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:
- 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.
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Culture environment and hatchery of origin influence growth, condition and feeding organ morphology in the Pacific oyster Crassostrea gigas in South Africa
- Nel, A, Pitcher, G, Richoux, Nicole B, Jackson, S
- Authors: Nel, A , Pitcher, G , Richoux, Nicole B , Jackson, S
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457215 , vital:75617 , xlink:href="https://doi.org/10.2989/1814232X.2014.982187"
- Description: South Africa lacks a commercial oyster hatchery. To inform the sourcing of seed for future hatchery establishments, we compared half-sib Pacific oyster Crassostrea gigas cohorts from hatcheries in Namibia and Chile. We measured oyster growth, mortality, condition and feeding organ morphology in Algoa Bay (AB, Eastern Cape) and Saldanha Bay (SB, Western Cape), South Africa, from July 2011 to June 2012. Within SB, 14.3% of mean daily sea temperatures exceeded this species’ thermal optimum of 19 °C, compared to 50.5% in AB. Food abundance (mean daily chlorophyll a concentration) in SB (7.8 mg m–3) was double that in AB (3.9 mg m–3) where, presumably to increase particle clearance rates in a relatively phytoplankton-poor environment, oysters had larger gill:palp surface area ratios. Plankton fatty acid profiles (indicators of food quality) differed between locations. In AB, instantaneous growth rates differed between cohorts, and trends varied seasonally. Within both locations, condition index was usually higher in Chilean oysters, whereas shell density was higher in Namibian oysters. In AB only, Chilean seed suffered substantially higher summer mortalities than Namibian seed, suggesting that the latter are more suited to temperatures in AB. AB should also be assessed for culture of the indigenous oyster species that occur there.
- Full Text:
- Authors: Nel, A , Pitcher, G , Richoux, Nicole B , Jackson, S
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457215 , vital:75617 , xlink:href="https://doi.org/10.2989/1814232X.2014.982187"
- Description: South Africa lacks a commercial oyster hatchery. To inform the sourcing of seed for future hatchery establishments, we compared half-sib Pacific oyster Crassostrea gigas cohorts from hatcheries in Namibia and Chile. We measured oyster growth, mortality, condition and feeding organ morphology in Algoa Bay (AB, Eastern Cape) and Saldanha Bay (SB, Western Cape), South Africa, from July 2011 to June 2012. Within SB, 14.3% of mean daily sea temperatures exceeded this species’ thermal optimum of 19 °C, compared to 50.5% in AB. Food abundance (mean daily chlorophyll a concentration) in SB (7.8 mg m–3) was double that in AB (3.9 mg m–3) where, presumably to increase particle clearance rates in a relatively phytoplankton-poor environment, oysters had larger gill:palp surface area ratios. Plankton fatty acid profiles (indicators of food quality) differed between locations. In AB, instantaneous growth rates differed between cohorts, and trends varied seasonally. Within both locations, condition index was usually higher in Chilean oysters, whereas shell density was higher in Namibian oysters. In AB only, Chilean seed suffered substantially higher summer mortalities than Namibian seed, suggesting that the latter are more suited to temperatures in AB. AB should also be assessed for culture of the indigenous oyster species that occur there.
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Evidence of spatial and temporal changes in sources of organic matter in estuarine sediments
- Bergamino, Leandro, Dalu, Tatenda, Richoux, Nicole B
- Authors: Bergamino, Leandro , Dalu, Tatenda , Richoux, Nicole B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457242 , vital:75619 , xlink:href="https://doi.org/10.1007/s10750-014-1853-1"
- Description: We investigated spatial and temporal changes in sources of organic matter in sediments within an estuarine environment in South Africa using fatty acids (FA) and stable isotopes (SI). Samples of sediments and sources of organic matter [i.e., particulate organic matter, microphytobenthos (MPB), macrophytes, salt marsh plants, and terrestrial leaves] were collected during spring and summer 2012, and autumn and winter 2013 from the upper, middle, and lower reaches. A Stable Isotope Analysis in R (SIAR) mixing model was used to identify the organic matter sources contributing to sediments in each estuarine reach and season. We found that diatom-associated fatty acids (20:5ω3; 16:1ω7) increased toward the upper reaches, while long-chained terrigenous fatty acids (24:0) tended to be more prevalent in lower reach sediments. In support of the FA results, the SI mixing model showed a substantial contribution from the marsh grass Spartina maritima in sediments of the lower estuary during periods of low-freshwater discharge (autumn and winter), while MPB was the main component in sediments from the upper and middle reaches during all seasons. Our results have implications for evaluating estuarine food webs since the spatial and seasonal variability in the organic matter deposited can influence estuarine community structure.
- Full Text:
- Authors: Bergamino, Leandro , Dalu, Tatenda , Richoux, Nicole B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457242 , vital:75619 , xlink:href="https://doi.org/10.1007/s10750-014-1853-1"
- Description: We investigated spatial and temporal changes in sources of organic matter in sediments within an estuarine environment in South Africa using fatty acids (FA) and stable isotopes (SI). Samples of sediments and sources of organic matter [i.e., particulate organic matter, microphytobenthos (MPB), macrophytes, salt marsh plants, and terrestrial leaves] were collected during spring and summer 2012, and autumn and winter 2013 from the upper, middle, and lower reaches. A Stable Isotope Analysis in R (SIAR) mixing model was used to identify the organic matter sources contributing to sediments in each estuarine reach and season. We found that diatom-associated fatty acids (20:5ω3; 16:1ω7) increased toward the upper reaches, while long-chained terrigenous fatty acids (24:0) tended to be more prevalent in lower reach sediments. In support of the FA results, the SI mixing model showed a substantial contribution from the marsh grass Spartina maritima in sediments of the lower estuary during periods of low-freshwater discharge (autumn and winter), while MPB was the main component in sediments from the upper and middle reaches during all seasons. Our results have implications for evaluating estuarine food webs since the spatial and seasonal variability in the organic matter deposited can influence estuarine community structure.
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Fatty acid profiles reveal temporal and spatial differentiation in diets within and among syntopic rocky shore suspension-feeders:
- Richoux, Nicole B, Vermeulen, Ilke, Froneman, P William
- Authors: Richoux, Nicole B , Vermeulen, Ilke , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143346 , vital:38238 , doi: 10.3354/meps10581
- Description: Regional and temporal variations in the diets of rocky shore suspension-feeders (the volcano barnacle Tetraclita serrata, the brown mussel Perna perna and the reef-building polychaete Gunnarea gaimardi) were assessed using fatty acid profiling. Specimens were collected up-current and down-current of a river mouth in 2 coastal regions ~50 km apart along southeastern South Africa during March and July of 2009. One of the rivers represents a marine-dominated system, and the other a freshwater-dominated system. Our aims were to assess any dietary differences among the 3 suspension-feeders, spatial changes in diet within each species (at regional and local scales—50 and 15 km, respectively), and temporal changes in diet within each species.
- Full Text:
- Authors: Richoux, Nicole B , Vermeulen, Ilke , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143346 , vital:38238 , doi: 10.3354/meps10581
- Description: Regional and temporal variations in the diets of rocky shore suspension-feeders (the volcano barnacle Tetraclita serrata, the brown mussel Perna perna and the reef-building polychaete Gunnarea gaimardi) were assessed using fatty acid profiling. Specimens were collected up-current and down-current of a river mouth in 2 coastal regions ~50 km apart along southeastern South Africa during March and July of 2009. One of the rivers represents a marine-dominated system, and the other a freshwater-dominated system. Our aims were to assess any dietary differences among the 3 suspension-feeders, spatial changes in diet within each species (at regional and local scales—50 and 15 km, respectively), and temporal changes in diet within each species.
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Phytoplankton community diversity along a river-estuary continuum
- Dalu, Tatenda, Froneman, P William, Richoux, Nicole B
- Authors: Dalu, Tatenda , Froneman, P William , Richoux, Nicole B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457284 , vital:75622 , xlink:href="https://hdl.handle.net/10520/EJC156752"
- Description: In this paper we examine the aspects of phytoplankton communities along a riverine-estuarine continuum in the Kowie system, Eastern Cape (South Africa). This study aims to relate the phytoplankton population community structure to physicochemical parameters and estimate the different chlorophyll-a concentrations for the Kowie system. Eight sampling sites along a 70 km reach of the Kowie system were sampled over a one-year period. One hundred and seventy-eight species belonging to 78 genera were recorded within the riverine-estuarine continuum. Diatoms were predominant, accounting for 81.9% of the total abundance. The estuary had 98 species (55 genera) recorded whereas the river had 141 species (67 genera). Using a two-way analysis of variance (ANOVA), species richness was found to differ significantly amongst seasons. The chl-a concentration along the estuarine-riverine continuum increased from spring to a high in summer (river mean = 7.9 mg m -3 and estuary mean = 3.3 mg m -3 ) before decreasing to a low in winter. Kruskal Wallis ANOVA showed significant differences among chl-a concentration with seasons and sites. Redundancy analysis identified five factors salinity, water depth, aerial cover, nitrates and ammonia that were significant (p is less than 0.05) in affecting phytoplankton variation. The relatively small study indicates the need for further monitoring to gain a better understanding of Kowie system phytoplankton.
- Full Text:
- Authors: Dalu, Tatenda , Froneman, P William , Richoux, Nicole B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457284 , vital:75622 , xlink:href="https://hdl.handle.net/10520/EJC156752"
- Description: In this paper we examine the aspects of phytoplankton communities along a riverine-estuarine continuum in the Kowie system, Eastern Cape (South Africa). This study aims to relate the phytoplankton population community structure to physicochemical parameters and estimate the different chlorophyll-a concentrations for the Kowie system. Eight sampling sites along a 70 km reach of the Kowie system were sampled over a one-year period. One hundred and seventy-eight species belonging to 78 genera were recorded within the riverine-estuarine continuum. Diatoms were predominant, accounting for 81.9% of the total abundance. The estuary had 98 species (55 genera) recorded whereas the river had 141 species (67 genera). Using a two-way analysis of variance (ANOVA), species richness was found to differ significantly amongst seasons. The chl-a concentration along the estuarine-riverine continuum increased from spring to a high in summer (river mean = 7.9 mg m -3 and estuary mean = 3.3 mg m -3 ) before decreasing to a low in winter. Kruskal Wallis ANOVA showed significant differences among chl-a concentration with seasons and sites. Redundancy analysis identified five factors salinity, water depth, aerial cover, nitrates and ammonia that were significant (p is less than 0.05) in affecting phytoplankton variation. The relatively small study indicates the need for further monitoring to gain a better understanding of Kowie system phytoplankton.
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Stable isotope evidence of food web connectivity by a top predatory fish (Argyrosomus japonicus: Sciaenidae: Teleostei) in the Kowie Estuary, South Africa
- Bergamino, Leandro, Dalu, Tatenda, Whitfield, Alan K, Carassou, Laure, Richoux, Nicole B
- Authors: Bergamino, Leandro , Dalu, Tatenda , Whitfield, Alan K , Carassou, Laure , Richoux, Nicole B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457322 , vital:75625 , xlink:href="https://doi.org/10.2989/1814232X.2014.923782"
- Description: In this study, food web connectivity within the Kowie Estuary on the south-east coast of South Africa was evidenced by the trophic behaviour of the predominantly piscivorous Argyrosomus japonicus. We examined stable isotopes of carbon (δ13C) and nitrogen (δ15N) in the dominant consumers (zooplankton, invertebrates and fishes) and food sources (particulate organic matter, epibionts and benthic microalgae) in the system. An SIAR (Stable Isotope Analysis in R) mixing model was used to interpret the possible food sources for this dominant top predatory fish. Small fishes and large epibenthic invertebrates dominated the diet of A. japonicus. Based on the contrasting diet of these prey fish and invertebrates, we propose that organic matter enters the predatory fish community via two major pathways: (1) a littoral pathway dominated by benthic microalgae production and epibionts, and (2) a channel pathway dominated by suspended particulate organic matter (including phytoplankton). We conclude that the highly mobile A. japonicus consumes both pelagic and benthic fauna from the littoral and channel zones of the estuary, thereby playing a key functional role in linking food webs. This dietary diversity may help explain the success of A. japonicus as a dominant top predator in the system, primarily by increasing the energy available to this species.
- Full Text:
- Authors: Bergamino, Leandro , Dalu, Tatenda , Whitfield, Alan K , Carassou, Laure , Richoux, Nicole B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457322 , vital:75625 , xlink:href="https://doi.org/10.2989/1814232X.2014.923782"
- Description: In this study, food web connectivity within the Kowie Estuary on the south-east coast of South Africa was evidenced by the trophic behaviour of the predominantly piscivorous Argyrosomus japonicus. We examined stable isotopes of carbon (δ13C) and nitrogen (δ15N) in the dominant consumers (zooplankton, invertebrates and fishes) and food sources (particulate organic matter, epibionts and benthic microalgae) in the system. An SIAR (Stable Isotope Analysis in R) mixing model was used to interpret the possible food sources for this dominant top predatory fish. Small fishes and large epibenthic invertebrates dominated the diet of A. japonicus. Based on the contrasting diet of these prey fish and invertebrates, we propose that organic matter enters the predatory fish community via two major pathways: (1) a littoral pathway dominated by benthic microalgae production and epibionts, and (2) a channel pathway dominated by suspended particulate organic matter (including phytoplankton). We conclude that the highly mobile A. japonicus consumes both pelagic and benthic fauna from the littoral and channel zones of the estuary, thereby playing a key functional role in linking food webs. This dietary diversity may help explain the success of A. japonicus as a dominant top predator in the system, primarily by increasing the energy available to this species.
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Stable isotope ratios indicate differential omnivory among syntopic rocky shore suspension-feeders
- Richoux, Nicole B, Vermeulen, Ilke, Froneman, P William
- Authors: Richoux, Nicole B , Vermeulen, Ilke , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68261 , vital:29224 , https://doi.org/10.1007/s00227-013-2358-6
- Description: Publisher version , We utilised stable isotope ratios to assess differences in diet among three indigenous and syntopic rocky shore suspension-feeders (mussels Perna perna, barnacles Tetraclita serrata, and polychaetes Gunnarea gaimardi). We also determined the spatial and temporal variability in the suspension-feeder diets by collecting specimens on two occasions from two regions adjacent to hydrologically distinct river mouths (i.e. one with larger annual freshwater throughput than the other). The results showed that the isotopic niches (used as proxies for trophic niches) of the three species did not overlap and that the barnacles occupied a trophic position (3.4) well above those of the mussels (2) and polychaetes (2.6). We ascribed the interspecific differences primarily to the disparate feeding mechanisms used by the species. Large-scale regional (~50 km) differences in suspension-feeder diets were apparent, but not small-scale (up to a few km north and south of each estuary mouth). The regional differences in diet resulted from the increased availability of estuarine-origin suspended particulate matter (SPM) and zooplankton in the region adjacent to the river with relatively larger freshwater output, although overall incorporation of zooplankton versus mixed SPM into consumer diets was relatively consistent between regions and through time. Temporal shifts in suspension-feeder diets were apparent from stable carbon isotope ratios in the consumers. Our results showcase the measurable effects of regional-scale processes that can alter the food sources for dominant primary consumers in the rocky intertidal, thus potentially affecting entire food webs through bottom-up processes. The clear evidence for trophic niche partitioning offers valuable insights into how potentially strong competitors can coexist.
- Full Text: false
- Authors: Richoux, Nicole B , Vermeulen, Ilke , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68261 , vital:29224 , https://doi.org/10.1007/s00227-013-2358-6
- Description: Publisher version , We utilised stable isotope ratios to assess differences in diet among three indigenous and syntopic rocky shore suspension-feeders (mussels Perna perna, barnacles Tetraclita serrata, and polychaetes Gunnarea gaimardi). We also determined the spatial and temporal variability in the suspension-feeder diets by collecting specimens on two occasions from two regions adjacent to hydrologically distinct river mouths (i.e. one with larger annual freshwater throughput than the other). The results showed that the isotopic niches (used as proxies for trophic niches) of the three species did not overlap and that the barnacles occupied a trophic position (3.4) well above those of the mussels (2) and polychaetes (2.6). We ascribed the interspecific differences primarily to the disparate feeding mechanisms used by the species. Large-scale regional (~50 km) differences in suspension-feeder diets were apparent, but not small-scale (up to a few km north and south of each estuary mouth). The regional differences in diet resulted from the increased availability of estuarine-origin suspended particulate matter (SPM) and zooplankton in the region adjacent to the river with relatively larger freshwater output, although overall incorporation of zooplankton versus mixed SPM into consumer diets was relatively consistent between regions and through time. Temporal shifts in suspension-feeder diets were apparent from stable carbon isotope ratios in the consumers. Our results showcase the measurable effects of regional-scale processes that can alter the food sources for dominant primary consumers in the rocky intertidal, thus potentially affecting entire food webs through bottom-up processes. The clear evidence for trophic niche partitioning offers valuable insights into how potentially strong competitors can coexist.
- Full Text: false
Temporal shifts in the fatty acid profiles of rocky intertidal invertebrates
- Richoux, Nicole B, Ndhlovu, Rachel T
- Authors: Richoux, Nicole B , Ndhlovu, Rachel T
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457336 , vital:75626 , xlink:href="https://doi.org/10.1007/s00227-014-2481-z"
- Description: Fatty acid profiles were determined in rocky intertidal suspension-feeders (mussels and polychaetes) and grazers (limpets and sea urchins) on a monthly basis over 1 year to assess potential dietary overlap between consumers occupying the same trophic guild, and any temporal shifts in diets. Both reproductive and non-reproductive tissues were assessed in an attempt to separate influences of food quality with those of life cycle. Relative variability in fatty acids over time could not be predicted from the feeding guild occupied by a consumer, and influential factors of the temporal shifts included both dietary and reproductive dynamics (even in muscle tissues). Species in the same trophic guild occupied separate trophic niches throughout the year, hence minimising competitive interactions regarding food acquisition. Based on overall variation in fatty acid profiles of muscle tissues, the suspension-feeders Perna perna and Gunnarea gaimardi and the grazing limpet Cymbula oculus occupied narrower feeding niches relative to the grazing sea urchin Parechinus angulosus. Our results provide compelling evidence for potentially large changes in the lipid composition of intertidal invertebrate populations over relatively small temporal scales (i.e. month to month), and these have important implications for short-term field collections intended for assessing invertebrate diets.
- Full Text:
- Authors: Richoux, Nicole B , Ndhlovu, Rachel T
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457336 , vital:75626 , xlink:href="https://doi.org/10.1007/s00227-014-2481-z"
- Description: Fatty acid profiles were determined in rocky intertidal suspension-feeders (mussels and polychaetes) and grazers (limpets and sea urchins) on a monthly basis over 1 year to assess potential dietary overlap between consumers occupying the same trophic guild, and any temporal shifts in diets. Both reproductive and non-reproductive tissues were assessed in an attempt to separate influences of food quality with those of life cycle. Relative variability in fatty acids over time could not be predicted from the feeding guild occupied by a consumer, and influential factors of the temporal shifts included both dietary and reproductive dynamics (even in muscle tissues). Species in the same trophic guild occupied separate trophic niches throughout the year, hence minimising competitive interactions regarding food acquisition. Based on overall variation in fatty acid profiles of muscle tissues, the suspension-feeders Perna perna and Gunnarea gaimardi and the grazing limpet Cymbula oculus occupied narrower feeding niches relative to the grazing sea urchin Parechinus angulosus. Our results provide compelling evidence for potentially large changes in the lipid composition of intertidal invertebrate populations over relatively small temporal scales (i.e. month to month), and these have important implications for short-term field collections intended for assessing invertebrate diets.
- Full Text:
Using multivariate analysis and stable isotopes to assess the effects of substrate type on phytobenthos communities
- Dalu, Tatenda, Richoux, Nicole B, Froneman, P William
- Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68123 , vital:29201 , https://doi.org/10.5268/IW-4.4.719
- Description: Publisher version , For more than a century, artificial substrates have been employed in phytobenthos studies. In the present study, we compared the phytobenthos community structure in a field experiment over 3 seasons (summer, autumn, and winter) on 3 types of artificial substrates (brick, brown clay tiles, and grey clay tiles) and 3 natural substrates (macrophytes, rocks, and sediment) in a small, temperate system. A combination of multivariate analyses (cluster, multi-response permutation procedure, indicator species [IndVal], and canonical correspondence analysis [CCA]) and stable isotope analysis was used. We identified 96 total phytobenthos taxa. Artificial substrates resulted in different substrate communities, as shown by stable isotope analysis, cluster analysis, and a multi-response permutation procedure, with only those communities growing on grey tiles being similar to natural substrate communities. Overall, artificial substrates exhibited slightly higher species richness compared to natural substrates over the 3 seasons, although there were no significant differences (p> 0.05). Phytobenthos grown on brown tiles, rocks, and bricks showed seasonal variability of the carbon isotope δ13C values using one-way ANOVA (p< 0.05). Phytobenthos community structure did not show great seasonal variation; however, CCA identified water flow, conductivity, ammonium, phosphate, and water depth as important in structuring phytobenthos communities on different substrates. IndVal analysis showed that common phytobenthos taxa were not restricted to a single substrate, but preference was generally high for natural substrate, especially rocks, compared to artificial substrates. Substrate microhabitat type seems to influence the communities within the study areas.
- Full Text: false
- Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68123 , vital:29201 , https://doi.org/10.5268/IW-4.4.719
- Description: Publisher version , For more than a century, artificial substrates have been employed in phytobenthos studies. In the present study, we compared the phytobenthos community structure in a field experiment over 3 seasons (summer, autumn, and winter) on 3 types of artificial substrates (brick, brown clay tiles, and grey clay tiles) and 3 natural substrates (macrophytes, rocks, and sediment) in a small, temperate system. A combination of multivariate analyses (cluster, multi-response permutation procedure, indicator species [IndVal], and canonical correspondence analysis [CCA]) and stable isotope analysis was used. We identified 96 total phytobenthos taxa. Artificial substrates resulted in different substrate communities, as shown by stable isotope analysis, cluster analysis, and a multi-response permutation procedure, with only those communities growing on grey tiles being similar to natural substrate communities. Overall, artificial substrates exhibited slightly higher species richness compared to natural substrates over the 3 seasons, although there were no significant differences (p> 0.05). Phytobenthos grown on brown tiles, rocks, and bricks showed seasonal variability of the carbon isotope δ13C values using one-way ANOVA (p< 0.05). Phytobenthos community structure did not show great seasonal variation; however, CCA identified water flow, conductivity, ammonium, phosphate, and water depth as important in structuring phytobenthos communities on different substrates. IndVal analysis showed that common phytobenthos taxa were not restricted to a single substrate, but preference was generally high for natural substrate, especially rocks, compared to artificial substrates. Substrate microhabitat type seems to influence the communities within the study areas.
- Full Text: false
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