| 摘要: |
| 摘 要：巢湖是我国第五大淡水湖，也是全国重点治理的“三河三湖”之一，作为长江下游的重要湖泊对支撑安徽省生态文明建设和推动长江大保护具有重要意义。过去几十年随着流域社会经济的快速发展，巢湖生态系统受到了强烈的人为胁迫，导致水质恶化和蓝藻水华频繁。近十余年来，随着巢湖综合治理纵深推进，其水生态环境趋于改善，但富营养化程度依然严重，有关水生生物特别是底栖动物群落结构长期变化的认识仍较为匮乏。本文结合野外调查数据及历史资料，获得了1980年以来五个时期的底栖动物及环境因子数据。通过主成分分析、典范对应分析，探讨了近40多年来巢湖底栖动物密度、群落结构和优势类群的变化特征。研究结果表明，1980-2022年间，累计记录到3门6纲77种(属)的底栖动物，其总密度和各类群密度变化显著。优势种类经历了从较清洁的软体动物为主，逐渐转变为以耐污的摇蚊科和寡毛纲为主，再到清洁种缓慢恢复的变化过程。具体变化情况为：1980-1981年，底栖动物物种多样性高，软体动物为优势种；2002-2003年，富营养化加剧，底栖动物群落快速退化，耐污种寡毛纲和摇蚊科占据优势，密度占比达96.1%；2008-2009年，寡毛纲和摇蚊科总密度下降至87%；2013-2014年，摇蚊科密度增加，但寡毛纲密度占比从55.1%下降至24.1%，两者共占比96.5%；2022年，底栖动物密度下降至历史最低水平(278 ind/m2)，寡毛纲密度下降至6.9%，软体动物双壳纲从2013-2014年的2种增加到5种，国家二级保护动物中国淡水蛏在9个点位发现，出现频率为30%，底栖动物多样性得到明显恢复。近四十年来，水体总氮、叶绿素a、溶解氧、水深、沉积物总氮和风速是影响底栖动物群落结构演变的主要环境因子。 |
| 关键词: 大型底栖无脊椎动物 群落结构 长期演变 富营养化 浅水湖泊 敞水区 |
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| Succession of macrozoobenthic communities and its drivers in Lake Chaohu during the past 40 years* |
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feijiaojiao1, wenshuke2, dongrui2, zhangyao1, gongzhijun2, chenkaining2, caiyongjiu2, 项1
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1.Anhui Normal University;2.Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences
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| Abstract: |
| Abstract: Lake Chaohu is the fifth largest freshwater lake in China and one of the key areas for water pollution prevention in China. As an important lake in the lower reaches of the Yangtze River, it plays a crucial role in supporting ecological civilization development in Anhui Province and promoting Yangtze River protection. The rapid socio-economic development in the Lake Chaohu Basin has exerted significant anthropogenic pressure on the Lake Chaohu, resulting in water quality deterioration and frequent cyanobacteria algae blooms. In the past ten years, despite the improvement in the water quality owing to comprehensive management efforts, eutrophication remains a critical issue, and knowledge about the long-term changes in aquatic biological community structures is still limited, especially for benthic macroinvertebrate. This study combined field survey and historical records to obtain data on benthic fauna and environmental factors from five different periods since 1980. Using Principal Component Analysis (PCA), Canonical Correspondence Analysis (CCA), the study explored the changes in benthic fauna density, community structure, and dominant groups over the past 40 years in Lake Chaohu. The results showed that from 1980 to 2022, a total of 77 species (genera) from three phyla and six classes of benthic fauna were recorded, with significant changes in density of entire community and different taxonomic groups. The dominant species have experienced a transition from being primarily composed of cleaner mollusks to a gradual shift towards pollution-tolerant families such as midges and oligochaetes, followed by a slow recovery of cleaner species. The specific changes are as follows: in 1980-1981, species diversity was high, with mollusks being dominant; in 2002-2003, eutrophication intensified, and the benthic community rapidly degraded, with pollution-tolerant oligochaetes and chironomids larvae dominating, accounting for 96.1% of the density; in 2008-2009, the total density of oligochaetes and chironomid larvae decreased to 87%; in 2013-2014, chironomids density increased, but the proportion of oligochaetes density decreased from 55.1% to 24.1%, with both groups accounting for 96.5%; in 2022, the density of benthic fauna dropped to the lowest historical level (278 ind/m2), oligochaetes density decreased to 6.9%, and the number of bivalve mollusks increased from two species in 2013-2014 to five species, with the national protected species, the Novaculina chinensis being found at nine sites with an occurrence of 30%. indicating a recovery of biodiversity. Over the past 40 years, total nitrogen, chlorophyll-a, dissolved oxygen, water depth, sediment total nitrogen, and wind speed have been the main environmental factors influencing the succession of the benthic fauna community structure. |
| Key words: Benthic macroinvertebrate community structure long-term succession eutrophication shallow lakes open water area |
