Dietary fatty acids of spiders reveal spatial and temporal variations in aquatic-terrestrial linkages
- Chari, Lenin D, Richoux, Nicole B, Moyo, Sydney, Villet, Martin H
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441919 , vital:73935 , https://doi.org/10.1016/j.fooweb.2020.e00152
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Date Issued: 2020
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441919 , vital:73935 , https://doi.org/10.1016/j.fooweb.2020.e00152
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Date Issued: 2020
Dietary fatty acids of spiders reveal spatial and temporal variations in aquatic-terrestrial linkages
- Chari, Lenin D, Richoux, Nicole B, Moyo, Sydney, Villet, Martin H
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454320 , vital:75335 , xlink:href="https://doi.org/10.1016/j.fooweb.2020.e00152"
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Date Issued: 2020
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454320 , vital:75335 , xlink:href="https://doi.org/10.1016/j.fooweb.2020.e00152"
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Date Issued: 2020
Trophic ecology of adult male O donata. II. D ietary contributions of aquatic food sources
- Chari, Lenin D, Moyo, Sydney, Richoux, Nicole B
- Authors: Chari, Lenin D , Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456403 , vital:75510 , xlink:href="https://doi.org/10.1111/een.12459"
- Description: 1. Insects that emerge from rivers provide nutritional subsidies to local riparian predators. Adult damselflies and dragonflies often benefit from aquatic resources, but their high mobility and evasiveness have made it difficult to monitor their diets. 2. A dual fatty acid and stable isotope analysis approach was used to investigate the links between Odonata size and behaviour with proportions of their aquatically derived nutri-tional sources. Additionally, the study investigated the variation in die-tary contributions of aquatic food sources to Odonata between two sec-tions of a river, each with different aquatic productivity rates. 3. Varia-tions in body size and foraging method of Odonata in the Kowie River (South Africa) contributed to differences in the contributions of aquatic food sources to their diets. Large Odonata that consumed prey in flight had smaller proportions of aquatic indicator fatty acids and stable iso-tope‐generated proportions of aquatic food sources than did the smaller Odonata that consumed prey from perches. 4. There was a considera-ble amount of interspecific variation in indicators of aquatic feeding, but Odonata at an upstream site had smaller proportions of aquatic indica-tors than those at a downstream site which had higher insect emer-gence rates. 5. The findings of this study contribute information on the dynamics of feeding ecology among adult Odonata, and the substantial contributions of aquatic prey (>80% of total diet in some cases) indicat-ed that cross‐boundary trophic linkages via odonates are strong in the Kowie River.
- Full Text:
- Date Issued: 2018
- Authors: Chari, Lenin D , Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456403 , vital:75510 , xlink:href="https://doi.org/10.1111/een.12459"
- Description: 1. Insects that emerge from rivers provide nutritional subsidies to local riparian predators. Adult damselflies and dragonflies often benefit from aquatic resources, but their high mobility and evasiveness have made it difficult to monitor their diets. 2. A dual fatty acid and stable isotope analysis approach was used to investigate the links between Odonata size and behaviour with proportions of their aquatically derived nutri-tional sources. Additionally, the study investigated the variation in die-tary contributions of aquatic food sources to Odonata between two sec-tions of a river, each with different aquatic productivity rates. 3. Varia-tions in body size and foraging method of Odonata in the Kowie River (South Africa) contributed to differences in the contributions of aquatic food sources to their diets. Large Odonata that consumed prey in flight had smaller proportions of aquatic indicator fatty acids and stable iso-tope‐generated proportions of aquatic food sources than did the smaller Odonata that consumed prey from perches. 4. There was a considera-ble amount of interspecific variation in indicators of aquatic feeding, but Odonata at an upstream site had smaller proportions of aquatic indica-tors than those at a downstream site which had higher insect emer-gence rates. 5. The findings of this study contribute information on the dynamics of feeding ecology among adult Odonata, and the substantial contributions of aquatic prey (>80% of total diet in some cases) indicat-ed that cross‐boundary trophic linkages via odonates are strong in the Kowie River.
- Full Text:
- Date Issued: 2018
Trophic ecology of adult male Odonata. I. Dietary niche metrics by foraging guild, species, body size, and location
- Chari, Lenin D, Moyo, Sydney, Richoux, Nicole B
- Authors: Chari, Lenin D , Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456379 , vital:75508 , xlink:href="https://doi.org/10.1111/een.12458"
- Description: 1. Information on the dietary niches of adult odonates is sparse, as they are highly mobile and evasive animals, which makes them difficult to observe in their natural habitat. Moreover, there is a lack of knowledge on how varying behavioural traits of odonates relate to phenomena like niche partitioning. 2. This study investigated niche partitioning amongst odonate species, foraging guilds and size classes in a riverine system in the Eastern Cape province of South Africa. A combination of stable isotope and fatty acid‐based niches was used to infer odonate feeding. 3. Both fatty acid and stable isotope‐based niches showed that there was niche separation amongst odonates that forage in flight (fliers) and those that forage from a perch (perchers), amongst odonates of different size classes (damselflies, medium‐ and large‐sized dragonflies), and amongst species, although varying levels of niche overlap were observed in each case. 4. Niche sizes of odonates varied between an upstream and a downstream site. Generally greater niche overlap was recorded at the narrow upstream site (associated with low insect emergence rates) than the wider downstream site (associated with high insect emergence rates), indicating that a greater degree of resource sharing occurred at the upstream site where aquatic food was less abundant. 5. The findings of this study suggest that dietary niches of odonates can be influenced by foraging guild, body size, and/or environmental conditions, and additional study in a variety of regions is recommended to determine the greater applicability of these findings.
- Full Text:
- Date Issued: 2018
- Authors: Chari, Lenin D , Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456379 , vital:75508 , xlink:href="https://doi.org/10.1111/een.12458"
- Description: 1. Information on the dietary niches of adult odonates is sparse, as they are highly mobile and evasive animals, which makes them difficult to observe in their natural habitat. Moreover, there is a lack of knowledge on how varying behavioural traits of odonates relate to phenomena like niche partitioning. 2. This study investigated niche partitioning amongst odonate species, foraging guilds and size classes in a riverine system in the Eastern Cape province of South Africa. A combination of stable isotope and fatty acid‐based niches was used to infer odonate feeding. 3. Both fatty acid and stable isotope‐based niches showed that there was niche separation amongst odonates that forage in flight (fliers) and those that forage from a perch (perchers), amongst odonates of different size classes (damselflies, medium‐ and large‐sized dragonflies), and amongst species, although varying levels of niche overlap were observed in each case. 4. Niche sizes of odonates varied between an upstream and a downstream site. Generally greater niche overlap was recorded at the narrow upstream site (associated with low insect emergence rates) than the wider downstream site (associated with high insect emergence rates), indicating that a greater degree of resource sharing occurred at the upstream site where aquatic food was less abundant. 5. The findings of this study suggest that dietary niches of odonates can be influenced by foraging guild, body size, and/or environmental conditions, and additional study in a variety of regions is recommended to determine the greater applicability of these findings.
- Full Text:
- Date Issued: 2018
Decoupled reciprocal subsidies of biomass and fatty acids in fluxes of invertebrates between a temperate river and the adjacent land:
- Moyo, Sydney, Chari, Lenin D, Villet, Martin H, Richoux, Nicole B
- Authors: Moyo, Sydney , Chari, Lenin D , Villet, Martin H , Richoux, Nicole B
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140843 , vital:37923 , DOI: 10.1007/s00027-017-0529-0
- Description: Streams and riparian areas are tightly coupled through reciprocal trophic subsidies, and there is evidence that these subsidies affect consumers in connected ecosystems. Most studies of subsidies consider only their quantity and not their quality. We determined the bidirectional exchange of organisms between the Kowie River and its riparian zone in South Africa using floating pyramidal traps (to measure insect emergence) and pan traps (to capture infalling invertebrates).
- Full Text:
- Date Issued: 2017
- Authors: Moyo, Sydney , Chari, Lenin D , Villet, Martin H , Richoux, Nicole B
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140843 , vital:37923 , DOI: 10.1007/s00027-017-0529-0
- Description: Streams and riparian areas are tightly coupled through reciprocal trophic subsidies, and there is evidence that these subsidies affect consumers in connected ecosystems. Most studies of subsidies consider only their quantity and not their quality. We determined the bidirectional exchange of organisms between the Kowie River and its riparian zone in South Africa using floating pyramidal traps (to measure insect emergence) and pan traps (to capture infalling invertebrates).
- Full Text:
- Date Issued: 2017
Connectivity through allochthony: Reciprocal links between adjacent aquatic and terrestrial ecosystems in South Africa
- Richoux, Nicole B, Moyo, Sydney, Chari, Lenin D, Bergamino, Leandro, Carassou, Laure, Dalu, Tatenda, Hean, Jeffrey W, Sikutshwa, Likho, Gininda, Simphiwe, Magoro, Mandla L, Perhar, Gurbir, Ni, Felicity, Villet, Martin H, Whitfield, Alan K, Parker, Daniel M, Froneman, P William, Arhonditsis, George, Craig, Adrian J F K
- Authors: Richoux, Nicole B , Moyo, Sydney , Chari, Lenin D , Bergamino, Leandro , Carassou, Laure , Dalu, Tatenda , Hean, Jeffrey W , Sikutshwa, Likho , Gininda, Simphiwe , Magoro, Mandla L , Perhar, Gurbir , Ni, Felicity , Villet, Martin H , Whitfield, Alan K , Parker, Daniel M , Froneman, P William , Arhonditsis, George , Craig, Adrian J F K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438363 , vital:73454 , ISBN 978-1-4312-0679-7 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2186-1-15.pdf
- Description: An important aspect of the dynamics of nutrients and pollutants in natural systems is captured in the concept of allochthony, founded on the observation that nutrients and energy in a variety of forms are transferred between adjacent habitats, com-munities and ecosystems that are not routinely considered as connected. Different forms of nutrients and energy move across the conceptual boundaries of habitats via organisms’ activities or physical processes such as wind or water currents, and these transfers can represent important food subsidies. Such cross-partition ecolog-ical subsidies can augment the nutritional condition, biomass and biodiversity of communities, particularly where local production (or autochthony) alone may be inadequate to support local food webs. Furthermore, organic subsidies can influ-ence population dynamics, community interactions and ecosystem processes, and can represent dominant flux inputs in ecosystem budgets. Our intention was to ex-plore organic nutrient fluxes in relation to a primarily lotic (i.e. flowing) aquatic sys-tem at the scale of a hydrological catchment.
- Full Text:
- Date Issued: 2015
- Authors: Richoux, Nicole B , Moyo, Sydney , Chari, Lenin D , Bergamino, Leandro , Carassou, Laure , Dalu, Tatenda , Hean, Jeffrey W , Sikutshwa, Likho , Gininda, Simphiwe , Magoro, Mandla L , Perhar, Gurbir , Ni, Felicity , Villet, Martin H , Whitfield, Alan K , Parker, Daniel M , Froneman, P William , Arhonditsis, George , Craig, Adrian J F K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438363 , vital:73454 , ISBN 978-1-4312-0679-7 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2186-1-15.pdf
- Description: An important aspect of the dynamics of nutrients and pollutants in natural systems is captured in the concept of allochthony, founded on the observation that nutrients and energy in a variety of forms are transferred between adjacent habitats, com-munities and ecosystems that are not routinely considered as connected. Different forms of nutrients and energy move across the conceptual boundaries of habitats via organisms’ activities or physical processes such as wind or water currents, and these transfers can represent important food subsidies. Such cross-partition ecolog-ical subsidies can augment the nutritional condition, biomass and biodiversity of communities, particularly where local production (or autochthony) alone may be inadequate to support local food webs. Furthermore, organic subsidies can influ-ence population dynamics, community interactions and ecosystem processes, and can represent dominant flux inputs in ecosystem budgets. Our intention was to ex-plore organic nutrient fluxes in relation to a primarily lotic (i.e. flowing) aquatic sys-tem at the scale of a hydrological catchment.
- Full Text:
- Date Issued: 2015
Colonisation and community structure of benthic diatoms on artificial substrates following a major flood event: a case of the Kowie River (Eastern Cape, South Africa)
- Dalu, Tatenda, Froneman, P William, Chari, Lenin D, Richoux, Nicole B
- Authors: Dalu, Tatenda , Froneman, P William , Chari, Lenin D , Richoux, Nicole B
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143357 , vital:38239 , http://dx.doi.org/10.4314/wsa.v40i3.10
- Description: A major flooding event that occurred during October–November 2012 caused major changes in the Kowie River hydromorphology and aquatic communities. The aim of our study was to identify the environmental variables that structure riverine benthic diatom communities at upstream and downstream locations 25 km apart on the Kowie River, South Africa. This was undertaken using tiles as artificial substrates so that we could study how the communities developed after the flood disturbance. The diatom community structure was assessed over a 28-day period following a flood event in October 2012. The Mann Whitney test indicated that there was a statistically significant difference (p 0.05) in total dissolved solids, salinity, pH and oxygen reduction potential between the two sites. In total, 58 diatom species belonging to 30 genera were identified over the 28-day study.
- Full Text:
- Date Issued: 2014
- Authors: Dalu, Tatenda , Froneman, P William , Chari, Lenin D , Richoux, Nicole B
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143357 , vital:38239 , http://dx.doi.org/10.4314/wsa.v40i3.10
- Description: A major flooding event that occurred during October–November 2012 caused major changes in the Kowie River hydromorphology and aquatic communities. The aim of our study was to identify the environmental variables that structure riverine benthic diatom communities at upstream and downstream locations 25 km apart on the Kowie River, South Africa. This was undertaken using tiles as artificial substrates so that we could study how the communities developed after the flood disturbance. The diatom community structure was assessed over a 28-day period following a flood event in October 2012. The Mann Whitney test indicated that there was a statistically significant difference (p 0.05) in total dissolved solids, salinity, pH and oxygen reduction potential between the two sites. In total, 58 diatom species belonging to 30 genera were identified over the 28-day study.
- Full Text:
- Date Issued: 2014
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