東京湾産珪藻Cyclotella atomusの新変種, C. atomus var. marina

概要

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Cyclotella atomus var. marina var. nov., a small diatom that is abundant in nutrient-rich waters in Tokyo Bay (35°30'N, 139°50'E), is named and described. The new variety is a variety of C. atomus Hustedt, a cosmopolitan Cyclotella species that occurs mainly in fresh- to brackish-water (0-20 psu). Poorly developed costae are characteristic of the new variety. The new variety has no valve-face fultoportula, whereas C. atomus has one (and very occasionally two or nothing). The geographic variation in fluxes for the variety was calculated from sedimentation rates estimated from ^210Pb dates for 16 cores, in terms of valves/cm^2/year. The fluxes are high off the mouths of three major rivers flowing into the bay (3.7-6.6×10^7 valves/cm^2/year), with a conspicuous decrease toward the middle of the bay (0.1-1.5×10^7 valves/cm^2/year), suggesting the ecology of the new variety; it grows abundantly in waters of around 30 psu salinity, and is abundant in waters with higher nitrogen/phosphorus input from the catchment area of major rivers flowing into the northwestern part of the bay.
国立科学博物館の論文
2004-12-22