Seasonal variation in habitat use by marsh fishes

Abstract— We used I-m² throw traps to examine habitat use by smallsized fishes within a mosaic of wet prairies and sloughs in the headwaters of the St. Johns River, Florida between August 1992 and November 1995. Estimates of total fish density and biomass varied temporally, but did not differ significantly between habitats. Patterns of habitat use, however, differed among the five numerically dominant species. Bluefin killifish, mosquitofish, and golden topminnows were more abundant in sloughs than in wet prairies. In contrast, Everglades pygmy sunfish were more abundant in wet prairies than in sloughs. Finally, the abundance of least killifish did not differ between habitats. Fish densities were positively correlated with plant biomass (i. e., habitat complexity) and negatively correlated with water depth (i. e., hydrology). Species richness and composition were similar among habitats. However, consistent differences in the relative abundance of numerically dominant species between habitats indicated some degree of habitat-specific assemblage structure. Most species were concentrated into deeper sloughs during drying events. This assemblage of small-sized fishes appears to respond relatively rapidly to changes in habitat structure and hydrologic conditions. We therefore recommend that resource managers consider using fishes as indicator taxa to evaluate the efficacy of ongoing restoration and management efforts in wetland systems.     

造纸废水灌溉对湿地土壤和芦苇中总磷迁移的影响

在沈阳农业大学综合试验场内构建小试装置模拟辽河口天然芦苇湿地,对不同生育期湿地土壤和芦苇总磷含量的变化进行研究,分析废水灌溉条件下湿地土壤总磷的迁移特征。结果表明:不同废水质量浓度灌溉条件下,随着土层深度增加,土壤总磷含量变化趋势基本相同,在5~10cm土层中总磷含量最高。废水灌溉组土壤总磷含量在土层剖面分布规律为0~55~1020~4040~6010~20cm。废水质量浓度为300mg/L处理的土壤总磷含量变化量最大,175mg/L处理最小。芦苇总磷含量随生长期变化趋势为成熟期拔节期抽穗期展叶期发芽期。灌溉组芦苇中总磷含量高于对照组,总磷含量在芦苇内的分布特征为:茎叶根穗。相关性分析表明,土壤总磷、总氮、有机质及芦苇总磷呈极显著正相关关系,总磷与pH相关不显著。     

Linking vegetation patterns,wetlands conservation,and ecosystem services provision: From publication to application

1. Natural wetlands emerge as the best sites to preserve the diversity of aquatic and riparian vegetation; however, especially in the lowlands, pristine wetlands and aquatic ecosystems have almost completely disappeared through land reclamation and agricultural development. Actions are needed, therefore, to maintain and recreate a wide network of wetlands able to preserve adequate levels of vegetation diversity.
2. Focusing on a complex wetland system located in an overexploited plain, the article entitled ‘The importance of being natural in a human‐altered riverscape: Role of wetland type in supporting habitat heterogeneity and the functional diversity of vegetation’, published in 2016 in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) explored the role of wetland origin and hydrology as the main drivers of physical and vegetation functional diversity, following a hierarchical sampling approach.
3. The main results reinforced the key contribution of natural sites in maintaining vegetation diversity in heavily impaired riverine contexts, suggesting a direct effect of the interannual and seasonal dynamics of water‐level variations in the observed vegetation patterns.
4. The article offered an important contribution to our knowledge of vegetation patterns in wetlands, partly attributed to the innovative functional, hierarchical approach applied which is able to guarantee reliable data on the distribution patterns of physical heterogeneity and wetland vegetation.
5. The findings of the article have been applied and adopted in a series of technical handbooks designed, inter alia, to support the monitoring programmes of habitats of community interest or vegetation of relevance for aquatic biodiversity conservation. In addition, this article has helped to raise awareness of the essential roles played by wetlands in agricultural landscapes and has emphasized the need for a better synergy between the European Habitats Directive and the Water Framework Directive. Several ecological recovery projects have been funded in line with the results described in the AQC article.

     

Drivers of biodiversity loss in freshwater environments: A bibliometric analysis of the recent literature

1. Species are disappearing at a rate comparable with previous mass extinctions. Freshwater environments are being particularly affected, with biodiversity losses occurring much faster in freshwater than in terrestrial or marine ecosystems.
2. This study assessed the research on drivers of biodiversity loss in freshwater environments as described in nearly 37,000 articles published in the last decade. Articles on biodiversity published between 2010 and 2019 were retrieved from the Web of Science to determine the number of articles that addressed a particular driver of biodiversity loss, by analysing the titles, abstracts, and keywords. The biodiversity and development status of a country was also investigated to see how it affects its scientific output (i.e. number of published articles).
3. Twenty per cent of the articles on biodiversity addressed freshwater biodiversity. Researchers devoted considerable effort to six drivers – climate change, water pollution, flow modification, expanding hydropower, species invasions, and habitat degradation – but practically ignored other threats, such as plastic and light pollution. It was also found that megadiverse countries, which for the most part were also developing countries, published substantially fewer articles than developed but less biodiverse countries.
4. We recommend a series of actions that could contribute to mitigate the biases found in this study.

     

Temporal spawning migration patterns of landlocked Atlantic salmon (Salmo salar) in a constructed stream

Landlocked Atlantic salmon (ouananiche, Salmo salar) spawning migration timing varies throughout its range and is influenced by a variety of environmental variables. This study examined the spawning migration time of landlocked Atlantic salmon in a small (4 ha) constructed stream linked to a large reservoir (32,600 ha) in Newfoundland, Canada. Salmon use of the stream was passively monitored using Passive Integrated Transponder (PIT) Tags from 2006 to 2012. Of the salmon tagged throughout the reservoir, 48% entered the stream during the spawning season and remained there for 18–36 days from late September to November before they returned to the reservoir. Most fish entered the stream at dusk (32%). The lunar cycle influenced the timing of migration each year. Mean stream discharge (cubic metres per second) influenced migration timing in some years, and water temperature appeared to have minimal impact on migration timing. Twenty per cent of fish migrated to the stream in multiple years and 51% of these individuals appeared to use the stream on a biennial or alternate year cycle. These results demonstrate that small constructed streams can attract salmon from throughout a large reservoir and can provide valuable habitat in areas where spawning habitat is limited.     

沙田人工湿地植物生长特性及除污能力的研究

采用人工模拟小试系统,研究了沙田人工湿地9种植物的长势、生物量变化及对污染物的去除能力,分析了各种植物的生长特性、环境适应性和在系统中的作用。结果表明,在深圳的气候条件下,植物生长期可贯穿全年,但长势受季节等环境因素的影响仍非常明显。植物茎叶的生物量受收割季节和周期的影响较大,根系的生物量及根区范围随植物收割呈周期性变化。在热带砾石床中,红花美人蕉(Cannaindica)、水葱(S.tabernaemotaniGmel)难以适应环境,芦苇(Ph.australisTrin)、再力花(Thaliadealbata)、荻(M.sacchariflorus)一直生长旺盛,但荻的除污能力较差;纸莎草(Cyperuspapyrus)和美人蕉长速较快,较适合于需快速启动的湿地系统。     

博斯腾湖人工湿地中微生物群落空间分布特征

博斯腾湖人工湿地是典型的多级表面流污水人工湿地处理系统。本研究采集博斯腾湖人工湿地各级子系统进水和出水口的水样及沉积物,通过高通量测序技术,分析了多级湿地系统中水和沉积物中的微生物群落空间分布特征。结果表明:总体上人工湿地沉积物中的微生物多样性和丰度高于水体。在多级湿地系统中微生物群落丰度及多样性自入口起始,先增加后由潜流湿地排入博斯腾湖后减小。水中核心门类为变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)及浮霉菌门(Planctomycetes)。其中变形菌门整体呈上升趋势,从初始进水口的59.11%上升至最终出水口的84.80%,而厚壁菌门类整体呈下降趋势,从24.05%降至6.83%。但厚壁菌门类细菌仍是优势菌种,这表明该门类细菌在废水处理系统中是优势菌种。沉积物中变形菌门类和厚壁菌门类细菌依然占主导地位,厚壁菌门类细菌丰度也是先增加后减少,而变形菌门类细菌整体上随处理深度呈下降趋势;拟杆菌门(Bacteroidetes)和绿弯菌门(Chloroflexi),两者在整个处理过程中呈现出完全相反的趋势。尽管水和沉积物中优势门类细菌均为变形菌门,并且最主要的功能类群均为氨基酸运输和代谢,但微生物群落整体结构及功能仍显著不同。     

向海湿地鸟类资源现状与保护对策

2001~2007年连续7a对向海湿地内迁徙和重要繁殖水鸟进行了调查分析,结果表明,区内鸟类数量资源显著下降,由2001年的127644只降为2007年的58 216只,降幅达54.4%;鸟类种类由2001年的63种上升为2007年的64种,有小幅度上升。向海自然保护区的湿地功能正在逐步退化,缺水旱化和人为活动是两个主要因素;加强湿地保护与恢复植被、保证生态用水、适度移民是适宜的保护对策。     

长白山区沟谷沼泽乌拉苔草湿地铁循环规律的研究

长白山沟谷沼泽乌拉苔草湿地,土壤有效铁含量不同土壤层变化均呈波动变化,A、B二层的变化趋势一致,表层和C层随着季节的积水和植物生长变化波动较大。有效铁活性A层表层B层;而土壤有效铁活性与土壤环境的关系为:土壤氧化还原电位对有效铁在6、8月份呈显著相关;土壤孔隙度均与之不显著相关;放线菌在表层土壤和有效铁含量极显著负相关外,8月份细菌、真菌、放线菌和有效铁呈极显著的相关;土壤剖面的蛋白酶、尿酶、纤维素酶和磷酸酶对有效铁均不显著相关(P0.05);脲酶对有效铁有显著的影响,因此脲酶可以作为有效铁的衡量指标。乌拉苔草丛生根部含铁量最多;而不同季节乌拉苔草对土壤有效铁的吸收率在7月份最大;而枯落物中铁向下迁移最大月份是8月。     

海水人工湿地对梭鱼室内越冬养殖废水的净化效果

为开发海水低温环境下人工湿地在水产养殖上的应用,研究人工湿地在海水环境下对梭鱼亲本室内越冬养殖废水的处理效果和净化效能。海水(16.8‰~19.6‰)人工湿地对室内越冬养殖废水的净化效果:总凯氏氮去除率为13.4%,总氨氮为32.1%,亚硝氮为33.1%,浊度为55.1%,COD为35.6%,总磷为34.6%。越冬期间养殖池水质稳定。低温对总凯氏氮和三态氮的去除率有一定影响,并制约人工湿地脱氮过程;对浊度、COD、总磷去除率影响并不明显。海水人工湿地能维持连续运转并保持越冬养殖池的水质稳定。养殖负载量、越冬期间水力负荷尚有提升空间。