Marine Debris Pollution Research Articles

Assessing the scale and ecological impact of derelict and discarded fishing gear across Thailand via the MARsCI citizen science protocol

South-East Asia is among the least studied regions for the growing issue of marine debris pollution, despite being a major contributor towards global marine debris. In the present study, we provide the preliminary results from the MARsCI project, a survey protocol designed to utilise citizen science to facilitate data collection on the ecological impact of discarded fishing gear (DFG) in Thailand. Over a three-year period, 103 surveys were carried out across Thailand, resulting in impact assessment of 606 pieces of DFG. Our findings indicate corals are regularly impacted by DFG in Thai waters and that isolated marine habitats may be more severely impacted than near-shore sites. We further identify crabs, muricid snails, and demersal fish to be among the most regularly entangled animals. We discuss our findings in the context of earlier work from Thailand, and conduct a critical review of the protocol itself, identifying improvements for future efforts.

Gujarat’s plastic plight: unveiling characterization, abundance, and pollution index of beachside plastic pollution

Plastic pollution poses a pervasive threat to ecosystems worldwide, jeopardizing marine life, contaminating water sources, and perpetuating a global environmental crisis. Spatial and temporal distribution of beach debris was quantitatively assessed on three recreational beaches in Gujarat State, India. A total of six debris categories were recorded with a mean of 0.9 items/m2 in number and 3.62 g/m2 in weight. A total of Mean debris concentrations and weight per debris item did not vary significantly between study sites. Highest debris concentrations were observed in October 2021 at all sites. Around 90% was macro-debris (2.5–100 cm), with white and transparent colours most frequently encountered. Based on Clean Coast Index findings, all sites were categorized as "dirty". Plastic Abundance Index revealed that all sites had a very high abundance of plastics compared to other beach debris. Recreational activities on beaches, tourism, and extensive fishing can be the possible source of marine debris on Gujarat State. The findings of the current investigation is vital to understanding its pervasive environmental impact, encompassing threats to biodiversity, water quality, and ecosystems, while guiding effective policies to mitigate these repercussions on a global scale. It can be helpful to establish mitigation strategies urgently required to reduce marine debris pollution along the Gujarat Coast. It is recomanded to implement urgently needed mitigation strategies to diminish marine debris pollution along the Gujarat Coast.

Dynamics of marine debris in the point calimere wildlife and bird sanctuary wetland, southeastern coast of India

Marine debris pollution in wetlands is a largely neglected problem despite its impact on the biodiversity. This manuscript presents the findings of a comprehensive study conducted in the Point Calimere wetland, spanning March 2022 to February 2023, to assess the abundance, composition, and sources of anthropogenic debris. During the survey, 1760 debris items weighing 192.51 kg were collected from fifteen transects, revealing significant variations in both count and weight across the sampling sites. Plastic debris was predominant in terms of both count and weight, followed by cloth/fabric. They emerged as the most prevalent type, exhibiting the widest count range and maximum abundance per transect. Specific debris types, such as plastic rope/small net pieces, were more prevalent in both count and weight. Analysis of debris per square meter indicated an average abundance of 1.23 ± 1.17 items and an average weight of 144.34 ± 70.01 g. Statistical analysis confirmed the significant influence of transects and quadrats on debris count abundance, with varying effects across different transects. The study also identified shoreline and recreational activities and ocean/water activities as primary sources of marine debris. Land-based sources had a higher count, while sea-based sources contributed more to the overall weight. These findings provide valuable insights into marine debris distribution, composition, and sources, which can inform targeted mitigation strategies and conservation efforts.

Sosialisasi dan Edukasi Konservasi Penyu di KKP3K Paloh “Menjaga Penyu, Menjaga Alam, Menjaga Kehidupan”

Paloh District is a turtle conservation area designated by the Minister of Maritime Affairs and Fisheries. This conservation area is managed by local community groups and the WWF-Indonesia Foundation under the authority of the West Kalimantan Province Maritime and Fisheries Service. Turtles are protected biota because of their endangered status. However, the community, especially local residents, do not yet have awareness of the importance of protecting this biota and also maintaining the balance of the surrounding ecosystem. Several cases occurred in Paloh, namely poaching for turtle eggs, degradation of turtle nesting beach habitat and marine debris pollution. Therefore, socialization and education on turtle conservation needs to be carried out, especially in the Paloh turtle conservation area. Activity participants are pupils, students and the community. The education and socalization provided includes the types of turtles, their conservation status and the protection efforts that can be taken. The aim of this community services was provided awareness for the community so that they participate in efforts to protect turtles and their habitat. Participants were very enthusiastic in taking part in the entire series of activities. There were five (5) participants who answered the questions correctly and received gifts from the organizing committee.

Lost and found: Patterns of marine litter accumulation on the remote Island of Santa Luzia, Cabo Verde

Santa Luzia, an uninhabited island in the archipelago of Cabo Verde, serves as a natural laboratory and important nesting site for loggerhead turtles Carettacaretta. The island constitutes an Integral Natural Reserve and a Marine Protected Area. We assessed marine litter accumulation on sandy beaches of the island and analysed their spatial patterns using two sampling methods: at a fine scale, sand samples from 1 × 1 m squares were collected, identifying debris larger than 1 mm; at a coarse scale, drone surveys were conducted to identify visible marine debris (>25 mm) in aerial images. We sampled six points on three beaches of the island: Achados (three points), Francisca (two points) and Palmo Tostão (one point). Then, we modelled the abundance of marine debris using topographical variables as explanatory factors, derived from digital surface models (DSM). Our findings reveal that the island is a significant repository for marine litter (>84% composed of plastics), with up to 917 plastic items per m2 in the sand samples and a maximum of 38 macro-debris items per m2 in the drone surveys. Plastic fragments dominate, followed by plastic pellets (at the fine-scale approach) and fishing materials (at the coarse-scale approach). We observed that north-facing, higher-elevation beaches accumulate more large marine litter, while slope and elevation affect their spatial distribution within the beach. Achados Beach faces severe marine debris pollution challenges, and the upcoming climate changes could exacerbate this problem.

Coastal clean-up in Southeast Asia: lessons learned, challenges, and future strategies

The significant accumulation of marine debris on beaches poses a challenge and raises serious concerns to the global environmental sustainability. It has been previously reported that Southeast Asian (SEA) is one of the global hotspots of marine debris contributor to almost 30% of marine debris pollution to the world oceans. This review discusses the challenge and provide the information of mitigation efforts associated with beach clean-up initiatives to combat the marine debris in Southeast Asia. We employ the comprehensive of qualitative data analysis from relevant literature reviews and conducting a structured study specific to the region, therefore, this research highlights the prevalence and characteristics of marine debris that addressed Coastal Cleanup Activities (CCA) in Southeast Asian. Plastic debris remains type of marine debris commonly found across the beaches. Furthermore, Coastal Clean Up (CCU) activities involving local communities have progressively gained prominence in addressing marine debris issues by utilizing educational outreach to raise awareness effectively. Participants in these initiatives include students, tourists, and high school students. The crucial gap of Coastal CCA required the consistent application of scientific methods during beach clean-ups in Southeast Asian. The importance of community involvement, the adoption of scientific methodology, regular clean-up initiatives, and the potential of marine citizen science formulation could potentially contribute in facilitating an effective approach of marine debris management and education in Southeast Asia. Given the substantial component of initiatives, the result of this study proposes the focus on marine citizen science emerges in the future as a potential avenue for educating and engaging the public awareness towards understanding and tackling marine debris accumulation in Southeast Asian beaches.

Spatial distribution and composition of marine litter on sandy beaches along the Indian Ocean coastline in the south Java region, Indonesia

Marine litter in coastal areas can bring economic, social, and environmental damage, especially the loss of aesthetic value of a tourist site. Therefore, research on the composition of marine litter to identify its sources is important for planning strategic action to minimize the problem. This study analyzed beach litter composition on five beaches (Kondangmerak, Balekambang, Ungapan, Ngudel, and Goa Cina) along the Indian Ocean coastline in the eastern part of the south Java region, Indonesia. All the beaches are known as the famous touristic beaches of Malang City, and receive many visitors, especially during the holiday season. Beach litter composition was obtained by collecting different types of litter in a 5 x 5 m square transect. Five square transects were placed along the beach strandline at each beach, and intervals of 20 m separated each transect. In each transect, the litter was collected and counted based on its category (plastic, paper, rubber, fabric, processed wood, metal, glass, ceramic, and hazardous items) and size (0.5–2.5cm, 2.5–5cm, 5–10 cm, and > 10 cm). There was a statistically significant variation in the number of litters among the sizes (p<0.05). However, the distribution of beach litter remained consistent across beaches regardless of its size. In general, beach litter with a size > 10 cm was found least on all beaches (< 15%), while the other three size categories were found in similar numbers (in the range of 20% to 50%). Plastic was the dominating type of litter on all beaches. Based on the Clean Coastal Index, all beaches were considered dirty to extremely dirty. All litter on the beaches was the product of tourism activities, and littering habits play a significant role as the source of marine litter in the study areas. Since this is the first study on the marine litter composition in the eastern part of south Java, the results of this study can be used as a baseline for future studies to prevent marine debris pollution and to develop management strategies for reducing the impact of marine debris on the environment.

Distribution and pollution assessment of marine debris off-shore Shandong from 2014 to 2022

This study analysed marine debris monitoring data for Shandong from 2014 to 2022 to obtain a better understanding of marine debris stocking off-shore Shandong in order to reduce marine debris pollution and improving the ecological environment of ocean. The results indicated that the abundance of coastal marine debris was 45,832 items/km2 (1118.5 kg/km2); the abundance of small/medium sized floating marine debris was 8976 items/km2 (1.38 kg/km2); and the abundance of large floating marine debris was 35 items/km2; the abundance of seafloor debris was 104 item/km2 (0.22 kg/km2). Compared with the nationwide abundance of marine debris, the quantity density of floating marine debris in Shandong was higher; the abundance of coastal marine debris and quality density of floating marine debris were lower. The majority of the Shandong marine debris was small/medium plastic, mostly from human activities. And we found no significant correlation between precipitation and the abundance of marine debris by statistical analysis.

Detection and quantification of microplastic pollution in the endangered Galapagos sea lion

Marine debris pollution poses a significant global threat to biodiversity, with plastics being the primary debris type found in oceans due to their low-cost production and high demand worldwide. Microplastics (MPs, <5 mm in size) are highly bioavailable to a wide range of marine taxa, including marine mammals, through direct and indirect ingestion routes (i.e., trophic transfer). Recently, MP pollution has been detected on the Galapagos Marine Reserve, so in this study we developed a baseline framework for MP pollution in the Galapagos sea lion (GSL, Zalophus wollebaeki) through scat-based analysis. We collected 180 GSL scat samples from the southeast region following strict quality assurance/quality control protocols to detect, quantify and characterize physical-chemical properties of MPs through visual observations and μFT-IR spectroscopy. We recovered 81 MPs of varying sizes and colors in 37 % of samples (n = 66/180), consisting mostly of fibers (69 %, x¯ = 0.31 ± 0.57 particles scat−1). The number of particles per gram of sample wet weight ranged from 0.02 to 0.22 (x¯ = 0.04 ± 0.05 particles scat wet g−1). El Malecón and Punta Pitt rookeries at San Cristobal Island had the highest number of MPs (x¯ = 0.67 ± 0.51 and 0.43 ± 0.41 particles scat−1, respectively), and blue-colored particles were the most common in all samples. We identified eleven polymers in 46 particles, consisting mostly of polypropylene-polyethylene copolymer, polypropylene, cellulose, polyethylene, and polyvinyl chloride. The textile, fishing, and packaging industries are likely significant sources of microfibers into this insular ecosystem. Our results suggest that the GSL is exposed to MPs due to anthropogenic contamination that is subsequently transferred through trophic processes. These findings provide an important baseline framework and insights for future research on MP pollution in the region, as well as for management actions that will contribute to the long-term conservation of the GSL.

Marine debris provide long-distance pathways for spreading invasive corals

Anthropogenic marine debris and invasive species are pervasive in the ocean. However, research on the mechanisms and dynamics controlling their distribution in marine systems (e.g.; by floating debris acting as vectors for invasive species) is limited. Applying a numerical modeling approach, we demonstrate that rafting invasive corals (Tubastraea spp.) can be transported over long distances and reach important tropical receptor regions. In <180 days, buoyant debris can cover distances between 264 and 7170 km moving from the Brazilian semiarid coast to the Amazon coast and reaching eight regions in the Wider Caribbean (mainly the Eastern Caribbean and Greater Antilles). Analyzing 48 simulated scenarios (4 years × 3 depths × 4 months), we demonstrate that in ~86 % of the scenarios the particles are stranded in the Caribbean and in ~71 % they end up in the Amazon coast. Our results showed litter floating trajectories at 0–10 m water depth, transported every year to the Caribbean province. However, in August this transport is frequently blocked by the retroflection of the North Brazil Current adjacent to the Amazon River estuarine plume. Our results indicate routes for fast and long-distance transport of litter-rafting invasive species. We hypothesized a high risk of bioinvasion on important marine ecosystems (e.g., coral reefs) likely becoming increasingly threatened by these invasive species and debris. This highlights the imperative need for an ocean governance shift in prevention, control, and eradication, not only focused on local actions to prevent the spread of invasive species but also a broad international action to decrease and mitigate marine debris pollution globally.

The Impact of Weak Marine Debris Governance on the Increased Environmental Insecurity in Southeast Asia

The Southeast Asian region is home to five countries that are included in the list of the top 10 countries that produce marine debris in the world. Although there are a lot of efforts to handle the situation through the creation of marine debris governance in the region such as the ASEAN Regional Action Plan, not much has changed. This article aims to determine what Is the cause of weak marine debris governance and how it is impacted the increasing environmental insecurity In Southeast Asia based on the concept of policy harmonization and environmental security according to John Barnett's thinking which divides its meaning into three forms, namely changes in the environment, threats to national security, human security, and triggers for conflict. The research method used is descriptive qualitative research. Researchers found that weak marine debris governance formed as the result of a lack of policy harmonization between countries in the region regarding marine debris pollution and that environmental degradation that ensued had implications for the scarcity of marine resources, which is one of the main economic driving sectors for countries in the region and the possibility to contribute to fisheries conflicts that often occur in the South China Sea, which poses a threat to the national security of the surrounding countries. In addition, this environmental issue also creates human insecurity in the form of economic losses for coastal communities as well as health hazards for the human body.

Beaching model for buoyant marine debris in bore-driven swash

Marine debris pollution is a growing problem impacting aquatic ecosystems, coastal recreation and human society. Beaches are known to be a sink for debris, and beaching needs to be accounted for in marine debris mass balances, but the process of buoyant debris beaching is not yet sufficiently well understood in order for it to be included in coastal models. We develop a simplified model for buoyant marine debris transport in bore-driven swash (where swash refers to the area that the water wets the beach with each incoming wave). We validate the model with laboratory experiments and use the combined results from the model and experiments to understand the parameters that are important for dictating particle beaching. The most relevant parameters are the particle inertia and the initial conditions with which debris particles enter the swash zone.

Preliminary Study Of Marine Debris Composition From Fisherman Activities : A Case Study On Cikidang Fishing Port, Pangandaran

Marine debris pollution has become an important issue in recent years. It has an impact on marine environment and marine life, as well as effecting human health. The objective of this study was to identify the composition of waste that was produced from the fishermen’s activities. The research was conducted in Cikidang Fishing Port, Pangandaran. The data of waste types from fishing vessel were grouped based on the vessel’s dimension. The result show that plastics dominated the waste composition, and based on the vessel dimension when compared the amount of waste generated, the amount of waste from one day fishing (small vessel) was greater than the ten days fishing (big vessel). The amount of waste generated from small vessel was 0.009 tons-1.vessel-1.year-1, meanwhile from big vessel was 0.09 tons-1.vessel-1.years-1. This indicates that the fishers habit to dispose waste not in the right place can become a potential source of marine debris pollution. Maintaining the quality of fishery products is very important starting from improving the fisherman behaviour to the fishing port facilities to achieve the sustainability fishery product.

Distribution and Abundance of Marine Debris on Intertidal Zone at Three Selected Small Islands, Sabah

The issue of marine debris has become worldwide attention since it occurs almost everywhere globally Thus, it is crucial to focus on this area to sustain the life below the water as stated by United Nations (SDG 14). This study evaluated the distribution, abundance, and composition of marine debris in three selected islands at Sabah namely Manukan, Mamutik and Sapi Islands. Marine debris was identified according to its categories as stated by the Department of Environment (DOE). The study was carried out to compare the waste abundance of three islands since the different beach types represent various activities that produce debris. The sampling design was conducted with two plot areas plotted and observed on each island for three consecutive weeks. Based on the assessment done, Mamutik Island recorded the most abundance of marine debris with 12.185 kg (66.2%) of debris found followed by Manukan Island with 5.487 kg (29.8%) of debris and Sapi Island with 0.746 kg (4.1%). It was observed that plastic debris especially plastic bags, plastic bottles, plastic straws, general plastics, polystyrene, and plastic cups were the main contributors to marine debris pollution. While among all the three islands studied, Sapi Island is considered the cleanest and smallest Island compared to others since the location of this island is quite far from the mainland. The solid and waste management on each island has been identified in order to formulate a new strategy to reduce the impact of marine debris on the intertidal zone especially on human health and the environment. These studies have provided a clear understanding of the distribution of marine debris in these islands. Several recommendations and suggestions have been listed to reduce and prevent marine debris pollution.

The Establishment of ASEAN Framework of Action on Marine Debris: The Role of Shared Knowledge

Since the 1970s, marine debris pollution has been considered a global environmental problem because of the serious threat it poses. Based on 2010 data, the amount of marine debris pollution from the four ASEAN countries plus China has exceeded a quarter of the total global pollution. In 2015, the Sustainable Development Goals (SDGs), in particular the 14th goal regarding life under water, were implemented to address this issue in the global realm. But regionally, ASEAN as the biggest pollutant has just formed the ASEAN Framework of Action on Marine Debris in 2019. The time lag is large considering the urgency to respond has emerged since 2010. Even since 2011, ASEAN countries have started research and individual handling efforts. Therefore, knowledge about this issue has emerged since the early 2010s. However, this knowledge does not necessarily get the attention of ASEAN to deal with it collectively. We see that there is an unexplained link between the emergence of urgency and knowledge regarding marine debris pollution in the early 2010s and the formation of the regime in 2019. In this paper, we attempt to analyze how this urgency and knowledge ultimately gained the attention of ASEAN and ultimately formed the regime. The analysis will be carried out using the Weak Cognitivism approach in Knowledge-based theory, focusing on the role of the epistemic community in creating shared knowledge as the key to the formation of an international regime.

Optimization on hybrid energy vessel routing and energy management for floating marine debris cleanup

Marine debris pollution is increasingly threatening the marine environment and human health. The most effective way to remove macro-debris floating offshore is to send vessels to collect it. We employ advanced remote sensing technology to locate debris and vessels equipped with a hybrid energy system composed of photovoltaic, battery packs and diesel to collect debris. In order to establish an effective collection mechanism in an economical and eco-friendly manner, we propose a two-stage optimization approach of vessel routing and energy management strategy. In the first stage, a mixed integer linear programming is to minimize the vessel travel time for removing debris, which is reduced to the vessel routing problem with time window considering discrete speed. Advanced remote sensing technology and trajectory prediction software are used to locate debris at sea. An adaptive large neighborhood search algorithm with pheromone heuristic rule is tailored to solve the problem. A mixed integer linear programming model is proposed to optimize the power flow for the hybrid energy system in the second stage. The objective is to minimize the total cost, taking into account of the constraints of power load balance, battery charge and discharge state and output limit of each energy source. The proposed models and algorithm are validated by a group of numerical examples with different sizes. Compared with VRP Spreadsheet Solver and CPLEX solver, our proposed algorithm not only has obvious advantages in both time and results, but also has cubic function fitting property in time complexity within 100 data. We also compare the optimal power flow and total cost under three illumination intensity scenarios and analyze the optimal power flow for each energy. We find that in optimal power flow, diesel can charge the battery only if it supplies power to vessel load. The results show that compared with the pure diesel system, the hybrid energy system has an overwhelming advantage in terms of total cost and carbon emissions, which can be reduced by 65.78% and 82.69%, respectively. We also find no change in the cost savings of hybrid vessels when considering battery and diesel life-cycle carbon emissions.

Seasonal deposition of marine debris on an important marine turtle nesting beach in Costa Rica

Marine debris pollution poses a threat for wildlife and can negatively impact the economy of communities whose livelihoods depend on tourism. Playa Norte, in northeastern Costa Rica, is an important nesting ground for four marine turtle species identified as vulnerable or endangered on the IUCN Red List. It is highly polluted but has low human occupancy. We conducted accumulation rate surveys following a standardized marine debris protocol from March 2016 to January 2018. Macro-debris was categorized by size and material type. Of the 191,030 debris items retrieved during the two-year study period, 96.2% of them were plastic. Debris accumulation was higher during the dry season (January – September). This study contributes towards understanding the drivers of marine debris pollution in critical wildlife nesting habitats; and informs managers and the local community on possible strategies to prevent and reduce marine pollution, thereby aiding in tourism derived economies.

Characterization of anthropogenic marine macro-debris affecting coral habitat in the highly urbanized seascape of Mumbai megacity

Marine debris has become a major form of pollution and a serious ecosystem health concern. The present study evaluates the accumulation, origin, and fate of debris in intertidal coral habitats of Mumbai-one of the world's highly populated coastal cities on the west coast of India. Predominantly, seven hermatypic coral species belonging to seven genera and five families were identified and mainly represented by Pseudosidastrea, Porites, and Bernardpora. In terms of number, the mean density of marine debris was 1.60 ± 0.13 SE items/m2, which is higher than the global average. The mean density of plastic debris was 1.46 ± 0.14 SE items/m2. Approximately 9% of total coral colonies were in physical contact with debris, and 22% of these colonies showed visible signs of partial bleaching. Single use plastic bags and wrappers were dominant plastic debris. The study area was characterized as ‘very poor cleanliness’ according to the Beach Quality Indexes, which include the Clean Coast Index, General Index, and Hazardous Items Index. The numerical model indicates the influence of river discharge and probable areas of plastic accumulation with high tidal currents in this region, maneuvering the spatial advection of litter in the nearshore areas. Combined analysis of ground-truthing and model simulation implies that the possible contributing sources of litter were representatives of land-based and sea-originated. The overall results point to increasing anthropogenic stressors threatening coastal coral communities, including marine debris pollution. It is advocated to adopt an integrated coastal zone management approach supported by coordinated policy frameworks could guide the mitigation of the debris footprint in coastal environments.

Analysis of marine debris at Alue Naga and Ulee Lheue beaches in Banda Aceh City using the transect method

Alue Naga Beach and Ulee Lheue Beach are beaches located in Banda Aceh City, Aceh Province, these two beaches have a fairly large role in the fields of fisheries, transportation, and tourism. During the last few years, the population growth rate of Banda Aceh City has increased by 2% per year, this causes the volume of waste generated to be even greater, unfortunately, the municipal waste management office cannot manage it fully. Most of the untreated waste enters water bodies and has the potential to pollute the marine and coastal environment. So it is necessary to do research to provide an overview of the level of marine debris pollution on the two beaches. This study uses the transect method, the waste obtained is grouped according to size and type. The results showed that marine debris on Ulee Lheue beach was found to be more numerous and varied than marine debris on Alue Naga beach. Overall, macro waste with a size range of 2.5−1 m was the most commonly found and plastic was the waste with the highest yield with a density value of 65.8 g/m 2 , an abundance of 6.56 items/m 2 , and a percentage of 75%.

Monitoring coastal aquaculture devices in Taiwan with the radio frequency identification combination system

ABSTRACT Marine debris significantly influences the environment and economics of marine ecosystems. Measures to ban illegally discarded materials using monitoring techniques are expected to mitigate marine debris mismanagement. For example, derelict oyster farming rafts along the southwestern coast of Taiwan have been a source of marine debris pollution since the 1980s. An efficient inspection system is an urgent requirement for monitoring oyster farming areas and, is expected to implement control and surveillance measures for litter discarded from coastal fisheries. To address this issue, this study examined combinations of radio frequency identification (RFID), drone archiving, and onshore receiving systems to ascertain the positions of oyster rafts and their owners with digitally tagged labels. The results showed that the two proposed monitoring systems are feasible for use in marine environments. The RFID signals archived by the drone reached 100% of the 200 tags with a spatial bias ranging from 2.38 to 59.99 m. RFID-GPS hybrid tag signals received by the onshore station covered 100% of the 20 tags with spatial bias ranging from 1.27 to 10.47 m. The RFID-GPS hybrid system was confirmed as a feasible approach for monitoring oyster rafts within 3 km of the coast. The real-time (1 h intervals) position and attributes of each raft detected by the system indicated that our designed techniques enhance responsible fishery surveillance and management of coastal aquaculture worldwide.