Search Results (20)

Digital Twins of the Ocean (DTO) are a rapidly emerging topic that has attracted significant interest from scientists in recent years. The initiative, strongly driven by the EU, aims to create a digital replica of the ocean to better understand and manage marine environments. The Iliad project, funded under the EU Green Deal call, is developing a framework to support multiple interoperable DTO using a federated systems-of-systems approach across various fields of applications and ocean areas, called pilots. This paper presents the results of a Water Quality DTO pilot located in the Trondheim fjord in Norway. This paper details the building blocks of DTO, specific to this environmental monitoring pilot. A crucial aspect of any DTO is data, which can be sourced internally, externally, or through a hybrid approach utilizing both. To realistically twin ocean processes, the Water Quality pilot acquires data from both surface and benthic observatories, as well as from mobile sensor platforms for on-demand data collection. Data ingested into an InfluxDB are made available to users via an API or an interface for interacting with the DTO and setting up alerts or events to support ’what-if’ scenarios. Grafana, an interactive visualization application, is used to visualize and interact with not only time-series data but also more complex data such as video streams, maps, and embedded applications. An additional visualization approach leverages game technology based on Unity and Cesium, utilizing their advanced rendering capabilities and physical computations to integrate and dynamically render real-time data from the pilot and diverse sources. This paper includes two case studies that illustrate the use of particle sensors to detect microplastics and monitor algae blooms in the fjord. Numerical models for particle fate and transport, OpenDrift and DREAM, are used to forecast the evolution of these events, simulating the distribution of observed plankton and microplastics during the forecasting period. Full article

Red algae Pterocladiella capillacea off the coast of China were investigated for genetic diversity. With 176 samples categorized into six populations based on concatenated rbcL and cox1 sequences, the results rang warning bells for the genetic diversity of Pterocladiella capillacea along the Chinese coastline: (1) a good diversity of haplotype (H_d > 0.5) in Naozhou and Hui’an populations situated along the southern coast of China, but highest in the former; (2) less nucleotide diversity in each of the six populations (P_i < 0.005); (3) genetic differentiation occurred between the north population in Changdao and the two southern grown populations in Nan’ao, and Naozhou. To identify molecular markers, an MP phylogenetic tree was used to illustrate genetic profiles in detail, with 161 concatenated sequences clustered into four branches: Changdao (north), Nan’ao (south), Naozhou (south), and the remaining regions (middle). The F_st value for each of Changdao, Nan’ao, and Naozhou was greater than 0.5, which denotes that these three populations are genetically different to those growing in the middle coast. Moreover, a 30-haplotype-based median-joining network corroborated this genetic differentiation, though variations between all the investigated populations were not very high due to the relatively smaller values of genetic distance between the six (D_xy < 0.01). Overall, red algae P. capillacea in Chinese coastal seawater showed a higher haplotype diversity and lower nucleotide diversity. Such a genetic profile indicates that both natural random genetic drift and interference from human activities have possibly affected the distribution of gene frequencies in red algae P. capillacea along the Chinese coastline. Full article

The arrival of a new invasive alga, Rugulopteryx okamurae, in the Strait of Gibraltar (SoG) in 2015 marked an unprecedented milestone in the North African and, later, in the European marine ecosystems. Nowadays, it is colonising vast infralittoral areas and significantly modifying some habitats and associated communities of the southern Iberian Peninsula. In recent expeditions, a high amount of free drifted thalli of this alga has been detected in different circalittoral and bathyal habitats of the northern SoG and the Alboran Sea. The present study combines quantitative data of this alga obtained with the use of a remotely operated vehicle (ROV) and a bottom otter trawl. The coverage–entanglement level of the drifted thalli on circalittoral and bathyal benthic invertebrates (e.g., not covering, covering only the basal part, covering one-third of the invertebrate, etc.) was also annotated from picture frames taken in locations with abundant drifted thalli. In underwater images, drifted thalli were mainly detected in circalittoral and bathyal bottoms of the northern SoG and the north-western Alboran Sea, between 50 to ca. 450 m depth. Nevertheless, abundant drifted thalli were also detected in bottom otter trawl samples from circalittoral bottoms of the north-central and north-eastern Alboran Sea. Small benthic organisms (e.g., encrusting sponges, hydrozoans, etc.) generally displayed low coverage–entanglement levels of drifted thalli. Nevertheless, large sessile and colonial benthic organisms with a complex three-dimensional morphology (e.g., gorgonians, colonial scleractinians) reached high levels of R. okamurae thalli entangled in different parts of their colonies. The drifted R. okamurae thalli entangled in these colonial suspension feeding organisms may hinder their feeding capability in the long term, resulting in habitat deterioration in the near future. Full article

Due to climate change and its associated factors, there has been an increased influx of pelagic brown algae biomass drifting freely in the Caribbean Sea in recent years. Its use as an industrial recyclable material is feasible, although pelagic Sargassum species have Arsenic (As) heavy metal content; among 531 tested pesticide residues applied to vegetables, fruit, infant food, herbs, and spices, zero were found in Sargassum. Sargassum also contains sulfated polysaccharides and oligosaccharides, which are known to be beneficial immunomodulators. Our results thus suggest Sargassum to be a functionally useful organic material in small quantities as an additive in animal feed. With improved chemical extraction methods, it could also be highly effective in adjusted proportions in cosmetics and for other industrial uses. A viable solution for predicting and tracking the large-scale movements of algal masses is provided. Furthermore, a method for addressing increasing Sargassum influx is proposed via its use as an industrial recyclable material following composition analysis, evaluation and safety assessments for cosmetic use, and research and design of new beauty products and other functional cosmetics. Full article

Extensive floating macroalgae have drifted from the East China Sea to Japan’s offshore area, and field observation cannot sufficiently grasp their extensive spatial and temporal changes. High-spatial-resolution satellite data, which contain multiple spectral bands, have advanced remote sensing analysis. Several indexes for recognizing vegetation in satellite images, namely, the normalized difference vegetation index (NDVI), normalized difference water index (NDWI), and floating algae index (FAI), are useful for detecting floating macroalgae. Thresholds are defined to separate macroalgae-containing image pixels from other pixels, and adaptive thresholding increases the reliability of image segmentation. This study proposes adaptive thresholding using Sentinel-2 satellite data with a 10 m spatial resolution. We compare the abilities of Otsu’s, exclusion, and standard deviation methods to define the floating macroalgae detection thresholds of NDVI, NDWI, and FAI images. This comparison determines the most advantageous method for the automatic detection of floating macroalgae. Finally, the spatial coverage of floating macroalgae and the reproducible combination needed for the automatic detection of floating macroalgae in Kagoshima, Japan, are examined. Full article

Phytobenthos, major primary producers in freshwater, may be periodically exposed to herbicides through runoff, spray drift, and leaching, but experimental work on their response to herbicides is limited. Outdoor flumes were used to measure the recovery of intact phytobenthic biofilms, following a short-term pulse to a glyphosate-based herbicide (GBH) and chlorotoluron (CLT), singly or as a mixture (GBHC). Two days following the removal of the herbicides, significant declines in biomass and rates of areal gross maximum photosynthesis were recorded in GBH and GBHC-treated flumes. Herbicide pulses negatively impacted the biomass of phytobenthos, measured as chlorophyll a, which in turn may have alleviated resource limitation, evidenced by significant increases in biomass-specific rates of gross maximum photosynthesis. After 4.5 days, biomass concentrations were similar in controls and treatments, indicating biofilm recovery in the GBH and GBHC biofilms, though the proportion of green algae relative to diatoms was significantly higher in GBH and GBHC-impacted biofilms. Significant increases were recorded in the Trophic Diatom Index (TDI), indicating benthic diatom development along different trajectories, following the herbicide pulse. Collectively, these results indicate greater insights into herbicide impacts on phytobenthos may be gained by working with the whole phytobenthic community. Full article

Ice scouring is one of the strongest agents of disturbance in nearshore environments at high latitudes. In depths, less than 20 m, grounding icebergs reshape the soft-sediment seabed by gouging furrows called ice pits. Large amounts of drift algae (up to 5.6 kg/m²) that would otherwise be transported to deeper water accumulate inside these features, representing an underestimated subsidy. Our work documents the distribution and dimensions of ice pits in Fildes Bay, Antarctica, and evaluates their relationship to the biomass and species composition of algae found within them. It also assesses the rates of deposition and advective loss of algae in the pits. The 17 ice pits found in the study area covered only 4.2% of the seabed but contained 98% of drift algal biomass, i.e., 60 times the density (kg/m²) of the surrounding seabed. Larger ice pits had larger and denser algal accumulations than small pits and had different species compositions. The accumulations were stable over time: experimentally cleared pits regained initial biomass levels after one year, and advective loss was less than 15% annually. Further research is needed to understand the impacts of ice scouring and subsequent algal retention on ecosystem functioning in this rapidly changing polar environment. Full article

Due to the limited reaction rate of the oxygen reduction reaction (ORR), it is considered as a limiting factor in the performance of fuel cells and metal-air batteries. Platinum is considered the benchmark catalyst for ORR; however, the scarcity of platinum, its high price, the drift phenomenon, its insufficient durability, and its susceptibility to gas poisoning are the reasons for the constant search for new ORR catalysts. Carbon-based catalysts show exceptional promise in this respect considering economic profitability and activity, and, in addition, they have favorable conductivity and often a large specific surface area. The use of chitin, cellulose, lignin, coconut shell particles, shrimp shells, and even hair for this purpose was reported, as they had similar electrochemical activity regarding Pt. Alginate, a natural polymer and a constituent of brown algae, can be successfully used to obtain carbon materials that catalyze ORR. In addition, metal atomic-level catalysts and metal N-doped porous carbon materials, obtained from sodium alginate as a precursor, have been proposed as efficient electrocatalysts for ORR. Except for alginate, other biopolymers have been reported to play an important role in the preparation of ORR catalysts. In this review, recent advances regarding biopolymer-derived ORR catalysts are summarized, with a focus on alginate as a source. Full article

For several years, industrial damages caused by massive blooming and drifting of Sargassum horneri (S. horneri) called “golden tides” seaweeds have been continuously reported in Korea. National efforts have been made to produce useful cases of application by using the troublesome S. horneri. As a part of that, a CNDs–ZnO nanocomposite with antibacterial and antifungal properties was synthesized through a simple hydrothermal reaction using S. horneri, and the results were verified in this paper. The antibacterial and antifungal activities were mainly determined by the disk diffusion test against five bacterial and fungal strains, respectively. Of note, the inhibitory effect of the CNDs–ZnO on the growth of both Gram-positive (Bacillus cereus and Staphylococcus aureus) and Gram-negative (Escherichia coli, Salmonella typhimurium, and Vibrio alginolyticus) bacteria was highly effective. Moreover, the nanocomposite showed low toxicity compared to chlorine bleach. In addition, the CNDs–ZnO showed antifungal activities against both yeast (Saccharomyces cerevisiae and Rhodotorula mucilaginosa) and mold (Aspergillus flavus, Aspergillus niger, and Aspergillus terreus). This work showed the potential usability in antimicrobial application based on poor marine brown alga considered as useless in Korea. Through this paper, it seems that sufficient utility and possibility can be expected upon various unappreciated and uninterested marine species. Full article

“Sargassum” is a pelagic species of algae that drifts and aggregates in the tropical Atlantic Ocean. The number of Sargassum aggregations increased in the Caribbean Sea during the last decade. The aggregations eventually wash up on shores thus leading to a socio-economic issue for the population and the coastal ecosystem. Satellite ocean color data, such as those provided by the Sentinel-3/OLCI satellite sensor (Copernicus), can be used to detect the occurrences of Sargassum and to estimate their abundance per pixel using the Maximum Chlorophyll Index (noted MCI). Such an index is, however, ineffective if the algae are located beneath the sea surface, which frequently happens, considering the rough Caribbean oceanic waters. The objective of this study is to propose a relevant methodology that enables the detection of underwater Sargassum aggregations. The methodology relies on the inversion of the radiative transfer equation in the water column. The inverted model provides the immersion depth of the Sargassum aggregations (per pixel) and their fractional coverage from the above water reflectances. The overall methodology has been applied to Sentinel-3/OLCI data. The comparison with the MCI method, which is solely devoted to the sea surface retrieval of Sargassum aggregations, shows that the proposed methodology allows retrieving about twice more Sargassum aggregation occurrences than the MCI estimates. A relative increase of 31% of the fractional coverage over the entire study area is observed when using the proposed method in comparison to MCI method. For the satellite scenes considered here, the rate of Sargassum aggregations immersed between 2 m and 5 m depth ranges between 30% and 51% over the total amount (i.e., surface + in-water), which clearly demonstrates the importance of considering the retrieval of in-water aggregations to gain understanding on Sargassum spatial variability in the oceanic and coastal ecosystems. Full article

Sargassum golden tides (GT) are common in numerous coastal areas all over the world, and it adversely affects local marine life. Eutrophication is critical for Sargassum GT development. However, its physiological and ecological mechanism remains unclear. To investigate the responses of drifting Sargassum horneri, the species causing GT in the western Pacific, to light and enriched nitrogen, we set three light conditions (Low-light (LL), 10 μmol photons m⁻² s⁻¹; Middle-light (ML), 60 μmol photons m⁻² s⁻¹; and High-light (HL), 300 μmol photons m⁻² s⁻¹) and three nitrogen conditions (Natural seawater, the final concentration of N was 31.8 μmol L⁻¹, including 30.5 μmol L⁻¹ of NO₃⁻ and 1.3 μmol L⁻¹ of NH₄⁺; Enrichment of NO₃⁻, final concentration of N was 200 μmol L⁻¹; and Enrichment of NH₄⁺, the final concentration of N was 200 μmol L⁻¹), and grew the thalli under varying conditions for 10 days before determining the growth and utilization of carbon and nitrogen. Based on the accumulated data, the elevated light level led to a higher growth rate of alga. In the LL culture, the higher capacity for carbon utilization, which was reflected by the higher maximum photosynthetic carbon fixation rate (V_max), resulted in the elevated growth rates of thalli in the nitrogen-enriched media as compared with the natural seawater. Furthermore, a higher growth rate was found in the enrichment of NH₄⁺ despite a low affinity for inorganic carbon indicated by a higher value of the half-saturation constant (K_0.5). In the ML treatment, an insignificant difference in growth rate was found in three nitrogen cultures, except for a slight increase in the enrichment of NH₄⁺ than the enrichment of NO₃⁻. In the HL treatment, compared with natural seawater culture, enrichment of NO₃⁻ or NH₄⁺ accelerated the growth of alga, with no significant difference between the two nitrogen sources. Such enhancement in growth was related to the more photosynthetic carbon fixation, indicated by the higher value of V_max and soluble carbohydrates content of alga cultured with NO₃⁻ and NH₄⁺ enrichments. Additionally, the uptake and assimilation products of nitrogen, such as pigments and soluble proteins, remained unaffected by nitrogen source enrichment of NO₃⁻ or NH₄⁺ at all three light levels. In conclusion, enrichment of NO₃⁻ and NH₄⁺ exhibited different influences on the growth of S. horneri at different light levels, which was mainly associated with the capacity and efficiency of photosynthetic carbon utilization. At the HL level, both the enrichment of NO₃⁻ and NH₄⁺ dramatically accelerate the growth of alga by stimulating the photosynthetic carbon fixation. Accordingly, we speculated that drifting S. horneri, exposed to HL level on the surface of the sea, were likely to develop rapidly to form GT in eutrophic oceanic areas with upwelled and river plume NO₃⁻ or NH₄⁺ nutrients. Full article

The number of scientists and tourists visiting Antarctica is on the rise and, despite the management framework for environmental protection, some coastal areas, particularly in the Antarctic Peninsula region, are affected by plastic contamination. The few data available on the occurrence of microplastics (<5 mm) are difficult to compare, due to the different methodologies used in monitoring studies. However, indications are emerging to guide future research and to implement environmental protocols. In the surface and subsurface waters of the Southern Ocean, plastic debris >300 µm appears to be scarce and far less abundant than paint chips released from research vessels. Yet, near some coastal scientific stations, the fragmentation and degradation of larger plastic items, as well as microbeads and microfibers released into wastewater from personal care products and laundry, could potentially affect marine organisms. Some studies indicate that, through long-range atmospheric transport, plastic fibers produced on other continents can be deposited in Antarctica. Drifting plastic debris can also cross the Polar Front, with the potential to carry alien fouling organisms into the Southern Ocean. Sea ice dynamics appear to favor the uptake of microplastics by ice algae and Antarctic krill, the key species in the Antarctic marine food web. Euphausia superba apparently has the ability to fragment and expel ingested plastic particles at the nanoscale. However, most Antarctic organisms are endemic species, with unique ecophysiological adaptations to extreme environmental conditions and are likely highly sensitive to cumulative stresses caused by climate change, microplastics and other anthropogenic disturbances. Although there is limited evidence to date that micro- and nanoplastics have direct biological effects, our review aims at raising awareness of the problem and, in order to assess the real potential impact of microplastics in Antarctica, underlines the urgency to fill the methodological gaps for their detection in all environmental matrices, and to equip scientific stations and ships with adequate wastewater treatment plants to reduce the release of microfibers. Full article

The excess biomass of drifting algae and their casting to the Baltic Sea coast imposes a significant environmental burden. The analysis of beach-cast algae showed that the dominant species are macroalgae Ulva sp., Furcellaria lumbricalis, Cladophora sp., and Polysiphonia fucoides. The biomass of Furcellaria and Polysiphonia algae, containing 25.6% and 19.98% sugars, respectively, has the greatest resource potential in terms of obtaining carbohydrates. Fucose, glucose, and galactose were found to be the most common carbohydrates. The lipid content did not exceed 4.3% (2.3–4.3%), while the fatty acid composition was represented by saturated fatty acids (palmitic, stearic, methyloleic, behenic, etc.). The highest content of crude protein was found in samples of macroalgae of the genus Polysiphonia and amounted to 28.2%. A study of the elemental composition of drifting algae revealed that they have a high carbon content (31.3–37.5%) and a low hydrogen (4.96–5.82%), and sulfur (1.75–3.00%) content. Red algal biomass has the most resource potential in terms of biofuel generation, as it has a high number of lipids and proteins that can produce melanoidins during hydrothermal liquefaction, enhancing the fuel yield. The study noted the feasibility of using the biomass of the studied algae taxa to produce polysaccharides and biofuels. The analyses of antioxidant properties, fat content, and fat composition do not provide convincing evidence of the viability of using the aforementioned macroalgae for their production. Full article

Periphytic algae exist widely in different waters. However, little is known about periphytic algae in long-distance water diversion channels across watersheds. We investigated the periphytic algae and the environmental factors at twenty sampling sites in the middle route of the South-to-North Water Diversion Project (MRP). The dominant species were Desmodesmus intermedius (Hegewald), Calothrix thermalis (Bornet & Flahault), Calothrix parietina (Bornet & Flahault) and Leptolyngbya benthonica (Anagnostidis) (dominance > 0.02) as measured in a whole year. Habitat heterogeneity in the MRP led to lower spatial heterogeneity and higher temporal heterogeneity of the periphytic algal community. Stochastic processes are the major process in periphytic community assembly. In deterministic processes, homogeneous selection had the major role in structuring the periphytic community, whereas the role of heterogeneous selection was less significant. In stochastic processes, dispersal limitations had the major role in structuring the periphytic community, whereas the role of homogenizing dispersal and drift were less significant. The variation in total nitrogen and total phosphorus promoted more stochastic processes (−1.96 < βNTI < 1.96). The variations in water temperature and water velocity promoted more heterogeneous selection (βNTI > 1.96). In integrating all of this empirical evidence, we explore the role of environmental factors in the action of ecological processes shaping thecommunity assembly of the periphytic algal community. Full article

PAHs and heavy metals are characteristic pollutants in urbanized coastal areas, especially those with industrial activity. Given this context and the ability of Macrocystis pyrifera to drift when detached and provide trophic subsidy in coastal systems, we analyzed the potential transfer of pollutants to the herbivore Tetrapygus niger, through diet, in an industrialized coastal zone in Central Chile (Caleta Horcón) and characterized the impacted zone using diverse polluted ecotoxicological indices. For this purpose, a culture experiment was conducted where M. pyrifera individuals from Algarrobo (control site) were cultivated in Caleta Horcón and then used as food for T. niger. The contents of both PAHs and heavy metal contents were subsequently determined in algal tissue and sea urchin gonads as well as in the seawater. The results show that algae cultivated in Caleta Horcón had higher concentrations of naphthalene (NAF) compared to those from a low industrial impact zone (Algarrobo) (2.5 and 1.8 mg kg⁻¹, respectively). The concentrations of Cu, As, and Cd were higher in Caleta Horcón than in Algarrobo in both M. pyrifera and T. niger. For all metals, including Pb, higher concentrations were present in T. niger than in M. pyrifera (between 5 and 798 times higher). Additionally, as indicated by the toxicological indices MPI (0.00804) and PLI (10.89), Caleta Horcón is highly contaminated with metals compared to Algarrobo (0.0006 and 0.015, respectively). Finally, the bioconcentration factor (BCF) and trophic transfer factor (TTF) values were greater than one in most cases, with values in Caleta Horcón exceeding those in Algarrobo by one or two orders of magnitude. This study provides evidence that Caleta Horcón is a highly impacted zone (HIZ) compared to Algarrobo, in addition to evidence that the biomagnification of certain pollutants, including the possible responses to contaminants, are apparently not exclusively transferred to T. niger through diet. Full article