Mesopelagic fish(meso-fish)are central species within the Southern Ocean(SO).However,their ecosystem role and adaptive capacity to climate change are rarely integrated into protected areas assessments.This is a pity g...Mesopelagic fish(meso-fish)are central species within the Southern Ocean(SO).However,their ecosystem role and adaptive capacity to climate change are rarely integrated into protected areas assessments.This is a pity given their importance as crucial prey and predators in food webs,coupled with the impacts of climate change.Here,we estimate the habitat distribution of nine meso-fish using an ensemble model approach(MAXENT,random forest,and boosted regression tree).Four climate model simulations were used to project their distribution under two representative concentration pathways(RCP4.5 and RCP8.5)for short-term(2006–2055)and long-term(2050–2099)periods.In addition,we assess the ecological representativeness of protected areas under climate change scenarios using meso-fish as indicator species.Our models show that all species shift poleward in the future.Lanternfishes(family Myctophidae)are predicted to migrate poleward more than other families(Paralepididae,Nototheniidae,Bathylagidae,and Gonostomatidae).In comparison,lanternfishes were projected to increase habitat area in the eastern SO but lose area in the western SO;the opposite was projected for species in other families.Important areas(IAs)of meso-fish are mainly distributed near the Antarctic Peninsula and East Antarctica.Negotiated protected area cover 23% of IAs at present and 38%of IAs in the future(RCP8.5,long-term future).Many IAs of meso-fish still need to be included in protected areas,such as the Prydz Bay and the seas around the Antarctic Peninsula.Our results provide a framework for evaluating protected areas incorporating climate change adaptation strategies for protected areas management.展开更多
The mesozooplankton in both epipelagic and mesopelagic zones is essentially important for the study of ecosystem and biological carbon pump. Previous studies showed that the diel vertical migration (DVM) pattern of me...The mesozooplankton in both epipelagic and mesopelagic zones is essentially important for the study of ecosystem and biological carbon pump. Previous studies showed that the diel vertical migration (DVM) pattern of mesozooplankton varied among ecosystems. However, that pattern was largely unknown in the Western Pacific Warm Pool (WPWP). The vertical distribution, DVM and community structure of mesozooplankton from the surface to 1 000 m were compared at Stas JL7K (WPWP) and MA (North Pacific Subtropical Gyre, NPSG). Two sites showed similarly low biomass in both epipelagic and mesopelagic zones, which were in accordance with oligotrophic conditions of these two ecosystems. Stronger DVM (night/day ratio) was found at JL7K (1.31) than that at MA (1.09) on surface 0–100 m, and an obvious night increase of mesopelagic biomass was observed at JL7K, which was probably due to migrators from bathypelagic zone. Active carbon flux by DVM of zooplankton was estimated to be 0.23 mmol/(m2·d) at JL7K and 0.16 mmol/(m2·d) at MA. The community structure analysis showed that calanoid copepods, cnidarians and appendicularians were the main contributors to DVM of mesozooplankton at both sites. We also compared the present result with previous studies of the two ecosystems, and suggested that the DVM of mesozooplankton was more homogeneous within the WPWP and more variable within the NPSG, though both ecosystems showed typically extremely oligotrophic conditions. The different diel vertical migration strength of mesozooplankton between NPSG and WPWP implied different efficiency of carbon pump in these two ecosystems.展开更多
Compound-specific stable isotope analysis of individual amino acids(CSIA-AA)has been widely used in ecological and biogeochemical studies.It has been proven to be powerful in tracing the diet sources and trophic inter...Compound-specific stable isotope analysis of individual amino acids(CSIA-AA)has been widely used in ecological and biogeochemical studies.It has been proven to be powerful in tracing the diet sources and trophic interactions.However,assessing the N sources of mesopelagic fishes has been inconclusive because the mesopelagic fishes’unique domain(water depth ranged from 0 to 1000 m)and unresolved nitrogen isotopes of various forms.This study proposes a new method for coupling instruments(ion chromatography and PreconIRMS)and chemical method of oxidation-reduction of amino acids,and also combinedδ15N of AAs withδ13C of fatty acids(FAs)to analyze the trophic interactions of mesopelagic fishes in the South China Sea(SCS).AAs were isolated by ion chromatography with high peak resolution and collected by an automated fraction collector.The chemical method then converted the AAs into N2 O with a robust oxidation yields and suitable molar ratio of NH2 OH to.Finally,theδ15N of AAs at 20 nmol were measured with a reasonable precision(<0.6‰).With this method,this study report the first batch high precisionδ15N of AAs andδ13C of FAs of mesopelagic fishes collected from SCS.Diaphus luetkeni,Chauliodus minimus and Bathygadus antrodes showed similarδ13C values of 20:4 n-6(~-28‰),while Argyropelecus affinis and Stomias had similar values(~-32‰).These results reflect that mesopelagic fishes had complex diet sources.An increase of 4‰inδ15N of glutamic acid(Glu)was found between piscivorous and planktivorous fishes,which might suggest a trophic discrimination factor of mesopelagic fishes in the SCS.This study usedδ13C of 20:4 n-6 to reveal the diet sources of mesopelagic fishes andδ15N of Glu to clarify trophic level between piscivorous and planktivorous fishes.Thus,this combinative method could therefore ultimately be applied in a variety of deep-sea ecosystem.展开更多
Three species of dinophysoid planktonic dinoflagellates are described from the eastern Mediterranean Sea.Amphisolenia sp.aff.brevicauda was collected at 70-m depth in the Ionian Sea.This small species showed a more as...Three species of dinophysoid planktonic dinoflagellates are described from the eastern Mediterranean Sea.Amphisolenia sp.aff.brevicauda was collected at 70-m depth in the Ionian Sea.This small species showed a more asymmetric midbody and a proportionally longer neck when compared to the closer relative A.brevicauda.Three individuals of Dinofurcula tricornuta sp.nov.collected at 154-m depth in the Marmara Sea are characterized by three posterior-oriented processes when compared to its congeneric species.This is the first record of the genus Dinofurcula beyond the eastern tropical Pacific Ocean.Dinophysis profunda sp.nov.collected at 500-m depth in the Ionian Sea is characterized by ovate hypotheca and a serrate crest-like left sulcal list when compared to its close relative D.alata.These findings evidence an undescribed biodiversity in the under-sampled subphotic depths.展开更多
Mesopelagic fish,the most important daily vertically migrating community in the oceans,are characterized by high lipid content which may obscure the interpretation of stable isotopes analysis.Demersal fish,which are i...Mesopelagic fish,the most important daily vertically migrating community in the oceans,are characterized by high lipid content which may obscure the interpretation of stable isotopes analysis.Demersal fish,which are important consumers in the food web dominated by mesopelagic fish,also have a high lipid content.Here we collected 127 fish samples from the South China Sea and evaluated the effect of lipid contents on△δ^(13)C of mesopelagic and demersal fish.In lipid-extracted mesopelagic fish,the C/N content ratio(<5.5)shows a clear correlation withΔδ^(13)C(the offset of bulk and lipid-extractedδ^(13)C values),especially in non-migratory and semi-migratory species;these values were less correlation in demersal fish.Based on our results,we suggest that mesopelagic and demersal fish in different regions of the South China Sea should be studied separately using appropriate correction models and less fit for the traditional model.Moreover,the C/N content ratio should be used cautiously for establishing the lipid normalization model,especially for the fish in migratory mesopelagic fish and demersal fish.Our results also reveal that mesopelagic fish across nearby regions could be analyzed together.The new models described here can be applied in future studies of mesopelagic and demersal fish in the South China Sea.展开更多
This study used specimens of marine organisms caught by rectangular midwater trawl in the Cosmonaut Sea,Southern Ocean,in austral summer 2019/2020,to determine species composition and spatial distributions of mesopela...This study used specimens of marine organisms caught by rectangular midwater trawl in the Cosmonaut Sea,Southern Ocean,in austral summer 2019/2020,to determine species composition and spatial distributions of mesopelagic fauna in this sea.The data were also used to calculate the length-weight relationships of three common fishes captured during the survey(Electrona antarctica,Bathylagus antarcticus,and Cyclothone microdon).A total of 385 individual organisms with a total weight of 15462.2 g and representing 17 species were collected across the 11 stations visited.The small-sized crown jellyfish Atolla wyvillei(order Coronatae)was the most-dominant species by number(96 individuals),and the zooplankton Cyllopus lucasii(Amphipoda)also showed high abundance(54 individuals).Among fishes,81 individuals of Notolepis coatsorum(Paralepididae)were caught,followed by 71 individuals of E.antarctica(Myctophidae),25 individuals of B.antarcticus(Bathylagidae),and 16 individuals of C.microdon(Gonostomatidae).Clustering analysis divided the mesopelagic community into“west”and“east”groups,and a greater number of individuals were collected in the western part of the sea.The length-weight relationships of the three common fishes revealed positive allometric growth for B.antarcticus(b=3.16),and negative allometric growth for E.antarctica and C.microdon(both b=2.53).Our descriptions of the mesopelagic-zone community structure and biological features of three common fishes provide basic information on the ecology of the Cosmonaut Sea,Southern Ocean,and will be useful for ecosystem-based fisheries management in this region.展开更多
The mesopelagic communities are important for food web and carbon pump in ocean,but the large-scale studies of them are still limited until now because of the difficulties on sampling and analyzing of mesopelagic orga...The mesopelagic communities are important for food web and carbon pump in ocean,but the large-scale studies of them are still limited until now because of the difficulties on sampling and analyzing of mesopelagic organisms.Mesopelagic organisms,especially micronekton,can form acoustic deep scattering layers(DSLs)and DSLs are widely observed.To explore the spatial patterns of DSLs and their possible influencing factors,the DSLs during daytime(10:00–14:00)were investigated in the subtropical northwestern Pacific Ocean(13°–23.5°N,153°–163°E)using a shipboard acoustic Doppler current profiler at 38 kHz.The study area was divided into three parts using k-means cluster analysis:the northern part(NP,22°–24°N),the central part(CP,17°–22°N),and the southern part(SP,12°–17°N).The characteristics of DSLs varied widely with latitudinal gradient.Deepest core DSLs(523.5 m±17.4 m),largest nautical area scattering coefficient(NASC)(130.8 m^(2)/n mile^(2)±41.0 m^(2)/n mile^(2)),and most concentrated DSLs(mesopelagic organisms gathering level,6.7%±0.7%)were observed in NP.The proportion of migration was also stronger in NP(39.7%)than those in other parts(18.6%in CP and 21.5%in SP)for mesopelagic organisms.The latitudinal variation of DSLs was probably caused by changes in oxygen concentration and light intensity of mesopelagic zones.A positive relationship between NASC and primary productivity was identified.A four-months lag was seemed to exist.This study provides the first basin-scale baselines information of mesopelagic communities in the northwest Pacific with acoustic approach.Further researches are suggested to gain understandings of seasonal and annual variations of DSLs in the region.展开更多
Though mesopelagic fish respond to natural light(e.g.,diurnal vertical migration),few studies have looked at how they respond to artificial light and if artificial lights could be used in commercial operations to impr...Though mesopelagic fish respond to natural light(e.g.,diurnal vertical migration),few studies have looked at how they respond to artificial light and if artificial lights could be used in commercial operations to improve catchability of mesopelagic fish.Here we present a preliminary study on how mesopelagic organisms respond to blue and green spotlights,as well as red and white diffuse lights in Masfjorden(Norway;max depth of 480 m).The response of organisms in each of the three sound scattering layers(SSLs)was observed when a)artificial lights were positioned in a layer or b)moved with a constant speed(generally 0.03 ms1)towards a layer.The artificial lights were attached to a rig with a self-contained echosounder,which recorded the vertical and horizontal avoidance of organisms in each SSL to different artificial lights.Net hauls(MIC-net)and video footage confirmed that Maurolicus muelleri and siphonophores were present in the upper layer(100-150 m),while Benthosema glaciale were present in the deeper layers(~200 m and~300 m to seabed).Our findings suggest that M.muelleri(SSL1)horizontally avoid blue spotlight and white diffuse light,while B.glaciale(SSL2 and SSL3)mainly avoid the same lights downwards and can be herded downwards over 250 m.Though this study should be regarded as preliminary,the observed avoidance/herding response suggests artificial lights could be applied to improve existing fish capture methods for mesopelagic fish.展开更多
本研究利用Simrad EK60科学探鱼仪(38 k Hz)于2013年春季和2014年春季采集的南沙和中沙、西沙海域渔业声学数据,结合中层拖网取样,采用回声积分法研究了南海中南部中层鱼的资源量及其时空分布特征。结果显示,2014年春季中、西沙海域9次...本研究利用Simrad EK60科学探鱼仪(38 k Hz)于2013年春季和2014年春季采集的南沙和中沙、西沙海域渔业声学数据,结合中层拖网取样,采用回声积分法研究了南海中南部中层鱼的资源量及其时空分布特征。结果显示,2014年春季中、西沙海域9次中层拖网作业共捕获和鉴定鱼类和头足类79种,隶属于3纲16目37科60属,其中硬骨鱼纲的种类最多(65种),鞘亚纲次之(13种),软骨鱼纲1种,硬骨鱼纲中巨口鱼科、灯笼鱼科和钻光鱼科的种类最多,分别有20种、13种和6种;南沙海域中层鱼声学积分值(nautical area scattering coefficient,m^2/nmi^2)显著低于中沙、西沙及邻近海域,前者夜间向上迁移的强度高于后者;2013年春季南沙海域夜间10~200 m和白天200~1000 m声学积分值构成没有显著差异(P>0.05),而2014年春季中沙、西沙海域夜间10~200 m和白天200~1000 m声学积分值构成有极显著差异(P<0.01);南沙海域白天200~1000 m不同纬度组间中层鱼声学积分值构成有极显著差异(P<0.01),中沙、西沙海域声学积分值构成亦有极显著差异(P<0.01);南海中南部中层鱼声学积分值是(2387±601)m^2/nmi^2,基于现存公开发表的中层鱼的声学目标强度数据并取其均值,推算南海中南部中层鱼资源量是(8200±2100)万t。研究表明,南海中南部中层鱼声学积分值比全球平均值高约29.2%,可能是我国未来具有开发价值的大宗生物资源。展开更多
基金supported by the research project“Impact and Response of Antarctic Seas to Climate Change”(IRASCC2020-2022-No.01-02-05C)from the Chinese Arctic and Antarctic Administration,Ministry of Natural Resources of the People’s Republic of China.
文摘Mesopelagic fish(meso-fish)are central species within the Southern Ocean(SO).However,their ecosystem role and adaptive capacity to climate change are rarely integrated into protected areas assessments.This is a pity given their importance as crucial prey and predators in food webs,coupled with the impacts of climate change.Here,we estimate the habitat distribution of nine meso-fish using an ensemble model approach(MAXENT,random forest,and boosted regression tree).Four climate model simulations were used to project their distribution under two representative concentration pathways(RCP4.5 and RCP8.5)for short-term(2006–2055)and long-term(2050–2099)periods.In addition,we assess the ecological representativeness of protected areas under climate change scenarios using meso-fish as indicator species.Our models show that all species shift poleward in the future.Lanternfishes(family Myctophidae)are predicted to migrate poleward more than other families(Paralepididae,Nototheniidae,Bathylagidae,and Gonostomatidae).In comparison,lanternfishes were projected to increase habitat area in the eastern SO but lose area in the western SO;the opposite was projected for species in other families.Important areas(IAs)of meso-fish are mainly distributed near the Antarctic Peninsula and East Antarctica.Negotiated protected area cover 23% of IAs at present and 38%of IAs in the future(RCP8.5,long-term future).Many IAs of meso-fish still need to be included in protected areas,such as the Prydz Bay and the seas around the Antarctic Peninsula.Our results provide a framework for evaluating protected areas incorporating climate change adaptation strategies for protected areas management.
基金The National Basic Research Program(973 Program)of China under contract No.2015CB755902the China Ocean Mineral Resources Research and Development Association Program under contract No.DY135-E2-2-4+1 种基金the Scientific Research Fund of the Second Institute of Oceanography,SOA under contract No.JG1712the National Natural Science Foundation of China under contract No.41406116
文摘The mesozooplankton in both epipelagic and mesopelagic zones is essentially important for the study of ecosystem and biological carbon pump. Previous studies showed that the diel vertical migration (DVM) pattern of mesozooplankton varied among ecosystems. However, that pattern was largely unknown in the Western Pacific Warm Pool (WPWP). The vertical distribution, DVM and community structure of mesozooplankton from the surface to 1 000 m were compared at Stas JL7K (WPWP) and MA (North Pacific Subtropical Gyre, NPSG). Two sites showed similarly low biomass in both epipelagic and mesopelagic zones, which were in accordance with oligotrophic conditions of these two ecosystems. Stronger DVM (night/day ratio) was found at JL7K (1.31) than that at MA (1.09) on surface 0–100 m, and an obvious night increase of mesopelagic biomass was observed at JL7K, which was probably due to migrators from bathypelagic zone. Active carbon flux by DVM of zooplankton was estimated to be 0.23 mmol/(m2·d) at JL7K and 0.16 mmol/(m2·d) at MA. The community structure analysis showed that calanoid copepods, cnidarians and appendicularians were the main contributors to DVM of mesozooplankton at both sites. We also compared the present result with previous studies of the two ecosystems, and suggested that the DVM of mesozooplankton was more homogeneous within the WPWP and more variable within the NPSG, though both ecosystems showed typically extremely oligotrophic conditions. The different diel vertical migration strength of mesozooplankton between NPSG and WPWP implied different efficiency of carbon pump in these two ecosystems.
基金The National Basic Research Program(973 Program)of China under contract No.2014CB441502the National Natural Science Foundation of China under contract No.41876074the Cross-research Center Project by QNLM under contract No.JCZX202007。
文摘Compound-specific stable isotope analysis of individual amino acids(CSIA-AA)has been widely used in ecological and biogeochemical studies.It has been proven to be powerful in tracing the diet sources and trophic interactions.However,assessing the N sources of mesopelagic fishes has been inconclusive because the mesopelagic fishes’unique domain(water depth ranged from 0 to 1000 m)and unresolved nitrogen isotopes of various forms.This study proposes a new method for coupling instruments(ion chromatography and PreconIRMS)and chemical method of oxidation-reduction of amino acids,and also combinedδ15N of AAs withδ13C of fatty acids(FAs)to analyze the trophic interactions of mesopelagic fishes in the South China Sea(SCS).AAs were isolated by ion chromatography with high peak resolution and collected by an automated fraction collector.The chemical method then converted the AAs into N2 O with a robust oxidation yields and suitable molar ratio of NH2 OH to.Finally,theδ15N of AAs at 20 nmol were measured with a reasonable precision(<0.6‰).With this method,this study report the first batch high precisionδ15N of AAs andδ13C of FAs of mesopelagic fishes collected from SCS.Diaphus luetkeni,Chauliodus minimus and Bathygadus antrodes showed similarδ13C values of 20:4 n-6(~-28‰),while Argyropelecus affinis and Stomias had similar values(~-32‰).These results reflect that mesopelagic fishes had complex diet sources.An increase of 4‰inδ15N of glutamic acid(Glu)was found between piscivorous and planktivorous fishes,which might suggest a trophic discrimination factor of mesopelagic fishes in the SCS.This study usedδ13C of 20:4 n-6 to reveal the diet sources of mesopelagic fishes andδ15N of Glu to clarify trophic level between piscivorous and planktivorous fishes.Thus,this combinative method could therefore ultimately be applied in a variety of deep-sea ecosystem.
基金Supported by the Spanish Ministry of Science and Technology(No.MEC2007#0213)the French CNRS ANR Biodiversity program‘Aquaparadox’(No.ANR-07-BDIV-004)the Spanish Ministry of Science and Technology(No.JCI-2010-08492)。
文摘Three species of dinophysoid planktonic dinoflagellates are described from the eastern Mediterranean Sea.Amphisolenia sp.aff.brevicauda was collected at 70-m depth in the Ionian Sea.This small species showed a more asymmetric midbody and a proportionally longer neck when compared to the closer relative A.brevicauda.Three individuals of Dinofurcula tricornuta sp.nov.collected at 154-m depth in the Marmara Sea are characterized by three posterior-oriented processes when compared to its congeneric species.This is the first record of the genus Dinofurcula beyond the eastern tropical Pacific Ocean.Dinophysis profunda sp.nov.collected at 500-m depth in the Ionian Sea is characterized by ovate hypotheca and a serrate crest-like left sulcal list when compared to its close relative D.alata.These findings evidence an undescribed biodiversity in the under-sampled subphotic depths.
基金the National Natural Science Foundation of China under contract Nos 42090043 and 41876074the National Basic Research Program(973 Program)of China under contract No.2014CB441502.
文摘Mesopelagic fish,the most important daily vertically migrating community in the oceans,are characterized by high lipid content which may obscure the interpretation of stable isotopes analysis.Demersal fish,which are important consumers in the food web dominated by mesopelagic fish,also have a high lipid content.Here we collected 127 fish samples from the South China Sea and evaluated the effect of lipid contents on△δ^(13)C of mesopelagic and demersal fish.In lipid-extracted mesopelagic fish,the C/N content ratio(<5.5)shows a clear correlation withΔδ^(13)C(the offset of bulk and lipid-extractedδ^(13)C values),especially in non-migratory and semi-migratory species;these values were less correlation in demersal fish.Based on our results,we suggest that mesopelagic and demersal fish in different regions of the South China Sea should be studied separately using appropriate correction models and less fit for the traditional model.Moreover,the C/N content ratio should be used cautiously for establishing the lipid normalization model,especially for the fish in migratory mesopelagic fish and demersal fish.Our results also reveal that mesopelagic fish across nearby regions could be analyzed together.The new models described here can be applied in future studies of mesopelagic and demersal fish in the South China Sea.
基金financially supported by National Polar Special Program“Impact and Response of Antarctic Seas to Climate Change”(Grant no.IRASCC 01-02-05C).
文摘This study used specimens of marine organisms caught by rectangular midwater trawl in the Cosmonaut Sea,Southern Ocean,in austral summer 2019/2020,to determine species composition and spatial distributions of mesopelagic fauna in this sea.The data were also used to calculate the length-weight relationships of three common fishes captured during the survey(Electrona antarctica,Bathylagus antarcticus,and Cyclothone microdon).A total of 385 individual organisms with a total weight of 15462.2 g and representing 17 species were collected across the 11 stations visited.The small-sized crown jellyfish Atolla wyvillei(order Coronatae)was the most-dominant species by number(96 individuals),and the zooplankton Cyllopus lucasii(Amphipoda)also showed high abundance(54 individuals).Among fishes,81 individuals of Notolepis coatsorum(Paralepididae)were caught,followed by 71 individuals of E.antarctica(Myctophidae),25 individuals of B.antarcticus(Bathylagidae),and 16 individuals of C.microdon(Gonostomatidae).Clustering analysis divided the mesopelagic community into“west”and“east”groups,and a greater number of individuals were collected in the western part of the sea.The length-weight relationships of the three common fishes revealed positive allometric growth for B.antarcticus(b=3.16),and negative allometric growth for E.antarctica and C.microdon(both b=2.53).Our descriptions of the mesopelagic-zone community structure and biological features of three common fishes provide basic information on the ecology of the Cosmonaut Sea,Southern Ocean,and will be useful for ecosystem-based fisheries management in this region.
基金The National Natural Science Foundation of China under contract No.42076122the China Ocean Mineral Resources Research and Development Association Program under contract Nos DY135-E2-3-04,DY135-E2-2-04 and JS-KTFA-2018-01.
文摘The mesopelagic communities are important for food web and carbon pump in ocean,but the large-scale studies of them are still limited until now because of the difficulties on sampling and analyzing of mesopelagic organisms.Mesopelagic organisms,especially micronekton,can form acoustic deep scattering layers(DSLs)and DSLs are widely observed.To explore the spatial patterns of DSLs and their possible influencing factors,the DSLs during daytime(10:00–14:00)were investigated in the subtropical northwestern Pacific Ocean(13°–23.5°N,153°–163°E)using a shipboard acoustic Doppler current profiler at 38 kHz.The study area was divided into three parts using k-means cluster analysis:the northern part(NP,22°–24°N),the central part(CP,17°–22°N),and the southern part(SP,12°–17°N).The characteristics of DSLs varied widely with latitudinal gradient.Deepest core DSLs(523.5 m±17.4 m),largest nautical area scattering coefficient(NASC)(130.8 m^(2)/n mile^(2)±41.0 m^(2)/n mile^(2)),and most concentrated DSLs(mesopelagic organisms gathering level,6.7%±0.7%)were observed in NP.The proportion of migration was also stronger in NP(39.7%)than those in other parts(18.6%in CP and 21.5%in SP)for mesopelagic organisms.The latitudinal variation of DSLs was probably caused by changes in oxygen concentration and light intensity of mesopelagic zones.A positive relationship between NASC and primary productivity was identified.A four-months lag was seemed to exist.This study provides the first basin-scale baselines information of mesopelagic communities in the northwest Pacific with acoustic approach.Further researches are suggested to gain understandings of seasonal and annual variations of DSLs in the region.
文摘Though mesopelagic fish respond to natural light(e.g.,diurnal vertical migration),few studies have looked at how they respond to artificial light and if artificial lights could be used in commercial operations to improve catchability of mesopelagic fish.Here we present a preliminary study on how mesopelagic organisms respond to blue and green spotlights,as well as red and white diffuse lights in Masfjorden(Norway;max depth of 480 m).The response of organisms in each of the three sound scattering layers(SSLs)was observed when a)artificial lights were positioned in a layer or b)moved with a constant speed(generally 0.03 ms1)towards a layer.The artificial lights were attached to a rig with a self-contained echosounder,which recorded the vertical and horizontal avoidance of organisms in each SSL to different artificial lights.Net hauls(MIC-net)and video footage confirmed that Maurolicus muelleri and siphonophores were present in the upper layer(100-150 m),while Benthosema glaciale were present in the deeper layers(~200 m and~300 m to seabed).Our findings suggest that M.muelleri(SSL1)horizontally avoid blue spotlight and white diffuse light,while B.glaciale(SSL2 and SSL3)mainly avoid the same lights downwards and can be herded downwards over 250 m.Though this study should be regarded as preliminary,the observed avoidance/herding response suggests artificial lights could be applied to improve existing fish capture methods for mesopelagic fish.
