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Masina FM, Wasserman RJ, Wu N, Mungenge CP, Dondofema F, Keates C, Shikwambana P, Dalu T. Macroinvertebrate diversity in relation to limnochemistry in an Austral semi-arid transboundary aquifer region pan system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 878:163161. [PMID: 37004768 DOI: 10.1016/j.scitotenv.2023.163161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/15/2023] [Accepted: 03/26/2023] [Indexed: 05/13/2023]
Abstract
Pan-wetland systems are one of the world's essential and productive ecosystems and are considered important, unique and complex ecosystems. Anthropogenic activities around the temporary pans in the Khakhea Bray Transboundary Aquifer region are increasingly becoming a big issue of concern as this may affect pan biodiversity. The study specifically aimed to investigate spatial and temporal distributions of metal and nutrient concentrations within the pans in relation to land use, identify potential pollution sources in this water-scarce region, and assess macroinvertebrate diversity and distribution in relation to pan limnochemistry using a combination of multivariate analyses from 10 pans across three seasons. Environmental and anthropogenic variables influence water quality and the distribution of metals concentration in Khakhea-Bray pan systems. Anthropogenic activities such as animal grazing, infrastructure degradation, water withdrawal and littering have resulted in poor water quality within temporary pans, which may strongly influence macroinvertebrate diversity and distribution. Forty-one macroinvertebrate species from 5 insect orders (i.e., Coleoptera, Hemiptera, Odonata, Ephemeroptera, Diptera), Crustacea and Mollusca were identified. Significant differences were observed across the seasons for macroinvertebrate taxa, with high and low species richness being observed in autumn and winter, respectively. Water (i.e., temperature, dissolved oxygen, pH, salinity, conductivity), physical (i.e., stone composition) and sediment (i.e., sulphur, sodium) parameters were found to have a significant impact on the macroinvertebrate communities. Therefore, understanding the relationships between macroinvertebrates and their environment is crucial in understanding how the ecosystem taxa are structured and is vital for informing conservation managers on how to properly manage and protect these systems from further degradation.
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Affiliation(s)
- Fannie M Masina
- Aquatic Systems Research Group, School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit 1200, South Africa
| | - Ryan J Wasserman
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa; South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
| | - Naicheng Wu
- Department of Geography and Spatial Information Techniques, Ningbo University, Ningbo 315211, China
| | - Chipo P Mungenge
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa
| | - Farai Dondofema
- Department of Geography and Environmental Sciences, University of Venda, Thohoyandou 0950, South Africa
| | - Chad Keates
- South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
| | - Purvance Shikwambana
- Aquatic Systems Research Group, School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit 1200, South Africa
| | - Tatenda Dalu
- Aquatic Systems Research Group, School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit 1200, South Africa; South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa; Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa.
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Cuthbert RN, Dalu T, Wasserman RJ, Sentis A, Weyl OLF, Froneman PW, Callaghan A, Dick JTA. Prey and predator density-dependent interactions under different water volumes. Ecol Evol 2021; 11:6504-6512. [PMID: 34141235 PMCID: PMC8207356 DOI: 10.1002/ece3.7503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/09/2021] [Accepted: 03/15/2021] [Indexed: 01/28/2023] Open
Abstract
Predation is a critical ecological process that directly and indirectly mediates population stabilities, as well as ecosystem structure and function. The strength of interactions between predators and prey may be mediated by multiple density dependences concerning numbers of predators and prey. In temporary wetland ecosystems in particular, fluctuating water volumes may alter predation rates through differing search space and prey encounter rates. Using a functional response approach, we examined the influence of predator and prey densities on interaction strengths of the temporary pond specialist copepod Lovenula raynerae preying on cladoceran prey, Daphnia pulex, under contrasting water volumes. Further, using a population dynamic modeling approach, we quantified multiple predator effects across differences in prey density and water volume. Predators exhibited type II functional responses under both water volumes, with significant antagonistic multiple predator effects (i.e., antagonisms) exhibited overall. The strengths of antagonistic interactions were, however, enhanced under reduced water volumes and at intermediate prey densities. These findings indicate important biotic and abiotic contexts that mediate predator-prey dynamics, whereby multiple predator effects are contingent on both prey density and search area characteristics. In particular, reduced search areas (i.e., water volumes) under intermediate prey densities could enhance antagonisms by heightening predator-predator interference effects.
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Affiliation(s)
- Ross N. Cuthbert
- GEOMAR Helmholtz‐Zentrum für Ozeanforschung KielKielGermany
- Institute for Global Food Security, School of Biological SciencesQueen's University BelfastBelfastUK
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
| | - Tatenda Dalu
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
- School of Biology and Environmental SciencesUniversity of MpumalangaNelspruitSouth Africa
| | - Ryan J. Wasserman
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
- Department of Zoology and EntomologyRhodes UniversityMakhandaSouth Africa
| | - Arnaud Sentis
- INRAEAix Marseille University, UMR RECOVERAix‐en‐ProvenceFrance
| | - Olaf L. F. Weyl
- DSI/NRF Research Chair in Inland Fisheries and Freshwater EcologySouth African Institute for Aquatic BiodiversityMakhandaSouth Africa
| | | | - Amanda Callaghan
- Ecology and Evolutionary Biology, School of Biological SciencesUniversity of ReadingReadingUK
| | - Jaimie T. A. Dick
- Institute for Global Food Security, School of Biological SciencesQueen's University BelfastBelfastUK
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Cuthbert RN, Dalu T, Wasserman RJ, Weyl OLF, Froneman PW, Callaghan A, Dick JTA. Inter-Population Similarities and Differences in Predation Efficiency of a Mosquito Natural Enemy. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:1983-1987. [PMID: 32459349 DOI: 10.1093/jme/tjaa093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Indexed: 06/11/2023]
Abstract
Predation is a critical factor that mediates population stability, community structure, and ecosystem function. Predatory natural enemies can contribute to the regulation of disease vector groups such as mosquitoes, particularly where they naturally co-occur across landscapes. However, we must understand inter-population variation in predatory efficiency if we are to enhance vector control. The present study thus employs a functional response (FR; resource use under different densities) approach to quantify and compare predatory interaction strengths among six populations of a predatory temporary pond specialist copepod, Lovenula raynerae, from the Eastern Cape of South Africa preying on second instar Culex pipiens complex mosquito larvae. All individuals from the sampled populations were predatory and drove significant mortality through per capita predation rates of 0.75-1.10 mosquitoes/h at maximum densities over a 5-h feeding time. Individuals from all copepod populations exhibited Type II FRs with no significant differences in attack rates. On the other hand, there were significant differences in handling times, and therefore also maximum feeding rates (maximum experimental prey density: 32), suggesting possible genetic differences among populations that influenced predation. Owing to a widespread distribution in arid landscapes, we propose that predatory calanoid copepods such as L. raynerae play a key regulatory role at the landscape scale in the control of disease vector mosquito populations. We propose that these ecosystems and their specialist biota should thus be conserved and enhanced (e.g., via selective breeding) owing to the ecosystem services they provide in the context of public health.
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Affiliation(s)
- Ross N Cuthbert
- GEOMAR, Helmholtz-Zentrum für Ozeanforschung Kiel, Kiel, Germany
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, Northern Ireland
- South African Institute for Aquatic Biodiversity, Makhanda, South Africa
| | - Tatenda Dalu
- South African Institute for Aquatic Biodiversity, Makhanda, South Africa
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
| | - Ryan J Wasserman
- South African Institute for Aquatic Biodiversity, Makhanda, South Africa
- Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa
| | - Olaf L F Weyl
- DSI/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity, Makhanda, South Africa
| | - P William Froneman
- Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa
| | - Amanda Callaghan
- Ecology and Evolutionary Biology, School of Biological Sciences, University of Reading, Harborne Building, Reading, United Kingdom
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, Northern Ireland
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Cuthbert RN, Wasserman RJ, Dalu T. Arid-adapted paradiaptomid copepods contribute to mosquito regulation. AFRICAN ZOOLOGY 2020. [DOI: 10.1080/15627020.2020.1769498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Ross N Cuthbert
- GEOMAR, Helmholtz-Zentrum für Ozeanforschung Kiel, Germany
- South African Institute for Aquatic Biodiversity (SAIAB), Makhanda, South Africa
| | - Ryan J Wasserman
- South African Institute for Aquatic Biodiversity (SAIAB), Makhanda, South Africa
- Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa
| | - Tatenda Dalu
- South African Institute for Aquatic Biodiversity (SAIAB), Makhanda, South Africa
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
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Buxton M, Cuthbert RN, Dalu T, Nyamukondiwa C, Wasserman RJ. Predator density modifies mosquito regulation in increasingly complex environments. PEST MANAGEMENT SCIENCE 2020; 76:2079-2086. [PMID: 31943746 DOI: 10.1002/ps.5746] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/16/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND Predation plays a pivotal role in the composition and functioning of ecosystems. Both habitat complexity and predator density are important contexts which may determine the strength of trophic and non-trophic interactions. In aquatic systems, the efficacy of natural enemies in regulating vector pest species could be modified by such context dependencies. Here, we use a functional response (FR) approach to experimentally quantify conspecific multiple predator effects across a habitat complexity gradient of two notonectids, Anisops sardea and Enithares chinai, towards larvae of the vector mosquito Culex pipiens pipiens. RESULTS E. chinai exhibited significantly greater consumption rates than A. sardea across habitat complexities, both as individuals and conspecific pairs. Each predator type displayed Type II FRs across experimental treatments, with synergistic multiple predator effects (i.e. prey risk enhancement) displayed in the absence of habitat complexity. Effects of increasing habitat complexity modified multiple predator effects differentially between species given behavioral differences, with habitat complexity causing significant antagonism (i.e. prey risk reduction) with multiple A. sardea compared to E. chinai. CONCLUSION Habitat complexity effects on multiple predator interactions can manifest differently at the species level, suggesting emergent effects which complicate predictions of natural enemy impact in heterogenous environments. Considerations of density, diversity and habitat effects on efficacies of natural enemies should thus be considered by pest management practitioners to better explain biocontrol efficacies in increasingly diverse environments. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Mmabaledi Buxton
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
| | - Ross N Cuthbert
- School of Biological Sciences, Queen's University Belfast, Belfast, UK
| | - Tatenda Dalu
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
| | - Casper Nyamukondiwa
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
| | - Ryan J Wasserman
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
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Dalal A, Cuthbert RN, Dick JT, Gupta S. Prey preferences of notonectids towards larval mosquitoes across prey ontogeny and search area. PEST MANAGEMENT SCIENCE 2020; 76:609-616. [PMID: 31313450 DOI: 10.1002/ps.5556] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/29/2019] [Accepted: 07/14/2019] [Indexed: 05/25/2023]
Abstract
BACKGROUND Predatory biological control agents can be effective natural means of managing pests, vectors and invasive species. However, the strength of predator-prey interactions can be regulated through context-dependencies that often remain unquantified. In particular, refuge effects can influence the efficacy of biological agents towards target species, and such effects are often driven by prey size and search area differences. In this study, we quantify the prey preferences of two predaceous notonectids, Anisops breddini and Anisops sardeus, towards four different aquatic larval instar stages of the medically important mosquito Culex quinquefasciatus across variations in surface area and water depth. RESULTS Consumption rates differed significantly among the four larval sizes but not between the notonectids. Search area variations also elicited differences in consumption rates. Both predators tended to prefer second-instar mosquito prey among surface area and water depth variations, while generally avoiding the largest (fourth instar) and smallest (first instar) prey instar stages. For both predators, differential selectivity traits were emergent across surface area variations and water depth, with refuge effects for small prey generally greatest at intermediate-large depths with high surface areas. We thus demonstrate that predatory impacts of notonectids towards mosquito larvae differ significantly according to prey size, and likely peak at intermediate size classes. CONCLUSION Different mosquito size classes often coexist and compete, selectivity has important implications for adult mosquito proliferations. Further, in ephemeral aquatic habitats where surface areas and water depths are highly variable spatiotemporally, the efficacy of notonectids in controlling mosquito prey may differ substantially. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Arpita Dalal
- Department of Ecology and Environmental Science, Assam University, Silchar, India
| | - Ross N Cuthbert
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, UK
| | - Jaimie Ta Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, UK
| | - Susmita Gupta
- Department of Ecology and Environmental Science, Assam University, Silchar, India
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Cuthbert RN, Dalu T, Wasserman RJ, Callaghan A, Weyl OL, Dick JT. Using functional responses to quantify notonectid predatory impacts across increasingly complex environments. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2019. [DOI: 10.1016/j.actao.2018.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Jooste CM, Emami-Khoyi A, Gan HM, Wasserman RJ, Dalu T, Teske PR. The complete mitochondrial genome of Africa's largest freshwater copepod, Lovenula raynerae. Mitochondrial DNA B Resour 2019. [DOI: 10.1080/23802359.2018.1555013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Affiliation(s)
- Candice M. Jooste
- Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, South Africa
| | - Arsalan Emami-Khoyi
- Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, South Africa
| | - Han Ming Gan
- Deakin Genomics Centre, Deakin University, Geelong, Victoria, Australia
- School of Science, Monash University Malaysia, Bandar Sunway, Selangor, Malaysia
| | - Ryan J. Wasserman
- School of Science, Monash University Malaysia, Bandar Sunway, Selangor, Malaysia
- South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, South Africa
| | - Tatenda Dalu
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
| | - Peter R. Teske
- Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, South Africa
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Cuthbert RN, Dalu T, Wasserman RJ, Dick JTA, Mofu L, Callaghan A, Weyl OLF. Intermediate predator naïveté and sex-skewed vulnerability predict the impact of an invasive higher predator. Sci Rep 2018; 8:14282. [PMID: 30250163 PMCID: PMC6155278 DOI: 10.1038/s41598-018-32728-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/14/2018] [Indexed: 12/03/2022] Open
Abstract
The spread of invasive species continues to reduce biodiversity across all regions and habitat types globally. However, invader impact prediction can be nebulous, and approaches often fail to integrate coupled direct and indirect invader effects. Here, we examine the ecological impacts of an invasive higher predator on lower trophic groups, further developing methodologies to more holistically quantify invader impact. We employ functional response (FR, resource use under different densities) and prey switching experiments to examine the trait- and density-mediated impacts of the invasive mosquitofish Gambusia affinis on an endemic intermediate predator Lovenula raynerae (Copepoda). Lovenula raynerae effectively consumed larval mosquitoes, but was naïve to mosquitofish cues, with attack rates and handling times of the intermediate predator unaffected by mosquitofish cue-treated water. Mosquitofish did not switch between male and female prey, consistently displaying a strong preference for female copepods. We thus demonstrate a lack of risk-reduction activity in the presence of invasive fish by L. raynerae and, in turn, high susceptibility of such intermediate trophic groups to invader impact. Further, we show that mosquitofish demonstrate sex-skewed predator selectivity towards intermediate predators of mosquito larvae, which may affect predator population demographics and, perversely, increase disease vector proliferations. We advocate the utility of FRs and prey switching combined to holistically quantify invasive species impact potential on native organisms at multiple trophic levels.
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Affiliation(s)
- Ross N Cuthbert
- Institute for Global Food Security, School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK. .,DST/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa. .,Ecology and Evolutionary Biology, School of Biological Sciences, University of Reading, Harborne Building, Reading, RG6 6AS, England, UK.
| | - Tatenda Dalu
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, 0950, South Africa.,South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
| | - Ryan J Wasserman
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P. Bag 16, Palapye, Botswana.,South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK
| | - Lubabalo Mofu
- South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
| | - Amanda Callaghan
- Ecology and Evolutionary Biology, School of Biological Sciences, University of Reading, Harborne Building, Reading, RG6 6AS, England, UK
| | - Olaf L F Weyl
- DST/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
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