Current research focus areas are the freshwater requirements of estuaries, water quality management of shallow water ecosystems, seagrasses, mangroves, salt marshes and responses to climate change. Past research has successfully linked science, policy and management through extensive collaboration and networking with different universities, institutes and government departments
Eutrophication and concomitant harmful algal blooms (HABs) are on the rise globally and pose a th... more Eutrophication and concomitant harmful algal blooms (HABs) are on the rise globally and pose a threat to larval stages of fishes that rely on estuarine nursery habitats for growth and survival. The anthropogenically altered low inflow estuary (LIE), Sundays Estuary, South Africa, supports persistent and predictable HABs. This study investigated the effects of HABs on the environmental conditions and larval fish assemblage of this warm temperate nursery area. Sampling took place during the austral spring of 2016 and 2018 at three sites in the mesohaline zone where both larval fish abundance and HABs are known to reach maxima. Physico-chemical and phytoplankton data were collected during the day and night, while larval fishes were sampled after nightfall. Physico-chemical parameters and larval fish assemblages were compared by water column (surface and bottom) and sites within the mesohaline zone, years, and HAB intensity (hypereutrophic ≥ 2781 H. akashiwo cells•mL−1; standard ≥ 205 H...
This review study investigated the response of low-inflow estuaries (LIEs) to dam releases as thi... more This review study investigated the response of low-inflow estuaries (LIEs) to dam releases as this type of estuary is particularly sensitive to freshwater inflow modification. LIEs occur in arid and semi-arid regions and are subject to periods of little to no freshwater inflow. Case studies were used to identify ecological health and societal benefits associated with flow releases. Successful releases have been made to keep the estuary mouth open, ensure mixing, facilitate a salinity gradient and provide recruitment pulses to the marine environment for fish and invertebrates. Baseflow inputs ensured ecosystem connectivity and maintained estuary water quality gradients. Flow pulse releases in certain seasons stimulated spawning migrations of fish between freshwater and estuarine habitats. Holistic and adaptive restoration approaches were successful in terms of providing ecosystem services and societal benefits such as improved fisheries and livelihoods. Ongoing engagement, inclusion ...
Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes tha... more Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes that rely on estuaries as nurseries. However, few studies worldwide have quantified these effects despite the global rise in eutrophication. This study presents a novel approach using biochemical body condition analyses to evaluate the impact of HABs on the growth and body condition of the larvae of an estuarine resident fish. Recurrent phytoplankton blooms of Heterosigma akashiwo occur in the warm-temperate Sundays Estuary on the southeast coast of South Africa. The response in body condition and assemblage structure on larval estuarine roundherring (Gilchristella aestuaria) was measured in conjunction with bloom conditions, water quality and zooplanktonic prey and predators. Larvae and early juveniles were sampled during varying intensity levels, duration and frequency of hypereutrophic blooms. This study demonstrated that extensive HABs could significantly impact larval roundherring, G. ...
This review evaluates the vulnerability of South African estuaries to Climate Change in a data-li... more This review evaluates the vulnerability of South African estuaries to Climate Change in a data-limited environment. The regional-scale assessment is based on physical characteristics and predicted/measured changes in the abiotic drivers and ecosystem responses. The major Climate Change stressors were identified in order of importance as change in climatic and hydrological processes, ocean circulation and temperature regimes, sea level rise, increase in frequency and intensity of sea storms, and ocean acidification. Flow-related ecosystem responses included changes in mouth state, salinity regimes, biochemical regimes (nutrient fluxes), and floods and related sediment deposition/erosion cycles. The regional vulnerability assessment provides a summary of the key shifts scaled as high, medium, and low in estuary state. Changes in oceanic processes and temperature regimes drive shifts in nearshore temperatures of the transitional zones, with related ecological responses (e.g., range exp...
This study investigated the ability of common reed, Phragmites australis to take up organophospha... more This study investigated the ability of common reed, Phragmites australis to take up organophosphate pesticides (OPPs). The study site was the agriculturally polluted Sundays Estuary in South Africa. Surface water, leaves, roots, and deep-rooted-sediments of P. australis were collected along the length of the estuary and analysed for 13 different OPPS. The extraction of OPPs in plant tissues was performed by QuEChERS method followed by GC-MS analysis. The highest concentration of OPPs was found in leaves (16.41-31.39 μg kg-1 dw), followed by roots (13.92-30.88 μg kg-1 dw), and sediments (3.30-8.07 μg kg-1 dw). Of the 13 targeted OPPs, only one compound was not detected across the four sample matrices, thus reflecting widespread contamination in the Sundays Estuary. The biota sediment accumulation factor (BSAF) values of pyraclofos, quinalphos, fenitrothion, phosalone, EPN, diazinon, chlorpyrifos, pyrazophos, and isazophos were higher than one implying that P. australis possesses the ability to bioaccumulate these compounds. The root-leaf translocation factors (TFr-l) of these pesticides were higher than 1, suggesting that P. australis possesses the capacity to move these pesticides from roots to leaves. The insignificant correlation observed between log BSAF and log Kow and log TFr-l and log Kow implies that OPPs uptake by P. australis tissues were not dependent on log Kow. Our study demonstrates that P. australis possesses the potential to effectively remove OPPs from contaminated water and sediment.
Eutrophication and concomitant harmful algal blooms (HABs) are on the rise globally and pose a th... more Eutrophication and concomitant harmful algal blooms (HABs) are on the rise globally and pose a threat to larval stages of fishes that rely on estuarine nursery habitats for growth and survival. The anthropogenically altered low inflow estuary (LIE), Sundays Estuary, South Africa, supports persistent and predictable HABs. This study investigated the effects of HABs on the environmental conditions and larval fish assemblage of this warm temperate nursery area. Sampling took place during the austral spring of 2016 and 2018 at three sites in the mesohaline zone where both larval fish abundance and HABs are known to reach maxima. Physico-chemical and phytoplankton data were collected during the day and night, while larval fishes were sampled after nightfall. Physico-chemical parameters and larval fish assemblages were compared by water column (surface and bottom) and sites within the mesohaline zone, years, and HAB intensity (hypereutrophic ≥ 2781 H. akashiwo cells•mL−1; standard ≥ 205 H...
This review study investigated the response of low-inflow estuaries (LIEs) to dam releases as thi... more This review study investigated the response of low-inflow estuaries (LIEs) to dam releases as this type of estuary is particularly sensitive to freshwater inflow modification. LIEs occur in arid and semi-arid regions and are subject to periods of little to no freshwater inflow. Case studies were used to identify ecological health and societal benefits associated with flow releases. Successful releases have been made to keep the estuary mouth open, ensure mixing, facilitate a salinity gradient and provide recruitment pulses to the marine environment for fish and invertebrates. Baseflow inputs ensured ecosystem connectivity and maintained estuary water quality gradients. Flow pulse releases in certain seasons stimulated spawning migrations of fish between freshwater and estuarine habitats. Holistic and adaptive restoration approaches were successful in terms of providing ecosystem services and societal benefits such as improved fisheries and livelihoods. Ongoing engagement, inclusion ...
Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes tha... more Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes that rely on estuaries as nurseries. However, few studies worldwide have quantified these effects despite the global rise in eutrophication. This study presents a novel approach using biochemical body condition analyses to evaluate the impact of HABs on the growth and body condition of the larvae of an estuarine resident fish. Recurrent phytoplankton blooms of Heterosigma akashiwo occur in the warm-temperate Sundays Estuary on the southeast coast of South Africa. The response in body condition and assemblage structure on larval estuarine roundherring (Gilchristella aestuaria) was measured in conjunction with bloom conditions, water quality and zooplanktonic prey and predators. Larvae and early juveniles were sampled during varying intensity levels, duration and frequency of hypereutrophic blooms. This study demonstrated that extensive HABs could significantly impact larval roundherring, G. ...
This review evaluates the vulnerability of South African estuaries to Climate Change in a data-li... more This review evaluates the vulnerability of South African estuaries to Climate Change in a data-limited environment. The regional-scale assessment is based on physical characteristics and predicted/measured changes in the abiotic drivers and ecosystem responses. The major Climate Change stressors were identified in order of importance as change in climatic and hydrological processes, ocean circulation and temperature regimes, sea level rise, increase in frequency and intensity of sea storms, and ocean acidification. Flow-related ecosystem responses included changes in mouth state, salinity regimes, biochemical regimes (nutrient fluxes), and floods and related sediment deposition/erosion cycles. The regional vulnerability assessment provides a summary of the key shifts scaled as high, medium, and low in estuary state. Changes in oceanic processes and temperature regimes drive shifts in nearshore temperatures of the transitional zones, with related ecological responses (e.g., range exp...
This study investigated the ability of common reed, Phragmites australis to take up organophospha... more This study investigated the ability of common reed, Phragmites australis to take up organophosphate pesticides (OPPs). The study site was the agriculturally polluted Sundays Estuary in South Africa. Surface water, leaves, roots, and deep-rooted-sediments of P. australis were collected along the length of the estuary and analysed for 13 different OPPS. The extraction of OPPs in plant tissues was performed by QuEChERS method followed by GC-MS analysis. The highest concentration of OPPs was found in leaves (16.41-31.39 μg kg-1 dw), followed by roots (13.92-30.88 μg kg-1 dw), and sediments (3.30-8.07 μg kg-1 dw). Of the 13 targeted OPPs, only one compound was not detected across the four sample matrices, thus reflecting widespread contamination in the Sundays Estuary. The biota sediment accumulation factor (BSAF) values of pyraclofos, quinalphos, fenitrothion, phosalone, EPN, diazinon, chlorpyrifos, pyrazophos, and isazophos were higher than one implying that P. australis possesses the ability to bioaccumulate these compounds. The root-leaf translocation factors (TFr-l) of these pesticides were higher than 1, suggesting that P. australis possesses the capacity to move these pesticides from roots to leaves. The insignificant correlation observed between log BSAF and log Kow and log TFr-l and log Kow implies that OPPs uptake by P. australis tissues were not dependent on log Kow. Our study demonstrates that P. australis possesses the potential to effectively remove OPPs from contaminated water and sediment.
Uploads
Papers by Janine Adams