Систематическое положение и распределение пелагических остракод рода Alacia (Ostracoda: Halocyprididae) в северной части тихого океана

• Main Authors: Чавтур, В., Ржаникова, М.
• Format: Text
• Language: unknown
• Published: Федеральное государственное унитарное предприятие «Тихоокеанский научно-исследовательский рыбохозяйственный центр» 2004
• Subjects: Bering Sea; Gulf of Alaska; Okhotsk; Pacific; Kamchatka; Subarctic; Alaska; Aleutian Islands
• Online Access: http://cyberleninka.ru/article/n/sistematicheskoe-polozhenie-i-raspredelenie-pelagicheskih-ostrakod-roda-alacia-ostracoda-halocyprididae-v-severnoy-chasti-tihogo; http://cyberleninka.ru/article_covers/6769604.png

Изучены материалы по остракодам многочисленных российских экспедиций в Северной Пацифике (севернее 300 с.ш.). Установлено систематическое положение и дана картина пространственного распределения видов рода Alacia (A. major and A. minor) в условиях вод субарктической и субтропической структур в диапазоне глубин 0-2500 м. Приведена определительная таблица и рисунки дифференциальных признаков видов рода Alacia Северной Пацифики. Extensive plankton materials on pelagic ostracods of the genus Alacia collected in 1932-1990 by numerous Russian expeditions in temperate latitudes of the North Pacific and adjacent subtropical waters (northward from 300 N) in depth range 0-2500 m are examined. Within the area, only two species belonged to this genus were identified: Alacia major (Rudjakov, 1962), nov. comb. and A. minor (McHardy, 1964) nov. comb. (key and morphological remarks are given). Their geographical and vertical distribution is described in detail. A. major is widely distributed in the North-West Pacific in the area between 340 and 620 N (including the Okhotsk and Bering Seas, but excluding the Japan Sea) at the depth range 0-2000 m. Its vertical distribution has been studied in the area of Kuril-Kamchatka Trench, where both its abundance and biomass are the greatest in 300-500 m layer and steadily declines below to a particularly abrupt decline at 750 m depth. The percentage contribution of A. major to halocyprid populations is relatively high: 50-70 % of their number and 85-95 % of their biomass in the samples collected in 300-750 m layer. In the North-East Pacific, it occurs from Aleutian Islands and Gulf of Alaska to 360 N at the depth 50-1500 m, with similar vertical distribution the greatest absolute and relative abundance at 300-500 m. However, it is absent there in surface layer (0-50 m) and below 1500 m. A. major is a component of boreal, oceanic and interzonal plankton communities. Generally, it is indicator of subarctic waters in the Pacific. Other species, A. minor, belongs to epipelagical and neritic group. Previously it was known for the area off Vancouver Island only, but we found it wider in Martin Arm Bay and Boca de Quadra Fjord. Probably, it inhabits also the southeastern Bering Sea. The distribution of this species is discussed.