Water mass of the northward throughflow in the Bering Strait in the summer of 2003

The temperature and salinity data obtained by the Chinese national arctic research expedition （CHINARE2003） are used to study the water structure in the Bering Strait and ambient regions. Four water masses appeared in the research region： the intermediate Bering Sea water mass （IBWM）, the Alaska coastal water （ACW）, the Anadyr water （AW） and the Bering shelf water （BSW）. The AW originates from the IBWM, but the upper layer water has been greatly altered. In the cruise on 28/29 July 2003, there were only the BSW and ACW in a section across the Bering Strait （BS section）, but in the September 12/13 cruise, the AW, BSW and ACW flowed parallelly into the Bering Strait. The upper waters of these water masses were all altered due to ice melting, runoff, solar radiation, and wind mixing. The waters in the central and northern parts of Bering Strait stratified by two uniform layers,were expressed as the typical feature of the water masses originating from the pacific. A two-layer structure also dominated the vertical stratification in most part of the Chukchi Sea. An obvious subseasonal variation was observed in the BS section, which caused varying transportation of fresh water, heat, and substance, and produced a long-term and extensive impact on the Arctic Ocean.

The fundamental characteristics of current in the Bering Strait and the Chukchi Sea from July to September 2003

The characteristics of current in the Bering Strait and the Chukchi Sea areanalyzed based on the two current data on the mooring stations during the Second National ArcticResearch Expedition of China in 2003. The tidal currents of the principal diurnal and semidiurnalellipses rotate clockwise in the upper layer, except for N_2, S_2, and Q_1 at Sta. ST. In the BeringStrait (Sta. ST), the major semi-axis of tidal current constituent M_2 is 2.9 cm/s in the upperlayer, which is much smaller than that of semi-monthly oscillation (11.8 cm/s); and the mean currentflows northwestward at the amplitude of about 20 cm/s and varies a little with depth. During thecruise, the current has significant semi-monthly oscillation at the two mooring stations. Thespectra analyses of the air pressure gradient and the wind stress show that there are thesemi-monthly oscillations in these two data series. The near-inertial current, approximately 4 cm/s,presents almost the same magnitude of the principal tidal currents in the Bering Strait.

Cumulative human impacts in the Bering Strait Region

Introduction:Human impacts on Arctic marine ecosystems are increasing in extent and intensity as sea ice shrinks and utilization of marine resources expands.The effects of climate change are being felt across the arctic while stressors such as commercial fishing and shipping continue to grow as the Arctic becomes more accessible.Given these emerging changes,there is need for an assessment of the current cumulative impact of human activities to better anticipate and manage for a changing Arctic.Cumulative human impacts(CHI)assessments have been widely applied around the world in a variety of ecosystem types but have yet to incorporate temporal dynamics of individual stressors.Such dynamics are funda-mental to Arctic ecosystems.Outcomes:Here,we present the first CHI assessment of an Arctic ecosystem to incorporate sea ice as a habitat and assess impact seasonality,using the Bering Strait Region(BSR)as a case study.We find that cumulative impacts differ seasonally,with lower impacts in winter and higher impacts in summer months.Large portions of the BSR have significantly different impacts within each season when compared to a mean annual cumulative impact map.Cumulative impacts also have great spatial variability,with Russian waters between 2.38 and 3.63 times as impacted as US waters.Conclusion:This assessment of seasonal and spatial cumulative impacts provides an under-standing of the current reality in the BSR and can be used to support development and evaluation of future management scenarios that address expected impacts from climate change and increasing interest in the Arctic.

Mesozooplankton distribution and diversity from the Bering Sea shelf to the Chukchi Sea

In recent decades,environmental changes in the Arctic have aroused widespread concern around the world.To better understand ecology issues such as ecosystem dynamics,the Arctic and the subarctic regions were integrated as the“pan-Arctic”region.In this study,mesozooplankton were sampled from the Bering Sea shelf to the northern Chukchi Sea during the 10th Chinese National Arctic Research Expedition in 2019.Based on the species composition and abundance,three geographical communities were identified:the Bering Sea shelf community(BSS),the Bering Strait transitional community(BST),and the Chukchi Sea shelf community(CSS).The BSS was characterized by Bering Sea oceanic species such as Eucalanus bungii;the BST was mainly composed of the pan-Arctic distributed Calanus glacialis,meroplankton of benthos,and neritic species such as Centropages abdominalis;copepods,especially the copepodite of C.glacialis,were predominant in the CSS community.The BSS community structure was strongly affected by the inflow of Bering Shelf Water,while those of BST and CSS were determined by the recruitment of local species.The zooplankton community structure is influenced by both advection and environmental changes such as warming and a prolonged productivity period.Here,it was difficult to distinguish the changes induced by climate change from the effects of the Bering Sea Water.The key to solving this problem is the accumulation of comparable data,which requires continuous monitoring of key species such as C.glacialis and Calanus hyperboreus.

Composition and distribution of fish species collectedduring the fourth Chinese National Arctic Research Ex-pedition in 2010

There are awareness and concerns caused by the decreasing sea ice coverage around the Arctic and Antarctic due to effects of climate change. Emphasis in this study was on rapid changes in Arctic sea ice coverage and its impacts on the marine ecology during the fourth Chinese National Arctic Research Expedition in 2010. Our purpose was to establish a baseline of Arctic fish compositions, and consequent effects of climate change on the fish community and biogeography. Fish specimens were col- lected using a multinet middle-water trawl, French-type beam trawl, otter trawl, and triangular bottom trawl. In total, 36 tows were carried out along the shelf of the Bering Sea, Bering Strait, and Chukchi Sea in the Arctic Ocean. in total, 41 fish species belonging to 14 families in 7 orders were collected during the expedition. Among them, the Scorpaeniformes, including 17 species, accounted for almost one third of the total number （34.8%）, followed by 14 species of the Perciformes （27.0%）, 5 species of the Pleuronecti- formes （22.3%）, and 2 species of the Gadiformes （15.4%）. The top 6 most abundant species were Hippoglossoides robustus, Bore- gadus saida, Myoxocephalus scorpius, Lumpenus fabricii, Artediellus scaber, and Gymnoeanthus trieuspis. Abundant species var- ied according to the different fishing methods; numbers of families and species recorded did not differ with the various fishing methods; species and abundances decreased with depth and latitude; and species extending over their known geographic ranges were observed during the expedition. Station information, species list, and color photographs of all fishes are provided.