Prey and predator density‐dependent interactions under different water volumes
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Sentis, Arnaud, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Sentis, Arnaud , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466957 , vital:76802 , https://doi.org/10.1002/ece3.7503
- Description: 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.
- Full Text:
- Date Issued: 2021
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Sentis, Arnaud , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466957 , vital:76802 , https://doi.org/10.1002/ece3.7503
- Description: 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.
- Full Text:
- Date Issued: 2021
Alternative prey impedes the efficacy of a natural enemy of mosquitoes
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Coughlan, Neil E, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Coughlan, Neil E , Dick, Jaimie T A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467148 , vital:76831 , https://doi.org/10.1016/j.biocontrol.2019.104146
- Description: Adaptive foraging behaviour in the presence of multiple prey types may mediate stability to predator-prey relationships. For biological control agents, the presence of alternative prey may thus reduce ecological impacts towards target organisms, presenting a key challenge to the derivation of agent efficacies. Quantifications of non-target effects are especially important for generalist biocontrol agents in their regulation of pests, vectors and invasive species. We examined the predatory impact of the notonectid Anisops debilis towards larvae of the vector mosquito complex Culex pipiens in the presence of varying densities of alternative daphniid prey. Experimentally, we quantified functional responses of A. debilis towards target mosquito prey under different background daphniid compositions, and also tested for prey switching propensities by the notonectid predator.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Coughlan, Neil E , Dick, Jaimie T A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467148 , vital:76831 , https://doi.org/10.1016/j.biocontrol.2019.104146
- Description: Adaptive foraging behaviour in the presence of multiple prey types may mediate stability to predator-prey relationships. For biological control agents, the presence of alternative prey may thus reduce ecological impacts towards target organisms, presenting a key challenge to the derivation of agent efficacies. Quantifications of non-target effects are especially important for generalist biocontrol agents in their regulation of pests, vectors and invasive species. We examined the predatory impact of the notonectid Anisops debilis towards larvae of the vector mosquito complex Culex pipiens in the presence of varying densities of alternative daphniid prey. Experimentally, we quantified functional responses of A. debilis towards target mosquito prey under different background daphniid compositions, and also tested for prey switching propensities by the notonectid predator.
- Full Text:
- Date Issued: 2020
Arid-adapted paradiaptomid copepods contribute to mosquito regulation
- Cuthbert, Ross N, Wasserman, Ryan J, Dalu, Tatenda
- Authors: Cuthbert, Ross N , Wasserman, Ryan J , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443260 , vital:74103 , https://hdl.handle.net/10520/ejc-afzoo-v55-n3-a1
- Description: We are writing to describe the predatory potential of calanoid copepods for the regulation of mosquito larval populations in aquatic environments. Mosquito-borne diseases continue to drive unparalleled human morbidity and mortality (Ferguson 2018), and directly threaten other wildlife (George et al. 2015). This disease burden is most concentrated in Sub-Saharan Africa, where aquatic habitats exploited by mosquitoes are often temporary and, under natural conditions, characterised by arid-adapted ecological communities. These communities can be predator rich, contributing to the regulation of aquatic larval mosquito populations and therefore the adult vectors of the diseases at the landscape scale. A newly described southern African copepod species, Lovenula raynerae Suárez-Morales, Wasserman and Dalu 2015 (Paradiaptominae) (Figure 1), has been identified as an efficacious predatory agent for the natural regulation of medically important mosquito populations in temporary aquatic environments (Cuthbert et al. 2018).
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Wasserman, Ryan J , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443260 , vital:74103 , https://hdl.handle.net/10520/ejc-afzoo-v55-n3-a1
- Description: We are writing to describe the predatory potential of calanoid copepods for the regulation of mosquito larval populations in aquatic environments. Mosquito-borne diseases continue to drive unparalleled human morbidity and mortality (Ferguson 2018), and directly threaten other wildlife (George et al. 2015). This disease burden is most concentrated in Sub-Saharan Africa, where aquatic habitats exploited by mosquitoes are often temporary and, under natural conditions, characterised by arid-adapted ecological communities. These communities can be predator rich, contributing to the regulation of aquatic larval mosquito populations and therefore the adult vectors of the diseases at the landscape scale. A newly described southern African copepod species, Lovenula raynerae Suárez-Morales, Wasserman and Dalu 2015 (Paradiaptominae) (Figure 1), has been identified as an efficacious predatory agent for the natural regulation of medically important mosquito populations in temporary aquatic environments (Cuthbert et al. 2018).
- Full Text:
- Date Issued: 2020
Assessing sediment particle-size effects on benthic algal colonisation and total carbohydrate production
- Dalu, Tatenda, Cuthbert, Ross N, Chavalala, Tiyisani L, Froneman, P William, Wasserman, Ryan J
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Chavalala, Tiyisani L , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466815 , vital:76789 , https://doi.org/10.1016/j.scitotenv.2019.136348
- Description: Increased sedimentation and siltation associated with anthropogenic environmental change may alter microbial biofilms and the carbohydrates they produce, with potential bottom-up effects in these ecosystems. The present study aimed to examine to what extent carbohydrate (associated with biofilm exopolymer) concentration and benthic algal biomass vary among different sediment types (size-structure categories) using a microcosm experiment conducted over a period of 28 days. Substrate treatment and time had a significant effect on the total chlorophyll-a concentrations, whilst a significant interaction was present in the case of total sediment carbohydrates. Total sediment carbohydrates did not relate significantly to chlorophyll-a concentrations overall, nor for any substrate treatments owing to a non-significant ‘chlorophyll-a × substrate’ interaction term. The diatom community characteristics across sediment sizes were unique for each treatment in our study, with unique dominant diatom taxa compositions within each sediment size class. The finest sediment particle-size (greater than 63 μm) may be the least stable, most likely due to lower binding. We anticipate that the current study findings will lead to a better understanding of how different sediment types due to sedimentation and siltation will impact on primary productivity and the composition of diatom communities in aquatic systems.
- Full Text:
- Date Issued: 2020
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Chavalala, Tiyisani L , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466815 , vital:76789 , https://doi.org/10.1016/j.scitotenv.2019.136348
- Description: Increased sedimentation and siltation associated with anthropogenic environmental change may alter microbial biofilms and the carbohydrates they produce, with potential bottom-up effects in these ecosystems. The present study aimed to examine to what extent carbohydrate (associated with biofilm exopolymer) concentration and benthic algal biomass vary among different sediment types (size-structure categories) using a microcosm experiment conducted over a period of 28 days. Substrate treatment and time had a significant effect on the total chlorophyll-a concentrations, whilst a significant interaction was present in the case of total sediment carbohydrates. Total sediment carbohydrates did not relate significantly to chlorophyll-a concentrations overall, nor for any substrate treatments owing to a non-significant ‘chlorophyll-a × substrate’ interaction term. The diatom community characteristics across sediment sizes were unique for each treatment in our study, with unique dominant diatom taxa compositions within each sediment size class. The finest sediment particle-size (greater than 63 μm) may be the least stable, most likely due to lower binding. We anticipate that the current study findings will lead to a better understanding of how different sediment types due to sedimentation and siltation will impact on primary productivity and the composition of diatom communities in aquatic systems.
- Full Text:
- Date Issued: 2020
Benthic diatom-based indices and isotopic biomonitoring of nitrogen pollution in a warm temperate Austral river system
- Dalu, Tatenda, Cuthbert, Ross N, Taylor, Jonathan C, Magoro, Mandla L, Weyl, Olaf L F, Froneman, P William, Wasserman, Ryan J
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Taylor, Jonathan C , Magoro, Mandla L , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466917 , vital:76798 , https://doi.org/10.1016/j.scitotenv.2020.142452
- Description: Rivers are impacted by pollutants from anthropogenic activities such as urbanisation and agricultural practices. Whilst point source pollution has been widely studied and in some cases remediated, non-point pollutant sources remain pervasive, particularly in developing countries that lack economic and human specialist capacity. Monitoring of pollution levels in many regions is additionally challenged by a lack of robust indicators for nitrogen inputs, however, diatom community indices and analysis of variation in microphytobenthos (MBP) stable isotope analysis variations have potential. The present study investigates variations and utilities in benthic diatom indices and MPB δ15N along different river sections (n = 31) of an austral river between two seasons (wet and dry), testing for relationships with key environmental variables (physical, water and sediment), in the context of N monitoring. One hundred and eighteen diatom taxa belonging to 36 genera were identified, with physical (water flow), water (nitrate, P and total dissolved solids) and sediment (B, Ca, Cr, Na, N, P, SOM, Pb and Zn) variables correlating to one or more of the 12 diatom indices presented. In particular, Biological Diatom Index, Biological Index of Water Quality, Central Economic Community, Index of Artois-Picardie Diatom (IDAP) and Sládeček's Index were strongly explained by sediment variables, whilst Descy's Pollution Index and Schiefele and Schreiner's Index were explained by water and physical variables.
- Full Text:
- Date Issued: 2020
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Taylor, Jonathan C , Magoro, Mandla L , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466917 , vital:76798 , https://doi.org/10.1016/j.scitotenv.2020.142452
- Description: Rivers are impacted by pollutants from anthropogenic activities such as urbanisation and agricultural practices. Whilst point source pollution has been widely studied and in some cases remediated, non-point pollutant sources remain pervasive, particularly in developing countries that lack economic and human specialist capacity. Monitoring of pollution levels in many regions is additionally challenged by a lack of robust indicators for nitrogen inputs, however, diatom community indices and analysis of variation in microphytobenthos (MBP) stable isotope analysis variations have potential. The present study investigates variations and utilities in benthic diatom indices and MPB δ15N along different river sections (n = 31) of an austral river between two seasons (wet and dry), testing for relationships with key environmental variables (physical, water and sediment), in the context of N monitoring. One hundred and eighteen diatom taxa belonging to 36 genera were identified, with physical (water flow), water (nitrate, P and total dissolved solids) and sediment (B, Ca, Cr, Na, N, P, SOM, Pb and Zn) variables correlating to one or more of the 12 diatom indices presented. In particular, Biological Diatom Index, Biological Index of Water Quality, Central Economic Community, Index of Artois-Picardie Diatom (IDAP) and Sládeček's Index were strongly explained by sediment variables, whilst Descy's Pollution Index and Schiefele and Schreiner's Index were explained by water and physical variables.
- Full Text:
- Date Issued: 2020
Examining intraspecific multiple predator effects across shifting predator sex ratios:
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150119 , vital:38941 , https://doi.org/10.1016/j.baae.2020.03.002
- Description: Predator-predator interactions, or “multiple predator effects” (MPEs), are pervasive in the structuring of communities and complicate predictive quantifications of ecosystem dynamics. The nature of MPEs is also context-dependent, manifesting differently among species, prey densities and habitat structures. However, there has hitherto been a lack of consideration for the implications of intraspecific demographic variation within populations for the strength of MPEs. The present study extends MPE concepts to examine intraspecific interactions among male and female predators across differences in prey densities using a functional response approach. Focusing on a copepod-mosquito model predator-prey system, interaction strengths of different sex ratio pairs of Lovenula raynerae were quantified towards larval Culex pipiens complex prey, with observations compared to both additive and substitutive model predictions.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150119 , vital:38941 , https://doi.org/10.1016/j.baae.2020.03.002
- Description: Predator-predator interactions, or “multiple predator effects” (MPEs), are pervasive in the structuring of communities and complicate predictive quantifications of ecosystem dynamics. The nature of MPEs is also context-dependent, manifesting differently among species, prey densities and habitat structures. However, there has hitherto been a lack of consideration for the implications of intraspecific demographic variation within populations for the strength of MPEs. The present study extends MPE concepts to examine intraspecific interactions among male and female predators across differences in prey densities using a functional response approach. Focusing on a copepod-mosquito model predator-prey system, interaction strengths of different sex ratio pairs of Lovenula raynerae were quantified towards larval Culex pipiens complex prey, with observations compared to both additive and substitutive model predictions.
- Full Text:
- Date Issued: 2020
Influence of intra-and interspecific variation in predator–prey body size ratios on trophic interaction strengths:
- Cuthbert, Ross N, Wasserman, Ryan J, Dalu, Tatenda, Kaiser, Horst, Weyl, Olaf L F, Dick, Jaimie T A, Sentis, Arnaud, McCoy, Michael W, Alexander, Mhairi E
- Authors: Cuthbert, Ross N , Wasserman, Ryan J , Dalu, Tatenda , Kaiser, Horst , Weyl, Olaf L F , Dick, Jaimie T A , Sentis, Arnaud , McCoy, Michael W , Alexander, Mhairi E
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149358 , vital:38839 , https://0-doi.org.wam.seals.ac.za/10.1002/ece3.6332
- Description: Predation is a pervasive force that structures food webs and directly influences ecosystem functioning. The relative body sizes of predators and prey may be an important determinant of interaction strengths. However, studies quantifying the combined influence of intra‐ and interspecific variation in predator–prey body size ratios are lacking. We use a comparative functional response approach to examine interaction strengths between three size classes of invasive bluegill and largemouth bass toward three scaled size classes of their tilapia prey. We then quantify the influence of intra‐ and interspecific predator–prey body mass ratios on the scaling of attack rates and handling times.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Wasserman, Ryan J , Dalu, Tatenda , Kaiser, Horst , Weyl, Olaf L F , Dick, Jaimie T A , Sentis, Arnaud , McCoy, Michael W , Alexander, Mhairi E
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149358 , vital:38839 , https://0-doi.org.wam.seals.ac.za/10.1002/ece3.6332
- Description: Predation is a pervasive force that structures food webs and directly influences ecosystem functioning. The relative body sizes of predators and prey may be an important determinant of interaction strengths. However, studies quantifying the combined influence of intra‐ and interspecific variation in predator–prey body size ratios are lacking. We use a comparative functional response approach to examine interaction strengths between three size classes of invasive bluegill and largemouth bass toward three scaled size classes of their tilapia prey. We then quantify the influence of intra‐ and interspecific predator–prey body mass ratios on the scaling of attack rates and handling times.
- Full Text:
- Date Issued: 2020
Inter-population similarities and differences in predation efficiency of a mosquito natural enemy
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466928 , vital:76799 , https://doi.org/10.1093/jme/tjaa093
- Description: 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.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466928 , vital:76799 , https://doi.org/10.1093/jme/tjaa093
- Description: 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.
- Full Text:
- Date Issued: 2020
Lack of prey switching and strong preference for mosquito prey by a temporary pond specialist predator
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466946 , vital:76801 , https://doi.org/10.1111/een.12801
- Description: The strengths of trophic interactions within ecosystems can be mediated by complex mechanisms that require elucidation if researchers are to understand and predict population‐ and community‐level stabilities. Where multiple prey types co‐occur, prey switching (i.e. frequency‐dependent predation) by predators may facilitate low‐density prey refuge effects which promote coexistence. On the other hand, lack of switching and strong preferences by predators can strongly suppress prey populations, which is especially important considering vector species such as mosquitoes.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466946 , vital:76801 , https://doi.org/10.1111/een.12801
- Description: The strengths of trophic interactions within ecosystems can be mediated by complex mechanisms that require elucidation if researchers are to understand and predict population‐ and community‐level stabilities. Where multiple prey types co‐occur, prey switching (i.e. frequency‐dependent predation) by predators may facilitate low‐density prey refuge effects which promote coexistence. On the other hand, lack of switching and strong preferences by predators can strongly suppress prey populations, which is especially important considering vector species such as mosquitoes.
- Full Text:
- Date Issued: 2020
Nutrient release dynamics associated with native and invasive leaf litter decomposition: a Mesocosm Experiment
- Mutshekwa, Thendo, Cuthbert, Ross N, Wasserman, Ryan J, Murungweni, Florence M, Dalu, Tatenda
- Authors: Mutshekwa, Thendo , Cuthbert, Ross N , Wasserman, Ryan J , Murungweni, Florence M , Dalu, Tatenda
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160467 , vital:40448 , https://doi.org/10.3390/w12092350
- Description: Leaf litter contributes to the functioning of aquatic ecosystems through allochthonous inputs of carbon, nitrogen, and other elements. Here, we examine leaf litter nutrient inputs and decomposition associated with four plant species using a mesocosm approach. Native sycamore fig Ficus sycomorus L., and silver cluster–leaf Terminalia sericea Burch. ex DC. decomposition dynamics were compared to invasive tickberry Lantana camara L. and guava Psidium guajava L., whereby phosphate, nitrate, nitrite, silicate, and ammonium releases were quantified over time. Leaf inputs significantly reduced pH, with reductions most marked by invasive L. camara. Conductivity was heightened by all leaf input treatments, except native T. sericea.
- Full Text:
- Date Issued: 2020
- Authors: Mutshekwa, Thendo , Cuthbert, Ross N , Wasserman, Ryan J , Murungweni, Florence M , Dalu, Tatenda
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160467 , vital:40448 , https://doi.org/10.3390/w12092350
- Description: Leaf litter contributes to the functioning of aquatic ecosystems through allochthonous inputs of carbon, nitrogen, and other elements. Here, we examine leaf litter nutrient inputs and decomposition associated with four plant species using a mesocosm approach. Native sycamore fig Ficus sycomorus L., and silver cluster–leaf Terminalia sericea Burch. ex DC. decomposition dynamics were compared to invasive tickberry Lantana camara L. and guava Psidium guajava L., whereby phosphate, nitrate, nitrite, silicate, and ammonium releases were quantified over time. Leaf inputs significantly reduced pH, with reductions most marked by invasive L. camara. Conductivity was heightened by all leaf input treatments, except native T. sericea.
- Full Text:
- Date Issued: 2020
Sex demographics alter the effect of habitat structure on predation by a temporary pond specialist
- Cuthbert, Ross N, Sithagu, Rotondwa, Weyl, Olaf L F, Froneman, P William, Wasserman, Ryan J, Dick, Jaimie T A, Callaghan, Amanda, Foord, Stefan, Dalu, Tatenda
- Authors: Cuthbert, Ross N , Sithagu, Rotondwa , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J , Dick, Jaimie T A , Callaghan, Amanda , Foord, Stefan , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466968 , vital:76803 , https://doi.org/10.1016/j.limno.2020.125747
- Description: Habitat structure can profoundly influence interaction strengths between predators and prey. Spatio-temporal habitat structure in temporary wetland ecosystems is particularly variable because of fluctuations in water levels and vegetation colonisation dynamics. Demographic characteristics within animal populations may also alter the influence of habitat structure on biotic interactions, but have remained untested. Here, we investigate the influence of vegetation habitat structure on the consumption of larval mosquito prey by the calanoid copepod Lovenula raynerae, a temporary pond specialist. Increased habitat complexity reduced predation, and gravid female copepods were generally more voracious than male copepods in simplified habitats. However, sexes were more similar as habitat complexity increased. Type II functional responses were exhibited by the copepods irrespective of habitat complexity and sex, owing to consistent high prey acquisition at low prey densities. Attack rates by copepods were relatively unaffected by the complexity gradient, whilst handling times lengthened under more complex environments in gravid female copepods. We demonstrate emergent effects of habitat complexity across species demographics, with predation by males more robust to differences in habitat complexity than females. For ecosystems such as temporary ponds where sex-skewed predator ratios develop, our laboratory findings suggest habitat complexity and sex demographics mediate prey risk.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Sithagu, Rotondwa , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J , Dick, Jaimie T A , Callaghan, Amanda , Foord, Stefan , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466968 , vital:76803 , https://doi.org/10.1016/j.limno.2020.125747
- Description: Habitat structure can profoundly influence interaction strengths between predators and prey. Spatio-temporal habitat structure in temporary wetland ecosystems is particularly variable because of fluctuations in water levels and vegetation colonisation dynamics. Demographic characteristics within animal populations may also alter the influence of habitat structure on biotic interactions, but have remained untested. Here, we investigate the influence of vegetation habitat structure on the consumption of larval mosquito prey by the calanoid copepod Lovenula raynerae, a temporary pond specialist. Increased habitat complexity reduced predation, and gravid female copepods were generally more voracious than male copepods in simplified habitats. However, sexes were more similar as habitat complexity increased. Type II functional responses were exhibited by the copepods irrespective of habitat complexity and sex, owing to consistent high prey acquisition at low prey densities. Attack rates by copepods were relatively unaffected by the complexity gradient, whilst handling times lengthened under more complex environments in gravid female copepods. We demonstrate emergent effects of habitat complexity across species demographics, with predation by males more robust to differences in habitat complexity than females. For ecosystems such as temporary ponds where sex-skewed predator ratios develop, our laboratory findings suggest habitat complexity and sex demographics mediate prey risk.
- Full Text:
- Date Issued: 2020
Water volume differentially modifies copepod predatory strengths on two prey types
- Cuthbert, Ross N, Sithagu, Rotondwa, Weyl, Olaf L F, Froneman, P William, Wasserman, Ryan J, Dick, Jaimie T A, Callaghan, Amanda, Foord, Stefan, Dalu, Tatenda
- Authors: Cuthbert, Ross N , Sithagu, Rotondwa , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J , Dick, Jaimie T A , Callaghan, Amanda , Foord, Stefan , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466979 , vital:76804 , https://doi.org/10.1016/j.limno.2020.125747
- Description: Predatory interaction strengths are highly context-dependent, and in temporary aquatic ecosystems, may be affected by water volume changes. We examine the influence of water volume on Lovenula raynerae (Copepoda) functional responses towards two temporary pond prey types. Daphnia prey risk was not affected by increasing water volume, whereas for Culex prey risk was reduced. Accordingly, water volume changes through the hydroperiod may have species-specific effects on prey, with implications for population persistence under environmental change.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Sithagu, Rotondwa , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J , Dick, Jaimie T A , Callaghan, Amanda , Foord, Stefan , Dalu, Tatenda
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466979 , vital:76804 , https://doi.org/10.1016/j.limno.2020.125747
- Description: Predatory interaction strengths are highly context-dependent, and in temporary aquatic ecosystems, may be affected by water volume changes. We examine the influence of water volume on Lovenula raynerae (Copepoda) functional responses towards two temporary pond prey types. Daphnia prey risk was not affected by increasing water volume, whereas for Culex prey risk was reduced. Accordingly, water volume changes through the hydroperiod may have species-specific effects on prey, with implications for population persistence under environmental change.
- Full Text:
- Date Issued: 2020
Additive multiple predator effects of two specialist paradiaptomid copepods towards larval mosquitoes
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467137 , vital:76828 , https://doi.org/10.1016/j.limno.2019.125727
- Description: Interactions between multiple predators can profoundly affect prey risk, with implications for prey population stability and ecosystem functioning. In austral temporary wetlands, arid-area adapted specialist copepods are key predators for much of the hydroperiod. Limited autoecological information relating to species interactions negates understandings of trophic dynamics in these systems. In the present study, we examined multiple predator effects of two key predatory paradiaptomid copepods which often coexist in austral temporary wetlands, Lovenula raynerae Suárez-Morales, Wasserman and Dalu 2015 and Paradiaptomus lamellatus Sars, 1985. Predation rates towards larval mosquito prey across different water depths were quantified.
- Full Text:
- Date Issued: 2019
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467137 , vital:76828 , https://doi.org/10.1016/j.limno.2019.125727
- Description: Interactions between multiple predators can profoundly affect prey risk, with implications for prey population stability and ecosystem functioning. In austral temporary wetlands, arid-area adapted specialist copepods are key predators for much of the hydroperiod. Limited autoecological information relating to species interactions negates understandings of trophic dynamics in these systems. In the present study, we examined multiple predator effects of two key predatory paradiaptomid copepods which often coexist in austral temporary wetlands, Lovenula raynerae Suárez-Morales, Wasserman and Dalu 2015 and Paradiaptomus lamellatus Sars, 1985. Predation rates towards larval mosquito prey across different water depths were quantified.
- Full Text:
- Date Issued: 2019
Combined impacts of warming and salinisation on trophic interactions and mortality of a specialist ephemeral wetland predator
- Cuthbert, Ross N, Weyl, Olaf L F, Wasserman, Ryan J, Dick, Jaimie T A, Froneman, P William, Callaghan, Amanda, Dalu, Tatenda
- Authors: Cuthbert, Ross N , Weyl, Olaf L F , Wasserman, Ryan J , Dick, Jaimie T A , Froneman, P William , Callaghan, Amanda , Dalu, Tatenda
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467160 , vital:76832 , https://doi.org/10.1111/fwb.13353
- Description: Wetlands are of enormous importance for biodiversity globally but are under increasing risk from multiple stressors driven by ongoing anthro-pogenic environmental change. As the trophic structure and dynamics of ephemeral wetlands are poorly understood, it is difficult to predict how these biodiverse ecosystems will be impacted by global change. In particular, warming and salinisation are projected to have profound im-pacts on these wetlands in future. The present study examined the combined effects of warming and salinisation on species interaction strengths and mortality rates for two ephemeral wetland species. Using an ephemeral pond specialist copepod, Lovenula raynerae Suárez‐Morales, Wasserman, and Dalu, (2015) as a model predator species, we applied a functional response approach to derive warming and salinisa-tion effects on trophic interactions with a prey species. Furthermore, the effects of a salinisation gradient on mortality rates of adult copepods were quantified.
- Full Text:
- Date Issued: 2019
- Authors: Cuthbert, Ross N , Weyl, Olaf L F , Wasserman, Ryan J , Dick, Jaimie T A , Froneman, P William , Callaghan, Amanda , Dalu, Tatenda
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467160 , vital:76832 , https://doi.org/10.1111/fwb.13353
- Description: Wetlands are of enormous importance for biodiversity globally but are under increasing risk from multiple stressors driven by ongoing anthro-pogenic environmental change. As the trophic structure and dynamics of ephemeral wetlands are poorly understood, it is difficult to predict how these biodiverse ecosystems will be impacted by global change. In particular, warming and salinisation are projected to have profound im-pacts on these wetlands in future. The present study examined the combined effects of warming and salinisation on species interaction strengths and mortality rates for two ephemeral wetland species. Using an ephemeral pond specialist copepod, Lovenula raynerae Suárez‐Morales, Wasserman, and Dalu, (2015) as a model predator species, we applied a functional response approach to derive warming and salinisa-tion effects on trophic interactions with a prey species. Furthermore, the effects of a salinisation gradient on mortality rates of adult copepods were quantified.
- Full Text:
- Date Issued: 2019
Quantifying reproductive state and predator effects on copepod motility in ephemeral ecosystems
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Dick, Jaimie T A, Callaghan, Amanda, Froneman, P William, Weyl, Olaf L F
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Dick, Jaimie T A , Callaghan, Amanda , Froneman, P William , Weyl, Olaf L F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467171 , vital:76836 , https://doi.org/10.1016/j.jaridenv.2019.05.010
- Description: Ephemeral wetlands in arid environments are unique ecosystems with atypical trophic structuring, often dominated by invertebrate predation. Copepod behavioural traits and vulnerabilities to predation can vary substantially according to reproductive status. Gravid female copepods may be more vulnerable to predation due to reduced escape speeds or higher visibility to predators. Here, we quantify how reproductive status modulates horizontal motility rates of the predatory ephemeral pond specialist copepod Lovenula raynerae, and the responsiveness of the copepod to predator cues of the notonectid Anisops debilis. Males exhibited significantly higher motility rates than gravid female copepods, however chemical predator cues did not significantly influence activity rates in either sex. The lack of responsiveness to predator cues by specialist copepods in ephemeral wetlands may result from a lack of predation pressure in these systems, or due to time stress to reproduce during short hydroperiods. In turn, this could increase predation risk to copepods from externally-recruited top predators in ephemeral wetlands, and potentially contribute to the development of skewed sex ratios in favour of females.
- Full Text:
- Date Issued: 2019
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Dick, Jaimie T A , Callaghan, Amanda , Froneman, P William , Weyl, Olaf L F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467171 , vital:76836 , https://doi.org/10.1016/j.jaridenv.2019.05.010
- Description: Ephemeral wetlands in arid environments are unique ecosystems with atypical trophic structuring, often dominated by invertebrate predation. Copepod behavioural traits and vulnerabilities to predation can vary substantially according to reproductive status. Gravid female copepods may be more vulnerable to predation due to reduced escape speeds or higher visibility to predators. Here, we quantify how reproductive status modulates horizontal motility rates of the predatory ephemeral pond specialist copepod Lovenula raynerae, and the responsiveness of the copepod to predator cues of the notonectid Anisops debilis. Males exhibited significantly higher motility rates than gravid female copepods, however chemical predator cues did not significantly influence activity rates in either sex. The lack of responsiveness to predator cues by specialist copepods in ephemeral wetlands may result from a lack of predation pressure in these systems, or due to time stress to reproduce during short hydroperiods. In turn, this could increase predation risk to copepods from externally-recruited top predators in ephemeral wetlands, and potentially contribute to the development of skewed sex ratios in favour of females.
- Full Text:
- Date Issued: 2019
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