Offshore eastern Taiwan situated in the West Pacific active zone, there are multiple hydrothermal vents among which Kueishantao (KST) and Lutao (LT) host the most active systems. This paper reviewed the progress of the geochemical characteristics and biological responses of the KST and LT hydrothermal systems. The vent fluids emanated from the shallow KST hydrothermal vents have the world's lowest pH (1.52) values of any submarine vents. The fluids are rich in heavy metals and are accompanied by gases composed mostly by CO₂. The hydrothermal vents are considered to be a source for chromophoric and fluorescent dissolved organic matter in the oceans. The hydrothermal systems showed the world’s lowest concentration of dissolved organic carbon (14 μmol/L) and unique kinetic characteristics in Lutao. Native sulfur chimneys and sulfur balls were found around the KST vents. The highly toxic and acidic KST vent fluids have disturbed the behavior of ambient macro-organisms including crabs which have developed detoxication measures. The active bacteria groups in the KST field are dominated by Gammaproteobacteria and Epsilonbacteraeota that are involved in the carbon, sulfur, and nitrogen metabolic pathways. Sulfur-reducing and sulfide-oxidizing chemolithoautotrophs account for most of the primary biomass synthesis, which fuels microbial energy flow and element cycling in the hydrothermal systems. Vent crab evolved an adaptive modulation of reproductive behavior to survive in the hydrothermal vent field. Under the stress of the KST hydrothermal activity, the microorganisms have generated cryptic compounds and metabolic products. Furthermore, both the KST and LD hydrothermal systems are affected by tides and catastrophic events such as typhoons and earthquakes. The studies on the hydrothermal systems at offshore Taiwan are of essential importance for investigating the geochemical cycles and eco-environmental impacts of global hydrothermal systems.

The research progress of macrobenthic biodiversity and ecology from the deep-sea in the world is reviewed in the present paper, especially the advances on the investigations and studies of macrobenthic biodiversity and ecology from the hydrotherms, cold seeps, seamounts, abysses and whale carcasses in China. The prospect of the future researches in China is also discussed.

Ocean observation is to observe unknown ocean by acquiring time serial data from the ocean which is the must for ocean science research and attracts more and more interests recently. The paper defines and classifies the ocean observation and discusses how to tell the differences between ocean observing and ocean monitoring. Based on the understanding of ocean observation, ocean observing methodology are discussed in detail, differently in the aspects of observing technology, real-time performance, cost effectiveness and applicability. The author’s research work shows that the better understanding of observing data secures the ocean observation quality; the observing measure especially its platform is critical for the real-time observating performance , which meets the requirement of ocean observation; the cost effectiveness determines the selection of observing methods, and its applicability defines the best form of observation and even creates brand-new kinds of observing technology.

Coupled ocean and sea-ice models, developed based on Version 3.6 of the Nucleus for European Modelling of the Ocean (NEMO), with the sea-ice component being Version 3 of Louvain-la-Neuve Sea Ice Model (LIM), are applied for hindcast simulations covering the North Atlantic-North Pacific-Arctic Oceans (NAPA). The two model configurations, NAPA1/4 and NAPA1/12, have nominal horizontal resolutions of (1/4)° and (1/12)° in latitude/longitude, respectively. The model domains cover the Pacific Ocean north of 45°N, the whole Arctic, and the North Atlantic north of 26°N for NAPA1/4 and 7°N for NAPA1/12. A decade-long hindcast from 1993 to 2015 using NAPA1/4 has been completed. The hindcast results of sea-ice, circulation and hydrography variations in the Arctic Ocean are evaluated with available observational data and previously published results. The evaluation suggests that NAPA1/4 possesses reasonable skills in reproducing the key thermal and dynamic processes, and can be applied to study the seasonal and inter-annual variations of sea-ice, water masses, and Atlantic/Pacific inflows/outflows. Preliminary analysis of the NAPA1/12 hindcast during 1993-1996 suggests that increasing horizontal resolution simulates more details of the spatial structures of sea-ice, water-mass properties, and ocean circulation.

Based on the 34th Chinese Antarctic scientific expedition "Xiangyanghong 01" cruise around the Antarctic Peninsula from January to February 2018, the properties and exchanges of water masses in the region of Antarctic Peninsula were analyzed. The main water masses are Antarctic Surface Water, Circumpolar Deep Water, Warm Deep Water, Antarctic Bottom Water, Bransfield Srait Bottom Water. Weddell Sea Warm Deep Water and Weddell Sea Deep Water flow into Scotia Sea through the Orkney Passage, the Bruce Passage on the east of the South Orkney Plateau and the Hesperides Gap on the west of the South Orkney Plateau. Among them, the deepest current velocity is 0.25 m/s in Orkney Passage, which allow denser Weddell Sea Deep Water to flow to Scotia Sea; the current velocity is 0.13 m/s in Bruce Passage, which allow warmer Warm Deep Water flows and the temperature of Warm Deep Water passing through this gap is the lowest, and the current velocity is 0.10 m/s in Hesperides Gap, only colder Warm Deep Water and lighter Weddell Sea Deep Water can pass. Southward currents and northward currents were observed on both sides of the South Orkney Plateau, but northward currents and water exchange are stronger. Water flow westward along the north side of the South Scotia Ridge after entering the Scotia Sea through the Passages on both sides of the South Orkney Plateau, with a velocity of 0.21 m/s. A branch of Antarctic Circumpolar Current in Drake Passage flow eastward to Scotia Sea, and influenced by Warm Deep Water and Weddell Sea Deep Water flowing westward, Circumpolar Deep Water in the Scotia Sea is obviously weaker than that in the Drake Passage. Affected by the eastward Antarctic Circumpolar Current, Weddell Sea Deep Water on the north side of the South Scotia Ridge is warmer than that on the south side. The water on the South Scotia Ridge may be affected by the Circumpolar Deep Water and Warm Deep Water in the north, Shelf Water in the West and Winter Water in the east, so the structure of the water on the South Scotia Ridge is much complex.

Sea ice is an important part of the global climate system. Landfast ice is commonly found in the Antarctic coastal area, which reached the thickest in the middle and late November around Zhongshan Station. Sea ice thickness is one of the important parameters of the sea ice. We presented measurements by taken 1 SIMBA (Snow and Ice Mass Balance Array) buoy and 3 TY buoys to monitor ice thickness based on the bias of different linear temperature gradient in air, snow, ice and sea water in three different landfast ice stations (S1, S2 and S3) in the Prydz Bay outside Zhongshan Station in 2016. The SIMBA measures vertical temperature profiles 4 times a day and TY measures vertical temperature per hour. Both SIMBA and TY buoys were set up in S3 station. Compared with borehole in situ measurements, the ice thickness derived by TY buoys had a mean bias and RMSE of 3.3 cm and 14.7 cm in S1 Station, 6.6 cm and 6.9 cm in S2 Station and 4.0 cm and 4.8 cm in S3 Station. And the mean bias and RMSE for the SIMBA buoys in S3 Station compared with borehole in situ measurements were 8.2 cm and 9.7 cm. The sea ice thickness derived by TY buoys were more agreement with the borehole in situ measurements compared with the sea ice thickness derives from SIMBA buoys in S3 Station. The result of Stefan’s law of ice growth model shows the sea ice growth process and the ice growth rate varied between 0.1 cm/d to 0.8 cm/d, which is faster than the result of TY buoys and is affected by the snow thickness. While compare with limited borehole in situ sea ice thickness measurements and the great uncertain in the sea ice thickness derived by remote sense data, the error for both the TY and SIMBA buoys are reasonable, which will benefit to the future sea ice thickness monitor near Zhongshan Station.

Core AMS01 dredged on the northwestern continental rise of the Amundsen Sea was used to reconstruct the history of ice sheet and paleoproductivity since MIS9 (about 34 ka BP) based on the analyses of color reflectance, grain size and geochemical proxies. The results show that: (1) Grain size and paleoproductivity proxies of the core exhibits evident glacial–interglacial cycles of Quaternary; (2) The interglacials such as MIS9, MIS7 and MIS5 have low sedimentation rates, brown sediments, low ice-rafted detritus (IRD) contents and high paleoproductivity, indicating warm climate, limited sea ice and large-scale retreat of the ice sheet in the Amundsen Sea sector; (3) Glacial ages such as MIS8c, MIS8a, MIS6 and MIS2 have relatively high sedimentation rates, gray sediments, high IRD and low biological components, which indicate the ice sheet expanded greatly to the edge of the continental shelf, and the continental rise became a proximal environment close to the grounded ice sheet and/or floating ice shelf with dense sea ice and icebergs, and significantly lowered marine productivity; (4) In the glacials and interglacials, ice sheet and paleoproductivity also have certain fluctuations, especially in MIS8b interstadial, the light brown sediments with low IRD and elevated marine productivity make it be like the environment of interglacial period, which indicates that the ice sheet and ocean in the Amundsen Sea sector are more sensitive to climate change than those in the East Antarctica.

Analyses of grain size, organic carbon and biomarker have been carried out for the core ANT32-RB16C, in order to identify the source of organic matter and reconstruct the sedimentary environment since the Last Glacial Maximum in the western Ross Sea. From the bottom to the top within the core, sub-ice-shelf, pre-ice-shelf and open-marine sedimentary environments can be differentiated. The combined parameters of biomarker indicate that organic matter is mainly a mixed input of terrigenous and marine origin. During the Last Glacial Maximum (24.8–20 ka BP), under the influence of ice sheet and the current condition, the organic matter content was low and its source was associated mainly with a marine origin, with a relatively low plankton productivity. During the Last Deglaciation (20–11.7 ka BP), the organic matter released by the dissolution of the glaciers in the retreat process of the Ross Ice Shelf, caused the increase of terrestrial organic matter. During the Holocene, the content of organic matter increased significantly, together with the proportion of marine origin input. The number of prokaryotes such as bacteria increased, resulting in a greater degree of degradation of short-chain n-alkanes. The redox condition in the study area is mainly affected by the ice shelf and sea ice limitation, and has little relationship with the organic matter content and the high-oxygen Antarctic Bottom Water. In general, from the Last Glacial Maximum to the Last Deglaciation, the study area sedimentary environment was affected by the Ross Ice Shelf, and by the climate since the Holocene.

Eco-dynamics of marine plankton are remarkably sensitive to changes in their environments. The Arctic Ocean is undergoing rapid environmental changes as the global climate change intensifies. Understanding the seasonal distribution and variation of low-trophic plankton is a prerequisite for exploring the response of ecosystem to changing environment in the Arctic Ocean, and is also an important basis for assessing the carbon sequestration capacity of the Arctic Ocean. Based on above, a coupled ocean-sea ice-biogeochemical cycling model was developed and applied to evaluate the temporal-spatial variations of chlorophyll a concentration and planktonic structures in the Arctic Ocean. The results suggested that: (1) surface chlorophyll a concentration mainly peaks in May, with the higher values on the Pacific side than the Atlantic; since stratification occurs, subsurface chlorophyll a maximums are found in areas having limited nutrients at surface, and the depth of subsurface chlorophyll a maximums gradually deepens from the shelf towards the basin; in September, the high chlorophyll a concentration returns to the upper layer from the subsurface, presenting a sub-peak of surface chlorophyll a concentration on the Pacific side. (2) Substantial regional differences in surface plankton communities exist in the Arctic Ocean due to the influences of the Pacific and Atlantic inflows with variations in nutrients concentrations and structures. Diatom and mesozooplankton are dominant species on the Pacific side where diatom biomass exhibits two peaks in May and September, meanwhile nanophytoplankton maintains relatively high biomass in March, May and June. Atlantic side experiences a seasonal succession from nanophytoplankton to diatom then to nanophytoplankton corresponding to early spring, late spring-early summer, and summer-autumn, respectively. Over the entire growth season, nanophytoplankton and microzooplankton dominate on the Atlantic side. Generally, the peak biomass of zooplankton has a lag for half a month to the peak of phytoplankton biomass in the Arctic Ocean.

To investigate the heat stress responding strategies of Antarctic ice algae, the characteristics of a catalase gene CiCAT from the transcriptome of Antarctic ice alga Chlamydomonas sp. ICE-L were analyzed. The length of CiCAT is 2 066 bp encoding a catalase of 492 amino acids. In the phylogenetic tree of catalase amino acid sequences, Antarctic ice alga is clustered with green algae. The amino acid sequence identities of CiCAT are about 80.5% and 78.9% to the catalase from Dunaliella salina and Haematococcus lacustris, respectively. The changes of CiCAT gene expression and catalase activity in Antarctic ice alga were also investigated. Under heat stress, both the relative expression state of CiCAT gene and catalase activity changed from up-regulation to down-regulation over time. After heat stress treatment for 24 h, the expression of CiCAT gene was almost unchanged, while the enzyme activity in the heat treatment group was significantly higher than that in the control group. After 72 h's heat stress treatment, both gene expression and enzyme activity reached the highest level. Our preliminary results show that antioxidase system plays an important role in Antarctic ice algae responding to heat stress, which is similar to that in temperate algae and higher plants.