Metabolism of free-living and particle-associated prokaryotes Consequences for carbon flux around a Southern Ocean archipelago
- Schapira, Mathilde, McQuaid, Christopher D, Froneman, P William
- Authors: Schapira, Mathilde , McQuaid, Christopher D , Froneman, P William
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/480906 , vital:78492 , https://doi.org/10.1016/j.jmarsys.2011.08.009
- Description: The sub-Antarctic Prince Edward archipelago lies in the path of the Antarctic Circumpolar Current, giving the islands a distinct upstream/downstream axis. Here we examined the possibility of an Island Mass Effect on the prokaryotic community, comparing prokaryotic metabolism in the upstream, inter-island and downstream regions of the islands. Abundance and flow cytometric community structure, heterotrophic production (PHP) and respiration rates (R-ETS) were investigated separately for the particle-associated (PA) and free-living (FL) prokaryote communities.
- Full Text:
- Date Issued: 2012
- Authors: Schapira, Mathilde , McQuaid, Christopher D , Froneman, P William
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/480906 , vital:78492 , https://doi.org/10.1016/j.jmarsys.2011.08.009
- Description: The sub-Antarctic Prince Edward archipelago lies in the path of the Antarctic Circumpolar Current, giving the islands a distinct upstream/downstream axis. Here we examined the possibility of an Island Mass Effect on the prokaryotic community, comparing prokaryotic metabolism in the upstream, inter-island and downstream regions of the islands. Abundance and flow cytometric community structure, heterotrophic production (PHP) and respiration rates (R-ETS) were investigated separately for the particle-associated (PA) and free-living (FL) prokaryote communities.
- Full Text:
- Date Issued: 2012
Aspects of population dynamics and feeding by piscivorous birds in the intermittently open Riet River estuary, Eastern Cape, South Africa
- Froneman, P William, Blake, Justin D, Hulley, Patrick E
- Authors: Froneman, P William , Blake, Justin D , Hulley, Patrick E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481864 , vital:78592 , https://doi.org/10.2989/16085914.2011.559706
- Description: Aspects of the population dynamics and feeding activity of piscivorous birds in the small (c. 5 ha) intermittently open Riet River estuary, on the south-eastern coastline of South Africa, were investigated monthly from August 2005 to July 2006. A total of 188 birds of 13 species were recorded, of which six were wading piscivores, four aerial divers and three were pursuit swimmers. The Reed Cormorant (Phalacrocorax africanus) was the numerically dominant species, with a mean of 8.25 (SD ± 7.90) individuals per count.
- Full Text:
- Date Issued: 2011
- Authors: Froneman, P William , Blake, Justin D , Hulley, Patrick E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481864 , vital:78592 , https://doi.org/10.2989/16085914.2011.559706
- Description: Aspects of the population dynamics and feeding activity of piscivorous birds in the small (c. 5 ha) intermittently open Riet River estuary, on the south-eastern coastline of South Africa, were investigated monthly from August 2005 to July 2006. A total of 188 birds of 13 species were recorded, of which six were wading piscivores, four aerial divers and three were pursuit swimmers. The Reed Cormorant (Phalacrocorax africanus) was the numerically dominant species, with a mean of 8.25 (SD ± 7.90) individuals per count.
- Full Text:
- Date Issued: 2011
Macrofaunal community structure in the littoral zone of a freshwater-deprived, permanently open Eastern Cape estuary
- Henninger, Tony O, Froneman, P William
- Authors: Henninger, Tony O , Froneman, P William
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443954 , vital:74174 , https://doi.org/10.1080/15627020.2011.11407500
- Description: Spatial patterns in the macrofauna community structure within four distinct zones of the permanently open, freshwater-deprived Kariega Estuary on the southeastern coastline of southern Africa were investigated in March–May 2010. The zones within the littoral zone comprised a band of Zostera capensis (Setchell) exposed at spring low tide and comprising Zone I; a band of mud or sand, lacking vegetation, corresponded to Zone II; stands of Spartina maritima (Curtis) formed Zone III and a belt of Sarcocornia perennis (Miller) constituted Zone IV.
- Full Text:
- Date Issued: 2011
- Authors: Henninger, Tony O , Froneman, P William
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443954 , vital:74174 , https://doi.org/10.1080/15627020.2011.11407500
- Description: Spatial patterns in the macrofauna community structure within four distinct zones of the permanently open, freshwater-deprived Kariega Estuary on the southeastern coastline of southern Africa were investigated in March–May 2010. The zones within the littoral zone comprised a band of Zostera capensis (Setchell) exposed at spring low tide and comprising Zone I; a band of mud or sand, lacking vegetation, corresponded to Zone II; stands of Spartina maritima (Curtis) formed Zone III and a belt of Sarcocornia perennis (Miller) constituted Zone IV.
- Full Text:
- Date Issued: 2011
Determining spatial changes in the diet of nearshore suspension-feeders along the South African coastline: stable isotope and fatty acid signatures
- Allan, E Louise, Ambrose, Shan T, Richoux, Nicole B, Froneman, P William
- Authors: Allan, E Louise , Ambrose, Shan T , Richoux, Nicole B , Froneman, P William
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457945 , vital:75697 , xlink:href="https://doi.org/10.1016/j.ecss.2010.02.004"
- Description: Mesoscale oceanographic features, such as upwellings, are known to play an important role in regulating the structure and productivity of nearshore marine communities. Stable isotope (δ13C and δ15N) and fatty acid analyses were employed to assess the influence of an upwelling cell along the south-eastern coastline of southern Africa on the diet of the mussel, Perna perna. Eight sites were sampled: two upstream, three in the vicinity and three downstream of the upwelling cell. Stable isotope and fatty acid signatures indicated that the mussels consumed a diet of detritus derived mainly from macroalgae, diatoms and dinoflagellates. One-way ANOVA on the δ13C and δ15N signatures and the principal component analysis of the fatty acid profiles of the mussels identified distinct groups corresponding to the above mentioned regions. The proportion of diatom biomarkers in the fatty acid profiles decreased downstream of the upwelling region while the proportion of dinoflagellate biomarkers increased. Upwelling regions are typically associated with elevated levels of productivity; however, these systems usually become silicon depleted and result in the replacement of diatoms with dinoflagellates. The highest proportions of the dinoflagellate markers were recorded in the two furthest sites downstream of the upwelling cell. The spatial variation in the diet of the mussels, therefore, appears to reflect the presence of the upwelling cell in the nearshore biology of the region.
- Full Text:
- Date Issued: 2010
- Authors: Allan, E Louise , Ambrose, Shan T , Richoux, Nicole B , Froneman, P William
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457945 , vital:75697 , xlink:href="https://doi.org/10.1016/j.ecss.2010.02.004"
- Description: Mesoscale oceanographic features, such as upwellings, are known to play an important role in regulating the structure and productivity of nearshore marine communities. Stable isotope (δ13C and δ15N) and fatty acid analyses were employed to assess the influence of an upwelling cell along the south-eastern coastline of southern Africa on the diet of the mussel, Perna perna. Eight sites were sampled: two upstream, three in the vicinity and three downstream of the upwelling cell. Stable isotope and fatty acid signatures indicated that the mussels consumed a diet of detritus derived mainly from macroalgae, diatoms and dinoflagellates. One-way ANOVA on the δ13C and δ15N signatures and the principal component analysis of the fatty acid profiles of the mussels identified distinct groups corresponding to the above mentioned regions. The proportion of diatom biomarkers in the fatty acid profiles decreased downstream of the upwelling region while the proportion of dinoflagellate biomarkers increased. Upwelling regions are typically associated with elevated levels of productivity; however, these systems usually become silicon depleted and result in the replacement of diatoms with dinoflagellates. The highest proportions of the dinoflagellate markers were recorded in the two furthest sites downstream of the upwelling cell. The spatial variation in the diet of the mussels, therefore, appears to reflect the presence of the upwelling cell in the nearshore biology of the region.
- Full Text:
- Date Issued: 2010
Feeding dynamics of Palaemon peringueyi (Decapoda, Caridea) in the temporarily openclosed Kasouga Estuary, South Africa
- Froneman, P William, Henninger, Tony O
- Authors: Froneman, P William , Henninger, Tony O
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481875 , vital:78593 , https://doi.org/10.2989/16085914.2010.490982
- Description: The feeding ecology of the caridean shrimp Palaemon peringueyi in the temporarily open/closed Kasouga Estuary, Eastern Cape, was examined during summer and winter employing stomach fullness index (SFI) analysis. Mean SFI values for male and female shrimp during summer ranged from 0.85% to 2.36% and from 0.56% and 2.61% body dry weight, respectively. During winter, SFI values for males and females were lower, and varied between 0.23% and 1.56% and 0.36% and 1.84% body dry weight, respectively.
- Full Text:
- Date Issued: 2010
- Authors: Froneman, P William , Henninger, Tony O
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481875 , vital:78593 , https://doi.org/10.2989/16085914.2010.490982
- Description: The feeding ecology of the caridean shrimp Palaemon peringueyi in the temporarily open/closed Kasouga Estuary, Eastern Cape, was examined during summer and winter employing stomach fullness index (SFI) analysis. Mean SFI values for male and female shrimp during summer ranged from 0.85% to 2.36% and from 0.56% and 2.61% body dry weight, respectively. During winter, SFI values for males and females were lower, and varied between 0.23% and 1.56% and 0.36% and 1.84% body dry weight, respectively.
- Full Text:
- Date Issued: 2010
Growth and longevity of Exosphaeroma hylocoetes (Isopoda) under varying conditions of salinity and temperature
- Henninger, Tony O, Froneman, P William, Booth, Anthony J, Hodgson, Alan N
- Authors: Henninger, Tony O , Froneman, P William , Booth, Anthony J , Hodgson, Alan N
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124571 , vital:35630 , https://doi.org/10.3377/004.045.0118
- Description: Numerous studies have documented the importance of both temperature and salinity in influencing aquatic crustacean metabolic processes such as respiration and growth. For example, increased water temperatures have been shown to increase respiration rates in various species of shrimp (Chen & Nan 1993; Spanonopoulos-Hernándeza et al. 2005; Allan et al. 2006), and copepods (Isla & Perissinotto 2004). The response of invertebrates to changes in salinity is more complex, largely reflecting their evolutionary origins (Kinne 1966). For example, juvenile blue swimming crabs, Portunus pelagicus, displayed significantly faster growth and higher survival in response to increasingsalinity (Romano & Zeng 2006). Additional factors that may influence the growth rates of crustaceans include photoperiod (Gambardella et al. 1997), food availability (Shuster & Guthrie 1999) and sex (Newman et al. 2007).
- Full Text:
- Date Issued: 2010
- Authors: Henninger, Tony O , Froneman, P William , Booth, Anthony J , Hodgson, Alan N
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124571 , vital:35630 , https://doi.org/10.3377/004.045.0118
- Description: Numerous studies have documented the importance of both temperature and salinity in influencing aquatic crustacean metabolic processes such as respiration and growth. For example, increased water temperatures have been shown to increase respiration rates in various species of shrimp (Chen & Nan 1993; Spanonopoulos-Hernándeza et al. 2005; Allan et al. 2006), and copepods (Isla & Perissinotto 2004). The response of invertebrates to changes in salinity is more complex, largely reflecting their evolutionary origins (Kinne 1966). For example, juvenile blue swimming crabs, Portunus pelagicus, displayed significantly faster growth and higher survival in response to increasingsalinity (Romano & Zeng 2006). Additional factors that may influence the growth rates of crustaceans include photoperiod (Gambardella et al. 1997), food availability (Shuster & Guthrie 1999) and sex (Newman et al. 2007).
- Full Text:
- Date Issued: 2010
Plankton trophodynamics at the subtropical convergence, Southern Ocean
- Richoux, Nicole B, Froneman, P William
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457967 , vital:75704 , xlink:href="https://doi.org/10.1093/plankt/fbp054"
- Description: Stable isotope signatures (δ13C, δ15N) in zooplankton tissues and particulate organic matter (POM) were determined to assess regional differences in the trophodynamics of zooplankton communities between 38 and 43°S, where the cool nutrient-rich subantarctic waters of the Southern Ocean meet the warm nutrient-poor subtropical waters of the southwest Indian Ocean at the subtropical convergence (STC). Significantly enriched values of δ15N were noted in populations of all major zooplankton groups inhabiting the warm and saline water mass north of the STC (maximum surface temperature 21°C), including the euphausiids, salps, amphipods, copepods, ostracods, pyrosomes, pteropods and chaetognaths, compared with those in the cool, less saline southern water mass (minimum surface temperature 11°C). Similar patterns of δ15N in POM collected throughout the region suggest that the large changes in zooplankton δ15N values across the frontal region are driven by variations in the phytoplankton communities. The differing trophodynamics in communities north and south of the STC provide compelling evidence of distinct bottom-up effects on planktonic food webs which have important implications in the determination of trophic positions and motility of plankton and higher consumers using δ15N signatures. Although expected, similar latitudinal variations in δ13C signatures were not found.
- Full Text:
- Date Issued: 2009
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457967 , vital:75704 , xlink:href="https://doi.org/10.1093/plankt/fbp054"
- Description: Stable isotope signatures (δ13C, δ15N) in zooplankton tissues and particulate organic matter (POM) were determined to assess regional differences in the trophodynamics of zooplankton communities between 38 and 43°S, where the cool nutrient-rich subantarctic waters of the Southern Ocean meet the warm nutrient-poor subtropical waters of the southwest Indian Ocean at the subtropical convergence (STC). Significantly enriched values of δ15N were noted in populations of all major zooplankton groups inhabiting the warm and saline water mass north of the STC (maximum surface temperature 21°C), including the euphausiids, salps, amphipods, copepods, ostracods, pyrosomes, pteropods and chaetognaths, compared with those in the cool, less saline southern water mass (minimum surface temperature 11°C). Similar patterns of δ15N in POM collected throughout the region suggest that the large changes in zooplankton δ15N values across the frontal region are driven by variations in the phytoplankton communities. The differing trophodynamics in communities north and south of the STC provide compelling evidence of distinct bottom-up effects on planktonic food webs which have important implications in the determination of trophic positions and motility of plankton and higher consumers using δ15N signatures. Although expected, similar latitudinal variations in δ13C signatures were not found.
- Full Text:
- Date Issued: 2009
The role of macrophytes as a refuge and food source for the estuarine isopod Exosphaeroma hylocoetes ()
- Henninger, Tony O, Froneman, P William, Richoux, Nicole B, Hodgson, Alan N
- Authors: Henninger, Tony O , Froneman, P William , Richoux, Nicole B , Hodgson, Alan N
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458360 , vital:75735 , xlink:href="https://doi.org/10.1016/j.ecss.2009.01.01"
- Description: The role of submerged macrophytes as refugia from fish predation and as possible food sources for the estuarine isopod Exosphaeroma hylocoetes (Barnard, K.H., 1940) was investigated. Laboratory experiments tested the effectiveness of artificial vegetation, replicating submerged vegetation, in enabling isopods to elude selected fish predators Rhabdosargus holubi, Glossogobius callidus, Monodactylus falciformis and Clinus cottoides. Isopods preferentially hid in the vegetation (>90%), even in absence of fish. The predatory fish had varying success in finding isopods within the vegetation. Isopod mortality ranged from 2% (R. holubi) to a maximum of 87% (C. cottoides) within vegetation, depending on the fish predator present. Stable isotope and fatty acid analyses ruled out the submerged macrophyte Ruppia maritima and inundated fringing grasses as direct food sources, but highlighted the epiphytic biota (mainly diatoms) found on the submerged vegetation and sediments as more likely food sources. These findings are consistent with gut content analyses. The results suggest that the close association of E. hylocoetes with R. maritima is the result of the vegetation providing the isopod with a refuge against fish predation as well as areas of increased food availability.
- Full Text:
- Date Issued: 2009
- Authors: Henninger, Tony O , Froneman, P William , Richoux, Nicole B , Hodgson, Alan N
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458360 , vital:75735 , xlink:href="https://doi.org/10.1016/j.ecss.2009.01.01"
- Description: The role of submerged macrophytes as refugia from fish predation and as possible food sources for the estuarine isopod Exosphaeroma hylocoetes (Barnard, K.H., 1940) was investigated. Laboratory experiments tested the effectiveness of artificial vegetation, replicating submerged vegetation, in enabling isopods to elude selected fish predators Rhabdosargus holubi, Glossogobius callidus, Monodactylus falciformis and Clinus cottoides. Isopods preferentially hid in the vegetation (>90%), even in absence of fish. The predatory fish had varying success in finding isopods within the vegetation. Isopod mortality ranged from 2% (R. holubi) to a maximum of 87% (C. cottoides) within vegetation, depending on the fish predator present. Stable isotope and fatty acid analyses ruled out the submerged macrophyte Ruppia maritima and inundated fringing grasses as direct food sources, but highlighted the epiphytic biota (mainly diatoms) found on the submerged vegetation and sediments as more likely food sources. These findings are consistent with gut content analyses. The results suggest that the close association of E. hylocoetes with R. maritima is the result of the vegetation providing the isopod with a refuge against fish predation as well as areas of increased food availability.
- Full Text:
- Date Issued: 2009
A multidisciplinary study of a small, temporarily open/closed South African estuary, with particular emphasis on the influence of mouth state on the ecology of the system
- Whitfield, Alan K, Adams, Janine B, Bate, G C, Bezuidenhout, K, Bornman, Thomas G, Cowley, Paul D, Froneman, P William, Gama, P T, James, Nicola C, Mackenzie, B, Riddin, T, Snow, G C, Strydom, Nadine A, Taljaard, S, Terörde, A I, Theron, A K, Turpie, J K, Van Niekerk, L, Vorwerk, Paul D, Wooldridge, T H
- Authors: Whitfield, Alan K , Adams, Janine B , Bate, G C , Bezuidenhout, K , Bornman, Thomas G , Cowley, Paul D , Froneman, P William , Gama, P T , James, Nicola C , Mackenzie, B , Riddin, T , Snow, G C , Strydom, Nadine A , Taljaard, S , Terörde, A I , Theron, A K , Turpie, J K , Van Niekerk, L , Vorwerk, Paul D , Wooldridge, T H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/480839 , vital:78481 , https://doi.org/10.2989/AJMS.2008.30.3.2.636
- Description: In 2005/2006 a multidisciplinary research programme that included studies on the hydrodynamics, sediment dynamics, macronutrients, microalgae, macrophytes, zoobenthos, hyperbenthos, zooplankton, ichthyoplankton, fish and birds of the temporarily open/closed East Kleinemonde Estuary was conducted. Particular attention was given to the responses of the different ecosystem components to the opening and closing of the estuary mouth and how this is driven by both riverine and marine events. Using a complementary dataset of daily estuary mouth conditions spanning a 14-year period, five distinct phases of the estuary were identified, including closed (average = 90% of the days), outflow (below1%), tidal (9%) and semi-closed (below1%). The open-mouth phase is critical for the movements of a number of estuary-associated fish (e.g. Rhabdosargus holubi) and invertebrates (e.g. Scylla serrata) between the estuary and sea.
- Full Text:
- Date Issued: 2008
- Authors: Whitfield, Alan K , Adams, Janine B , Bate, G C , Bezuidenhout, K , Bornman, Thomas G , Cowley, Paul D , Froneman, P William , Gama, P T , James, Nicola C , Mackenzie, B , Riddin, T , Snow, G C , Strydom, Nadine A , Taljaard, S , Terörde, A I , Theron, A K , Turpie, J K , Van Niekerk, L , Vorwerk, Paul D , Wooldridge, T H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/480839 , vital:78481 , https://doi.org/10.2989/AJMS.2008.30.3.2.636
- Description: In 2005/2006 a multidisciplinary research programme that included studies on the hydrodynamics, sediment dynamics, macronutrients, microalgae, macrophytes, zoobenthos, hyperbenthos, zooplankton, ichthyoplankton, fish and birds of the temporarily open/closed East Kleinemonde Estuary was conducted. Particular attention was given to the responses of the different ecosystem components to the opening and closing of the estuary mouth and how this is driven by both riverine and marine events. Using a complementary dataset of daily estuary mouth conditions spanning a 14-year period, five distinct phases of the estuary were identified, including closed (average = 90% of the days), outflow (below1%), tidal (9%) and semi-closed (below1%). The open-mouth phase is critical for the movements of a number of estuary-associated fish (e.g. Rhabdosargus holubi) and invertebrates (e.g. Scylla serrata) between the estuary and sea.
- Full Text:
- Date Issued: 2008
Biological responses to a resumption in river flow in a freshwater-deprived, permanently open Southern African estuary
- Vorwerk, Paul D, Froneman, P William, Paterson, Angus W, Strydom, Nadine A, Whitfield, Alan K
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Strydom, Nadine A , Whitfield, Alan K
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6886 , http://hdl.handle.net/10962/d1011645
- Description: The Kariega Estuary is a freshwater-deprived system due to numerous impoundments in the catchment. This system has had little or no horizontal salinity gradient over the last 15 years, with hypersaline conditions sometimes predominating in the upper reaches. Following high rainfall events in the catchment during the spring of 2006, including a flood event (approximate 1:10 year) in August 2006, a series of riverine pulses entered the estuary and a horizontal salinity gradient was established. This study examined the influence of this freshwater pulse on four components of the biota within the estuary, namely the zooplankton, and larval, littoral and demersal fishes. The study demonstrated that in three of these components elevated densities were recorded following the riverine input, with only the littoral fishes retaining an almost constant density. In addition, changes in the relative contributions of the estuarine utilisation classes for all three fish groups examined indicated that freshwater input into these systems positively influences the abundances. This has significant implications for water managers as it demonstrates the importance of an Ecological Reserve (defined as ‘the water required to protect the aquatic ecosystems of the water resource’) for this system.
- Full Text:
- Date Issued: 2008
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Strydom, Nadine A , Whitfield, Alan K
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6886 , http://hdl.handle.net/10962/d1011645
- Description: The Kariega Estuary is a freshwater-deprived system due to numerous impoundments in the catchment. This system has had little or no horizontal salinity gradient over the last 15 years, with hypersaline conditions sometimes predominating in the upper reaches. Following high rainfall events in the catchment during the spring of 2006, including a flood event (approximate 1:10 year) in August 2006, a series of riverine pulses entered the estuary and a horizontal salinity gradient was established. This study examined the influence of this freshwater pulse on four components of the biota within the estuary, namely the zooplankton, and larval, littoral and demersal fishes. The study demonstrated that in three of these components elevated densities were recorded following the riverine input, with only the littoral fishes retaining an almost constant density. In addition, changes in the relative contributions of the estuarine utilisation classes for all three fish groups examined indicated that freshwater input into these systems positively influences the abundances. This has significant implications for water managers as it demonstrates the importance of an Ecological Reserve (defined as ‘the water required to protect the aquatic ecosystems of the water resource’) for this system.
- Full Text:
- Date Issued: 2008
Fish community response to increased river flow in the Kariega Estuary, a freshwater-deprived, permanently open southern African system
- Vorwerk, Paul D, Froneman, P William, Paterson, Angus W, Whitfield, Alan K
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Whitfield, Alan K
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481886 , vital:78594 , https://doi.org/10.2989/AJAS.2008.33.3.1.613
- Description: The littoral and demersal ichthyofaunal community structure in the freshwater-deprived, permanently open Kariega Estuary was investigated following heavy rain in November 2006 and was compared to low-flow condition data from 1991 and 1996. All surveys took place during the spring months and allowed for a comparison of a wet and a dry spring period.
- Full Text:
- Date Issued: 2008
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Whitfield, Alan K
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481886 , vital:78594 , https://doi.org/10.2989/AJAS.2008.33.3.1.613
- Description: The littoral and demersal ichthyofaunal community structure in the freshwater-deprived, permanently open Kariega Estuary was investigated following heavy rain in November 2006 and was compared to low-flow condition data from 1991 and 1996. All surveys took place during the spring months and allowed for a comparison of a wet and a dry spring period.
- Full Text:
- Date Issued: 2008
The effects of increased freshwater inflow on metal enrichment in selected Eastern Cape estuaries, South Africa
- Orr, Kyla K, Burgess, Jo E, Froneman, P William
- Authors: Orr, Kyla K , Burgess, Jo E , Froneman, P William
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6967 , http://hdl.handle.net/10962/d1012032
- Description: The concentrations of select metals (Cd, Co, Cu, Fe, Pb, Ni and Zn) within the water column and sediment of the permanently open Kariega Estuary and temporary open / closed Riet and East Kleinemonde Estuaries were investigated during a dry and a wet season. Enrichment factors (EFs), using Fe as a reference element, and baseline linear regression models for metals vs Fe were used to assess the extent of metal enrichment in the sediments. The results of the study indicate that Cd, Co Ni and Pb were enriched above baseline concentrations (1.0 < EF < 4.1) in the sediments of all three estuaries. Co, Pb and Ni enrichment in the Kariega Estuary sediments was significantly higher during the dry season, and the mean concentrations of Pb and Cd in the water column were 19-fold and 66-fold higher in the dry season. The elevated concentration of metals during the dry season could be related to accumulation of diffuse pollution from human activities within the catchment area. Conversely, inflow of freshwater into the estuary had the net effect of reducing the concentration and enrichment of these metals within the Kariega Estuary due to scouring and outflow of estuarine water and sediment into the marine environment. The temporal variations in metal concentrations and enrichment factors were less pronounced in the temporary open / closed estuaries than the Kariega Estuary. The observed trend can probably be related to the low anthropogenic impact within the catchment areas of these systems, and the relatively smaller size of the catchments. Significant spatial variations existed in metal enrichment in the sediment of both the East Kleinemonde and Riet Estuaries, with the highest degrees of enrichment occurring in the sediments from the marine environment and lower reaches.
- Full Text:
- Date Issued: 2008
- Authors: Orr, Kyla K , Burgess, Jo E , Froneman, P William
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6967 , http://hdl.handle.net/10962/d1012032
- Description: The concentrations of select metals (Cd, Co, Cu, Fe, Pb, Ni and Zn) within the water column and sediment of the permanently open Kariega Estuary and temporary open / closed Riet and East Kleinemonde Estuaries were investigated during a dry and a wet season. Enrichment factors (EFs), using Fe as a reference element, and baseline linear regression models for metals vs Fe were used to assess the extent of metal enrichment in the sediments. The results of the study indicate that Cd, Co Ni and Pb were enriched above baseline concentrations (1.0 < EF < 4.1) in the sediments of all three estuaries. Co, Pb and Ni enrichment in the Kariega Estuary sediments was significantly higher during the dry season, and the mean concentrations of Pb and Cd in the water column were 19-fold and 66-fold higher in the dry season. The elevated concentration of metals during the dry season could be related to accumulation of diffuse pollution from human activities within the catchment area. Conversely, inflow of freshwater into the estuary had the net effect of reducing the concentration and enrichment of these metals within the Kariega Estuary due to scouring and outflow of estuarine water and sediment into the marine environment. The temporal variations in metal concentrations and enrichment factors were less pronounced in the temporary open / closed estuaries than the Kariega Estuary. The observed trend can probably be related to the low anthropogenic impact within the catchment areas of these systems, and the relatively smaller size of the catchments. Significant spatial variations existed in metal enrichment in the sediment of both the East Kleinemonde and Riet Estuaries, with the highest degrees of enrichment occurring in the sediments from the marine environment and lower reaches.
- Full Text:
- Date Issued: 2008
The population dynamics of the estuarine isopod Exosphaeroma hylocoetes (Barnard, 1940) within three temporarily open/closed southern African estuaries
- Henninger, Tony O, Froneman, P William, Hodgson, Alan N
- Authors: Henninger, Tony O , Froneman, P William , Hodgson, Alan N
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447627 , vital:74662 , https://doi.org/10.1080/15627020.2008.11657237
- Description: The population dynamics of the estuarine isopod, Exosphaeroma hylocoetes, was investigated monthly from February 2006 to August 2007 in three temporarily open/closed Eastern Cape estuaries, the East and West Kleinemonde and Kasouga Estuaries. Mean isopod abundances and biomasses ranged between 0 and 4791 ind/m2 and 0 and 9.65 mg/dwt/m2 in the West Kleinemonde Estuary and between 0 and 108 ind/m2 and 0 and 0.318 mg/dwt/m2 in the nearby East Kleinemonde Estuary. In the Kasouga Estuary, the values ranged between 0 and 3650 ind/m2 and 0 and 5.105 mg/dwt/m2. Temporal changes in the abundance and biomass of E. hylocoetes within the three systems was primarily linked to mouth phase, with populations crashing when the mouth was open and to a lesser extent, seasonality. In all three estuaries maximum abundance and biomass was recorded in the middle reaches, which could be ascribed to the presence of submerged macrophytes. E. hylocoetes demonstrates strong sexual dimorphism, with males being significantly larger than females (P 0.05). Sex ratios were skewed in favour of females in all three estuaries.
- Full Text:
- Date Issued: 2008
- Authors: Henninger, Tony O , Froneman, P William , Hodgson, Alan N
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447627 , vital:74662 , https://doi.org/10.1080/15627020.2008.11657237
- Description: The population dynamics of the estuarine isopod, Exosphaeroma hylocoetes, was investigated monthly from February 2006 to August 2007 in three temporarily open/closed Eastern Cape estuaries, the East and West Kleinemonde and Kasouga Estuaries. Mean isopod abundances and biomasses ranged between 0 and 4791 ind/m2 and 0 and 9.65 mg/dwt/m2 in the West Kleinemonde Estuary and between 0 and 108 ind/m2 and 0 and 0.318 mg/dwt/m2 in the nearby East Kleinemonde Estuary. In the Kasouga Estuary, the values ranged between 0 and 3650 ind/m2 and 0 and 5.105 mg/dwt/m2. Temporal changes in the abundance and biomass of E. hylocoetes within the three systems was primarily linked to mouth phase, with populations crashing when the mouth was open and to a lesser extent, seasonality. In all three estuaries maximum abundance and biomass was recorded in the middle reaches, which could be ascribed to the presence of submerged macrophytes. E. hylocoetes demonstrates strong sexual dimorphism, with males being significantly larger than females (P 0.05). Sex ratios were skewed in favour of females in all three estuaries.
- Full Text:
- Date Issued: 2008
Trophic ecology of dominant zooplankton and macrofauna in a temperate, oligotrophic South African estuary: a fatty acid approach
- Richoux, Nicole B, Froneman, P William
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/478883 , vital:78235 , https://doi.org/10.3354/meps07323
- Description: Fatty acid profiles of food sources, dominant zooplankton, macrofauna and a few small ichthyofauna in a temperate estuary on the southeastern coast of South Africa were used to trace the original carbon sources and the degree of feeding plasticity of consumers within an oligotrophic environment. Fatty acid analysis is seldom used to examine food web ecology in estuaries, as these systems are typically highly complex owing to the variety of potential food sources and the variable nature of detritus. We hypothesized that generalist consumers would exhibit similar and overlapping fatty acid compositions, whereas any specialist consumers would ‘stand out’as they may contain high proportions of fatty acids specific to their preferred food sources. Within-species variation was very small in the food sources, and Principal Component Analysis (PCA) allowed resolution of most species and sample types into distinct clusters. Variation of fatty acid composition was greater within the consumers, with PCA resolving several clusters by collection location within the site and feeding mode of the animals (suspension feeders, grazers and omnivores). We considered the fatty acid profiles (with particular reference to polyunsaturated fatty acids and essential fatty acids) of the consumers in relation to the food sources to determine which organisms played significant roles in the sequestration and cycling of high quality organic material within the estuary.
- Full Text:
- Date Issued: 2008
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/478883 , vital:78235 , https://doi.org/10.3354/meps07323
- Description: Fatty acid profiles of food sources, dominant zooplankton, macrofauna and a few small ichthyofauna in a temperate estuary on the southeastern coast of South Africa were used to trace the original carbon sources and the degree of feeding plasticity of consumers within an oligotrophic environment. Fatty acid analysis is seldom used to examine food web ecology in estuaries, as these systems are typically highly complex owing to the variety of potential food sources and the variable nature of detritus. We hypothesized that generalist consumers would exhibit similar and overlapping fatty acid compositions, whereas any specialist consumers would ‘stand out’as they may contain high proportions of fatty acids specific to their preferred food sources. Within-species variation was very small in the food sources, and Principal Component Analysis (PCA) allowed resolution of most species and sample types into distinct clusters. Variation of fatty acid composition was greater within the consumers, with PCA resolving several clusters by collection location within the site and feeding mode of the animals (suspension feeders, grazers and omnivores). We considered the fatty acid profiles (with particular reference to polyunsaturated fatty acids and essential fatty acids) of the consumers in relation to the food sources to determine which organisms played significant roles in the sequestration and cycling of high quality organic material within the estuary.
- Full Text:
- Date Issued: 2008
Assessment of spatial variation in carbon utilization by benthic and pelagic invertebrates in a temperate South African estuary using stable isotope signatures
- Richoux, Nicole B, Froneman, P William
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457923 , vital:75695 , xlink:href="https://doi.org/10.1016/j.ecss.2006.09.007 "
- Description: Stable isotope analyses (δ13C and δ15N) were used to evaluate the spatial variations in carbon flow from primary producers to consumers at two sites in the temperate and permanently open Kariega Estuary on the southeastern coast of South Africa during October 2005 and February 2006. One site was located opposite a salt marsh while the second was upstream of the marsh. Except for significantly enriched δ13C values of Zostera capensis and surface sediments near the salt marsh, the δ13C and δ15N signatures of the producers were similar between sites. The invertebrates were clustered into groups roughly corresponding to the predominant feeding modes. The suspension feeders showed δ13C values closest to the seston, whereas the deposit feeders, detritivores and scavengers/predators had more enriched δ13C values reflecting primary carbon sources that were likely a combination of seston, Spartina maritima and Z. capensis at the upstream site, with an increased influence of benthic algae and Z. capensis at the salt marsh site. The δ15N signatures of the consumers showed a stepwise continuum rather than distinct levels of fractionation, indicating highly complex trophic linkages and significant dietary overlap among the species. Consumers exhibited significantly enriched δ13C values at the salt marsh site, an effect that was attributed to enriched Z. capensis detritus in this region in addition to increased phytoplankton biomass in their diets compared with invertebrates living upstream. The data reinforce the concept that between-site variations in the stable isotope ratios of consumers can result not only from dietary shifts, but also from alterations in the isotope ratios of primary producers.
- Full Text:
- Date Issued: 2007
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457923 , vital:75695 , xlink:href="https://doi.org/10.1016/j.ecss.2006.09.007 "
- Description: Stable isotope analyses (δ13C and δ15N) were used to evaluate the spatial variations in carbon flow from primary producers to consumers at two sites in the temperate and permanently open Kariega Estuary on the southeastern coast of South Africa during October 2005 and February 2006. One site was located opposite a salt marsh while the second was upstream of the marsh. Except for significantly enriched δ13C values of Zostera capensis and surface sediments near the salt marsh, the δ13C and δ15N signatures of the producers were similar between sites. The invertebrates were clustered into groups roughly corresponding to the predominant feeding modes. The suspension feeders showed δ13C values closest to the seston, whereas the deposit feeders, detritivores and scavengers/predators had more enriched δ13C values reflecting primary carbon sources that were likely a combination of seston, Spartina maritima and Z. capensis at the upstream site, with an increased influence of benthic algae and Z. capensis at the salt marsh site. The δ15N signatures of the consumers showed a stepwise continuum rather than distinct levels of fractionation, indicating highly complex trophic linkages and significant dietary overlap among the species. Consumers exhibited significantly enriched δ13C values at the salt marsh site, an effect that was attributed to enriched Z. capensis detritus in this region in addition to increased phytoplankton biomass in their diets compared with invertebrates living upstream. The data reinforce the concept that between-site variations in the stable isotope ratios of consumers can result not only from dietary shifts, but also from alterations in the isotope ratios of primary producers.
- Full Text:
- Date Issued: 2007
Conserving pattern and process in the Southern Ocean: designing a Marine Protected Area for the Prince Edward Islands
- Lombard, Amanda T, Reyers, B, Schonegevel, L Y, Cooper, J, Smith-Adao, L B, Nel, D C, Froneman, P William, Ansorge, Isabelle J, Bester, Marthán N, Tosh, C A, Strauss, T, Akkers, T, Gon, Ofer, Leslie, Rob W, Chown, Steven L
- Authors: Lombard, Amanda T , Reyers, B , Schonegevel, L Y , Cooper, J , Smith-Adao, L B , Nel, D C , Froneman, P William , Ansorge, Isabelle J , Bester, Marthán N , Tosh, C A , Strauss, T , Akkers, T , Gon, Ofer , Leslie, Rob W , Chown, Steven L
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6881 , http://hdl.handle.net/10962/d1011637
- Description: South Africa is currently proclaiming a Marine Protected Area (MPA) in the Exclusive Economic Zone (EEZ) of its sub-Antarctic Prince Edward Islands. The objectives of the MPA are to: 1) contribute to a national and global representative system of MPAs, 2) serve as a scientific reference point to inform future management, 3) contribute to the recovery of the Patagonian toothfish (Dissostichus eleginoides), and 4) reduce the bird bycatch of the toothfish fishery, particularly of albatrosses and petrels. This study employs systematic conservation planning methods to delineate a MPA within the EEZ that will conserve biodiversity patterns and processes within sensible management boundaries, while minimizing conflict with the legal toothfish fishery. After collating all available distributional data on species, benthic habitats and ecosystem processes, we used C-Plan software to delineate a MPA with three management zones: four IUCN Category Ia reserves (13% of EEZ); two Conservation Zones (21% of EEZ); and three Category IV reserves (remainder of EEZ). Compromises between conservation target achievement and the area required by the MPA are apparent in the final reserve design. The proposed MPA boundaries are expected to change over time as new data become available and as impacts of climate change become more evident.
- Full Text:
- Date Issued: 2007
- Authors: Lombard, Amanda T , Reyers, B , Schonegevel, L Y , Cooper, J , Smith-Adao, L B , Nel, D C , Froneman, P William , Ansorge, Isabelle J , Bester, Marthán N , Tosh, C A , Strauss, T , Akkers, T , Gon, Ofer , Leslie, Rob W , Chown, Steven L
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6881 , http://hdl.handle.net/10962/d1011637
- Description: South Africa is currently proclaiming a Marine Protected Area (MPA) in the Exclusive Economic Zone (EEZ) of its sub-Antarctic Prince Edward Islands. The objectives of the MPA are to: 1) contribute to a national and global representative system of MPAs, 2) serve as a scientific reference point to inform future management, 3) contribute to the recovery of the Patagonian toothfish (Dissostichus eleginoides), and 4) reduce the bird bycatch of the toothfish fishery, particularly of albatrosses and petrels. This study employs systematic conservation planning methods to delineate a MPA within the EEZ that will conserve biodiversity patterns and processes within sensible management boundaries, while minimizing conflict with the legal toothfish fishery. After collating all available distributional data on species, benthic habitats and ecosystem processes, we used C-Plan software to delineate a MPA with three management zones: four IUCN Category Ia reserves (13% of EEZ); two Conservation Zones (21% of EEZ); and three Category IV reserves (remainder of EEZ). Compromises between conservation target achievement and the area required by the MPA are apparent in the final reserve design. The proposed MPA boundaries are expected to change over time as new data become available and as impacts of climate change become more evident.
- Full Text:
- Date Issued: 2007
Exploring trophodynamics in the Southern Ocean: applications of fatty acid biomarkers and stable isotope ratios
- Richoux, Nicole B, Froneman, P William
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457956 , vital:75703 , xlink:href="http://hdl.handle.net/123456789/28541"
- Description: The dynamics of transfer of organic carbon among producers and consumers has interested trophic ecologists for several decades1. This field of research has proven to be particularly challenging for those investigating aquatic environments, as organisms of interest are often very small, remote and/or behaviourally complex. Furthermore, many species of plankton demonstrate a high degree of feeding plasticity, as the nature and availability of food can vary considerably both spatially and temporally. The diets of consumers are classically studied using gut contents and/or gut fluorescence analyses, approaches that are limited to freshly ingested prey, and in the latter case to herbivorous feeding2. Two methods that provide a time-integrated view of an organism's assimilated feeding history and incorporate both herbivorous and carnivorous pathways involve the determination of stable isotope ratios and fatty acid profiles3 4. Stable isotope ratios in animal tissues can be used as tracers to original sources of carbon at the base of a food chain as well as indicators of the trophic level of a population5, and fatty acids can provide information on the type and quality of resources assimilated by aquatic animals over ecologically meaningful time periods6,7. The aims of our current study are to determine trophodynamics among the numerically dominant zooplankton species and to assess regional differences in ecosystem fitness within the Subtropical Convergence zone (STC) using both stable isotope ratios and fatty acid profiles. As the STC can act as an effective biogeographical barrier8 food webs and the dynamics of energy transfer from primary producers to consumers on either side of this barrier are expected to differ. As global climate change has the potential to cause major shifts in the location, strength and physical and biological properties of the STC9 it is important to understand the potential effects on the biological communities inhabiting the region. Any changes in the food quality or availability for the dominant species or in the trophic relationships among producers and consumers may have serious implications for top consumers such as fish, birds and mammals. Successful characterization of food webs in the STC will provide an excellent framework for future studies in Southern Ocean trophic ecology.
- Full Text:
- Date Issued: 2007
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457956 , vital:75703 , xlink:href="http://hdl.handle.net/123456789/28541"
- Description: The dynamics of transfer of organic carbon among producers and consumers has interested trophic ecologists for several decades1. This field of research has proven to be particularly challenging for those investigating aquatic environments, as organisms of interest are often very small, remote and/or behaviourally complex. Furthermore, many species of plankton demonstrate a high degree of feeding plasticity, as the nature and availability of food can vary considerably both spatially and temporally. The diets of consumers are classically studied using gut contents and/or gut fluorescence analyses, approaches that are limited to freshly ingested prey, and in the latter case to herbivorous feeding2. Two methods that provide a time-integrated view of an organism's assimilated feeding history and incorporate both herbivorous and carnivorous pathways involve the determination of stable isotope ratios and fatty acid profiles3 4. Stable isotope ratios in animal tissues can be used as tracers to original sources of carbon at the base of a food chain as well as indicators of the trophic level of a population5, and fatty acids can provide information on the type and quality of resources assimilated by aquatic animals over ecologically meaningful time periods6,7. The aims of our current study are to determine trophodynamics among the numerically dominant zooplankton species and to assess regional differences in ecosystem fitness within the Subtropical Convergence zone (STC) using both stable isotope ratios and fatty acid profiles. As the STC can act as an effective biogeographical barrier8 food webs and the dynamics of energy transfer from primary producers to consumers on either side of this barrier are expected to differ. As global climate change has the potential to cause major shifts in the location, strength and physical and biological properties of the STC9 it is important to understand the potential effects on the biological communities inhabiting the region. Any changes in the food quality or availability for the dominant species or in the trophic relationships among producers and consumers may have serious implications for top consumers such as fish, birds and mammals. Successful characterization of food webs in the STC will provide an excellent framework for future studies in Southern Ocean trophic ecology.
- Full Text:
- Date Issued: 2007
Phylogeographic structure of the caridean shrimp Palaemon peringueyi in South Africa: further evidence for intraspecific genetic units associated with marine biogeographic provinces
- Teske, Peter R, Froneman, P William, Barker, Nigel P, McQuaid, Christopher D
- Authors: Teske, Peter R , Froneman, P William , Barker, Nigel P , McQuaid, Christopher D
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445486 , vital:74392 , https://doi.org/10.2989/AJMS.2007.29.2.9.192
- Description: Recent genetic studies have shown that most widely distributed, passively dispersing invertebrates in southern Africa have regional intraspecific units that are associated with the three main marine biogeographic provinces (cool-temperate, warm-temperate and subtropical). The caridean shrimp Palaemon peringueyi also occurs in all three provinces, but the fact that it can disperse both actively and passively (i.e. larval drifting, adult walking/swimming and potential adult rafting by means of floating objects) suggests that the amount of gene flow between regions may be too high for evolutionary divergence to have taken place. Samples of P. peringueyi were collected throughout South Africa and an intraspecific phylogeny was reconstructed using mitochondrial COI and 16S rRNA sequences. Three major clades were recovered, which were broadly associated with the three biogeographic regions. This suggests that, even though P. peringueyi can disperse actively, the fact that neither larvae nor adults are strong swimmers has resulted in genetic subdivisons comparable to those of passively dispersing coastal invertebrates in southern Africa.
- Full Text:
- Date Issued: 2007
- Authors: Teske, Peter R , Froneman, P William , Barker, Nigel P , McQuaid, Christopher D
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445486 , vital:74392 , https://doi.org/10.2989/AJMS.2007.29.2.9.192
- Description: Recent genetic studies have shown that most widely distributed, passively dispersing invertebrates in southern Africa have regional intraspecific units that are associated with the three main marine biogeographic provinces (cool-temperate, warm-temperate and subtropical). The caridean shrimp Palaemon peringueyi also occurs in all three provinces, but the fact that it can disperse both actively and passively (i.e. larval drifting, adult walking/swimming and potential adult rafting by means of floating objects) suggests that the amount of gene flow between regions may be too high for evolutionary divergence to have taken place. Samples of P. peringueyi were collected throughout South Africa and an intraspecific phylogeny was reconstructed using mitochondrial COI and 16S rRNA sequences. Three major clades were recovered, which were broadly associated with the three biogeographic regions. This suggests that, even though P. peringueyi can disperse actively, the fact that neither larvae nor adults are strong swimmers has resulted in genetic subdivisons comparable to those of passively dispersing coastal invertebrates in southern Africa.
- Full Text:
- Date Issued: 2007
Physical and biological processes at the Subtropical Convergence in the South-west Indian Ocean
- Froneman, P William, Ansorge, Isabelle J, Richoux, Nicole B, Blake, Justin D, Daly, Ryan, Sterley, Jessica A, Mostert, Bruce P, Heyns, Elodie R, Sheppard, Jill N, Kuyper, B, Hart, N, George, C, Howard, J, Mustafa, E, Pey, F, Lutjeharms, Johan R E
- Authors: Froneman, P William , Ansorge, Isabelle J , Richoux, Nicole B , Blake, Justin D , Daly, Ryan , Sterley, Jessica A , Mostert, Bruce P , Heyns, Elodie R , Sheppard, Jill N , Kuyper, B , Hart, N , George, C , Howard, J , Mustafa, E , Pey, F , Lutjeharms, Johan R E
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6966 , http://hdl.handle.net/10962/d1012030
- Description: A detailed hydrographic and biological survey was conducted in the region of the Subtropical Convergence in the Indian sector of the Southern Ocean in April 2007. Hydrographic data revealed that the subsurface expression of the Subtropical Convergence (at 200 m), marked by the 10°C isotherm, appeared to meander considerably between 41°S and 42°15’S. Total surface chlorophyll- a concentration was low and ranged from 0.03 to 0.42 µg l–1 and was always dominated by the pico- (<2 µm) and nano- (2–120 µm) size classes, which contributed between 81% and 93% of the total pigment. The total chlorophyll-a integrated over the top 150m of the water column showed no distinct spatial trends, and ranged from 12.8 to 40.1mg chl-a m–2. There were no significant correlations between the total integrated chlorophyll- a concentration and temperature and salinity (P > 0.05). The zooplankton community was dominated, numerically and by biomass, by mesozooplankton comprising mainly copepods of the genera, Oithona,Paraeuchaeta, Pleuromamma, Calanus and Clausocalanus. An exception was recorded at those stations in the region of the front where the tunicate, Salpa thompsoni, dominated the total zooplankton biomass.
- Full Text:
- Date Issued: 2007
- Authors: Froneman, P William , Ansorge, Isabelle J , Richoux, Nicole B , Blake, Justin D , Daly, Ryan , Sterley, Jessica A , Mostert, Bruce P , Heyns, Elodie R , Sheppard, Jill N , Kuyper, B , Hart, N , George, C , Howard, J , Mustafa, E , Pey, F , Lutjeharms, Johan R E
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6966 , http://hdl.handle.net/10962/d1012030
- Description: A detailed hydrographic and biological survey was conducted in the region of the Subtropical Convergence in the Indian sector of the Southern Ocean in April 2007. Hydrographic data revealed that the subsurface expression of the Subtropical Convergence (at 200 m), marked by the 10°C isotherm, appeared to meander considerably between 41°S and 42°15’S. Total surface chlorophyll- a concentration was low and ranged from 0.03 to 0.42 µg l–1 and was always dominated by the pico- (<2 µm) and nano- (2–120 µm) size classes, which contributed between 81% and 93% of the total pigment. The total chlorophyll-a integrated over the top 150m of the water column showed no distinct spatial trends, and ranged from 12.8 to 40.1mg chl-a m–2. There were no significant correlations between the total integrated chlorophyll- a concentration and temperature and salinity (P > 0.05). The zooplankton community was dominated, numerically and by biomass, by mesozooplankton comprising mainly copepods of the genera, Oithona,Paraeuchaeta, Pleuromamma, Calanus and Clausocalanus. An exception was recorded at those stations in the region of the front where the tunicate, Salpa thompsoni, dominated the total zooplankton biomass.
- Full Text:
- Date Issued: 2007
Preliminary survey of indigenous, non-indigenous and cryptogenic benthic invertebrates in Burrard Inlet, Vancover, British Columbia
- Richoux, Nicole B, Froneman, P William
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457981 , vital:75705 , xlink:href="https://doi.org/10.1016/j.ecss.2006.09.007"
- Description: In a preliminary investigation into the presence of non-indigenous invertebrates in Burrard Inlet, Vancouver, British Columbia, qualitative sampling on rocky shores, pilings and floating docks was conducted in July and August 2004. Twenty-nine sites were established, 34 samples were analysed, and 103 different taxa were identified. Data were also obtained on habitat characteristics including substrate type, salinity and temperature. Identification of polychaetes, mussels from four sites, all amphipods, isopods and patellogastropods have been confirmed by taxonomic specialists.
- Full Text:
- Date Issued: 2007
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457981 , vital:75705 , xlink:href="https://doi.org/10.1016/j.ecss.2006.09.007"
- Description: In a preliminary investigation into the presence of non-indigenous invertebrates in Burrard Inlet, Vancouver, British Columbia, qualitative sampling on rocky shores, pilings and floating docks was conducted in July and August 2004. Twenty-nine sites were established, 34 samples were analysed, and 103 different taxa were identified. Data were also obtained on habitat characteristics including substrate type, salinity and temperature. Identification of polychaetes, mussels from four sites, all amphipods, isopods and patellogastropods have been confirmed by taxonomic specialists.
- Full Text:
- Date Issued: 2007