黄东海胶质浮游动物水母类研究

IOCAS-IR > 海洋环流与波动重点实验室

	黄东海胶质浮游动物水母类研究
其他题名	Medusas in the Yellow Sea and East China Sea
	张芳
学位类型	博士
	2008-06-05
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	大型水母小型水母水母暴发沙海蜇霞水母生活史生物量丰度摄食压力
摘要	近年来，胶质类浮游动物尤其是水母类在近岸高生产力的海洋生态系统中的作用越来越受到全球科学家们的关注。这种关注很大程度上是由于近年来很多海域或海湾出现水母类大量繁殖的现象而引起的，这种现象与过度捕捞、气候变化、富营养化以及生物入侵等因素有着内在的联系，给人们带来经济，社会和生态等各方面的损失。这种损失包括：当水母大量出现时，由于它们与鱼类存在食物和捕食竞争，使渔业资源和渔业生产锐减；由于它们会堵塞和撕破渔业生产网，干扰了人们的渔业生产活动；另外水母增多增加了海滨游泳爱好者被蛰伤甚至死亡事件发生的频率，对旅游者们的娱乐行为造成不便。到目前为止全球范围内报道了许多水母大量繁殖并对经济社会或海洋生态系统造成负面影响的事件。在北海水母数量爆发的频率与气候相关的事实表明了该海域将要面临一个更多的胶质类浮游动物的未来。所有这些都表明海洋中水母的生态学问题仍旧是全球的一个研究热点。到目前为止，在世界上许多海湾和海区有关水母生态学问题的研究上，均已取得方方面面有意义的进展。但在我国，由于对水母功能群的研究缺乏足够的重视，对于大型水母来讲它们被认为是渔业生产的副产品或者‘垃圾’，在渔业拖网捕获后把它们直接扔入海中并不去研究；对于小型水母来讲，因为它们为非饵料生物，并且有易碎，粘糊糊等难操作的特点，对浮游生物网同步采集到的水母的研究力度远不如对其他浮游动物类群的研究力度，因此我国对水母功能群生态学的研究基础相当薄弱。本论文基于以上背景对黄东海大型和小型水母类的生物地理分布格局进行了研究，对其生物量或丰度等生态学指标进行了定量研究。（1）利用浮游生物网样品对黄海小型水母类的种类组成及其丰度的时空变化进行了研究，表明黄海测区内小型水母整体丰度很低，且主要分布在50 m等深线以浅海域，各水母类群以及优势种类的季节更替非常明显。比较不同海区的小型水母的丰度水平及其占浮游动物丰度的比例，发现黄海的小型水母丰度水平最低，为0.8（0.04–1.3）ind. m-3，只占浮游动物丰度的 < 0.5 %，表明小型水母在黄海海域并非占优势的功能群。（2）在中国黄东海采集的沙海蜇和在日本采集的越前水母的COI基因序列差异（0.2%）处于种内水平，从分子水平上证明两者为同一个种类，基于形态学和分子生物学的证据，我国大型水母沙海蜇的分类地位可初步订正为：Nemopilema nomurai Kishinouye, 1922（Scyphozoa：Rhizostomeae：Rhizostomatidae）。（3）利用渔业底层拖网的方法对黄东海大型水母的种类组成，总生物量及各优势种类生物量的时空分布进行了半定量研究。结果共鉴定到11个种（类），其中沙海蜇（Nemopilema nomurai），洋须水母（Ulmaridae genus sp.）以及多管水母（Aequorea spp.）为黄海的优势种（类），沙海蜇（只在东海北部）和霞水母（Cyanea spp.）为东海的优势种（类）；这四个种（类）的湿重随着伞径的增大成冪增长的方式。大型水母平均总生物量的季节变化模式为：3月份水母总生物量最低，为4.6 ± 9.4 kg km–2，春夏季随着海水表层温度的升高，大型水母的生物量逐渐增加，9月初水母的总生物量达到最高值，为22891 ± 25888 kg km–2，随后随着海水的温度下降，生物量也逐渐下降。洋须水母的生物量在10月份达到最高值（2780 ind. km–2，1807 kg km–2），主要在黄海中部出现。多管水母在5月份丰度最高，为8262 kg km–2，且主要分布在30N以北海域。聚焦大量爆发的水母种（类）沙海蜇和霞水母，基于实测的拖网资料，提供了该种可见的浮游阶段1周年的地理发生和生物量数据；结果表明，这两个种（类）表现了不同的季节出现和生物量格局：首先是黄海出现的沙海蜇（5–12月在黄海出现），5月份少量幼水母体在黄东海的交界处出现，6月它们的分布范围在南黄海扩大，到8月末及9月初沙海蜇几乎遍布黄海，其生物量和丰度以压倒其他大型水母类的优势形成“bloom”（生物量占所有大型水母的96.7%，丰度占93%，在南黄海平均生物量20446 kg km-2，平均占渔获物生物量的86.1 %），10月份至12月，沙海蜇的生物量逐渐减少甚至为零，其分布区域也向北回缩。其次为东海出现的霞水母（5月–10月）：霞水母在5月初达到生物量的高值（平均生物量为380 kg km-2），其伞径随纬度的升高而变小，8月至10月其生物量骤然下降。这两个种类的生物量高值分布在温度或潮汐锋区。结合水文条件及沙海蜇和霞水母关键的生活史策略推测了黄东海该种浮游阶段的生活史模型。最后，通过对黄海8、9月份沙海蜇生物量的最高峰或暴发时期的呼吸率，摄食率进行估算，获得其每天对浮游动物现存量及生产力的潜在摄食压力，结果表明2006年9月在对沙海蜇最大捕获率的情况下，沙海蜇的摄食率为8.37（0.12–37.83）mg C m-2d-1，假设都以浮游动物为食，这时每天对浮游动物现存量及生产力的摄食压力分别为11.2%（0.17–50.6%），134.1%（1.98–605.7%）。因此在沙海蜇暴发期间对浮游动物的潜在的消耗非常大，甚至为毁灭性的。
其他摘要	In recent years, the ecological role of gelatinous zooplankton especially jellyfish and ctenophore within coastal marine ecosystems with high production has been increasingly concerned globally. This attention is largely a result of forming jellyfish and ctenophore blooms that may intrinsically be linked to over-fishing, eutrophication, climate change, and species invasions. Usually the nuisance blooms cause enormous ecological, economic and societal losses, e.g. diminishing the fish standing stock and commercial harvest due to potential food competitor or predator, hampering fishing activities by clogging and bursting trawl nets, and making swimmer or tourists stung and inconvenient in the beach. So far many cases of jellyfish bloom events affecting negatively to economies or ecosystem have been reported worldwide. Furthermore, it was thought for the North Sea that climate-related increases in jellyfish frequency suggested a more gelatinous future. All about that are suggesting this issue remain to be hotspot. By far various and significant advances on this theme have been made in many sea areas; however, the baseline knowledge of this issue such as ecology and biogeography of large jellyfish except species names was almost ignorant in coastal China Sea among East Asian waters. Because of lack of enough attention to medusas from scientists, basic studies on jellyfish functional group are very weak in our country. Large jellyfishes are usually not studied but directly thrown out to the sea considering as nuisance when they are collected in the trawl. The same status with large ones, not forage, slimy, frangible and hard to process, small medusas are usually ignored for study compared with other forage zooplankton. Based on background mentioned above, this thesis focus on the basic information on seasonal geographical distribution of medusas including large and small size, and qualify ecological indexes such as biomass or abundance in the Yellow Sea and East China Sea. This study, as a fundamental knowledge, may be helpful to describe problems with the causes and effects of jellyfish blooms in the YS and ECS There are some results: Temporal and spatial variation of species composition and abundance of small medusas in the Yellow Sea are studied using samples collected vertically by zooplankton net. Total abundance of small medusas is generally low in the Yellow Sea area. Small medusa mainly distributed the shallower water than 50m Isobath. Seasonal replacement of medusas classes such as hydromedusae, siphonophores and ctenophores, and dominant taxon are extremely apparent. Comparing abundance level and percentage of small medusas occupied total zooplankton abundance among several sea areas, we found that the abundance (0.8 (0.04–1.3) ind. m-3) and percentage (< 0.5 %) of small medusas in the Yellow Sea were all lowest, which indicate that small medusas are not dominant assemblage among zooplankton functional groups The difference of COI gene series is small (0.2%) between Stomolophus meleagris L. Agassiz, 1862 collected from China coastal sea and Nemopilema nomurai Kishinouye, 1922 collected from Japan Sea, which is species level. This result preliminarily indicates these two samples are same species. So the taxonomy position of S. meleagris collected from China coastal sea may change into N. nomurai (Scyphozoa：Rhizostomeae：Rhizostomatidae). Semi-qualification on seasonal geographical distribution of biomass/ abundance of large jellyfish in the Yellow Sea and East China Sea are studied, based on swept area method by bottom trawl surveys and surface investigation cruise. 11 taxon are identified, among them N. nomurai, Aequorea spp., Ulmaridae genus sp. are dominant taxon in the Yellow Sea, comparatively, N. nomurai and Cyanea spp., in the East China Sea. Wet weight of these four jellyfish taxon increase exponentially with the bell diameter. The seasonal pattern of total biomass of large jellyfish is: The total biomass is lowest (4.6 ± 9.4 kg km–2) in March when the surface temperature is also lowest during one year; they increase with the increasing temperature. The biomass reach to the highest (22891 ± 25888 kg km–2), and then they will decrease with the drop of temperature. The biomass of Ulmaridae genus sp., species preferring cold temperature, is up to the highest (2780 ind. km–2, 1807 kg km–2) in October, and they mainly distributed in the middle part of the Yellow Sea. N. nomurai and Aequorea spp. usually adapt themselves in cold waters. The biomass of Aequorea spp. is highest in May (8262 kg km–2), and this species mainly distributed northern part of 30N. Based on the in situ bottom trawl data, seasonal geographical occurrence and distribution of pelagic life stages of N. nomurai and Cyanea spp., bloom forming jellyfish, are studied. Two different patterns of seasonal occurrence and biomass are found: (1) the occurring N. nomurai in the YS (May–December), in May very few young medusas of this species appear at the junction of the YS and ECS; in June they began to expand distribution area in the southern YS; up to August and early September medusas are widespread throughout the YS, and form bloom with overwhelming other gelatinous species (Average biomass is 20446 kg km–2, and averagely account for 86.1 % of the total catch); and then the biomass and distribution area of them gradually shrink from October to December, even decrease to zero in the later month. (2) The appearing Cyanea spp. in ECS (May–October). The biomass of this species reach the maximum in May (Average biomass: 380 kg km–2) and early June; they decrease in August and later month. The high density of these two species distribute in the tidal front or temperature front area. Combining hydrographic condition and fishery data, distributional pattern and life cycle of N. nomurai and Cyanea spp. are discussed and speculated. At last, we acquire the potential feeding pressure of collective N. nomurai on standing stock and production of zooplankton per day, through estimating respiration rate and feeding rate of this species during blooming period. Results indicate that the feeding rate is 8.37 (0.12–37.83) mg C m-2 d-1 in September, 2006, the blooming time, assuming the capture rate of the bottom trawl is 0.1. The feeding pressure of collective N. nomurai on standing stock and production of zooplankton is 11.2% (0.17-50.6%), 134.1% (1.98-605.7%), respectively, assuming food requirement are all zooplankton. So the potential depletion of N. nomurai is very large, even destructive when they are blooming.
页数	130
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/915
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	张芳. 黄东海胶质浮游动物水母类研究[D]. 海洋研究所. 中国科学院海洋研究所,2008.

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