAHAN BUDIDAYA RUMPUT LAUT PADA PERAIRAN TELUK KAYELI KABUPATEN BURU

Background: Seaweed is widely cultivated in coastal areas of Indonesia, one of which can be found in Kayeli Bay, Buru Regency. One of the problems faced by farmers in cultivating seaweed in this area is that there is no division of suitable areas for cultivation land in the form of thematic maps, especially using physical-chemical parameters of waters. Method: This activity includes several stages, namely location survey, data collection or collection and preparation of a database. Measurements of physical and chemical parameters of waters are carried out directly in the field (in situ) and in the laboratory (ex situ). The measurement parameters include temperature, brightness, wave height, current speed, pH, salinity, DO, nitrate and phosphate. To create a thematic map of land suitability, the ArcGis application was used. Results: Most of the physical and chemical parameters of the waters are still suitable for seaweed cultivation, except for temperature and phosphate. The results of land suitability evaluation/analysis based on water physical-chemical parameters produce two land suitability categories, namely suitable (S2) and very suitable (S1). The category corresponds to an area of ​​110.2 ha or 29% and very corresponds to an area of ​​269.8 ha or 71%. Conclusion: The thematic map of Kayeli Bay waters, Buru Regency shows that the suitability of seaweed cultivation land is divided into two categories, namely suitable at 29% and very suitable at 71%. However, the temperature and phosphate parameters at the time of measurement were in the category not suitable for seaweed cultivation.

High Salinity Intensive Seaweed Growth Rate in Aquaponic Systems

Aquaponics is a closed recirculating aquaculture method combined with hydroponics. This method is very alternative for raising fish while growing plants in specially designed media. The mechanism obtained is very effective and efficient, plants can utilize fish waste as nutrients for plant growth. Poisonous fish waste in ponds can be reduced by plants as nutrients for organic substances. This can enhance profitable bio-integrated food production systems. Plants will serve as vegetation filters. This study aimed to determine the effectiveness of aquaponic treatment in high-salinity water by observing the growth in three species of seaweed namely Gracilaria sp., Sargassum sp., and Kappaphycus alvarezii. The research design used the LSD method and was carried out for 63 days. Data analysis using Analysis of Variance (ANOVA) then continued with the test Duncan's Multiple Range Test. The research method involved making aquaponic media including preparing containers for seaweed cultivation and fish and shrimp farming, observing seaweed growth rates, and measuring water quality. Aquaponic treatment can increase the growth rate of intensively cultivated seaweed. The results showed the best weight growth rate in the aquaponic treatment of Gracilaria sp. with a value of 12.33 grams than Kappaphycus alvarezii 11.33 grams and Sargassum sp. 10.83 grams.

Erosion of cultivated kelp facilitates dissolved organic carbon release

Growing trend of interests for contributions of cultivation of kelp to carbon sequestration have been driven globally. Saccharina japonica is an important cultivated seaweed, with erosion phenomenon usually occurs at the distal part of the frond in S. japonica throughout the growth cycle. However, the dynamics of dissolved organic carbon (DOC) release induced by erosion of S. japonica are not well understood. This study revealed that erosion induced a substantial increase in DOC release, with a 14% increase under low light (LL) conditions and a 54% increase under high light (HL) conditions. A 10 cm of long slit cut into the distal part of S. japonica increased the rate of DOC release by 56% under LL conditions, and by 13% under HL conditions. Additionally, the epibiotic microorganisms facilitate the release of DOC, and the effects were even more pronounced in erosive S. japonica. Conversely, the proximal part of S. japonica exhibited a higher photosynthetic carbon fixation capacity, with a carbon-to-nitrogen (C/N) ratio approximately 1.76 times higher than that in distal part. During the growth of S. japonica, excess photosynthetic products were often transported from the proximal part into distal part, further facilitating DOC release. In summary, DOC released induced by erosion of S. japonica could make contributions to oceanic carbon sequestration.

Seaweed as a feed additive to mitigate enteric methane emissions in ruminants: Opportunities and challenges1

Cutting farming-related methane emissions from ruminants is critical in the battle against climate change. Since scientists initially investigated the potential of marine macroalgae to reduce methane emissions, using seaweeds as an anti-methanogenic feed additive has become prevailing in recent years. Asparagopsis taxiformis is the preferred species because it contains a relatively higher concentration of bromoform. As a type of halogenated methane analogue, bromoform contained in A. taxiformis can specifically inhibit the activity of coenzyme M methyltransferase, thereby blocking the ruminal methanogenesis. However, bromoform is a potential toxin and ozone-depleting substance. In response, current research focuses on the effects of bromoform-enriched seaweed supplementation on ruminant productivity and safety, as well as the impact of large-scale cultivation of seaweeds on the atmospheric environment. The current research on seaweed still needs to be improved, especially in developing more species with low bromoform content, such as Bonnemaisonia hamifera, Dictyota bartayresii, and Cystoseira trinodis. Otherwise, seaweed is rich in bioactive substances and exhibits antibacterial, anti-inflammatory, and other physiological properties, but research on the role of these bioactive compounds in methane emissions is lacking. It is worthy of deeper investigation to identify more potential bioactive compounds. As a new focus of attention, seaweed has attracted the interest of many scientists. Nevertheless, seaweed still faces some challenges as a feed additive to ruminants, such as the residues of heavy metals (iodine and bromine) and bromoform in milk or meat, as well as the establishment of a supply chain for seaweed cultivation, preservation, and processing. We have concluded that the methane-reducing efficacy of seaweed is indisputable. However, its application as a commercial feed additive is still influenced by factors such as safety, costs, policy incentives, and regulations.

Social Capital in the Patron-Client Dimension towards the Sustainability of Seaweed Cultivation Businesses in Rural Areas, South Sulawesi, Indonesia

The system of livelihoods in seaweed cultivation becomes the subject of study because of the factor of production, and the distribution of the output of production requires a strategy of merging between something material and non-material that involves interaction with various actors in society. The social capital awakened by the actors in the seaweed cultivation business through the patron-client dimension is an effort to ensure the sustainability of the business. The study aims to characterize the components of social capital that bind, bridge, and connect in the context of the relationship between actors in seaweed cultivation, including the important role of the combination of these three types of social capital in the sustainability of the seaweed cultivation business. The Research methods use qualitative descriptive approaches. Data is collected through semi-structured interviews and analyzed with open, axial, and selective encoding. The results show that actors in seaweed cultivation enterprises combine the social capital components of bonding, bridging, and linking selectively, depending on the interests behind each interaction with different actors. Social bonding capital is owned by seaweed farmers in their interactions to gain access to financial capital (in the form of cash and loans). The patron-client relationship pattern is the most prominent of the reciprocity relationships, where the patron is the provider of corporate capital and the guarantor of subsistence is the cultivator. The social bridging and linking capital is owned in its interaction to gain access to social assistance and political support as well as networking. Mechanisms of sale of seaweed production are dominated by marketing networks using intermediary services (middlemen) through the concept of personalized exchange. In such market trading, the symptoms of “boro” (guarantees) are detected through subscription relationships between sellers and buyers characterized by regular personality contacts and through credit mechanisms known as “take now, pay later”. Therefore, social capital plays an important role in the sustainability of seaweed farming in the countryside. In a situation of economic or environmental change, social capital can help the farmer adapt and survive in his business and household life. We found that social capital plays an important role in the rural habitat system, where access to livelihoods depends on social relationships. Thus, support is needed to strengthen the capacity of social capital in societies because the configuration of the social capital elements can inherit the cognitive social capital, the social structural capital and the social relational capital necessary for the improved social, economic and cultural development of societies.

Quantifying growth, erosion and dislodgement rates of farmed kelp (Saccharina latissima) to examine the carbon sequestration potential of temperate seaweed farming

Seaweed cultivation, including kelp species, is rapidly expanding in many regions. A widely assumed co-benefit of seaweed farming is increased local carbon sequestration rates (thereby contributing to climate change mitigation), although direct field-based measurements of carbon assimilation and release are largely lacking. We quantified growth, erosion and dislodgement rates of farmed Saccharina latissima in Porthallow Bay (Cornwall, UK) throughout a typical cultivation season to provide insights into the carbon sequestration potential of small-scale kelp farms. Blade elongation rates increased from ~ 1.3 cm day−1 to ~ 2.3 cm day−1 in March–April, before declining to 1.4 cm day−1 by May. Meanwhile, erosion rates remained low, ranging from ~ 0.5 to ~ 0.8 cm day−1. Dislodgement rates decreased from 20% of plants in January–February to 5% in April–May. Rates of carbon accumulation and loss increased from January to May, related to an increase in standing stock. Conservative first-order estimates suggest that the farm captures 0.14 t C ha−1 y−1, of which up to 70% is released into the environment as particulate organic carbon. Based on previous estimates of carbon burial and storage rates, the farm may sequester 0.05 t CO2e ha−1 y−1. These values suggest that scaling-up European kelp farming should be motivated by other co-benefits, such as low-carbon product alternatives, job creation and potential biodiversity gains, and not be solely driven by a perceived meaningful increase in carbon sequestration. Importantly, further information needs to be obtained from a variety of cultivation sites to develop a better understanding of carbon dynamics associated with kelp farms.

A Review Paper on Bioremediation, A Panacea to Aquaculture Productivity

Aquaculture production encompasses the cultivation of aquatic organisms, including fish, shellfish, and plants, within controlled environments, playing a pivotal role in meeting the escalating global demand for fish and seafood. Various techniques are employed, ranging from fish farming in ponds, cages, or tanks to the cultivation of seaweed and other aquatic flora. The overarching objective is to achieve sustainable production while minimizing adverse environmental impacts. The utilization of bioremediation techniques in aquaculture entails harnessing microorganisms to degrade pollutants and ameliorate water quality, thereby fostering a healthier environment conducive to the thriving of aquatic organisms. Strategic interventions, such as the introduction of specific bacteria or plants capable of absorbing excess nutrients, contribute to ecosystem equilibrium, thereby promoting sustainable aquaculture practices. Leveraging living organisms to detoxify or eliminate pollutants represents a promising strategy for addressing environmental challenges associated with intensive aquaculture. The review delves into elucidating the mechanisms underlying microbial communities and selected organisms' capacity to mitigate water quality issues, notably excess nutrients and organic matter accumulation. Common bioremediation approaches encompass the utilization of beneficial bacteria, denitrifying bacteria, Nano remediation, biological filters, bioaugmentation, and oxygenation. By integrating these bioremediation techniques, aquaculture enterprises can bolster water quality, mitigate disease risks, and foster a more sustainable and productive aquatic environment conducive to the flourishing of aquatic organisms.

Seaweeds as holobionts: Current state, challenges, and potential applications.

Seaweeds play a strong ecological and economical role along the world's coastlines, where they support industries (e.g., aquaculture, bioproducts) and essential ecosystem services (e.g., biodiversity, fisheries, carbon capture). Evidence from wild and cultured seaweeds suggests that microorganisms play crucial roles in their health and functioning, prompting the need for considering seaweeds and their microbiome as a coherent entity or "holobiont." Here we show that the number of studies investigating seaweed hosts and their microbiome have increased in the last two decades. This likely reflects the increase in the appreciation of the importance of microbiomes for eukaryotic hosts, improved molecular approaches used to characterize their interactions, and increasing interest in commercial use of seaweeds. However, although increasing, most studies of seaweed holobionts have focused on (i) a few seaweed species of ecological or commercial significance, (ii) interactions involving only bacteria, and (iii) descriptive rather than experimental approaches. The relatively few experimental studies have mostly focused on manipulating abiotic factors to examine responses of seaweeds and their microbiome. Of the few studies that directly manipulated microorganisms to investigate their effects on seaweeds, most were done in laboratory or aquaria. We emphasize the need to move beyond the descriptions of patterns to experimental approaches for understanding causation and mechanisms. We argue that such experimental approaches are necessary for a better understanding of seaweed holobionts, for management actions for wild and cultivated seaweeds, and to better integrate studies of seaweed holobionts with the broader fields of seaweed ecology and biology, which are strongly experimental.

The past, present and future developments in mariculture in the coastal waters of mainland Tanzania

AbstractMarine coastal resources are crucial to Tanzania's socio‐economic development and are a lifeline for the livelihoods and incomes of coastal communities. This study provides an overview of the coastal development of mariculture in mainland Tanzania and suggests future development strategies. The review article covers extensive reports available through field interviews, government policy documents, library literature searches and field work carried out by the authors. Despite the immense potential of mariculture to improve food security for localcommunities, its development has been uneven. Specifically only seaweed farming has advanced to commercial‐scale production. Other mariculture activities, such as finfish farming (e.g. milkfish, silver pompano), shellfish farming (e.g. prawn, mud crab and half‐pearl) and sea cucumber farming, are underdeveloped and confined to small‐scale operations. Locally consumed finfish, such as milkfish and pompano, have not attracted investors out of fear that the recovery of investment may not be achieved due to the low prices offered in the market. In this context, the sustainable use of coastal resources through mariculture becomes paramount to alleviating poverty and facilitating controlled migration from rural to urban. This comprehensive review explores the historical evolution and current status of mariculture initiatives in the coastal waters of mainland Tanzania, which presents a crucial aspect of the socio‐economic development of the nation. With declining global capture fisheries production and a growing demand for fish protein, Tanzania has strategically embraced mariculture as a viable alternative. The article traced the development of mariculture since the 1970s, highlighting past and current initiatives managed by government agencies, non‐government organizations and the private sector. Notable successes, such as seaweed culture, are highlighted along with the challenges that hinder the growth of marine farming activities. The review integrates insights from a comprehensive survey in coastal Tanzania, focusing on mariculture activities and collecting information on people who have stopped such practices, elucidating reasons for quitting. By consolidating experiences from past and present mariculture initiatives, this review provides valuable guidance for decision‐making towards promoting sustainable mariculture that supports coastal communities while preserving marine biodiversity.

Assessing the potential for seaweed cultivation in EU seas through an integrated modelling approach

The potential of large-scale seaweed cultivation to contribute to achieving ambitious EU-wide objectives, such as food security, energy independence, carbon neutrality and ecosystems restoration, is widely recognized. However, there is a lack of information on the suitability of EU marine regions for the installation of floating macro-algae cultivation infrastructures. In this study, we utilize the World Offshore Macro Algae Production Potential (WOMAPP) model in conjunction with state-of-the-art coupled hydrodynamic-biogeochemical models, to assess the environmental suitability of EU marine regions for seaweed cultivation. Our analysis reveals that the EU Atlantic regions are the most suitable areas for seaweed cultivation, particularly for cold-water and intermediate-water species. The potential cultivation area is extensive, spanning over 1 million km2, and even taking a precautionary approach by occupying only 1% of that area could yield a yearly production of over 30 million tonnes dry weight. Adding logistical constraints (water depth and distance to coast) further limit the potential production to 5 million tonnes per year, only considering EU member states' waters. Furthermore, we discuss the opportunity to use integrated multi-trophic aquaculture (IMTA), to increase the potential for seaweed cultivation.

Marine heatwaves alter competition between the cultured macroalga Gracilariopsis lemaneiformis and the harmful bloom alga Skeletonema costatum

Seaweed cultivation can inhibit the occurrence of red tides. However, how seaweed aquaculture interactions with harmful algal blooms will be affected by the increasing occurrence and intensity of marine heatwaves (MHWs) is unknown. In this study, we run both monoculture and coculture systems to investigate the effects of a simulated heatwave on the competition of the economically important macroalga Gracilariopsis lemaneiformis against the harmful bloom diatom Skeletonema costatum. Coculture with G. lemaneiformis led to a growth decrease in S. costatum. Growth and photosynthetic activity (Fv/Fm) of G. lemaneiformis was greatly reduced by the heatwave treatment, and did not recover even after one week. Growth and photosynthetic activity of S. costatum was also reduced by the heatwave in coculture, but returned to normal during the recovery period. S. costatum also responded to the stressful environment by forming aggregates. Metabolomic analysis suggests that the negative effects on S. costatum were related to an allelochemical release from G. lemaneiformis. These findings show that MHWs may enhance the competitive advantages of S. costatum against G. lemaneiformis, leading to more severe harmful algal blooms in future extreme weather scenarios.

Analyzing the potential for Padina gymnospora cultivation in the coastal waters of St. Martin’s Island, Bay of Bengal, Bangladesh: Determining the fluctuations of physicochemical property across seasons and locations

Cultivating seaweed presents an opportunity to enhance the livelihoods of the inhabitants of St. Martin's Island inhabitants. This research investigates the suitability of the island's coastal waters for seaweed cultivation, taking into account variations in physicochemical factors in different seasons. The water temperature and salinity at various locations ranged from 24.22ºC to 27.64ºC and 23.8 to 33.76 psu, respectively. pH remained relatively constant throughout the year, fluctuating between 7.71 and 8.22. Dissolved oxygen levels were highest during the dry, cooler winter season (6.47±0.21 ppm) and lowest during the monsoon season (4.96±0.09 ppm). Electrical conductivity (EC) ranged from 39.00 mS/cm to 53.46 mS/cm, while total dissolved solids (TDS) varied between 20.35 and 27.90 g/l. Water clarity was at its peak during the dry, cooler winter season, averaging 4.14 meters. This investigation confirms the feasibility of year-round seaweed cultivation in the coastal waters around St. Martin's Island. In our study comparing cultivation methods for Padina gymnospora during the dry, cool winter season, the long-line approach resulted in a higher daily weight gain compared to the floating net method. This trend extended to growth rates by length, with the long-line method demonstrating a 5.09% daily growth and the floating net method showing 4.46%. However, net biomass production was 289.32 g/m² for the long-line method and 381.28 g/m² for the floating net method. Furthermore, the Cost-Benefit Ratio values for the long-line and floating net methods were 2.57 and 3.27, respectively. These findings affirm the viability of cultivating Padina gymnospora in coastal waters using the floating net method. Biodivers. Conserv. Bioresour. Manag. 2024, 10(1): 1-14

Structural Risk and Reliability Assessment of Offshore Aquaculture Floating System for Seaweed Cultivation

Structural Risk and Reliability Assessment of Offshore Aquaculture Floating System for Seaweed Cultivation

Indicators for ecological carrying capacity of bivalve and seaweed aquaculture

AbstractWithin the framework of Ecosystem Approach to Aquaculture (EAA), ecological carrying capacity (ECC) is a key concept that helps to determine the upper limit of production without compromising ecosystem functioning. The implementation of ECC is complex as ECC differs between type of farms and location and standardised methods should be developed for management. There is therefore a clear need for operational indicators. The objectives of this paper were: (1) to carry out a systematic literature review on shellfish and seaweed aquaculture‐environment interactions to list the most used environmental indicators, (2) to classify the indicators according to the effects they measure (i.e., benthic, water quality, food web interactions, cultured organism health, resource use) and the scale at which they are applied, and (3) to assess their potential based on four indicator criteria categories: sensitivity, accuracy and precision, feasibility and utility, and ecosystem‐level scalability. Overall, indicators describing benthic effects were the most highly cited and scored. Indicators identified for bivalve and seaweed culture were discussed and compared to previous work on salmon aquaculture indicators to highlight similarities and differences across trophic levels. In addition, questions related to the challenges of ECC indicators implementation were presented to a panel of experts. The scoring and consultation provided the source of discussion on environmental management consistent with EAA.

Potential to reduce methane production of using cultivated seaweeds supplementation to reshape the community structure of rumen microorganisms

Methane is a short-lived greenhouse gas but has a far greater warming effect than carbon dioxide. At the same time, the livestock sector serves as a large contributor to global emissions of anthropogenic methane. Herein, this work aimed to use cultivated seaweed supplementation to reduce methane emissions and investigate the potential influencing mechanism. To evaluate the feasibility, two cultivated seaweeds, Laminaria japonica Aresch, and Porphyra tenera, along with the enzymatic hydrolysates derived from L. japonica, underwent in vitro trials, and they were both added into corn silage feed (CSF) with different concentrations (1%, 5%, and 10% of CSF) for methane reduction evaluation. The results indicated that >75% and 50% reductions in methane production were observed for the seaweeds and seaweed enzymatic hydrolysates in 9- and 30-day, respectively. Combined high-throughput sequencing and multivariate analysis revealed that supplementation with seaweed and seaweed enzymatic hydrolysates had a notable impact on the prokaryotic community structure. Mantel tests further revealed that significant correlations between the prokaryotic community and methane accumulation (P < 0.05), implying the prokaryotic community plays a role in reducing methane emissions within the rumen. Correspondingly, the networks within the prokaryotic community unveiled the crucial role of propionate/butyrate-producing bacteria in regulating methane emissions through microbial interactions. The predicted function of the prokaryotic community exhibited a significant reduction in the presence of the narB gene in seaweed-supplemented treatments. This reduction may facilitate an increased rate of electron flow toward the nitrate reduction pathway while decreasing the conversion of H2 to methane. These results indicated the supplementation of cultivated seaweeds and the enzymatic hydrolysates has the potential to reshape the community structure of rumen microbial communities, and this alteration appears to be a key factor contributing to their methane production-reduction capability.