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Nutrient distributions and nitrogen-anomaly(N^(*))in the tropical North Pacific Ocean

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Acta Oceanologica Sinica 2022年第11期41卷 23-33页

作者： Aiqin Han Yu Wang Yunlong Huo Cai Lin Kaiwen Zhou Fangfang Kuang Hui Lin Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China

Based upon cruise observations broadly covering the tropical North Pacific during July-November 2017,together with data obtained from the World Ocean Circulation Experiment Hydrographic Program,this study examined the distribution of dissolved inorganic nitrogen(DIN,nitrate(NO_(3)^(-))+nitrite(NO_(2)^(-))),dissolved inorganic phosphorus(DIP)and related N^(*)(nitrogen-anomaly,N^(*)=N-16P+2.9,where N and P are the concentrations of DIN(>1.0μmol/L)and DIP(>0.1μmol/L)),used as an index of N2fixation,in the upper 1000 m of the water column.Nutrient concentrations displayed distinct spatial variability in the upper ocean but became relatively constant at a depth of 1000 m:they were high at low latitudes and in the eastern region,with an obvious nutricline at~150 m(DIN,~32.0μmol/L;DIP,~2.4μmol/L)and then generally increased with depth;they decreased markedly(DIN,~1.2μmol/L;DIP,~0.1μmol/L;at~150 m)at high latitudes and in the western region,where a nutricline was not apparent.The N^(*)index showed significant meridional and zonal variation,with the most negative values located at low latitudes and in the eastern region(~10°N,~150°-170°E),while becoming positive towards the northwest(the north of~18°N,~160°E westward).A N^(*)concentration larger than 2.0μmol/L which often used as an indicator of N2fixation,was observed between 155°E and 165°E;N^(*)values were 2.0μmol/L to6.0μmol/L at~15°-28°N,i.e.,much higher than those in the southern sector(0-2.0μmol/L at~5°-10°N).Zonally,N^(*)decreased gradually from west(-2.0μmol/L to 4.0μmol/L,~145°-165°E)to east(-2.0μmol/L to-8.0μmol/L,~155°W)along~10°N,which was consistent with the distribution of Trichodesmium abundance and N2fixation rates.Furthermore,since such region was also supplied with aeolian deposition,high N^(*)was probably not only induced by N2fixation but also influenced by iron and/or nitrogen deposition.

关键词： tropical North Pacific Ocean nutrients nitrogen anomaly nitrogen fixation aeolian deposition

Intra-seasonal variability of the abyssal currents in COMRA's contract area in the Clarion-Clipperton Zone

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Acta Oceanologica Sinica 2022年第11期41卷 1-11页

作者： Fangfang Kuang Jing Cha Junpeng Zhang Aijun Pan Hangyu Chen Xiwu Zhou Chunsheng Jing Xiaogang Guo Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China

In this paper,the intra-seasonal variability of the abyssal currents in the China Ocean Mineral Resources Association(COMRA)polymetallic nodule contact area,located in the western part of the Clarion and Clipperton Fraction Zone in the tropical East Pacific,is investigated using direct observations from subsurface mooring instruments as well as sea-surface height data and reanalysis products.Mooring observations were conducted from September 13,2017 to August 15,2018 in the COMRA contact area(10°N,154°W).The results were as follows:(1)At depths below 200 m,the kinetic energy of intra-seasonal variability(20-100 d)accounts for more than 40%of the overall low-frequency variability,while the ratio reaches more than 50%below 2000 m.(2)At depths below 200 m,currents show a synchronous oscillation with a characteristic time scale of 30 d,lasting from October to the following January;the energy of the 30-d oscillation increases with depth until the layer of approximately 4616 m,and the maximum velocity is approximately 10 cm/s.(3)The 30-d oscillation of deep currents is correlated with the tropical instability waves in the upper ocean.

关键词： intra-seasonal variability abyssal currents Clarion-Clipperton Zone tropical instability waves

Regional disparities of phytoplankton in relation to environmental factors in the western Arctic Ocean during summer of 2010

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Acta Oceanologica Sinica 2018年第4期37卷 109-120页

作者： LIN Gengming WANG Yanguo CHEN Yanghang YE Youyin WANG Yu YANG Qingliang Third Institute of Oceanography State Oceanic Administration

Global warming has caused Arctic sea ice to rapidly retreat,which is affecting phytoplankton,the primary producers at the base of the food chain,as well as the entire ecosystem.However,few studies with large spatial scales related to the Arctic Basin at high latitude have been conducted.This study aimed to investigate the relationship between changes in phytoplankton community structure and ice conditions.Fifty surface and 41 vertically stratified water samples from the western Arctic Ocean（67.0°–88°26′N,152°–178°54′W） were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30,2010 during China＇s fourth Arctic expedition.Using these samples,the species composition,spatial distribution,and regional disparities of phytoplankton during different stages of ice melt were assessed.A total of 157 phytoplankton taxa（〉5 μm） belonging to 69 genera were identified in the study area.The most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii,accounting for 31.23% and 14.12% of the total phytoplankton abundance,respectively.The average abundance during the departure trip and the return trip were 797.07×10~2 cells/L and 84.94×10~2 cells/L,respectively.The highest abundance was observed at Sta.R09 in the north of Herald Shoal,where Navicula pelagica was the dominant species accounting for 59.42% of the abundance.The vertical distribution of phytoplankton abundance displayed regional differences,and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline,thermocline,and nutricline.The species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return trips.The phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt,and there was shift in dominant species from centric to pennate diatoms.Results of canonical correspondence analysis（CCA） showed that there were two distinct communities of phytoplankton in the

关键词： phytoplankton regional disparity species composition spatial distribution western Arctic Ocean

The winter western boundary current of the South China Sea:physical structure and volume transport in December 1998

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Acta Oceanologica Sinica 2018年第3期37卷 1-7页

作者： LI Li GUO Xiaogang WU Risheng Third Institute of Oceanography State Oceanic Administration

The unique survey in December 1998 mapped the entire western boundary area of the South China Sea（SCS）,which reveals the three-dimensional structure and huge volume transport of the swift and narrow winter western boundary current of the SCS（SCSwwbc） in full scale. The current is found to flow all the way from the shelf edge off Hong Kong to the Sunda Shelf with a width around 100 km and a vertical scale of about 400 m. It appears to be the strongest off the Indo-China Peninsula, where its volume transport reached over 20×10~6 m^3/s. The current is weaker upstream in the northern SCS to the west of Hong Kong. A Kuroshio loop or detached eddy intruded through the Luzon Strait is observed farther east where the SCSwwbc no more exists. The results suggest that during the survey the SCSwwbc was fed primarily by the interior recirculation of the SCS rather than by the＂branching＂ of the Kuroshio from the Luzon Strait as indicated by surface drifters, which is likely a near-surface phenomenon and only contributes a minor part to the total transport of the SCSwwbc. Several topics related to the SCSwwbc are also discussed.

关键词： South China Sea western boundary current winter hydrographic structure volume transport

Next-generation sequencing revealed specific microbial symbionts in Porites lutea with pigment abnormalities in North Sulawesi, Indonesia

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Acta Oceanologica Sinica 2018年第12期37卷 78-84页

作者： OU Danyun CHEN Bin HADI Tri Aryono SUHARSONO NIU Wentao ALFIANSAH Yustian Rovi Third Institute of Oceanography Ministry of Natural Resources Research Center for oceanography Indonesian Institute of Sciences

Bacterial diseases affecting corals pose an enormous threat to the health of coral reefs. The relationship between certain bacterial species and coral diseases remain largely unknown. Pigment abnormalities are common in Porites lutea. Here we used Illumina 16S rRNA gene sequencing to analyze the bacterial communities associated with healthy P. lutea and P. lutea with pigment abnormalities. We observed an increase of alpha diversity of the bacterial community of P. lutea with pigment abnormalities, relative to healthy corals. We then identified changes in the abundance of individual operational taxonomic units(OTUs) between pigmented and healthy corals. We were able to identify eight OTUs associated with pigment abnormalities, which are possibly the causative agents of pigment abnormalities.

关键词： Porites lutea pigment abnormalities next-generation sequencing 16S rRNA bacterial diversity

Phytoplankton changes during SE monsoonal period in the Lembeh Strait of North Sulawesi, Indonesia,from 2012 to 2015

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Acta Oceanologica Sinica 2018年第12期37卷 9-17页

作者： TANG Senming RACHMAN Arief FITRIA Nurul THOHA Hikmah CHEN Bin Third Institute of Oceanography Ministry of Natural Resources Research Center for oceanography Indonesian Institute of Sciences

Phytoplankton species composition and abundance in the Lembeh Strait waters was studied in four cruises of April 2013, May 2014, June 2012 and October 2015, during the period of monsoon transition time of SE monsoon.With data obtained the seasonal alternations of phytoplankton community structures and its driving factors were discussed. A total of 416 taxa belonging to 5 classes of phytoplankton were recorded in the four month surveys.Phytoplankton density was averaged 2 348 cell/L and diatoms and dinoflagellates had the most diversified species. Cyanobacterium was characterized by its low species numbers but high abundance in the waters of Lembeh Strait. Total phytoplankton abundance occurred low in April and October in the monsoon transition period and it raised high in May and June during the SE monsoon. Frequently occurred species were pelagic diatoms in addition to cyanobacterium Trichodesmium. Abundance and diversity of phytoplankton significantly differed seasonally. The diatoms Thalassionema and Pseudo-nitzschia, and cyanobacterium Trichodesmium contributed most to the community dissimilarities. Due to potentially higher nutrient supply in the south of Lembeh Strait, diatoms and dinoflagellates showed higher densities in the south than in the north of the strait.Though, cyanobacterium preferred distributing much evenly in all waters, it had higher density in the southern Lembeh Strait. Total phytoplankton abundance is quite low compared with the Jakarta Bay and some bays in China. Analysis showed that nutrients from upwelling forced by SE monsoon are the key factor varying the monthly phytoplankton abundances. Due to its primitive nature state, Lembeh water can be an ideal location for the study of pelagic ecosystem under merely the influence of macro environment changes with lower background noise from human activities.

关键词： Lembeh Strait phytoplankton diversity community alternation Trichodesmium monsoon

Zooplankton composition and distribution in the Lembeh Strait of North Sulawesi, Indonesia

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Acta Oceanologica Sinica 2018年第12期37卷 35-44页

作者： WANG Yanguo CHEN Xiaoyin XING Bingpeng SUN Rouxin FITRIA Nurul XIANG Peng WANG Chunguang LIN Mao Third Institute of Oceanography Ministry of Natural Resources Research Center for oceanography Indonesian Institute of Sciences

Based on oceanographic survey data in June 2012 in the Lembeh Strait, the zooplankton ecological characteristics such as species composition, individual abundance, dominant species and distribution were analyzed. The results showed that 183 species(including 4 sp.) had been recognized, most of them belonged to copepoda.Cnidaria followed with 43 species(including 1 sp.) were identified. The average abundance of zooplankton was(150.47±58.91) ind./m3. As to the horizontal distribution, the abundance of the zooplankton was higher in the southern waters than in the northern waters. The dominant species in the study area were Lensia subtiloides,Sagitta enflata, Lucifer intermedius, Oikopleura rufescens, Diphyes chamissoni, Creseis acicula, Subeucalanus subcrassus, Temora discaudata, Aglaura hemistoma, Doliolum denticulatum, Canthocalanus pauper, Oikopleura longicauda and Nanomia bijuga. Zooplankton biodiversity indexes were higher in study area than previous study in the other regions. The findings from this study provide important baseline information for future research and monitoring programs.

关键词： zooplankton species composition dominant species distribution Lembeh Strait

Diversity and abundance of mangrove fiddle crabs, genus Uca(Decapoda, Ocypodidae) at a mangrove in Kema,North Sulawesi, Indonesia

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Acta Oceanologica Sinica 2018年第12期37卷 92-96页

作者： RIANTA Pratiwi ERNAWATI Widyastuti CHEN Guangcheng CHEN Shunyang Research Center for oceanography Indonesian Institute of Sciences Third Institute of Oceanography Ministry of Natural Resources

Mangrove ecosystems are sites with high biodiversity of benthic fauna, and fiddler crabs(genus Uca) are common benthic fauna in mangroves. The North Sulawesi in Indonesia has a good condition of mangrove while the information of the fiddler crabs is still limited. Manual samplings were conducted in wet, dry and transient seasons at a mangrove in Kema, North Sulawesi to investigate the species composition, density and distribution pattern of fiddler crabs. A total of 168 individuals, subjected to eight species of genus Uca crabs were collected at the mangrove, with U. triangularis having the highest abundance and U. annulipes having the lowest abundance.The densities of fiddle crabs were 27.56 ind./m2, 32.89 ind./m2and 14.22 ind./m2at the seaward, middle and landward zones, respectively, and the density was higher in dry and wet seasons than in transient season.

关键词： Crustacea genus Uca species mangrove North Sulawesi Indonesia

Spatial structure and seasonal changes of nekton assemblages in the Taiwan Strait

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Acta Oceanologica Sinica 2016年第6期35卷 59-67页

作者： SONG Puqing LIN Longshan LI Yuan ZHONG Zhihui The Third Institute of Oceanography State Oceanic Administration

The Taiwan Strait is a transition zone between the East China Sea and the South China Sea with unique hydrology and a geographical environment that creates special marine community features.To analyze the spatial structure and seasonal changes of the nekton assemblages in the Taiwan Strait,seasonal experimental trawl surveys were conducted during 2006-2007.The results showed that there were two assemblages in the area with different sets of species,and the average similarity within each group varies between 39.38% and 74.20%.By using multivariate statistical analysis and analyzing the distribution of dominant species,we found that the structures of the assemblages had obvious seasonal variation.The middle region from the Putian transect to the Xiamen transect could be considered a mixing area for the two assemblages.The analysis of the relationship between species assemblages and environmental factors indicated that temperature was the most important factor affecting the community structure in cold seasons,and 22.5°C and 17°C could be considered dividing lines for spring and winter,respectively.In warm seasons,the most important factor was water depth,but the relationship with depth was not as significant,with a correlation between 0.264 and 0.399.The seasonal changes of nekton assemblages basically reflected the dynamic currents in the Taiwan Strait.The south coastal assemblage extended to nearly the entire area of the Taiwan Strait along with a strong and intense warm current that shrinks in spring and winter when the southward intrusion of the cold Zhejiang-Fujian coastal current becomes stronger.The impact of shortterm and long-term environmental changes,such as extreme weather,global warming and human activity on nekton assemblages,had been recognized but need further research.Our study on nekton assemblages could be used as a baseline for measuring future changes.

关键词： nekton assemblages species composition spatial structure transition zone Taiwan Strait