福建中部近海浮游动物数量分布与水团变化的关系

根据2009—2010年在福建中部近海24°55'—25°13'N、119°11'—119°32'E水域冬、春、夏3个季节的调查资料,探讨了该水域浮游动物总丰度与生物量的平面分布、季节变化及其与台湾海峡水团变化的关系。结果表明,调查水域浮游动物的数量在冬、春之交变化较大,而在春、夏季变化较小。浮游动物冬、春两季的平均丰度分别为8.90 个/m³和245.65 个/m³,夏季为236.82 个/m³。冬、春两季,该水域浮游动物的分布特征相近。其数量在近岸较高,向外侧水域逐渐降低。冬季浮游动物的丰度最高为31.56 个/m³,春季最高达到831.67 个/m³。中华哲水蚤(Calanus sinicus)是冬、春季影响总丰度变化最主要的种类。与冬、春季不同,夏季浮游动物的数量在离岸水域较高,丰度最高达1053.13 个/m³,而在近岸较低,最低值仅19.17 个/m³。汉森莹虾(Lucifer hanseni)、双生水母(Diphyes chamissonis)是影响总丰度变化最主要的种类。浮游动物在各季的不同分布特征与台湾海峡的季节性水团变化有关。受季风转换影响,从冬季到夏季,海峡内沿岸流势力逐渐减弱,台湾暖流水势力逐渐增强,并影响到沿岸的水文环境。这导致调查水域内浮游动物的优势种类由暖温种向暖水种演替。由于冬、春季的重要优势种类中华哲水蚤与夏季的汉森莹虾、双生水母具有不同的温度适应性,受不同性质水团的影响,在近岸和离岸水域各自呈现出不同的数量高低。从而进一步影响到各季浮游动物总数量的分布。

Relating the distribution of zooplankton abundance in the coastal waters of central Fujian Province to the seasonal variation of water masses

In three oceanographic surveys conducted in the coastal waters of central Fujian Province (24°55'-25°13' N, 119°11'-119°32' E) in December 2009 and April and August 2010, the abundance, biomass, horizontal distribution, and seasonal variation of zooplankton were investigated, and their relation to the seasonal variation of water masses in the Taiwan Strait was examined. The results showed that the numbers of zooplankton changed between winter and spring, but remained steady between spring and summer. In winter and spring, the zooplankton showed similar patterns of distribution, though the distribution pattern was different in summer. The average number of zooplankton was 8.90 ind./m³ in winter and 245.65 ind./m³ in spring. In these two seasons, the zooplankton were most abundant in nearshore waters and gradually diminished offshore. In summer, the average number of zooplankton was 236.82 ind./m³. The zooplankton abundance in nearshore waters was low, but the zooplankton were abundant in offshore waters. To ascertain which species made the greatest contribution to these distribution patterns, the regression contribution of each dominant species' abundance was computed. In winter and spring, Calanus sinicus was the species whose distribution determined the distribution of zooplankton abundance. In summer, Lucifer hanseni and Diphyes chamissonis exerted the greatest influence on the distribution of zooplankton abundance. As a warm-temperate species, Calanus sinicus usually prospers in low-temperature waters. By contrast, Lucifer hanseni and Diphyes chamissonis are warm-water species; they are usually abundant in high-temperature waters. The adaptability of these three species to water temperature is an important factor in determining the distribution patterns of zooplankton abundance in each season. However, the most important factor is the seasonal variation of the water masses in the Taiwan Strait. This variation leads to the seasonal alternation of the dominant species. In winter, the west side of the Taiwan Strait is controlled by China's coastal water, which has a low temperature. The dominant species in the investigated waters in winter were warm-temperate species like Calanus sinicus. In spring, as the northeast monsoon weakens, China's coastal water wanes and the Taiwan Warm Current becomes stronger. However, the west side of the Taiwan Strait is still controlled by China's coastal water so warm-temperate species are still dominant. In winter and spring, the offshore water has a relatively high temperature because of the Taiwan Warm Current. Correspondingly, in the offshore water Calanus sinicus had a low abundance. The greatest abundance of Calanus sinicus was in the nearshore water. In summer, the southwest monsoon begins and the Taiwan Warm Current dominates. The major species were mainly warm-water species, such as Lucifer hanseni and Diphyes chamissonis. In summer, the water is heavily stratified, and there is an upwelling of bottom water in the nearshore region of the western side of the strait. As a result, the water temperature in this region was the lowest. Accordingly, warm-water species such as Lucifer hanseni and Diphyes chamissonis, were less abundant in the nearshore water. The different distribution patterns of these important zooplankton species further influenced the total abundance and overall distribution patterns in different seasons.