Larval fish dynamics within the coastal nearshore of the Eastern Cape, South Africa
- Authors: Sotshongaye, Oko
- Date: 2021-04
- Subjects: Fishes -- Larvae -- South Africa -- Eastern Cape , Fishes -- Larvae -- Development -- South Africa -- Eastern Cape , Fishes -- Larvae -- Ecology -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape , Fishes -- Larvae -- Dispersal -- South Africa -- Eastern Cape
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176977 , vital:42776
- Description: The coastal nearshore is important for the early development of fishes as it is used for spawning and/or as a nursery. One of the central concerns in coastal ecology is understanding the role of the nearshore for larvae, ultimately providing key knowledge on population dynamics and hence helping in making decisions pertaining to conservation and resource management. The aim of this study was to investigate the alongshore and cross-shore distribution of larval fishes and the links to the physio-chemical conditions (including prevailing winds) and hydrodynamics in the region of Algoa Bay, situated on the south east coast in the warm temperate region of South Africa. Fish larvae were sampled at nine sites for the first component of the study (January 2016 –March 2017) and at four sites for the second component (November 2019), near the surface and bottom (15-50 m) of the water column as well as at two different distances from shore (~400 m/~3 km) using a set of bongo plankton nets towed behind a boat. Environmental data were simultaneously collected using and acoustic Doppler current profiler (ADCP) and conductivity, temperature, depth (CTD) profiler. Larval fish abundance generally decreased with increasing distance from the shore, however, this varied in space and time, with some larval species recorded in high abundances offshore. Close inshore the larvae of coastal fish species producing benthic eggs (CBE) including the Blenniidae and Gobiesocidae mostly dominated, while offshore the larvae of coastal fish species producing pelagic eggs (CPE) i.e. Sparidae and Cynoglossidae, as well as pelagic fish species producing pelagic eggs (PPE) i.e. Clupeidae and Engraulidae mostly dominated. Vertical distribution of larvae differed according to taxon, with the Callionymidae (CPE), Cynoglossidae and Gobiesocidae occurring at high densities at the bottom of the water column, while the Blenniidae dominated near the surface. Fluorescence, temperature and salinity varied with depth (surface/bottom), being particularly high at the surface; currents moved faster at the surface than the bottom of the water column. Increased abundances of larval fishes were evident after upwelling events (associated with easterly winds) in the Bay, while during downwelling (associated with westerly winds), low densities were generally recorded, except for the sites situated near headlands/capes where there were higher densities of fish larvae during downwelling events. Overall, the results of this study suggest that spawning mode of the adults, oceanography and environmental conditions coupled with what is known of the behaviour of fish larvae, were important in shaping the larval fish community of the Algoa Bay region. These results highlight the importance of incorporating multiple biological (developmental stage, reproductive mode, species) and physical (currents, fluorescence, wind-driven up/down-welling) factors when addressing the mechanims of transport of larval fish in the coastal nearshore. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Sotshongaye, Oko
- Date: 2021-04
- Subjects: Fishes -- Larvae -- South Africa -- Eastern Cape , Fishes -- Larvae -- Development -- South Africa -- Eastern Cape , Fishes -- Larvae -- Ecology -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape , Fishes -- Larvae -- Dispersal -- South Africa -- Eastern Cape
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176977 , vital:42776
- Description: The coastal nearshore is important for the early development of fishes as it is used for spawning and/or as a nursery. One of the central concerns in coastal ecology is understanding the role of the nearshore for larvae, ultimately providing key knowledge on population dynamics and hence helping in making decisions pertaining to conservation and resource management. The aim of this study was to investigate the alongshore and cross-shore distribution of larval fishes and the links to the physio-chemical conditions (including prevailing winds) and hydrodynamics in the region of Algoa Bay, situated on the south east coast in the warm temperate region of South Africa. Fish larvae were sampled at nine sites for the first component of the study (January 2016 –March 2017) and at four sites for the second component (November 2019), near the surface and bottom (15-50 m) of the water column as well as at two different distances from shore (~400 m/~3 km) using a set of bongo plankton nets towed behind a boat. Environmental data were simultaneously collected using and acoustic Doppler current profiler (ADCP) and conductivity, temperature, depth (CTD) profiler. Larval fish abundance generally decreased with increasing distance from the shore, however, this varied in space and time, with some larval species recorded in high abundances offshore. Close inshore the larvae of coastal fish species producing benthic eggs (CBE) including the Blenniidae and Gobiesocidae mostly dominated, while offshore the larvae of coastal fish species producing pelagic eggs (CPE) i.e. Sparidae and Cynoglossidae, as well as pelagic fish species producing pelagic eggs (PPE) i.e. Clupeidae and Engraulidae mostly dominated. Vertical distribution of larvae differed according to taxon, with the Callionymidae (CPE), Cynoglossidae and Gobiesocidae occurring at high densities at the bottom of the water column, while the Blenniidae dominated near the surface. Fluorescence, temperature and salinity varied with depth (surface/bottom), being particularly high at the surface; currents moved faster at the surface than the bottom of the water column. Increased abundances of larval fishes were evident after upwelling events (associated with easterly winds) in the Bay, while during downwelling (associated with westerly winds), low densities were generally recorded, except for the sites situated near headlands/capes where there were higher densities of fish larvae during downwelling events. Overall, the results of this study suggest that spawning mode of the adults, oceanography and environmental conditions coupled with what is known of the behaviour of fish larvae, were important in shaping the larval fish community of the Algoa Bay region. These results highlight the importance of incorporating multiple biological (developmental stage, reproductive mode, species) and physical (currents, fluorescence, wind-driven up/down-welling) factors when addressing the mechanims of transport of larval fish in the coastal nearshore. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
Ecosystem health of the Nelson Mandela Bay sandy beaches
- Authors: Yani, Vuyolwethu Veronica
- Date: 2009
- Subjects: Seashore ecology -- South Africa -- Eastern Cape , Sand dune ecology -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape , Beaches -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10600 , http://hdl.handle.net/10948/1075 , Seashore ecology -- South Africa -- Eastern Cape , Sand dune ecology -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape , Beaches -- South Africa -- Eastern Cape
- Description: An investigation of ecosystem functioning of sandy beaches in the Nelson Mandela Bay Municipality (NMBM) was carried out with the aim of describing their type and pollution status. Water salinity, temperature, pH, beach slope, water inorganic nutrient concentrations, urea, and chlorophyll-a concentration as well as the composition of zooplankton, phytoplankton, meiofauna, benthic microalgae and bacteria were examined at thirteen beaches. The beaches were classified into three types: short beaches; long beaches with surf diatoms; and long beaches that import biomass (without surf diatoms). Of the thirteen beaches, five were non-polluted and eight polluted with polluting human activities in and around them. Most beaches were dominated by fine sand except for St. Georges Strand where the particles were medium to fine sand and Maitland’s River Beach, Bluewater Bay and Sardinia Bay that had coarse sand. Nutrient concentrations ranged from 1.98 ± 0.10 μM to 19.30 ± 3.02 μM nitrate; 4.88 ± 1.00 μM to 11.97 ± 1.00 μM ammonium; 0.67 ± 0.00 μM to 2.31 ±1.00 μM soluble reactive phosphorus; and 0.00 to 0.03 ± 0.00 μg l-1 urea-N. Chlorophyll-a concentrations ranged from 0.04 ± 0.02 to 1.57 ± 0.11 μg l-1. Chlorophyll-a concentrations were negatively correlated to ammonium for all beach types (short beaches: r = 0.94; long importing beaches: r = 0.95 and surf diatom beaches: 0.94) and to nitrate for short and long importing beaches (short: r = 0.97 and long importing: r = 0.85). By contrast, a positive correlation was found between observed between chlorophyll-a concentrations and urea for surf diatom beaches (r = 0.93) and for long importing beaches (r = 0.73). Chlorophyll-a concentrations were negatively correlated to short beaches (r = 0.99) and long importing beaches (r = 0.76). The E. coli and total coliforms in all the sampled beaches were within the recommended South African water quality guidelines for contact recreation as specified by DWAF (1995) except at New Brighton Beach (2 419 total coliforms/100 ml and 1 853 E. coli cells/100 ml) and St. Georges Strand (274 total coliforms/100 ml). Diatoms dominated the phytoplankton and benthic microflora; calanoid copepods dominated the zooplankton and deposit-feeding nematodes dominated the meiofauna in all the beaches with no changes found at polluted beaches.
- Full Text: false
- Date Issued: 2009
- Authors: Yani, Vuyolwethu Veronica
- Date: 2009
- Subjects: Seashore ecology -- South Africa -- Eastern Cape , Sand dune ecology -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape , Beaches -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10600 , http://hdl.handle.net/10948/1075 , Seashore ecology -- South Africa -- Eastern Cape , Sand dune ecology -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape , Beaches -- South Africa -- Eastern Cape
- Description: An investigation of ecosystem functioning of sandy beaches in the Nelson Mandela Bay Municipality (NMBM) was carried out with the aim of describing their type and pollution status. Water salinity, temperature, pH, beach slope, water inorganic nutrient concentrations, urea, and chlorophyll-a concentration as well as the composition of zooplankton, phytoplankton, meiofauna, benthic microalgae and bacteria were examined at thirteen beaches. The beaches were classified into three types: short beaches; long beaches with surf diatoms; and long beaches that import biomass (without surf diatoms). Of the thirteen beaches, five were non-polluted and eight polluted with polluting human activities in and around them. Most beaches were dominated by fine sand except for St. Georges Strand where the particles were medium to fine sand and Maitland’s River Beach, Bluewater Bay and Sardinia Bay that had coarse sand. Nutrient concentrations ranged from 1.98 ± 0.10 μM to 19.30 ± 3.02 μM nitrate; 4.88 ± 1.00 μM to 11.97 ± 1.00 μM ammonium; 0.67 ± 0.00 μM to 2.31 ±1.00 μM soluble reactive phosphorus; and 0.00 to 0.03 ± 0.00 μg l-1 urea-N. Chlorophyll-a concentrations ranged from 0.04 ± 0.02 to 1.57 ± 0.11 μg l-1. Chlorophyll-a concentrations were negatively correlated to ammonium for all beach types (short beaches: r = 0.94; long importing beaches: r = 0.95 and surf diatom beaches: 0.94) and to nitrate for short and long importing beaches (short: r = 0.97 and long importing: r = 0.85). By contrast, a positive correlation was found between observed between chlorophyll-a concentrations and urea for surf diatom beaches (r = 0.93) and for long importing beaches (r = 0.73). Chlorophyll-a concentrations were negatively correlated to short beaches (r = 0.99) and long importing beaches (r = 0.76). The E. coli and total coliforms in all the sampled beaches were within the recommended South African water quality guidelines for contact recreation as specified by DWAF (1995) except at New Brighton Beach (2 419 total coliforms/100 ml and 1 853 E. coli cells/100 ml) and St. Georges Strand (274 total coliforms/100 ml). Diatoms dominated the phytoplankton and benthic microflora; calanoid copepods dominated the zooplankton and deposit-feeding nematodes dominated the meiofauna in all the beaches with no changes found at polluted beaches.
- Full Text: false
- Date Issued: 2009
A geohydrological evaluation of the coastal area between Bushmans River Mouth and Cape Mouth and Cape Padrone, Eastern Cape, South Africa
- Authors: Jolly, J L
- Date: 1984 , 2013-03-15
- Subjects: Hydrogeology -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4859 , http://hdl.handle.net/10962/d1005635 , Hydrogeology -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape
- Full Text:
- Date Issued: 1984
- Authors: Jolly, J L
- Date: 1984 , 2013-03-15
- Subjects: Hydrogeology -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4859 , http://hdl.handle.net/10962/d1005635 , Hydrogeology -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape
- Full Text:
- Date Issued: 1984
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