Variabilities of the Sea Surface Height in the Kuril Basin of the Sea of Okhotsk: Coherent Shelf-Trapped Mode and Rossby Normal Modes

A time series analysis of the sea surface height anomaly (SSHa) was conducted in the Kuril Basin of the Sea of Okhotsk. The mapping of the satellite-derived SSHa data was optimized to mitigate the effects of sea ice on the SSHa field during winter and early spring. Complex empirical orthogonal functions (CEOFs) were then used to analyze the SSHa field, revealing that the first three modes account for 55% of the signal variance. Mode 1 mainly represents the coherent variability trapped over the shelves all along the coastal regions and the Kuril Islands. Both seasonal and interannual variations are strongly correlated with the alongshore wind stress and can be well explained by an arrested topographic wave. Mode 3 is a propagating mode that exhibits trains of southwestward-propagating, high-amplitude anomalies. One possible mechanism for this is first-mode baroclinic Rossby waves, whose energy propagates from the Kuril Straits toward the Kuril Basin. However, mode 3 can be better interpreted as barotropic Rossby normal modes generated in the deep Kuril Basin. Mode 2 is a standing mode that may encompass the baroclinic variability in the basin. The monthly mean of the SSHa in the Kuril Basin is primarily governed by variability in mode 1, with mode 2 contributing to a lesser extent, and mode 3 being insignificant.

Four new species of Careproctus (Cottoidei: Liparidae) from the deep-water vicinity of the southern Kuril Islands (Western North Pacific)

Four new species of Careproctus (Cottoidei: Liparidae) are described from the Bussol Strait (the deepest channel of the Kuril archipelago) and two neighboring abyssal basins of the Western North Pacific. Careproctus laperousei sp. nov. from the northern slope of the Kuril-Kamchatka Trench (depths of 4796–4803 m) has the following characters: vertebrae 57, pectoral-fin rays 26, principal caudal-fin rays 8 and pore pattern 2-6-7-1; it differs from the most similar congeners from the North Pacific in having a black peritoneum, short head (22.5 % of standard length, SL) and large disk (37.0 % of head length, lc). Careproctus brevipectoralis sp. nov. from the Kuril Basin of the Sea of Okhotsk (depths of 3301 m) has the following characters: vertebrae 55, pectoral-fin rays 26, caudal-fin rays 9, pore pattern 2-6-7-1 and peritoneum black; it differs from congeners by the absence of pleural ribs, deep and compressed leaf-like body (greatest depth 119 % lc, depth above anal-fin origin 113 % lc), small head (18 % SL), short pectoral fin (11 % SL) and cartilaginous-like tissue surrounding the dorsal fin. Careproctus pulcher sp. nov. and Careproctus globulus sp. nov., both having 46 vertebrae, are found on the Pacific side of the Bussol Strait at depths of 2350–2358 m. Careproctus pulcher sp. nov. is characterized by pectoral-fin rays 31–32, caudal-fin rays 10, pore pattern 2-6-7-1 and peritoneum pale; it differs from the most similar congeners in having a shorter head (25.5–26.3 % SL in adults) and gill opening reaching ventrally to 4th pectoral ray. Careproctus globulus sp. nov. has the following characters: pectoral-fin rays about 24, caudal-fin rays 8 and peritoneum black; it differs from other species in having a globular body, deep curve of vertebral column and pore pattern 2-5-6-1. Thus, based on these collections, the underwater sill of the Bussol Strait is inhabited by different species of Careproctus than the neighboring abyssal plains, Kuril-Kamchatka Trench and the Kuril Basin of the Sea of Okhotsk. Careproctus laperousei sp. nov. is the most deep-water Careproctus in the North Pacific.

Thoridae (Crustacea: Decapoda) can penetrate the Abyss: a new species of Lebbeus from the Sea of Okhotsk, representing the deepest record of the family

Lebbeus sokhobio sp. nov. is described from abyssal depths (3303−3366 m) in the Kuril Basin of the Sea of Okhotsk. The related congeners are deep-water dwellers with a very distant distribution and very similar morphology. The new species is separated by minor morphological features, such as the armature of the rostrum and telson, meral spinulation of ambulatory pereiopods and the shape of the pleonal pleurae. This species is the deepest dwelling representative of the genus Lebbeus and the family Thoridae. A list of records of caridean shrimps recorded from abyssal depths below 3000 m is given.