水母暴发后的消亡对海水环境的影响

	水母暴发后的消亡对海水环境的影响
	曲长凤
学位类型	博士
导师	宋金明
	2015-05-12
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	环境科学
关键词	水母消亡环境变化生源要素氨基酸脂肪酸颗粒态物质水母
摘要	近年来，中国近海水母暴发频率逐年增加，水母暴发后的消亡对海洋生态环境有重大影响，探明其影响的效应和机制对预警和防治水母生态灾害意义重大。本学位论文聚焦水母消亡与水体环境耦合关系的研究，通过模拟实验阐明了水母消亡过程中水体不同形态碳氮磷的释放特征，揭示了水母消亡中碳氮磷的转化规律，诠释了水母消亡对海水环境的影响途径；阐明了水母消亡过程中水体颗粒态氨基酸与脂肪酸的变化特征，探讨了水母消亡释放的生源要素与氨基酸、脂肪酸的耦合关系；揭示了水母暴发前-暴发中-消亡三个阶段黄东海悬浮颗粒物中氮磷的组成、分布与季节变化特征，探讨了颗粒态生源要素对水母暴发/消亡的响应和对水母丰度的指示意义。获得的主要结果如下： 1. 揭示了水母消亡对生源要素的释放特征及对水体环境的影响机制，发现不同种类水母释放生源要素的浓度积累存在明显差异。水母消亡伴随的是一个生源要素快速释放的过程，水母消亡时碳、氮、磷的释放速率均在消亡初期最高，水母消亡释放的碳、氮、磷量远高于活体水母的排泄量，水母消亡可导致高碳、高氮负荷。水母消亡释放的溶解态物质远高于颗粒态，溶解态碳、氮、磷分别占总量的51.8 - 81.9%，86.0 - 97.9%，53.6 - 86.3%。水母消亡还可造成水体明显的酸化与低氧，但沉积物具有明显缓冲水体酸化与低氧的作用。水母消亡是持续快速的过程，不同种类水母的消亡存在差异，一般消亡时间为7 - 14天，消亡过程均有强烈臭味产生。水母释放的生源要素以溶解态为主。溶解有机碳（DOC）的最大净释放速率为103.77 ± 12.6 mg kg^-1 h^-1，释放量是活体水母的253 - 288倍。水母释放的溶解态氮以NH₄⁺为主，占总氮（TN）的72.2 - 75.2%；PO₄^3-与溶解有机磷（DOP）呈此消彼长的变化规律，分别占总磷（TP）的39.3 - 40.7%与34.9 - 43.1%。NH₄⁺与PO₄^3-的释放速率分别是活体水母的3 - 5与8 - 13倍。颗粒有机碳（POC）的最大净释放速率为1.52 ± 0.37 mg kg^-1 h^-1，且POC与DOC的释放速率呈极显著正相关。水母释放的颗粒态氮磷以颗粒有机氮（PON）与颗粒无机磷（PIP）为主，分别占总颗粒氮（TPN）与总颗粒磷（TPP）的73.9 - 95.2%与52.5 - 83.4%。水母消亡过程中TC/TN比（2.1 - 3.3）与DC/DN比（1.2 - 2.9）均小于Redfield比与水母组织中的C/N比（4.3 - 4.5）；TN/TP比（29.5 - 35.8）与DN/DP比（28.5 - 69.0）均大于Redfield比与水母组织中的N/P比（22）。水母消亡导致C/N比的减少与N/P比的增加，可导致水体中相对高碳、高氮、低磷环境的出现，造成碳、氮的高负荷，加重海水中碳、氮、磷的不平衡分布。水母消亡均可引发水体pH的降低与溶解氧（DO）的消耗，pH的降幅可达0.77 - 0.96个单位，最大耗氧量可达7378.9 - 5550.8 μmol kg^-1 d^-1。沉积物对水母消亡导致的pH与DO的变化具有一定的缓冲作用。 2. 探讨了水母消亡时颗粒态氨基酸与脂肪酸的释放特征，诠释了颗粒物中氨基酸、脂肪酸与碳、氮变化的耦合关系。水母释放的颗粒态氨基酸以中性氨基酸与酸性氨基酸为主，约占总氨基酸（TAA）的37%与23%；颗粒态脂肪酸以饱和脂肪酸（SFA）为主，约占总脂肪酸（TFA）的67.2% ± 10.9%。水母消亡使水体中的颗粒态氨基酸组成从基本氨基酸（组氨酸His、精氨酸Arg、赖氨酸Lys）向酸性氨基酸（谷氨酸Glu、天冬氨酸Asp）转变，颗粒态脂肪酸组成从SFA向单不饱和脂肪酸（MUFA）转变。颗粒态TAA与POC、PN均呈显著正相关，颗粒态TFA与POC呈显著正相关，说明水母释放的颗粒态氨基酸与脂肪酸可成为水体生物重要的碳源与氮源。水母消亡时释放颗粒态氨基酸的种类有17种，可补充水体与沉积物中缺失的氨基酸。谷氨酸与天冬氨酸的释放比例较大，分别占TAA的10.7 - 17.2%与8.8 - 13.9%，谷氨酸、天冬氨酸与甘氨酸（Gly）是影响总氨基酸趋势的主要氨基酸种类。水母消亡使水体颗粒物中酸性氨基酸（天冬氨酸，谷氨酸）的比重增加了23%，是导致水体pH降低的原因之一。另外，TAA含量与POC、PN均呈显著正相关，说明水母释放的氨基酸是重要的颗粒态碳、氮来源。水母消亡释放的颗粒态脂肪酸有12种，SFA 是水母消亡时颗粒态脂肪酸的主要成分，占TFA的57.6 - 87.4%。SFA比例的减小与MUFA比例的增加说明水母消亡使水体中的脂肪酸组成从SFA向MUFA的转变。软脂酸（16:0）与硬脂酸（18:0）是SFA的主要组成成分，约占TFA的25.2 - 42.9%与15.0 - 40.9%；软油酸（16:1ω9）是MUFA的优势成分，约占2.7 - 17.6%；多不饱和脂肪酸（PUFA）则主要以亚油酸（18:2ω6）为主，约占1.2 - 1.8%。细菌型脂肪酸BFA（15:0、ISO14:0与18:1ω7）与真菌型脂肪酸FFA（18:1ω9 与18:2ω6）的增加，说明水母消亡时微生物的增加。对单体脂肪酸来说，除16:1ω9、18:1ω7、20:0外，其他脂肪酸均与POC呈显著相关，说明颗粒态脂肪酸是POC的重要来源。氨基酸与脂肪酸的释放增加了碳、氮的聚集，脂肪酸的减少、氨基酸的增加以及C/N比的减小，说明水母消亡使水体中颗粒物从富碳向富氮的转变。 3. 获取了水母暴发前-暴发中-消亡三个阶段黄东海水体颗粒氮、磷的时空变化特征，发现颗粒有机氮（PON）与颗粒无机磷（PIP）是颗粒态氮、磷的优势成分，分别占总颗粒氮（TPN）与总颗粒磷（TPP）的75.7%与67.0%。颗粒态氮、磷高值区的分布主要受江苏沿岸流、长江冲淡水的影响，并与浮游植物及水母的季节变化有关。由于水母消亡的影响，秋季底层颗粒态氮、磷浓度高于其他季节，水母消亡时TPN与TPP输入约为总输入量的15.3%与4.5%，PIN、PIP、PON、POP的输入为总输入量的92.1%、51.3%、12.5%、7.2%，说明水母消亡期颗粒态氮、磷的释放对底层水体中颗粒态氮、磷的输入有重要贡献。黄东海的颗粒态氮主要以PON形式存在，比例远大于颗粒态无机氮（PIN），约占TPN的72.5 - 77.6%，相反，颗粒态无机磷（PIP）的比例略大于POP，约占TPP的66.3 -67.8%，这与水母消亡时释放颗粒态氮、磷的比例一致。从夏季到秋季，颗粒态氮、磷的高值区从江苏沿岸向长江口转移，江苏沿岸流与长江颗粒态物质的输入是颗粒态氮、磷的主要来源。春末夏初，江苏沿岸流输入是颗粒态磷的主要来源，浮游植物是PIN的主要来源，江苏沿岸径流携带黄河三角洲再悬浮泥沙的输入是底层高值区集中在江苏沿岸以及PIP与POP集中在28.5 - 34°N陆架边缘的主要原因，此时为水母生长初期，丰度较小，对颗粒态氮磷的影响较小。夏季末，颗粒态氮、磷高值区南移到长江口附近，低值区位于东北部外海区域，造成高值区南移的主要原因是夏季长江入海径流量的增加，长江输入是近岸颗粒物的主要来源。表层水体受长江冲淡水的影响，高值区集中在长江口附近区域，底层则仍集中在江苏沿岸至长江口区域，呈略微南移。8月份的颗粒态氮、磷含量略高于6月份，除去受长江冲淡水与江苏沿岸流影响外，还受海洋生物活动的影响，除浮游植物外，8月份是沙海蜇生长旺盛时期，平均生物量为12140 kg km^-2，水母排泄颗粒物是颗粒态氮、磷的来源之一。秋季，长江径流量减小，对颗粒物的输入也相对减小，长江口相邻区域表层颗粒态氮、磷浓度均有所降低，但由于长江与杭州湾携带泥沙在近岸迅速沉降，导致长江口附近底层颗粒态氮、磷的浓度有所增加。秋季的初级生产力下降，浮游植物输入的颗粒态氮、磷减少，但秋季底层PON、PIP、POP的含量整体高于其他季节，且水母丰度大的断面底层颗粒态氮、磷含量高于丰度小的断面。秋季黄东海沙海蜇的最大生物量可达2.0 × 10⁵ kg km^-2，此时沙海蜇消亡可达到的TPN、TPP、PON、POP的释放量分别为2.83 mg m^-2 d^-1、0.67 mg m^-2 d^-1、2.06 mg m^-2 d^-1、0.19 mg m^-2 d^-1，约为颗粒态总输入量的15.3%、4.5%、12.5%、7.2%，可见水母消亡期颗粒态氮、磷的释放对底层水体中颗粒态氮、磷的输入有重要贡献。
其他摘要	In recent years, the jellyfish population increased has been reported in China marginal seas. Decomposition of jellyfish blooms has large influence on marine eco-environments. The study on effect and mechanism of jellyfish decomposition shows great significance for early warning and prevention of the ecological disaster caused by jellyfish bloom. This paper focused on the decomposition of jellyfish and its relationship coupling with marine environment. We illustrated the release and transformation characteristics of different forms of carbon (C), nitrogen (N) and phosphorus (P) in water column during jellyfish decomposing by simulation experiments, and clarified the pathway of jellyfish decomposition on marine environment. We also expounded the variation characteristics of amino acids and fatty acids in suspended particulate matters from jellyfish decomposition and discussed the coupling relationship between them and the biogenic elements. On this basis, we investigated the composition, distribution and variation of particulate nitrogen and phosphorus during three growth stages of jellyfish (the period before bloom, during bloom and during decomposition) in Yellow Sea and East China Sea, explored the response of particulate biogenic elements to jellyfish decomposition after bloom, and discussed the indicative significance of particulate biogenic elements for jellyfish abundance. Major results and conclusions are as following: 1. The release characteristics of biogenic elements during jellyfish decomposing and its influence on water environment were revealed. The accumulation of released biogenic elements varied between different jellyfish species. The results showed that jellyfish decomposed with the rapid release of biogenic elements. The release rate of C, N and P reached the maximum at the beginning of decomposing. The concentrations of dissolved matters released by jellyfish decomposition were much greater than that of particulate matters, and the dissolved C, N and P accounted for 51.8 - 81.9%, 86.0 - 97.9% and 53.6 - 86.3% of total amount respectively. Furthermore, the quantity of C, N, and P released by dead jellyfish was much greater than that excreted by living jellyfish. Jellyfish decomposition resulted in high C and N loads. In addition, jellyfish decomposition led to relative acidification and hypoxia/anoxia. However, sediments can relieve the changes of pH and oxygen caused by jellyfish decomposition. Jellyfish decomposition was a continuous and rapid process, which varied with jellyfish species. The times of jellyfish decomposition were 7 days for Nemopilema nomurai and 14 days for Cyanea nozakii, with a foul stench throughout the whole incubation time. The biogenic elements released by jellyfish were dominated by dissolved ones. The net release rates of dissolved organic carbon (DOC) reached a maximum value of 103.77 ± 12.6 mg kg^-1 h^-1, and the concentration of DOC released by dead jellyfish was 253 - 288 times greater than that excreted by living jellyfish. NH₄⁺ occurred predominantly for dissolved N, accounting for 72.2 - 75.2% of total nitrogen (TN), whereas PO₄^3- increased with the decrease of dissolved organic phosphorus (DOP), accounting for 39.3 - 40.7% and 34.9 - 43.1%, respectively. The release rate of NH₄⁺ and PO₄^3- was 3 - 5 and 8 - 13 times higher than that of living jellyfish. As for particulate matters, the net release rate of particulate organic carbon (POC) attained the maximum of 1.52 ± 0.37 mg kg^-1h^-1 and it had a significant positive correlation with DOC. Particulate organic nitrogen (PON) and inorganic phosphorus (PIP) was the major component of particulate N and P, accounting for 73.9 - 95.2% of total particulate nitrogen (TPN) and 52.5 - 83.4% of total particulate phosphorus (TPP). During jellyfish decomposing, the TC/TN ratios and DC/DN ratios were lower than the Redfield ratios and the C/N ratios of jellyfish tissues (4.3 - 4.5), with the ranges of 2.1 - 3.3 and 1.2 - 2.9, whereas the TN/TP ratios and DN/DP ratios were higher than the Redfield ratios and N/P ratios of jellyfish tissues (22), with the ranges of 29.5 - 35.8 and 28.5 - 69.0. The decrease of C/N ratios and increase of N/P owing to jellyfish decomposition resulted in the relative high C, high N and low P, which aggravated the unbalance of C, N and P in China marginal seas. Additionally, the study demonstrated that jellyfish decomposition led to the decrease of pH and the consumption of dissolved oxygen (DO), with the drop of 0.77 - 0.96 units for pH and the maximum DO consumption of 7378.9 - 5550.8 μmol kg^-1 d^-1. The sediments were beneficial to recover from acidification and hypoxia/anoxia and had buffer action to the change of seawater environment. 2. The release characteristics of amino acids (AA) and fatty acids (FA) in particulate matters during jellyfish decomposing were observed, and the coupling relationships between AA/FA and biogenic elements of particulate matters were explained. Particulate AA in greater quantity during decomposing process were neutral AA and acidic AA, accounting for 37% and 23% of total amino acids (TAA), while particulate FA were dominated by saturated fatty acid (SFA), constituting 67.2% ± 10.9% of total fatty acids (TFA). The study suggested that particulate AA composition changed from predominant basic AA including arginine (Arg) and histidine (His) to more acidic AA including aspartic acid (Asp) and glutamic acid (Glu), while particulate FA composition changed from predominant SFA to more monounsaturated fatty acids (MUFA). Furthermore, TAA had a significant correlation with POC and PON, whilst TFA significantly correlated with POC, indicating that particulate AA and FA released by dead jellyfish were principal sources of organic C and N for aquatic organism. 17 AA were detected in particulate matters during jellyfish decomposing，which can compensated the deficiencies of AA in marine water and sediment. The highest percentage of TAA was observed for glutamic acid, which contributed 10.7 - 17.2% of TAA, then followed by aspartic acid, which accounted for 8.8 - 13.9%. The glutamic acid, aspartic acid and glycine (Gly) were always found among the main AA which determined the overall trend of TAA. The acidic AA (Glu + Asp) in particulate matters increased by 23% owing to the addition of jellyfish, which may resulted in the decreased of pH in water column. In addition, a significantly positive correlation with TAA for POC and PN was observed, and it suggested that AA were important sources of POC and PN. 12 FA were detected in particulate matters during jellyfish decomposing. SFA were the most abundant FA in particulate matter, which accounted for 57.6 - 83.3% of TFA. The decline of proportion of SFA and increase of MUFA in particulate matters indicated that the FA composition changed from predominant SFA to more MUFA as jellyfish decomposed. Palmitic acid (16:0) and stearic acid (18:0) dominated the SFA with values ranging between 25.2% and 42.9% and between 15.0% and 40.9% of TFA, respectively, while palmitoleic acid (16:1ω9) dominated in MUFA groups with values ranging from 2.7% to 17.6% and PUFA were mostly rich in linoleic acid (18:2ω6), which ranged from 1.2% to 1.8%. The increase of bacterial fatty acids (BFA) including ISO14:0, 15:0 and 18:1ω7 and the fungal fatty acids (FFA) including 18:1ω9 and 18:2ω6 in particulate matters represented the significant increase of bacterial and fungal population. Most of individual FA, with the exception of 16:1ω9, 18:1ω7 and 20:0, were significantly correlated with POC, therefore, it suggested that FA may be the important sources of POC. The release of AA and FA contributed to the accumulation of C and N. The increase of AA and the decline of FA combined decrease of C/N during jellyfish decomposing indicated that jellyfish decomposition made the particulate matters of seawater transform from C-rich to N-rich. 3. The temporal and spatial variation of particulate nitrogen and phosphorus in Yellow Sea (YS) and East China Sea (ESC) during three phases (jellyfish pre-bloom phase, jellyfish boom phase and jellyfish decomposing phase) were analyzed. The results showed that particulate organic nitrogen (PON) and particulate inorganic phosphorus (PIP) were the major constitutions of total particulate nitrogen (TPN) and phosphorus (TPP), occupied 75.7% of TPN and 67.0% of TPP, respectively. The distribution of high concentrations of particulate nitrogen and phosphorus were under direct control of Jiangsu coastal current and Yangtze diluted water, which also related with the seasonal variation of phytoplankton and jellyfish population. The concentrations of particulate nitrogen and phosphorus of bottom water in autumn was higher than that in other seasons due to jellyfish decomposition (mainly Nemopilema nomurai). The input of TPN and TPP during jellyfish decomposing accounted for 15.3% of total input of particulate nitrogen and 4.5% of the total particulate phosphorus, while the input of PIN, PIP, PON, and POP accounted for approximate 92.1%, 51.3%, 12.5% and 7.2%. It indicated that jellyfish decomposition contributed to the input of particulate nitrogen and phosphorus to bottom water. In Yellow Sea and East China Sea, particulate nitrogen was dominated by PON, accounting for 72.5 - 77.6% of TPN, while PIP was the major components of particulate phosphorus, accounting for 66.3 - 67.8%, which was in accordance with that of jellyfish decomposition. The distribution of particulate nitrogen and phosphorus illustrated that Jiangsu costal current and Yangtze River were the main sources of particulate matters. The high value area of particulate nitrogen and phosphorus transferred from Jiangsu coastal area to Yangtze estuary from summer to autumn. In early summer, Jiangsu coastal current input was the main source of particulate phosphorus, while PIN was from phytoplankton input. The high value of PIP and POP concentrated in continental shelf margin waters of 28.5 - 34 ^oN due to the input of resuspended sediment taken by Jiangsu coastal current from Yellow River delta. Jellyfish had little influence on particulate matter in early growth period. In later summer, the high value area transferred into Yangtze estuary due to the increase of Yangtze River runoff, while low value area occurred in offshore. The sediments from Yangtze River were the major sources of particulate matters of inshore, so the particulate nitrogen and phosphorus were mainly from terrestrial input. The high value area of surface water was found in Yangtze estuary and adjacent area, while the high value area of bottom water still occurred in Jiangsu coastal area and Yangtze estuary. The concentrations of particulate nitrogen and phosphorus in August were higher than that in June, which affected by marine organism including phytoplankton and jellyfish. The average biomass of Nemopilema nomurai in August reached 12140 kg km^-2, and the excretion of jellyfish was one of the sources of particulate matters. In autumn, the content of particulate nitrogen and phosphorus of surface water in Yangtze estuary and adjacent area decreased owing to the reduce of discharge of Yangtze River, but the content in bottom water increased due to the sink of sediments. Furthermore, the reduction of primary production in autumn resulted in the decrease the input of particulate nitrogen and phosphorus from phytoplankton. However, the contents of PON, PIP and POP in bottom water in autumn were higher than that in other seasons and the contents in transect with abundant jellyfish were higher than that in transect of less jellyfish. The maximum biomass of Nemopilema nomurai reached 2.0 × 10⁵ kg km^-2 in autumn, on the basis of that, we calculated the release rate of TPN, TPP, PON and POP of Nemopilema nomurai, which was equivalent to 2.83 mg m^-2 d^-1, 0.67 mg m^-2 d^-1, 2.06 mg m^-2 d^-1 and 0.19 mg m^-2 d^-1. Therefore, we can evaluate the contribution of jellyfish decomposition to particulate nitrogen and phosphorus in YS and ECS. The results showed that Nemopilema nomurai decomposition could supply about 15.3% of TPN, 4.5% of TPP, 12.5% of PON and 7.2% of POP in YS and ECS, indicating the important contribution of jellyfish decomposition to particulate nitrogen and phosphorus in bottom water in YS and ECS system.
学科领域	海洋生态与环境科学
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/23253
专题	海洋生态与环境科学重点实验室
作者单位	中国科学院海洋研究所
第一作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	曲长凤. 水母暴发后的消亡对海水环境的影响[D]. 北京. 中国科学院大学,2015.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
曲长凤论文-最终版+原创声明.pdf（15584KB）	学位论文		限制开放	ODC PDDL	浏览