Influence of habitat structures on fish abundances and diversity: comparing mainstream and tributary communities in the urban uMsunduze Catchment, KwaZulu-Natal, South Africa.

IF 2.5 3区 环境科学与生态学 Q2 BIODIVERSITY CONSERVATION
Urban Ecosystems Pub Date : 2025-01-01 Epub Date: 2025-02-24 DOI:10.1007/s11252-025-01688-5
Nolwazi B Ngcobo, Matthew J Burnett, Colleen T Downs
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引用次数: 0

Abstract

Various factors drive the decline of freshwater vertebrate biodiversity. These include changing landscape and urbanisation, introduced invasive species, altered habitat, water quality deterioration, instream barriers, and climate change. In the present study, we evaluated the impact of different habitat features on the fish assemblages in an urban river using catch per unit effort (CPUE) as a proxy for fish assemblage per site and season. We sampled 17 main sites and 21 ad-hoc sites in the uMsunduze Catchment in Pietermaritzburg, uMgungundlovu District, KwaZulu-Natal, South Africa, during 2022-2023. We collected data using an electro-shocker, fyke nets, and gill nets, and we also recorded and calculated habitat features such as substrate types, hydraulic biotopes, in-situ water quality, ecohydraulics, average depth, and velocity. We used Generalised Linear Models to determine the habitat features driving fish communities. We calculated the Shannon-Weiner and Pielou diversity indices to compare between rivers. We used the Fish Response Assessment Index (FRAI) tool to understand each site's ecological integrity per season. Our results indicated that various features, including substrate (mud, sand, gravel), fast intermediate and fast deep ecohydraulics, electrical conductivity, habitat (glide, pool), and average velocity significantly impacted the CPUE of fish. There was no variation in diversity indices between tributaries, but there was a significant difference in fish diversity between the uMsunduze mainstream and its tributaries. The FRAI scores showed great deterioration in the system's ecological health, and most sites, especially the mainstream sites, were critically or extremely modified. We suggest that the relevant authorities take action to mitigate the pressures compromising the uMsunduze Catchment's ecological integrity. There is an urgent need for conservation measures for the two "near threatened" species, Enteromius gurneyi and Amphilius natalensis, the former now extirpated as per our study.

栖息地结构对鱼类丰度和多样性的影响:比较南非夸祖鲁-纳塔尔省城市uMsunduze流域的主流和支流群落
多种因素导致淡水脊椎动物生物多样性下降。这些问题包括景观和城市化的变化、入侵物种的引入、栖息地的改变、水质恶化、河流屏障和气候变化。在本研究中,我们以单位努力渔获量(CPUE)为代表,评估了不同生境特征对城市河流鱼类群落的影响。在2022-2023年期间,我们在南非夸祖鲁-纳塔尔省uMgungundlovu区Pietermaritzburg的uMsunduze流域取样了17个主要站点和21个临时站点。我们使用电击器、鱼网和刺网收集数据,并记录和计算栖息地特征,如基质类型、水力生物群落、原位水质、生态水力学、平均深度和流速。我们使用广义线性模型来确定驱动鱼类群落的栖息地特征。我们计算了Shannon-Weiner和Pielou多样性指数来比较河流之间的差异。我们使用鱼类反应评估指数(FRAI)工具来了解每个站点每个季节的生态完整性。结果表明,基材(泥、沙、砾石)、快速中层和快速深层生态水力、电导率、栖息地(滑行、水池)和平均流速等特征对鱼类的CPUE有显著影响。各支流间鱼类多样性指数无显著差异,但各支流间鱼类多样性差异显著。fri得分显示系统生态健康状况严重恶化,大多数站点,特别是主流站点,都受到了严重或极度的破坏。我们建议有关当局采取行动,减轻损害uMsunduze流域生态完整性的压力。根据我们的研究,近危物种Enteromius gurneyi和Amphilius natalensis目前已经灭绝,迫切需要采取保护措施。
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来源期刊
Urban Ecosystems
Urban Ecosystems BIODIVERSITY CONSERVATION-ECOLOGY
CiteScore
5.70
自引率
6.90%
发文量
113
期刊介绍: Urban Ecosystems is an international journal devoted to scientific investigations of urban environments and the relationships between socioeconomic and ecological structures and processes in urban environments. The scope of the journal is broad, including interactions between urban ecosystems and associated suburban and rural environments. Contributions may span a range of specific subject areas as they may apply to urban environments: biodiversity, biogeochemistry, conservation biology, wildlife and fisheries management, ecosystem ecology, ecosystem services, environmental chemistry, hydrology, landscape architecture, meteorology and climate, policy, population biology, social and human ecology, soil science, and urban planning.
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