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Chen J, Xu J, Yi Q, Peng J, Lang Y, Yang LE, Zhang J. Multidimensional water level and water quality response to severe drought in Xingyun Lake. Heliyon 2024; 10:e32213. [PMID: 38882358 PMCID: PMC11180315 DOI: 10.1016/j.heliyon.2024.e32213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 05/05/2024] [Accepted: 05/29/2024] [Indexed: 06/18/2024] Open
Abstract
Drought stress has a significant impact on the quality and quantity of lake water. Understanding this impact is crucial for preventing water security risks and pollution recovery. However, there is a lack of systemic understanding of how drought affects water quality and quantity, and how they change in multiple dimensions. This manuscript established a synthesized methodology with the principles to judge the applicability and three steps of application to detect the change in water quality and water level under severe drought in Xingyun Lake, China. Results show that (1) The water level and water quality of Xingyun Lake have a synchronous and evident response to drought during 2009-2014. The rainfall during 2008-2015 declined by 22.9 % to normal, and the inundated area and lake water depth in 2012 decreased by 10.50 % from 2002 to 1.38 m to the average depth, respectively. The pollution index climbed above 1.21 after 2008, fluctuating around 1.42. (2) Under drought, the water quality indicators significantly changed in the terms of the overall feature, trend, eigenvalue, and morphological characteristics. The water quality indicators of Set2008-2015 are significantly different from set2000-2007 and not in the groups of set1994-2000. The morphological characteristics of water quality indicators in set2008-2015 differs significantly from that in set2000-2007 shown by the minimum, maximum, median, quartiles, and extreme values. (3) Although NH3-N showed no significant change, the water quality deteriorated in the physical, chemical, and biological aspects. The TP, IMN, and BOD5 changed more evidently than DO and NH3-N. (4) Water quality grade and indicator concentration deteriorated significantly and sharply under severe drought and are threatened deeply by TP and TN. The synthesized methodology is scientifically constructed and canbe employed in the characteristics cognition of water quality and water level to severe drought in and out of this research. And the intervention time and various regulating measures for pollution degradation and water quality recovery canbe constructed based on the multi-dimensional analysis of water quality change under drought evolution.
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Affiliation(s)
- Junxu Chen
- International Joint Research Center for Karstology, Yunnan University, Kunming, 650091, China
- Yunnan Key Laboratory of Soil Erosion Prevention and Green Development, Yunnan University, Kunming, 650504, China
| | - Jia Xu
- International Joint Research Center for Karstology, Yunnan University, Kunming, 650091, China
| | - Qi Yi
- International Joint Research Center for Karstology, Yunnan University, Kunming, 650091, China
| | - Jiabin Peng
- International Joint Research Center for Karstology, Yunnan University, Kunming, 650091, China
- Yunnan International Joint Laboratory of China-Laos-Bangladesh-Myanmar Natural Resources Remote Sensing Monitoring, Yunnan University, Kunming, 650091, China
| | - Yang Lang
- International Joint Research Center for Karstology, Yunnan University, Kunming, 650091, China
| | - Liang Emlyn Yang
- Department of Geography, Ludwig Maximilian University of Munich (LMU), Munich, 80333, Germany
| | - Jihui Zhang
- International Joint Research Center for Karstology, Yunnan University, Kunming, 650091, China
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Gerber R, Pearson JJ, Wepener V, Malherbe W, de Necker L. Distribution, abundance, population structures, and potential impacts of the invasive snail, Tarebia granifera in aquatic ecosystems of north-eastern South Africa. Ecol Evol 2024; 14:e11544. [PMID: 38932941 PMCID: PMC11199171 DOI: 10.1002/ece3.11544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/15/2024] [Accepted: 05/25/2024] [Indexed: 06/28/2024] Open
Abstract
Aquatic ecosystems globally have been invaded by molluscs. Tarebia granifera is a highly successful invader, often becoming the dominant aquatic invertebrate species in an invaded ecosystem. Resultingly, it has been suggested that T. granifera may have severe negative impacts on these invaded ecosystems. Limited information is available regarding the population structures and densities of T. granifera, particularly in invaded countries such as South Africa, and information on this could assist in developing management and control strategies for this invasive species. The present study aimed to assess the current distribution, densities, and population structures of T. granifera in invaded habitats on the Limpopo and Phongolo River systems in South Africa. This was accomplished by collecting aquatic molluscs from sites across these systems. Water quality parameters were measured at each site and water samples were collected for chemical nutrient analyses. The density of snails was determined for each site and the population size and structure as well as birth rate was calculated for T. granifera. Tarebia granifera was found to be the dominant molluscan species in habitats where it was present and all size classes from newborn to mature adults were found throughout at some of the highest densities globally. Worryingly, native molluscan species, were often absent or in much lower densities than reported in literature at sites where T. granifera was present, suggesting a negative effect on the native molluscan density and diversity. Contrary to most previous studies, there were no significant correlations between T. granifera and the selected water quality parameters. Higher densities and newborn recruitment of T. granifera were observed in the spring than in autumn, likely in response to shifts in environmental conditions. This study provides crucial insights into the population structure, densities, and impacts of T. granifera in invaded habitats, particularly for relatively newly invaded regions such as southern Africa.
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Affiliation(s)
- Ruan Gerber
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Johannes J. Pearson
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Victor Wepener
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Wynand Malherbe
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Lizaan de Necker
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
- South African Institute for Aquatic Biodiversity (NRF‐SAIAB)MakhandaSouth Africa
- Animal Ecology, Global Change and Sustainable Development, Department of BiologyUniversity of LeuvenLeuvenBelgium
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de Necker L, van Rooyen D, Gerber R, Brendonck L, Wepener V, Smit NJ. Effects of river regulation on aquatic invertebrate community composition: A comparative analysis in two southern African rivers. Ecol Evol 2024; 14:e10963. [PMID: 38327690 PMCID: PMC10847884 DOI: 10.1002/ece3.10963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/02/2023] [Accepted: 12/04/2023] [Indexed: 02/09/2024] Open
Abstract
While natural floods play a crucial role in shaping the composition of aquatic communities, the most rivers worldwide are regulated or dammed for anthropogenic purposes, resulting in alterations to the biological and chemical composition of these ecosystems. Studies have demonstrated various negative effects of river regulation on aquatic invertebrate communities globally. However, there is a scarcity of research in Africa, despite its vulnerability to anthropogenic impacts. This study aimed to compare aquatic invertebrate communities in the Phongolo River, an impacted regulated river, and the Usuthu River, a less impacted unregulated river, in South Africa. It further aimed to ascertain whether Lake Nyamithi, a naturally saline lake receiving water from both of the aforementioned systems, exhibited a stronger similarity to one of the two rivers in terms of its aquatic invertebrate composition. Aquatic invertebrate and water samples were collected from 2012 to 2018 over several surveys. The Usuthu River demonstrated a diverse and sensitive aquatic invertebrate community, emphasising its high conservation value. The Phongolo River demonstrated effects of anthropogenic impact, with taxa more resilient to changes in water quality and flow compared to the Usuthu River. Mismanagement and excessive water use may lead to the loss of any remaining sensitive aquatic invertebrate communities in this river. The presence of invasive molluscan in the Phongolo River and Lake Nyamithi also poses a threat to the native aquatic invertebrate communities. These invasive species are currently absent from the Usuthu River although other invasive species, such as the Australian redclaw crayfish, are found in both river systems. Lake Nyamithi displayed a unique aquatic invertebrate community, distinct from both rivers and their floodplains. This study provides important baseline information on the Usuthu River's aquatic invertebrates and emphasises the need to maintain adequate water flow in rivers and floodplains to protect biodiversity and sensitive species.
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Affiliation(s)
- Lizaan de Necker
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
- South African Institute for Aquatic Biodiversity (NRF‐SAIAB)MakhandaSouth Africa
| | - Divan van Rooyen
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Ruan Gerber
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Luc Brendonck
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
- Animal Ecology, Global Change and Sustainable Development, Department of BiologyUniversity of LeuvenLeuvenBelgium
| | - Victor Wepener
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Nico J. Smit
- Water Research Group, Unit for Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
- South African Institute for Aquatic Biodiversity (NRF‐SAIAB)MakhandaSouth Africa
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Gerber R, de Necker L, van Vuren JHJ, Ikenaka Y, Nakayama SMM, Ishizuka M, Wepener V, Smit NJ. A stable isotope analysis of the dietary patterns of the aquatic apex predator, the African tigerfish (Hydrocynus vittatus). JOURNAL OF FISH BIOLOGY 2023; 103:1129-1143. [PMID: 37498144 DOI: 10.1111/jfb.15516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/19/2023] [Accepted: 07/26/2023] [Indexed: 07/28/2023]
Abstract
Stable isotope analyses, specifically δ13 C and δ15 N, are useful tools increasingly used to understand ecosystem function, food web structures, and consumer diets. Although the iconic tigerfish Hydrocynus vittatus is regarded as an apex predator in southern African freshwater systems, little information is available regarding their feeding behavior and how this may change with growth or differ between ecosystems, with most information stemming from stomach content analyses (SCA). The aim of the present study was to address this lack of information through a baseline study of the diet of large and small tigerfish in various lentic and lotic ecosystems in South Africa using stable isotope methods. Fish and various food web components and food sources were collected from two river and two lake ecosystems in South Africa. The δ13 C and δ15 N values for all samples were determined and multivariate analyses and Bayesian analytical techniques applied to determine the feeding ecology of H. vittatus and how this may differ with size and habitat type. Analyses revealed a substantial difference in the type and abundance of food sources contributing to the diet of H. vittatus between ecosystems, most prominently between the lotic systems, where less dietary specialization was observed, and lentic systems where more specialization was observed. Furthermore, there was a distinct difference in diet between small and large tigerfish, especially in the lotic system, indicating an ontogenetic diet shift as tigerfish grow and further supporting previous SCA studies. This is the first study of its kind on the African continent for H. vittatus and the findings illustrate the value of stable isotope analysis in providing in-depth information into the feeding ecology of consumers and how this may differ between size classes and habitat types.
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Grants
- 127549 Department of Science and Innovation Professional Development Programme
- 22KK0163 Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan
- 17KK0009 Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan
- 18KK028708 Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan
- 17K2003807 Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan
- 18H0413208 Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan
- 20K20633 Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan
- 105979 National Research Foundation of South Africa
- 85505 National Research Foundation of South Africa
- 105122 National Research Foundation of South Africa
- K5-1922 Water Research Commission of South Africa
- K5-2185 Water Research Commission of South Africa
- JPMJSA1501 JST/JICA SATREPS (Science and Technology Research Partnership for Sustainable Development
- JPMJAS2001 aXis (Accelerating Social Implementation for SDGs Achievement
- PJ36210002 JST AJ-CORE
- JSPS CORE to CORE program
- Hokkaido University SOUSEI Tokutei Research
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Affiliation(s)
- Ruan Gerber
- Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Lizaan de Necker
- Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
- South African Institute for Aquatic Biodiversity (NRF-SAIAB), Makhanda, South Africa
| | - Johan H J van Vuren
- Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Yoshinori Ikenaka
- Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
- Translational Research Unit, Veterinary Teaching hospital, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
| | - Shouta M M Nakayama
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Mayumi Ishizuka
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Victor Wepener
- Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Nico J Smit
- Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
- South African Institute for Aquatic Biodiversity (NRF-SAIAB), Makhanda, South Africa
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Catchpole Ahumada S, Carrera Suárez L, Rivera R. Could an event of extreme drought (2019-2020) affect the feeding ecology of Bubo magellanicus (Gmelin 1788) (Strigiformes: Strigidae) in a Mediterranean region of Chile? PeerJ 2023; 11:e15020. [PMID: 37151291 PMCID: PMC10158770 DOI: 10.7717/peerj.15020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 02/17/2023] [Indexed: 05/09/2023] Open
Abstract
Global warming generates changes in environmental conditions, affecting the spatial-temporal dynamics of precipitation and temperature. Droughts, events of low rainfall, are becoming more frequent and severe. In central Chile, from 2010 to date, an unprecedented drought event has developed, affecting the ecosystem and creating pressure on the dynamics of food webs. The present study analysed the trophic ecology of Bubo magellanicus, a top predator in the Mediterranean region of Chile, between 2019 and 2020 a period with a rainfall deficit of 72.6%. Our results established a diet mainly described by invertebrates (97.75%), in particular by the Gramnostola rosea spider (87.86%), and a low contribution of small vertebrates (2.24%). The trophic niche breadth (B = 0.37) and the standardised Levin's index (BSTA = 0.01) are the lowest recorded in the species B. magellanicus. A comparative analysis of trophic ecology with other studies developed in the same region established significant differences in the composition of the diet (frequency of occurrence of prey unit). This work provides evidence that droughts and other extreme environmental scenarios restructure the food webs of an ecosystem, with direct consequences on the trophic niche of the species, specifically top predators.
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Affiliation(s)
| | | | - Reinaldo Rivera
- Instituto Milenio de Oceanografía, Universidad de Concepción, Concepción, Biobío, Chile
- Facultad de Ciencias Naturales y Oceanográficas, Laboratorio de Ecología Evolutiva y Filoinformática, Concepción, Biobío, Chile
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