Cross-shelf Distribution of Summer Dinoflagellate Abundance in the East China Sea and Its Correlation to Environmental Factors

本研究於2002年七月兩度利用海洋研究船在橫跨東海陸棚之測線上調查渦鞭藻的種類組成與豐富度，目的在瞭解它們的地理分佈與影響分佈的環境因子。結果顯示渦鞭藻的豐富度大約在3.0至11.0 cells L^(-1)之間，相對高值均出現於沿岸與湧升流海域，尤其在七月底的大陸沿岸測站曾觀察到94.4 cells L^(-1)之高值。在種類組成方面，以Ceratium、Prorocentrum、與Protoperidinium等屬的種類最為常見。藉由相關分析比較優勢種間地理分佈之異同，並以類群分析(cluster analysis)進行歸納，發現東海渦鞭藻依分佈趨勢可分成三個群集：沿岸湧升群集是豐富度最高的群集，代表性的種類有C. furca及Prorocentrum micans等；外海群集以C. teres為代表，豐富度由黑潮向沿岸遞減；不規則群集則只包含極少的種類，它們的豐富度在兩個航次間差異很大。沿岸湧升群集的豐富度與硝酸鹽濃度呈正相關，分佈形態推測是由普遍存在的種類遇營養鹽充足供應時旺盛生長所造成。外海群集的豐富度與水溫呈正相關而與硝酸鹽濃度呈負相關，分佈形態推測是由生存於熱帶的種類經黑潮攜帶北上後，再與沿岸海水相互混台所造成。

關鍵字

大陸棚；渦鞭藻；東海；地理分佈；營養鹽；浮游植物；水溫

並列摘要

Two cruises were conducted to the East China Sea in July 2002 to investigate the cross-shelf distribution of pelagic dinoflagellates and its relationship to environmental factors. Samples for cell abundance and species composition were collected by oblique tows from 30 m depth to sea surface. In most cases, dinoflagellate abundance in the study area was between 3.0 and 11.0 cells L^(-1) with high values occurring at coastal and upwelling stations. The dinoflagellate community was dominated by species belonging to Ceratium, Prorocentrum, and Protoperidinium. A total of 3 dinoflagellate assemblages with characteristic distribution patterns were identified using the methods of correlation and cluster analysis. The Coastal-upwelling Assemblage was the numerically abundant group with C. furca and Prorocentrum micans as the representative species. In contrast, C. teres was the representative species in the Oceanic Assemblage, and cell abundance of this assemblage was high in Kuroshio but declines steadily toward the coastal zone. The Irregular Assemblage contained only a few species, and its distribution varied substantially between cruises. Correlation analysis between cell abundance and environmental factors, such as nutrient concentration and water temperature, indicated that Coastal-upwelling assemblage was composed of cosmopolitan species that grow actively in nutrient-rich regions. On the other hand, the majority of species in the Oceanic Assemblage are tropical in nature, and their high abundance in Kuroshio is probably a result of northward transportation mediated by current systems.

並列關鍵字

Continental shelf ； Dinoflagellates ； East China Sea ； Geographic distribution ； Nutrients ； Phytoplankton ； Water temperature

國際替代計量

Cross-shelf Distribution of Summer Dinoflagellate Abundance in the East China Sea and Its Correlation to Environmental Factors

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