King Leighton, Wienhues Giulia, Misra Pavani, Tylmann Wojciech, Lami Andrea, Bernasconi Stefano M, Jaggi Madalina, Courtney-Mustaphi Colin, Muschick Moritz, Ngoepe Nare, Mwaiko Salome, Kishe Mary A, Cohen Andrew, Heiri Oliver, Seehausen Ole, Vogel Hendrik, Grosjean Martin, Matthews Blake
Department of Fish Ecology and Evolution, Swiss Federal Institute for Aquatic Science and Technology (EAWAG), Kastanienbaum, Dübendorf, Switzerland.
Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
Ecosystems. 2024;27(4):577-591. doi: 10.1007/s10021-024-00908-x. Epub 2024 May 13.
Discerning ecosystem change and food web dynamics underlying anthropogenic eutrophication and the introduction of non-native species is necessary for ensuring the long-term sustainability of fisheries and lake biodiversity. Previous studies of eutrophication in Lake Victoria, eastern Africa, have focused on the loss of endemic fish biodiversity over the past several decades, but changes in the plankton communities over this same time remain unclear. To fill this gap, we examined sediment cores from a eutrophic embayment, Mwanza Gulf, to determine the timing and magnitude of changes in the phytoplankton and zooplankton assemblages over the past century. Biogeochemical proxies indicate nutrient enrichment began around ~ 1920 CE and led to rapid increases in primary production, and our analysis of photosynthetic pigments revealed three zones: pre-eutrophication (prior to 1920 CE), onset of eutrophication with increases in all pigments (1920-1990 CE), and sustained eutrophication with cyanobacterial dominance (1990 CE-present). Cladoceran remains indicate an abrupt decline in biomass in ~ 1960 CE, in response to the cumulative effects of eutrophication and lake-level rise, preceding the collapse of haplochromine cichlids in the 1980s. and , typically benthic littoral taxa, have remained at relatively low abundances since the 1960s, whereas the abundance of typically a planktonic taxon, increased in the 1990s concurrently with the biomass recovery of haplochromine cichlid fishes. Overall, our results demonstrate substantial changes over the past century in the biomass structure and taxonomic composition of Mwanza Gulf phytoplankton and zooplankton communities, providing a historical food web perspective that can help understand the recent changes and inform future resource management decisions in the Lake Victoria ecosystem.
The online version contains supplementary material available at 10.1007/s10021-024-00908-x.
识别生态系统变化以及人为富营养化和非本地物种引入背后的食物网动态，对于确保渔业和湖泊生物多样性的长期可持续性至关重要。此前对东非维多利亚湖富营养化的研究主要集中在过去几十年特有鱼类生物多样性的丧失，但同一时期浮游生物群落的变化仍不明确。为填补这一空白，我们研究了富营养化海湾姆万扎湾的沉积物岩芯，以确定过去一个世纪浮游植物和浮游动物组合变化的时间和幅度。生物地球化学指标表明，营养物质富集始于公元1920年左右，导致初级生产力迅速增加，我们对光合色素的分析揭示了三个区域：富营养化前（公元1920年之前）、所有色素增加的富营养化开始阶段（公元1920 - 1990年）以及蓝藻占主导的持续富营养化阶段（公元1990年至今）。枝角类动物残骸表明，公元1960年左右生物量急剧下降，这是富营养化和湖面上升累积效应的结果，早于20世纪80年代haplochromine丽鱼科鱼类的崩溃。 和 ，通常是底栖沿岸类群，自20世纪60年代以来一直保持相对较低的丰度，而 （通常是浮游类群）的丰度在20世纪90年代随着haplochromine丽鱼科鱼类生物量的恢复而增加。总体而言，我们的结果表明，过去一个世纪姆万扎湾浮游植物和浮游动物群落的生物量结构和分类组成发生了重大变化，提供了一个历史食物网视角，有助于理解近期变化并为维多利亚湖生态系统未来的资源管理决策提供参考。
在线版本包含可在10.1007/s10021 - 024 - 00908 - x获取的补充材料。
