土地利用和水环境因子对大型底栖动物次级生产力的影响:以东北地区连环湖为例

土地利用和水环境因子是影响湖泊生态系统的关键因素,探究大型底栖动物次级生产力受环境因子的作用机制,可揭示底栖动物栖息地的生态系统与外源环境的关系。为了解土地利用和水环境因子对大型底栖动物次级生产力的影响,2020年对连环湖13个主要湖泊的土地利用类型及6、8和10月的大型底栖动物、水环境因子进行调查,共采集到大型底栖动物75种,隶属于3门32科56属,其中优势种属及重要种属以摇蚊幼虫和腹足纲为主,前突摇蚊(Procladius sp.)为第一优势种。主成分分析表明,土地利用及水环境因子具备明显的时空梯度,而大型底栖动物次级生产力也存在明显的时空变化。春季、夏季、秋季次级生产力和P/B值分别为5.65、6.06、4.31 g/(m²·a)和2.74、2.55、2.40 a^-1,其中春季次级生产力集中于东北部湖区,龙虎泡集中于湖心区;夏季次级生产力逐渐向各湖区扩散,龙虎泡整体偏低;秋季次级生产力集中于西北部及东南部湖区,龙虎泡集中于东北部湖区。P/B值随季节的推移呈现由东部湖区向西部湖区逐渐递增的趋势,而龙虎泡始终集中于南部湖区。次级生产力和P/B值的结构分析表明,春季次级生产力主要由腹足纲构成,进入夏、秋季后以双壳纲对次级生产力的贡献最高。其中腹足纲、双壳纲、摇蚊幼虫和寡毛纲次级生产力主要集中于北部湖区、东南部湖区、中部湖区和龙虎泡,而甲壳纲仅出现于阿木塔泡。寡毛纲和双壳纲P/B 值随季节的推移逐渐降低,摇蚊幼虫和腹足纲P/B 值呈先升后降的趋势。通径分析表明,pH、人造地表和叶绿素a是影响年均大型底栖动物次级生产力的关键环境因子。典范对应分析表明,总磷和电导率是影响不同季节大型底栖动物次级生产力的重要环境变量。耕地、人造地表与总磷、电导率和悬浮物呈显著正相关,农业生产和城镇建设的增加是连环湖呈富营养化状态的重要原因,且此现象已对大型底栖动物次级生产力形成威胁。未来应通过控制农业面源污染、秸秆腐熟还田、鼓励粪便施肥、科学规划用地等措施改善连环湖流域的生态环境,以促进大型底栖动物资源合理的开发利用。

Effects of land use and aquatic environmental factors on secondary productivity of macroinvertebrates:A case of Lake Lianhuan Group, northeast China

Land use and water environment factors are the key factors which affecting lake ecosystems. Revealing the mechanisms how macroinvertebrates'' secondary productivity is influenced by environmental factors can understand the relationship between ecosystems and exogenous environments in macroinvertebrate habitats. To understand the effects of land use and aquatic environmental factors on the secondary productivity of macroinvertebrates, a survey of land use and macroinvertebrates, aquatic environmental factors in the 13 main lakes of Lake Lianhuan Group was carried out in June, August and October, 2020. A total of 75 macroinvertebrates species were collected, belonging to 56 genera and 32 families in 3 phyla, of which the dominant and important species were mainly larvae and gastropods, with Procladius sp. as the first dominant genus. Principal component analysis showed that land use and water environment factors had obvious temporal and spatial gradients, and macroinvertebrates secondary productivity also had obvious temporal and spatial variations. The secondary productivity and P/B ratio in spring, summer and autumn were 5.65, 6.06, 4.31 g/(m²·a) and 2.74, 2.55, 2.40 a^-1, respectively. In spring, secondary productivity was concentrated in the northeastern lakes and Lake Longhu was concentrated in the center of the lake; in summer, secondary productivity gradually spread to all lakes and Lake Longhu as a whole was low; in autumn, secondary productivity was concentrated in the northwestern and southeastern lakes and Lake Longhu was concentrated in the northeastern lakes. The P/B ratio showed an increasing trend from the eastern lake area to the western lake area with the passing of the season, while Lake Longhu was always concentrated in the southern lake area. The structural analysis of the secondary productivity and P/B ratio showed that the secondary productivity in spring was mainly composed of gastropods, and bivalves made the highest contribution to the secondary productivity in summer and autumn. The secondary productivity of gastropods mainly concentrated in the northern lakes; the secondary productivity of bivalves mainly concentrated in the southeastern lakes; the secondary productivity of chironomid larvae mainly concentrated in the central lake district; the secondary productivity of oligochaeta mainly concentrated in the Lake Longhu, while the crustacean only appeared in the Lake Amuta. The P/B ratio of oligochaeta and bivalve decreased gradually with the passing of the season, while the P/B ratio of chironomid larvae and gastropods increased first and then decreased. Path analysis showed that pH, artificial surface and chlorophyll-a were the key environmental factors affecting the secondary productivity of macroinvertebrates. Canonical correspondence analysis showed that total phosphorus and conductivity were important environmental variables affecting the secondary productivity of macroinvertebrates in different seasons. Arable and man-made surfaces were significantly and positively correlated with total phosphorus, conductivity and suspended matter, the increase in agricultural production and urban construction is an important reason for the eutrophication of the Lake Lianhuan Group, and this phenomenon has threatened the secondary productivity of macroinvertebrates. The ecological environment of the Lake Lianhuan Group watershed should be improved in the future through measures such as controlling agricultural surface pollution, returning straw to the land through decomposition, encouraging manure fertilization, and scientific land use planning, to promote the rational exploitation of macroinvertebrate resources.