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Changes in sea ice kinematics in the Arctic outflow region and their associations with Arctic Northeast Passage accessibility
Dawei Gui, Xiaoping Pang, Ruibo Lei, Xi Zhao, Jia Wang
doi: 10.1007/s13131-019-1451-1
Amplification of climate warming in the Arctic is causing a dramatic retreat of sea ice, which means the Arctic sea routes are becoming increasingly accessible. This study used a satellite-derived sea ice motion product to quantify the kinematic features of sea ice in the Arctic outflow region which specially referred to the Fram Strait and to the north of the Northeast Passage (NEP). An observed trend of increased southward sea ice displacement from the central Arctic to the Fram Strait indicated enhancement of the Transpolar Drift Stream (TDS). In the regions to the north of the NEP, the long-term trend of northward sea ice speed in the Kara sector was +0.04 cm/s per year in spring. A significant statistical relationship was found between the NEP open period and the northward speed of the sea ice to the north of the NEP. The offshore advection of sea ice could account for the opening of sea routes by 33% and 15% in the Kara and Laptev sectors, respectively. The difference in sea level pressure across the TDS, i.e., the Central Arctic Index (CAI), presented more significant correlation than for the Arctic atmospheric Dipole Anomaly index with the open period of the NEP, and the CAI could explain the southward displacement of sea ice toward the Fram Strait by more than 45%. The impact from the summer positive CAI reinforces the thinning and mechanical weakening of the sea ice in the NEP region, which improves the navigability of the NEP.
key words: sea ice, Arctic Northeast Passage, Transpolar Drift Stream, atmospheric circulation indices
Morphological characteristics and DNA barcoding of Pampus echinogaster (Basilewsky, 1855)
Yuan LI, Yan ZHANG, Tianxiang GAO, Zhiqiang HAN, Longshan LIN, Xiumei ZHANG
doi: 10.1007/s13131-017-1124-x
The morphological similarities of Pampus fishes have led to considerable confusion in species-level identification, and no accurate information on neotype or DNA barcoding of Pampus echinogaster is available. Two hundred and seven specimens of P. echinogaster were collected from the coastal waters of Dandong, Dongying, Qingdao, Nantong, Zhoushan, Wenzhou, Changle, Taiwan, and Wakayama (Japan), from June 2010 to April 2013. The diagnostic characteristics of P. echinogaster are as follows: dorsal fin VIII-XI-43–51, anal fin V-VIII-43–49, pectoral fin 22–27, caudal fin 19–22, pelvic fin absent; first gill rakers sparse, slender (pointed), 3–4+12–16=15–20; vertebrae 39–41; transverse occipital canal on top of head moderately small, wavy ridges not reaching upper origin of pectoral fin; ventral branch of lateral line canal spare, shorter than dorsal branch of lateral line canal. By combining congener sequences of the cytochrome oxidase I (COI) gene from GenBank, two absolute groups were detected among all specimens, which further indicated that two valid species were present based on genetic differences in amino acid sequences and the distance between the groups. The sequences of Group 1 can be regarded as DNA barcoding of P. echinogaster. The correct morphological redescription and DNA barcoding of P. echinogaster are presented here to provide a guarantee for efficient and accurate studies, a theoretical basis for classification, and enable appropriate fishery management and conservation strategies for the genus Pampus in the future.
key words: morphological characteristics, DNA barcoding, Pampus echinogaster, genetic differentiation, transverse occipital canal

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