Phosphorus loading and carp disturbance synergistically promote dominance of free-floating macrophytes over submerged plant competitors
Freshwater ecosystems increasingly face free-floating macrophyte invasions, which suppress submerged vegetation and phytoplankton, threatening biodiversity and ecosystem functions. Submerged macrophytes stabilize clear water conditions in shallow lakes and ponds, but anthropogenic nutrient inputs, b...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-09-01
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| Series: | Ecological Indicators |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1470160X25009896 |
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| Summary: | Freshwater ecosystems increasingly face free-floating macrophyte invasions, which suppress submerged vegetation and phytoplankton, threatening biodiversity and ecosystem functions. Submerged macrophytes stabilize clear water conditions in shallow lakes and ponds, but anthropogenic nutrient inputs, benthic fish proliferation and other global change processes accelerate their decline, shifting ecosystems toward free-floating plant or phytoplankton dominance. Using mesocosms with Vallisneria natans, Eichhornia crassipes, and juvenile common carp (Cyprinus carpio), we tested how nutrient loadings (N, P, or their combination) and benthic fish regulate water quality and competition between submerged and free-floating macrophytes. We found that P loading alone reduced both the biomass and dominance of the submerged macrophyte V. natans by increasing shading from free-floating E. crassipes. Fish promoted suspension of sediments and lowered pH, further promoting the growth of E. crassipes and resulting in a shift to a dominance of free-floating macrophytes under P loading. N loading alone had little effect on the biomass of both macrophytes and phytoplankton, and it even partially mitigated the negative impacts of fish on submerged macrophytes. However, simultaneous N and P loading produced synergistic responses in the system, significantly increasing the biomass of phytoplankton and free-floating macrophytes, especially in the presence of fish. Our results highlight P loading and benthic fish (juvenile common carp) as key drivers of free-floating plant dominance, mediated by light limitation and shifts in water chemistry (e.g., pH). Reducing P loading and implementing measures to control benthic fish abundance may enhance the resilience of submerged macrophyte-dominated states in shallow lakes and ponds, with additional reductions in N further mitigating the synergistic impacts of nutrient loading on ecosystem stability. |
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| ISSN: | 1470-160X |