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http://hdl.handle.net/2115/20049
2024-03-29T08:13:09ZEvaluation of flocculation performance of polysaccharide-protamine complex flocculant by flocculation model
http://hdl.handle.net/2115/91423
Title: Evaluation of flocculation performance of polysaccharide-protamine complex flocculant by flocculation model
Authors: Maruyama, Hideo; Seki, Hideshi
Abstract: Flocculation experiments were conducted with three kinds of polysaccharide-protamine complex flocculants. Alginate, κ-carrageenan, and pectin were used as typical polysaccharides. The polysaccharides have carboxyl and sulfate groups, and it can be considered that the polysaccharides could bind basic protein, such as protamine, at around the neutral pH (pH 6.5–7.5). The relative absorbance was used as an index of the flocculation efficiency. Influences of the mass ratio (polysaccharide/protamine) and dosage of the complex flocculants on the flocculation efficiency were investigated. Judging from the results, the optimum mass ratio of polysaccharide and protamine was found as 0.4 for alginate and 1.0 for κ-carrageenan and pectin. The previously proposed flocculation model was applied to the data successfully and the proportional constant, stoichiometric coefficients, and the equilibrium adsorption constant regarding as forming flocs were determined by fitting to the data and using a least square method. Judging from the model parameters, the total number of acidic groups, and the molecular weight of each polysaccharide, the alginate-protamine complex could be the most effective flocculant.2022-02-28T15:00:00ZMaruyama, HideoSeki, HideshiFlocculation experiments were conducted with three kinds of polysaccharide-protamine complex flocculants. Alginate, κ-carrageenan, and pectin were used as typical polysaccharides. The polysaccharides have carboxyl and sulfate groups, and it can be considered that the polysaccharides could bind basic protein, such as protamine, at around the neutral pH (pH 6.5–7.5). The relative absorbance was used as an index of the flocculation efficiency. Influences of the mass ratio (polysaccharide/protamine) and dosage of the complex flocculants on the flocculation efficiency were investigated. Judging from the results, the optimum mass ratio of polysaccharide and protamine was found as 0.4 for alginate and 1.0 for κ-carrageenan and pectin. The previously proposed flocculation model was applied to the data successfully and the proportional constant, stoichiometric coefficients, and the equilibrium adsorption constant regarding as forming flocs were determined by fitting to the data and using a least square method. Judging from the model parameters, the total number of acidic groups, and the molecular weight of each polysaccharide, the alginate-protamine complex could be the most effective flocculant.Recovery of milk whey proteins by foam separation
http://hdl.handle.net/2115/91419
Title: Recovery of milk whey proteins by foam separation
Authors: Maruyama, Hideo; Seki, Hideshi
Abstract: Milk whey proteins recovery was conducted with foam separation. Experiments were conducted by batch mode in pH 4–8. The separation rate was evaluated by the rate constant of the first-order kinetic equation. Both recovery efficiency and separation rate were highest at pH 7. Overall equilibrium adsorption constant, K, and saturated adsorption density, Xs, were determined from a proposed estimating method using data obtained in batch mode. At pH 7, K and Xs were determined using the data obtained in continuous mode. K and Xs determined by both operation modes were agreed well. Adsorption parameters of the major proteins in milk whey (bovine serum albumin (BSA), α-lactalbumin (LA), and β-lactoglobulin (LG)) were estimated by the proposed estimating method in pH 4–7. Xs is largest at pH 5 and the K of LG over pH 5 was larger, which suggested that LG was the most hydrophobic species among them.2022-02-28T15:00:00ZMaruyama, HideoSeki, HideshiMilk whey proteins recovery was conducted with foam separation. Experiments were conducted by batch mode in pH 4–8. The separation rate was evaluated by the rate constant of the first-order kinetic equation. Both recovery efficiency and separation rate were highest at pH 7. Overall equilibrium adsorption constant, K, and saturated adsorption density, Xs, were determined from a proposed estimating method using data obtained in batch mode. At pH 7, K and Xs were determined using the data obtained in continuous mode. K and Xs determined by both operation modes were agreed well. Adsorption parameters of the major proteins in milk whey (bovine serum albumin (BSA), α-lactalbumin (LA), and β-lactoglobulin (LG)) were estimated by the proposed estimating method in pH 4–7. Xs is largest at pH 5 and the K of LG over pH 5 was larger, which suggested that LG was the most hydrophobic species among them.Black-tailed gulls alter their flight height and airspeed according to wind conditions during their coastal commuting trips
http://hdl.handle.net/2115/91308
Title: Black-tailed gulls alter their flight height and airspeed according to wind conditions during their coastal commuting trips
Authors: Kumagai, Aya; Kazama, Kentaro; Mikami, Katsura; Watanuki, Yutaka
Abstract: Seabirds are expected to increase their flight height in tailwind and to increase their airspeed in headwind during goal-oriented flight to minimize their cost of transport. To understand how flapping birds respond to variability in wind speed and direction experienced during their commuting flights between their breeding colony and foraging areas, we measured the flight height and speed of black-tailed gulls Larus crassirostris using GPS loggers. We analyzed the relationships between these flight parameters and local wind speed and direction. Over the course of the 2016 to 2018 breeding seasons, we tagged 105 birds at 2 colonies in northern Hokkaido, Japan. A total of 90 flight track-lines within a 500 m radius of 5 coastal meteorological stations were analyzed. The median flight height ranged from 0 to 153.8 m, and the median ground speed and airspeed were between 18.6-82.1 and 19.5-93.0 km h-1, respectively. Gulls flew higher with greater tailwind speed, supporting the hypothesis that birds utilize greater wind assistance at higher altitudes. Furthermore, gulls increased their airspeed under strong headwind conditions, suggesting they adjust airspeed to achieve the most cost-effective speed to reach their destination. Better understanding the drivers of seabird flight height is key to assessing the potential for collisions with wind turbines in coastal and offshore wind farms. These findings provide useful information to reduce collisions with coastal and offshore wind facilities.2023-09-22T15:00:00ZKumagai, AyaKazama, KentaroMikami, KatsuraWatanuki, YutakaSeabirds are expected to increase their flight height in tailwind and to increase their airspeed in headwind during goal-oriented flight to minimize their cost of transport. To understand how flapping birds respond to variability in wind speed and direction experienced during their commuting flights between their breeding colony and foraging areas, we measured the flight height and speed of black-tailed gulls Larus crassirostris using GPS loggers. We analyzed the relationships between these flight parameters and local wind speed and direction. Over the course of the 2016 to 2018 breeding seasons, we tagged 105 birds at 2 colonies in northern Hokkaido, Japan. A total of 90 flight track-lines within a 500 m radius of 5 coastal meteorological stations were analyzed. The median flight height ranged from 0 to 153.8 m, and the median ground speed and airspeed were between 18.6-82.1 and 19.5-93.0 km h-1, respectively. Gulls flew higher with greater tailwind speed, supporting the hypothesis that birds utilize greater wind assistance at higher altitudes. Furthermore, gulls increased their airspeed under strong headwind conditions, suggesting they adjust airspeed to achieve the most cost-effective speed to reach their destination. Better understanding the drivers of seabird flight height is key to assessing the potential for collisions with wind turbines in coastal and offshore wind farms. These findings provide useful information to reduce collisions with coastal and offshore wind facilities.BODY LENGTH, DRY AND ASH-FREE DRY WEIGHTS, AND DEVELOPMENTAL CHANGES AT EACH COPEPODID STAGE IN FIVE SYMPATRIC MESOPELAGIC AETIDEID COPEPODS IN THE WESTERN ARCTIC OCEAN
http://hdl.handle.net/2115/91295
Title: BODY LENGTH, DRY AND ASH-FREE DRY WEIGHTS, AND DEVELOPMENTAL CHANGES AT EACH COPEPODID STAGE IN FIVE SYMPATRIC MESOPELAGIC AETIDEID COPEPODS IN THE WESTERN ARCTIC OCEAN
Authors: Koguchi, Yunosuke; Tokuhiro, Koki; Ashjian, Carin J.; Campbell, Robert G.; Yamaguchi, Atsushi
Abstract: Aetideid copepods dominate the mesopelagic layer of the Arctic Ocean and play an important role in the vertical material flux and biodiversity. However, little information about the lengths and weights of their copepodids is available. In this study, we collected five sympatric aetideid copepods, Chiridius obtusifrons Sars G.O., 1902, Gaetanus tenuispinus (Sars G.O., 1900), Gaetanus brevispinus (Sars G.O., 1900), Aetideopsis multiserrata (Wolfenden, 1904), and Aetideopsis rostrata Sars G.O., 1903, from the Arctic Ocean and examined their body lengths, dry and ash-free dry weights, and developmental growths at each copepodid stage. Highly significant length-weight relationships were obtained among copepodids for all species. Within genera, individuals of the same length were heavier at shallower depths. This may result from the greater nutritional availability to species within genera inhabiting shallower depths. Common to all species, the organic content (ash -free dry weight per dry weight) was high for the early copepodid stages. This may be due to the residual organic content of lipid-rich eggs retained in the non-feeding nauplii. The largest growth in females occurred at C5/C6, whereas the largest growth in males occurred at C4/C5, as determined by moult increment and proportion of growth in weight. These sex differences in weight growth could be due to the degeneration of the feeding appendage and cessation of feeding in C6 males of aetideid copepods.2023-01-31T15:00:00ZKoguchi, YunosukeTokuhiro, KokiAshjian, Carin J.Campbell, Robert G.Yamaguchi, AtsushiAetideid copepods dominate the mesopelagic layer of the Arctic Ocean and play an important role in the vertical material flux and biodiversity. However, little information about the lengths and weights of their copepodids is available. In this study, we collected five sympatric aetideid copepods, Chiridius obtusifrons Sars G.O., 1902, Gaetanus tenuispinus (Sars G.O., 1900), Gaetanus brevispinus (Sars G.O., 1900), Aetideopsis multiserrata (Wolfenden, 1904), and Aetideopsis rostrata Sars G.O., 1903, from the Arctic Ocean and examined their body lengths, dry and ash-free dry weights, and developmental growths at each copepodid stage. Highly significant length-weight relationships were obtained among copepodids for all species. Within genera, individuals of the same length were heavier at shallower depths. This may result from the greater nutritional availability to species within genera inhabiting shallower depths. Common to all species, the organic content (ash -free dry weight per dry weight) was high for the early copepodid stages. This may be due to the residual organic content of lipid-rich eggs retained in the non-feeding nauplii. The largest growth in females occurred at C5/C6, whereas the largest growth in males occurred at C4/C5, as determined by moult increment and proportion of growth in weight. These sex differences in weight growth could be due to the degeneration of the feeding appendage and cessation of feeding in C6 males of aetideid copepods.Nitrosophilus kaiyonis sp. nov., a hydrogen-, sulfur- and thiosulfate-oxidizing chemolithoautotroph within Campylobacteria isolated from a deep-sea hydrothermal vent in the Mid-Okinawa Trough
http://hdl.handle.net/2115/91292
Title: Nitrosophilus kaiyonis sp. nov., a hydrogen-, sulfur- and thiosulfate-oxidizing chemolithoautotroph within Campylobacteria isolated from a deep-sea hydrothermal vent in the Mid-Okinawa Trough
Authors: Fukazawa, So; Mino, Sayaka; Tsuchiya, Jiro; Nakagawa, Satoshi; Takai, Ken; Sawabe, Tomoo
Abstract: A novel bacterium, strain MOT50(T), was isolated from the chimney structure at the Iheya North field in the Mid-Okinawa Trough. The cells were motile short rods with a single polar flagellum. Growth was observed between 40 and 65 celcius (optimum, 52 celcius), at pH values between 5.0 and 7.1 (optimum, pH 6.1) and in the presence of 2.0-4.0% NaCl (optimum, 2.5%). The isolates utilized molecular hydrogen, thiosulfate, or elemental sulfur as the sole electron donor. Thiosulfate, elemental sulfur, nitrate, and molecular oxygen are utilized as the sole electron acceptor. Ammonium is required as a nitrogen source. Thiosulfate, elemental sulfur, sulfate, or sulfite serves as a sulfur source for growth. The G + C content of the genomic DNA was 28.9%. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain MOT50(T) belonged to the genus Nitrosophilus of the class Campylobacteria , and its closest relative was Nitrosophilus labii HRV44(T) (97.20%). On the basis of the phylogenetic, physiological, and molecular characteristics, it is proposed that the organism represents a novel species within the genus Nitrosophilus, Nitrosophilus kaiyonis sp. nov. The type strain is MOT50(T) (= JCM 39187(T) = KCTC 25251(T)).2022-12-31T15:00:00ZFukazawa, SoMino, SayakaTsuchiya, JiroNakagawa, SatoshiTakai, KenSawabe, TomooA novel bacterium, strain MOT50(T), was isolated from the chimney structure at the Iheya North field in the Mid-Okinawa Trough. The cells were motile short rods with a single polar flagellum. Growth was observed between 40 and 65 celcius (optimum, 52 celcius), at pH values between 5.0 and 7.1 (optimum, pH 6.1) and in the presence of 2.0-4.0% NaCl (optimum, 2.5%). The isolates utilized molecular hydrogen, thiosulfate, or elemental sulfur as the sole electron donor. Thiosulfate, elemental sulfur, nitrate, and molecular oxygen are utilized as the sole electron acceptor. Ammonium is required as a nitrogen source. Thiosulfate, elemental sulfur, sulfate, or sulfite serves as a sulfur source for growth. The G + C content of the genomic DNA was 28.9%. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain MOT50(T) belonged to the genus Nitrosophilus of the class Campylobacteria , and its closest relative was Nitrosophilus labii HRV44(T) (97.20%). On the basis of the phylogenetic, physiological, and molecular characteristics, it is proposed that the organism represents a novel species within the genus Nitrosophilus, Nitrosophilus kaiyonis sp. nov. The type strain is MOT50(T) (= JCM 39187(T) = KCTC 25251(T)).Morphological evolution reduces downstream displacement in juvenile landlocked salmon
http://hdl.handle.net/2115/91116
Title: Morphological evolution reduces downstream displacement in juvenile landlocked salmon
Authors: Yamada, Hiroyuki; Wada, Satoshi
Abstract: Severe flooding often leads to downstream displacement of aquatic animals. Despite this, many salmonid populations persist in habitats located upstream of tall barriers, such as artificial check dams and/or natural waterfalls, that completely block fishes from returning to the upstream areas after flooding. The evolution of such populations may be affected by spatial sorting due to differential rates of downstream displacement. This study examined whether a morphological trait (increased body depth) that allows individuals to better maintain their position during flooding has evolved in juvenile amago salmon Oncorhynchus masou ishikawae inhabiting above-barrier habitats in two rivers. In both rivers, juveniles collected at the stations with multiple downstream barriers had deeper bodies than those collected at other stations. Similar differences were found in juveniles reared in a common-garden experiment. Field experiments with natural flooding also indicated that deep bodies help juveniles resist downstream displacement. These results consistently suggest that juveniles in some above-barrier habitats have evolved deep bodies to resist downstream displacement due to flooding. Our study is the first to show the evolutionary outcomes of passive spatial sorting during severe climate events.2021-07-18T15:00:00ZYamada, HiroyukiWada, SatoshiSevere flooding often leads to downstream displacement of aquatic animals. Despite this, many salmonid populations persist in habitats located upstream of tall barriers, such as artificial check dams and/or natural waterfalls, that completely block fishes from returning to the upstream areas after flooding. The evolution of such populations may be affected by spatial sorting due to differential rates of downstream displacement. This study examined whether a morphological trait (increased body depth) that allows individuals to better maintain their position during flooding has evolved in juvenile amago salmon Oncorhynchus masou ishikawae inhabiting above-barrier habitats in two rivers. In both rivers, juveniles collected at the stations with multiple downstream barriers had deeper bodies than those collected at other stations. Similar differences were found in juveniles reared in a common-garden experiment. Field experiments with natural flooding also indicated that deep bodies help juveniles resist downstream displacement. These results consistently suggest that juveniles in some above-barrier habitats have evolved deep bodies to resist downstream displacement due to flooding. Our study is the first to show the evolutionary outcomes of passive spatial sorting during severe climate events.Extraction of chondroitin sulfate and type II collagen from sturgeon (Acipenser gueldenstaedti) notochord and characterization of their hybrid fibrils
http://hdl.handle.net/2115/91040
Title: Extraction of chondroitin sulfate and type II collagen from sturgeon (Acipenser gueldenstaedti) notochord and characterization of their hybrid fibrils
Authors: Meng, Dawei; Li, Wen; Leng, Xiaoqian; Takagi, Yasuaki; Dai, Zhiyuan; Du, Hao; Wei, Qiwei
Abstract: Chondroitin sulfate (CS) and undenatured type II collagen (Col II) are the two major, biological macromolecules of cartilage-related tissues. In this study, a new extraction. process was developed to obtain CS and Col II simultaneously. By this process, CS. and undenatured Col II were extracted from sturgeon notochord with the yields of 5.34, ± 0.74% and 45.25 ± 5.25%, respectively. The SEC-RI-MALLS result showed that the, average molecular weight of notochord CS was 38.4 kDa. FTIR NMR, and SAX-HPLC, results indicated the notochord CS was mainly composed of CS-A. The new extraction, process had no effect on the triple helical structure of Col II. To analyze the interaction, between the two macromolecules, the effect of CS on Col II fibril formation was, examined using turbidity assay and SEM observation. CS accelerated the completion, of Col II self-assembly and inhibited the lateral aggregation of fibrils. The results of this, study suggested that the sturgeon notochord is a valuable source of CS and Col II. The. new extraction method not only improves the utilization rate of sturgeon notochord, but,also reduces the waste of aquatic resources. CS and Col II derived from sturgeon, notochord have the potential for use in biomedical materials2022-12-31T15:00:00ZMeng, DaweiLi, WenLeng, XiaoqianTakagi, YasuakiDai, ZhiyuanDu, HaoWei, QiweiChondroitin sulfate (CS) and undenatured type II collagen (Col II) are the two major, biological macromolecules of cartilage-related tissues. In this study, a new extraction. process was developed to obtain CS and Col II simultaneously. By this process, CS. and undenatured Col II were extracted from sturgeon notochord with the yields of 5.34, ± 0.74% and 45.25 ± 5.25%, respectively. The SEC-RI-MALLS result showed that the, average molecular weight of notochord CS was 38.4 kDa. FTIR NMR, and SAX-HPLC, results indicated the notochord CS was mainly composed of CS-A. The new extraction, process had no effect on the triple helical structure of Col II. To analyze the interaction, between the two macromolecules, the effect of CS on Col II fibril formation was, examined using turbidity assay and SEM observation. CS accelerated the completion, of Col II self-assembly and inhibited the lateral aggregation of fibrils. The results of this, study suggested that the sturgeon notochord is a valuable source of CS and Col II. The. new extraction method not only improves the utilization rate of sturgeon notochord, but,also reduces the waste of aquatic resources. CS and Col II derived from sturgeon, notochord have the potential for use in biomedical materialsPhenology of Codium cylindricum (Ulvophyceae, Bryopsidales) on the central Pacific coast of Japan
http://hdl.handle.net/2115/91022
Title: Phenology of Codium cylindricum (Ulvophyceae, Bryopsidales) on the central Pacific coast of Japan
Authors: Miyadai, Minoru; Akita, Shingo; Fujita, Daisuke
Abstract: Codium cylindricum is a large green alga distributed along the temperate Northeast Pacific coasts. Although the species is edible and contains pharmaceutical substances, little is known about its ecology. In this study, we characterized the phenology of C. cylindricum by monthly observations in Tateyama on the central Pacific coast of Japan from March 2018 to February 2019. The average length of attached thalli in three quadrats (2 x 2 m) was 5 cm from April to July. After disappearing in August, recruits appeared in November and the maximum density (1.08 +/- 3.5 inds center dot m(-2)) was reached in February. On the sea bottom, detached thalli were present from April to October; the biomass monitored in a single quadrat (2 x 20 m) was high from June to August. Based on monthly observations of 50-100 utricles in each of 18-25 thalli, gametangium formation started in June and reached a peak (i.e., gametangia detected in 75% of thalli and 63.4% of utricles) in September, before the disappearance of the detached thalli. These results strongly suggest that C. cylindricum is annual and reproduces mainly while they are drifting. Therefore, growth during detached stage is critically important to increase biomass and dispersal.2022-10-25T15:00:00ZMiyadai, MinoruAkita, ShingoFujita, DaisukeCodium cylindricum is a large green alga distributed along the temperate Northeast Pacific coasts. Although the species is edible and contains pharmaceutical substances, little is known about its ecology. In this study, we characterized the phenology of C. cylindricum by monthly observations in Tateyama on the central Pacific coast of Japan from March 2018 to February 2019. The average length of attached thalli in three quadrats (2 x 2 m) was 5 cm from April to July. After disappearing in August, recruits appeared in November and the maximum density (1.08 +/- 3.5 inds center dot m(-2)) was reached in February. On the sea bottom, detached thalli were present from April to October; the biomass monitored in a single quadrat (2 x 20 m) was high from June to August. Based on monthly observations of 50-100 utricles in each of 18-25 thalli, gametangium formation started in June and reached a peak (i.e., gametangia detected in 75% of thalli and 63.4% of utricles) in September, before the disappearance of the detached thalli. These results strongly suggest that C. cylindricum is annual and reproduces mainly while they are drifting. Therefore, growth during detached stage is critically important to increase biomass and dispersal.Summer diet and feeding strategy of Pacific cod (Gadus macrocephalus) inhabiting the southern coast of Hokkaido, Japan
http://hdl.handle.net/2115/90823
Title: Summer diet and feeding strategy of Pacific cod (Gadus macrocephalus) inhabiting the southern coast of Hokkaido, Japan
Authors: Wang, Rongfu; Chimura, Masayuki; Sadayasu, Kazuhiro; Ishino, Mitsuhiro; Yamamura, Orio
Abstract: The ontogenetic and interannual variations in the diet and feeding strategy of Pacific cod (Gadus macrocephalus) were examined based on 1302 specimens collected by a trawling net off the southern coast of Hokkaido from late June to early July during 2016-2020. The diet comprised 63 species (13 taxa). Fish was the most important prey, followed by decapod crustaceans. In 2016, walleye pollock (Gadus chalcogrammus) was the dominant fish prey species, while amphipods, decapods and Japanese lanternfish (Notoscopelus japonicus) were prominent in the diet in 2017. Japanese sardine (Sardinops melanostictus) were more predominant during 2018-2020. An ontogenetic comparison of diet indicated that smaller individuals (<= 400 mm standard length, SL) preyed mainly on small prey items, such as decapod crustaceans and polychaetes, whereas larger individuals (>400 mm SL) preyed mainly on fish. Moreover, prey size exhibited a significant increasing trend with predator body length. These results suggest that Pacific cod has a flexible feeding strategy that differs by life stage. The updated information on predator-prey relationships provided herein improves our understanding of energy flow in the marine ecosystem and could facilitate ecosystem-based fishery management strategies.2023-12-04T15:00:00ZWang, RongfuChimura, MasayukiSadayasu, KazuhiroIshino, MitsuhiroYamamura, OrioThe ontogenetic and interannual variations in the diet and feeding strategy of Pacific cod (Gadus macrocephalus) were examined based on 1302 specimens collected by a trawling net off the southern coast of Hokkaido from late June to early July during 2016-2020. The diet comprised 63 species (13 taxa). Fish was the most important prey, followed by decapod crustaceans. In 2016, walleye pollock (Gadus chalcogrammus) was the dominant fish prey species, while amphipods, decapods and Japanese lanternfish (Notoscopelus japonicus) were prominent in the diet in 2017. Japanese sardine (Sardinops melanostictus) were more predominant during 2018-2020. An ontogenetic comparison of diet indicated that smaller individuals (<= 400 mm standard length, SL) preyed mainly on small prey items, such as decapod crustaceans and polychaetes, whereas larger individuals (>400 mm SL) preyed mainly on fish. Moreover, prey size exhibited a significant increasing trend with predator body length. These results suggest that Pacific cod has a flexible feeding strategy that differs by life stage. The updated information on predator-prey relationships provided herein improves our understanding of energy flow in the marine ecosystem and could facilitate ecosystem-based fishery management strategies.Analysis of microplastics in the intestines of stranded cetaceans
http://hdl.handle.net/2115/90628
Title: Analysis of microplastics in the intestines of stranded cetaceans
Authors: Liu, Yang; Ayaka, Matsuda; Toshikazu, Kawaguchi; Helena, Fortunato; Takashi, Matsuishi
Abstract: Microplastics derived from anthropogenic pollution have become a major issue today, as available data have shown they are present in all terrestrial and marine ecosystems. These pollutants originate from multiple sources, from trash dumped in rivers and lakes and travelling to the ocean, to fishing tools (such as nets, ropes, and baskets) abandoned at sea as well as various chemicals released in the water. As apex predators, cetaceans are critical in regulating the food web and maintaining ecosystem balance. They consume lower trophic-level organisms that have ingested microplastics, and, at present, the studies conducted on microplastics in cetaceans are insufficient. Further research on the prevalence and effects of microplastics in these animals is needed to support conservation efforts and shed light on the larger issue of plastic pollution in the oceans. Determining the concentration of microplastics in cetaceans can inform on the level of microplastic contamination in the entire food web, including seafood that humans consume. This research aimed to assess the presence and accumulation of microplastics in cetaceans to understand better their potential impacts on both these species and the marine environment. Microplastics were detected in 13 out of 17 samples of cetacean intestines; most of them were fibres and varied in length, size, and colour. Raman spectroscopy analysis showed that the microplastics were made of the polymer Nylon 6,6. The results of this study will contribute to the current knowledge of the impact of microplastics on marine life and ecosystems and can aid in developing strategies to mitigate and manage this urgent environmental issue.2023-09-28T15:00:00ZLiu, YangAyaka, MatsudaToshikazu, KawaguchiHelena, FortunatoTakashi, MatsuishiMicroplastics derived from anthropogenic pollution have become a major issue today, as available data have shown they are present in all terrestrial and marine ecosystems. These pollutants originate from multiple sources, from trash dumped in rivers and lakes and travelling to the ocean, to fishing tools (such as nets, ropes, and baskets) abandoned at sea as well as various chemicals released in the water. As apex predators, cetaceans are critical in regulating the food web and maintaining ecosystem balance. They consume lower trophic-level organisms that have ingested microplastics, and, at present, the studies conducted on microplastics in cetaceans are insufficient. Further research on the prevalence and effects of microplastics in these animals is needed to support conservation efforts and shed light on the larger issue of plastic pollution in the oceans. Determining the concentration of microplastics in cetaceans can inform on the level of microplastic contamination in the entire food web, including seafood that humans consume. This research aimed to assess the presence and accumulation of microplastics in cetaceans to understand better their potential impacts on both these species and the marine environment. Microplastics were detected in 13 out of 17 samples of cetacean intestines; most of them were fibres and varied in length, size, and colour. Raman spectroscopy analysis showed that the microplastics were made of the polymer Nylon 6,6. The results of this study will contribute to the current knowledge of the impact of microplastics on marine life and ecosystems and can aid in developing strategies to mitigate and manage this urgent environmental issue.