Papers by Natalie Degger
The wide occurrence of endocrine disrupting chemicals (EDCs) and heavy metals in coastal waters h... more The wide occurrence of endocrine disrupting chemicals (EDCs) and heavy metals in coastal waters has drawn global concern, and thus their removal efficiencies in sewage treatment processes should be estimated. However, low concentrations coupled with high temporal fluctuations of these pollutants present a monitoring challenge. Using semi-permeable membrane devices (SPMDs) and Artificial Mussels (AMs), this study investigates a novel approach to evaluating the removal efficiency of five EDCs and six heavy metals in primary treatment, secondary treatment and chemically enhanced primary treatment (CEPT) processes. In general, the small difference between maximum and minimum values of individual EDCs and heavy metals measured from influents/effluents of the same sewage treatment plant suggests that passive sampling devices can smooth and integrate temporal fluctuations, and therefore have the potential to serve as cost-effective monitoring devices for the estimation of the removal efficiencies of EDCs and heavy metals in sewage treatment works.
Marine Pollution Bulletin, 2014
Due to their close proximity to the point sources of pollution, estuaries and harbours are expose... more Due to their close proximity to the point sources of pollution, estuaries and harbours are exposed to metals. Mussels are used worldwide to monitor marine pollution due to their ability to take up contaminants and the ease of transplantation. Mussels were collected from two reference sites and transplanted in Richards Bay Harbour (2006 and and in three harbours. Transplanted and resident mussels were removed after 6 weeks exposure and metal concentrations were analysed using ICP-MS techniques. Transplanted mussels had higher metal concentrations than the resident mussels. This was attributed to regulation of metals by the resident mussels. Metal regulation was greater in mussels that are continuously submerged as opposed to those that undergo tidal influences. For monitoring it is essential that the reference population for transplantation is considered carefully as upwelling events in the pristine reference location results in significant increases in metal bioaccumulation.
A comprehensive study was carried out to assess metal contamination in five cities spanning from ... more A comprehensive study was carried out to assess metal contamination in five cities spanning from temperate to tropical environment along the coastal line of China with different hydrographical conditions. At each of the five cities, Artificial Mussels (AM) were deployed together with a native species of mussel at a control site and a polluted site. High levels of Cr, Cu and Hg were found in Qingdao, high level of Cd, Hg and Pb was found in Shanghai, and high level of Zn was found in Dalian. Furthermore, level of Cu contamination in all the five cities was consistently much higher than those reported in similar studies in other countries (e.g., Australia, Portugal, Scotland, Iceland, Korea, South Africa and Bangladesh). Levels of individual metal species in the AM showed a highly significant correlation with that in the native mussels (except for Zn in Mytilus edulis and Cd in Perna viridis), while no significant difference can be found between the regression relationships of metal in the AM and each of the two native mussel species. The results demonstrated that AM can provide a reliable time-integrated estimate of metal concentration in contrasting environments over large biogeographic areas and different hy-drographic conditions, and overcome the shortcomings of monitoring metals in water, sediment and the use of biomonitors.
Despite the influx of silver nanoparticles (nAg) into the marine environment, their effects on fi... more Despite the influx of silver nanoparticles (nAg) into the marine environment, their effects on fish reproduction remain completely unexplored. Using ovarian primary cells from marine medaka (Oryzias melastigma), in vitro studies were carried out to evaluate the effects of two differently coated nAg particles (Oleic Acid, (OA) nAg and Polyvinylpyrrolidone, (PVP) nAg) on fish ovarian tissues, using AgNO 3 as a positive control. Cytotoxicity was evaluated by MTT assay and expression of key genes regulating steroidogenesis (StAR, CYP 19a, CYP 11a, 3HSD and 20HSD) were determined by Q-RT-PCR. EC 50 values for PVP nAg, OA nAg and AgNO 3 were 7.25 g L −1 , 924.4 g L −1 , and 42.0 g L −1 respectively, showing that toxicity of silver was greatly enhanced in the PVP coated nano-form. Down regulation of CYP 19a was observed in both nAg and AgNO 3 treatments, while down regulation of 3HSD was only found in the OA nAg and AgNO 3 treatments. For the first time, our results demonstrated that nAg can affect specific genes regulating steroidogenesis, implicating nAg as a potential endocrine disruptor.
African Zoology, 2009
Recent work in the field of parasitology has drawn attention to the application of parasites as p... more Recent work in the field of parasitology has drawn attention to the application of parasites as pollution-accumulation indicators, particularly cestodes. A discrepancy in metal concentrations within cestode posterior and anterior tissue has led researchers to attribute this phenomenon to metals binding to the shells of their eggs. Thus, the objective of this study was to demonstrate metal presence through the implementation of fluorochromy. Tissue forms of a known metal accumulator, Bothriocephalus acheilognathi, were exposed to a Phen Green FL fluorescent probe specific for metal ions and examined with a fluorescence microscope. The results have shown that metal ions bind to the egg-shells of B. acheilognathi and that fluorescence microscopy can be employed successfully to demonstrate metal accumulation in tapeworms.
Metal oxide nanomaterials are widely used in practical applications and represent a class of nano... more Metal oxide nanomaterials are widely used in practical applications and represent a class of nanomaterials with the highest global annual production. Many of those, such as TiO2 and ZnO, are generally considered non-toxic due to the lack of toxicity of the bulk material. However, these materials typically exhibit toxicity to bacteria and fungi, and there have been emerging concerns about their ecotoxicity effects. The understanding of the toxicity mechanisms is incomplete, with different studies often reporting contradictory results. The relationship between the material properties and toxicity appears to be complex and diifficult to understand, which is partly due to incomplete characterization of the nanomaterial, and possibly due to experimental artefacts in the characterization of the nanomaterial and/or its interactions with living organisms. This review discusses the comprehensive characterization of metal oxide nanomaterials and the mechanisms of their toxicity.
The published literature on marine pollution monitoring research in South Africa from 1960 to pre... more The published literature on marine pollution monitoring research in South Africa from 1960 to present was evaluated. There has been a general decline in the number of papers from the 1980s and this can be linked to the absence of a marine pollution monitoring programme in South Africa. General trends observed were that contaminant exposure monitoring of metals predominates the research conducted to date. Monitoring results indicate that there has been a general decrease in metal concentrations in South African coastal waters and concentrations of metals and most organics in mussels are lower than in other industrialised nations. This is reflected in the general pristine nature and high biodiversity of the South African coastline. The establishment of a national marine pollution monitoring framework would stimulate marine pollution research.
Over the last three decades there has been a significant decline in the number of marine pollutio... more Over the last three decades there has been a significant decline in the number of marine pollution monitoring-related studies in South Africa. Thus, the current study was conducted to assess the current state of metal contamination within the South African marine environment through the validation of the artificial mussel (AM). Indigenous reference mussels ( Perna perna) were deployed alongside the passive device within the South African marine environment for a 6 week exposure period. Analysis of metal uptake (Cd, Cr, Cu, Pb and Zn) was determined by filtration and elution of the AM chelex resins, microwave digestion of the transplanted mussels, and determination of their metal concentrations by ICP-MS and ICP-OES analysis. Uptake patterns between the AM and transplanted mussels showed significant temporal and spatial correlation for the majority of the elements analysed. While the AM provided relevant and complementary information on the dissolved metal concentrations, limitations were also observed.
A distinct lack of historical and current data on the status of organic pollutant contaminants wi... more A distinct lack of historical and current data on the status of organic pollutant contaminants within the South African marine environment is evident. This has highlighted the need for more current organic pollutant assessments. Reference mussels and SPMDs were transplanted at five South African harbour sites to assess organic bioaccumulation in brown mussels (Perna perna) and semi-permeable membrane devices (SPMDs). Spatial patterns of PAH and PCB contaminants were determined by GC-MS and GC-ECD after appropriate sample preparation. Significant (p < 0.05) spatial differences were observed between the sites. Results indicate no correlations between the passive device and the transplanted mussels; however the SPMDs provided complementary information on the presence of dioxin-like PCBs within the environment not detected by the mussel. The results indicate that information provided by both the mussels and SPMDs allow for a more in depth scrutiny of environmental conditions as a result of anthropogenic influence.
Richards Bay Harbour is South Africa's premier bulk cargo port. It was constructed in the Mhlathu... more Richards Bay Harbour is South Africa's premier bulk cargo port. It was constructed in the Mhlathuze estuary in 1976 and over the past 34 years has become South Africa's most modern and largest cargo handling port. Although no official monitoring programme is in progress various studies by different groups have provided relevant data with respect to changing metal levels in brown mussel tissue (Perna perna) over the last 34 years. Eleven elements were analysed in brown mussels from the main channel in Richards Bay Harbour using ICP-MS. The results indicate that the metal concentrations in the mussel tissue remained relatively constant between 1974 and 2005. The mean metal concentrations increased significantly in 2005 possibly due to the construction of the new coal terminal and associated dredging activities. Mean metal concentrations in the 2008 sampling event were also elevated due to increased run off during an above average rainy season.
Recent work in the field of parasitology has drawn attention to the application of parasites as p... more Recent work in the field of parasitology has drawn attention to the application of parasites as pollution-accumulation indicators, particularly cestodes. A discrepancy in metal concentrations within cestode posterior and anterior tissue has led researchers to attribute this phenomenon to metals binding to the shells of their eggs. Thus, the objective of this study was to demonstrate metal presence through the implementation of fluorochromy. Tissue forms of a known metal accumulator, Bothriocephalus acheilognathi, were exposed to a Phen Green FL fluorescent probe specific for metal ions and examined with a fluorescence microscope. The results have shown that metal ions bind to the egg-shells of B. acheilognathi and that fluorescence microscopy can be employed successfully to demonstrate metal accumulation in tapeworms.
Conference Presentations by Natalie Degger
Silver nanoparticles (AgNPs) have gained much popularity on account of their antimicrobial proper... more Silver nanoparticles (AgNPs) have gained much popularity on account of their antimicrobial properties. The increase in the production of these nanoparticles and their wide occurrence has become a growing environmental concern. While toxicity effects of AgNPs on aquatic organisms have been identified, there is a lack of data concerning their effects on marine species, with particular emphasis on chronic sublethal effects.
It was hypothesised that exposure to nanoparticles may potentially interfere with steroidogenesis and hence reproduction in the marine medaka (Oryzias melastigma). This study has looked into the effects of AgNPs in vitro and in vivo and has made comparisons between the effects of AgNPs and AgNO3. Modulations of the expression of the steroidogenic genes and sex hormone levels were quantified by real-time polymerase chain reaction (Q-RT-PCR) and Enzyme-linked Immunosorbent Assays (ELISAs) respectively.
Our results indicate that changes in the gene expression pattern are elicited by AgNP treatment groups, and differences between the AgNO3 and AgNP treatments were clearly evident. It was also found that exposure to AgNPs affects the levels of estradiol and testosterone, thus disrupting the balance of the sex hormones.
The data presented here provides insight that exposure to these particles may affect steroidogenesis and sex hormone production in medaka, which subsequently compromises reproduction. Findings from this study suggest their potential to cause endocrine disrupting effects with implications that may extend beyond the marine environment.
Numerous studies have demonstrated the semi-permeable membrane device (SPMD) serves as a very too... more Numerous studies have demonstrated the semi-permeable membrane device (SPMD) serves as a very tool for indicating trace organic contaminants in the water column, and is able to provide standardised results between localities worldwide.
Using SPMDs, this study was carried out to investigate and compare the levels of endocrine disrupting chemicals (EDCs) in coastal waters of six cities (i.e. Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) along the entire coast of China, with a view to identify spatial and temporal variations and potential pollution hotspots. Within each of these six cities, four additional sites were selected along a pollution gradient.
4-Nonyl phenol, Bisphenol A, 17β-Estradiol and 17-α-Ethynylestradiol were measured in the SPMD, and significant temporal and spatial differences of these EDCs were found both within and between the six selected cities, and levels of which conform to the expected pollution levels within the cities.
Overall, the data acquired indicates that coastal waters of Shenzhen contains the highest recorded levels of the EDC’s measured (2309 ng/g lipid 4-Nonyl phenol; 584 ng/g lipid 17β-Estradiol; 361 ng/g lipid 17-α-Ethynylestradiol), with Dalian and Shantou showing the lowest concentrations, and the data obtained in this study revealed the contamination level and pattern of EDCs in China’s coastal waters.
A novel chemical sampling device, the Artificial Mussel (AM), has been developed for monitoring o... more A novel chemical sampling device, the Artificial Mussel (AM), has been developed for monitoring of heavy metals (Cd, Cr, Cu, Hg, Pb and Zn,) in aquatic environments. This novel device allows comparisons of trace metal levels in varied aquatic environments and different geographical areas beyond the natural distribution limits of biomonitors.
Recently, a regional field validation of the AM was completed along the coastline of China, covering both tropical and temperate coastal environments. AMs were deployed at four sites along a pollution gradient within six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) in China. Both temporal and spatial changes in the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) in the AM were analyzed and compared.
Results of this field study show significant temporal and spatial differences in metal concentrations between the six cities. In a direct city to city comparison to determine pollution hotspots, the results indicate that Qingdao contains the highest concentrations of Cr (1245 ug/g), Hg (0.152 ug/g) and Cu (234 ug/g), while Cd and Pb were highest in Shanghai (0.183 ug/g and 21.8 ug/g respectively). Overall, this field validation has shown that the AM provides relevant and complementary information on the dissolved, bioavailable metal concentrations along the entire China’s coast. Most importantly, the metal concentrations in the AM reflect the level of pollution of the sites selected in all the six cities, demonstrating once again, the effectiveness and reliability of the AM as a monitoring tool.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Global Artificial Mussel program now extended to 16 countries worldwide.
Metals are natural constituents of the marine environments which are generally found in low conce... more Metals are natural constituents of the marine environments which are generally found in low concentrations. Increased concentrations in the marine environment could be derived from several major sources, most notably riverine influx, atmospheric deposition and/or anthropogenic activities.
As a result, the burden of metals is now a serious environmental concern. The focus of these concerns is focused particularly on estuaries and harbours due to their highly productive nature and
their close proximity to the point sources of pollution. Mussels are one of the organisms that are used worldwide to monitor pollution in harbours due to their ability to take up contaminants and the
ease at which they can be transplanted. Mussels were collected from a reference site (Sheffield Beach) and transplanted in Richards Bay Harbour in two separate studies (in 2006 and 2010) for the
temporal assessment while reference mussels were transplanted to two other harbours along the South African coastline (2010). The transplanted mussels were removed after an exposure period of
7 weeks and together with resident mussels from the harbour, were analysed for metal concentrations. The mussels were analysed using standard microwave digestion and ICP-MS techniques. The results indicated that for both the spatial and temporal studies the transplanted mussels had higher metal concentrations than the resident mussels. This was attributed to two reasons. Long term exposure of the resident mussels probably resulted in adaptation through metal regulation and excretion. It would also seem that even though the control mussels that were used for the transplantation studies were collected from below the low tide level, their continuous emersion in the harbours presented a different exposure scenario than exposure under tidal influences. The choice of whether to make use of transplanted (no adaptation) or resident mussels (site specific
exposure scenario) would therefore be dependent on the objective of the monitoring programme.
Since the general trends in spatial and temporal bioaccumulation were similar (even though absolute levels differed) it is recommended that resident mussels be utilised for a national monitoring programme.
A novel chemical sampling device, the Artificial Mussel (AM), has been developed for monitoring o... more A novel chemical sampling device, the Artificial Mussel (AM), has been developed for monitoring of heavy metals (Cd, Cr, Cu, Hg, Pb and Zn,) in aquatic environments. This novel device allows comparisons of trace metal levels in varied aquatic environments and different geographical areas beyond the natural distribution limits of biomonitors.
Recently, a regional field validation of the AM was completed along the coastline of China, covering both tropical and temperate coastal environments. AMs were deployed at four sites along a pollution gradient within six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) in China. Both temporal and spatial changes in the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) in the AM were analyzed and compared.
Results of this field study show significant temporal and spatial differences in metal concentrations between the six cities. In a direct city to city comparison to determine pollution hotspots, the results indicate that Qingdao contains the highest concentrations of Cr (1245 ug/g), Hg (0.152 ug/g) and Cu (234 ug/g), while Cd and Pb were highest in Shanghai (0.183 ug/g and 21.8 ug/g respectively). Overall, this field validation has shown that the AM provides relevant and complementary information on the dissolved, bioavailable metal concentrations along the entire China’s coast. Most importantly, the metal concentrations in the AM reflect the level of pollution of the sites selected in all the six cities, demonstrating once again, the effectiveness and reliability of the AM as a monitoring tool.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Global Artificial Mussel program now extended to 16 countries worldwide.
A chemical sampling device, the Artificial Mussel (AM), has been developed for global monitoring ... more A chemical sampling device, the Artificial Mussel (AM), has been developed for global monitoring of heavy metals (Zn, Cd, Cu, Hg and Pb) in various aquatic environments. This device consists of a chelating resin (Chelex-100) suspended in artificial seawater within a Perspex tubing, and enclosed with semi-permeable gel at both ends. Laboratory comparisons of the uptake and release of metals of AM with those of the green-lipped mussel (Perna viridis) show higher or equivalent accumulation with the AM for the five metals, while uptake and release of metals by the AM are less affected by salinity and temperature changes. Previous field trials also demonstrate that the AM can provide a time-integrated estimate of metals concentrations in the marine environment, with some metal species showing a more consistent uptake pattern (compared with P. viridis) than others. Our overall results show that the AM can provide information on time-integrated environmental concentrations of metals additional to that produced solely with water, sediment and organism monitoring data. Importantly, it confers the additional advantage of allowing comparisons of trace metal levels in varied aquatic environments and different geographical areas beyond the natural distribution limits of biomonitors.
We have initiated a global “Artificial Watch” program with collaborators from Australia, Brazil, Canada, China, and India, to name a few. To date, this program includes 18 countries worldwide. .
Recently, a field validation of the AM was completed along the coastline of China. A temporal and spatial comparison of the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) among six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) along the Chinese coast, and among four sites along a pollution gradient within each of these cities.
Results of this study show that significant temporal and spatial differences could be observed between cities. Furthermore, this project has shown that the data obtained reflects the pollution status of the sites selected within the cities.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Artificial Mussel program
Silver nanoparticles (AgNPs) have gained much popularity on account of their antimicrobial proper... more Silver nanoparticles (AgNPs) have gained much popularity on account of their antimicrobial properties. The increase in the production of these nanoparticles will also increase public exposure to these materials as well as their release in the environment, which is becoming a growing concern. While literature is available on the toxicity effects of AgNPs on aquatic organisms, there is a lack of data concerning their effects on marine species.
This study primarily aimed to investigate the effects of two commercial AgNPs on ovarian follicular cells of marine medaka (Oryzias melastigma) utilising a primary cell culture. Since these cells play an important role in maintaining ovarian function and reproductive health, it was hypothesized that exposure to nanoparticles may potentially interfere with the production of sex steroid hormones and therefore have an effect on steroidogenesis.
After exposing the follicular cells to the AgNPs for 48 hours, dose-dependent cytotoxicity was evaluated by an MTT assay. Modulations of the expression of the steroidogenic genes were determined by measuring the mRNA concentrations by real-time polymerase chain reaction (Q-RT-PCR). Additionally, the level of mRNA expressions of the apoptotic and anti-apoptotic proteins (bax and bcl-2) were measured. At least three independent experiments were conducted.
The results not only indicate that changes in gene expression are elicited by AgNPs, but differences between the two commercial AgNPs can also be observed. The data presented here provides insight into the toxicological effects that AgNPs elicit on ovarian follicular cells of marine medaka and further contributes to the effects of nanoparticles on marine organisms.
Key words: marine medaka; silver nanoparticles, steroidogenesis, ovarian follicular culture
Validation of the AM under field conditions involved the transplantation of indigenous reference ... more Validation of the AM under field conditions involved the transplantation of indigenous reference mussels (Perna perna) alongside the passive device. Field studies were carried out
for six weeks at five localities along the South African coastline ranging from temperate to sub-tropical environment. Two-way analysis of variance, Pearson correlation and Discrimination Function Analysis were used to compare the concentrations of contaminants
in AMs and mussels across sites and exposure periods. While uptake patterns between the AM and transplanted mussels were significantly comparable for majority of the analysed metals, no positive correlations were observed at the reference site. The results indicated
positive correlations for Cd, Cu, Pb and Zn in Cape Town; Cd and Pb in Port Elizabeth; Pb in Saldanha Bay; Cd, Cu, Pb and Zn in Richards Bay and no positive relationships from the reference site in Tsitsikamma National Park.
Similar field study was carried out at nine locations along the Chinese coastal line with different levels of metal pollution. Results showed very high concentrations of Cu, Cr and Hg at Qingdao, an industrial city with heavy traffic (194-202, 3610-5010 μg/g and 85-139 ng/g.
respectively). The concentration of Pb in this location was nearly double of other locations. The second high concentrations by metal pollution were found in Shanghai (Cu, Zn, Cr and
Pb: 21.2-36.7, 20.9-37.7, 4.44-13.1 and 3.85-8.61 μg/g respectively). High concentrations of Zn was identified at Dalian and Shantou, which can be attributable to industrial pollution at these two sites.
The overall field results in South Africa and China showed that the AM can provide a good estimate on metal levels in the marine environment, and the uniformity in biomonitoring which mussels cannot.
With the support from the International Atomic Energy Agency (IAEA), our “Global Artificial Mussel Watch” has now extended to eight African countries.
Uploads
Papers by Natalie Degger
Conference Presentations by Natalie Degger
It was hypothesised that exposure to nanoparticles may potentially interfere with steroidogenesis and hence reproduction in the marine medaka (Oryzias melastigma). This study has looked into the effects of AgNPs in vitro and in vivo and has made comparisons between the effects of AgNPs and AgNO3. Modulations of the expression of the steroidogenic genes and sex hormone levels were quantified by real-time polymerase chain reaction (Q-RT-PCR) and Enzyme-linked Immunosorbent Assays (ELISAs) respectively.
Our results indicate that changes in the gene expression pattern are elicited by AgNP treatment groups, and differences between the AgNO3 and AgNP treatments were clearly evident. It was also found that exposure to AgNPs affects the levels of estradiol and testosterone, thus disrupting the balance of the sex hormones.
The data presented here provides insight that exposure to these particles may affect steroidogenesis and sex hormone production in medaka, which subsequently compromises reproduction. Findings from this study suggest their potential to cause endocrine disrupting effects with implications that may extend beyond the marine environment.
Using SPMDs, this study was carried out to investigate and compare the levels of endocrine disrupting chemicals (EDCs) in coastal waters of six cities (i.e. Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) along the entire coast of China, with a view to identify spatial and temporal variations and potential pollution hotspots. Within each of these six cities, four additional sites were selected along a pollution gradient.
4-Nonyl phenol, Bisphenol A, 17β-Estradiol and 17-α-Ethynylestradiol were measured in the SPMD, and significant temporal and spatial differences of these EDCs were found both within and between the six selected cities, and levels of which conform to the expected pollution levels within the cities.
Overall, the data acquired indicates that coastal waters of Shenzhen contains the highest recorded levels of the EDC’s measured (2309 ng/g lipid 4-Nonyl phenol; 584 ng/g lipid 17β-Estradiol; 361 ng/g lipid 17-α-Ethynylestradiol), with Dalian and Shantou showing the lowest concentrations, and the data obtained in this study revealed the contamination level and pattern of EDCs in China’s coastal waters.
Recently, a regional field validation of the AM was completed along the coastline of China, covering both tropical and temperate coastal environments. AMs were deployed at four sites along a pollution gradient within six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) in China. Both temporal and spatial changes in the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) in the AM were analyzed and compared.
Results of this field study show significant temporal and spatial differences in metal concentrations between the six cities. In a direct city to city comparison to determine pollution hotspots, the results indicate that Qingdao contains the highest concentrations of Cr (1245 ug/g), Hg (0.152 ug/g) and Cu (234 ug/g), while Cd and Pb were highest in Shanghai (0.183 ug/g and 21.8 ug/g respectively). Overall, this field validation has shown that the AM provides relevant and complementary information on the dissolved, bioavailable metal concentrations along the entire China’s coast. Most importantly, the metal concentrations in the AM reflect the level of pollution of the sites selected in all the six cities, demonstrating once again, the effectiveness and reliability of the AM as a monitoring tool.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Global Artificial Mussel program now extended to 16 countries worldwide.
As a result, the burden of metals is now a serious environmental concern. The focus of these concerns is focused particularly on estuaries and harbours due to their highly productive nature and
their close proximity to the point sources of pollution. Mussels are one of the organisms that are used worldwide to monitor pollution in harbours due to their ability to take up contaminants and the
ease at which they can be transplanted. Mussels were collected from a reference site (Sheffield Beach) and transplanted in Richards Bay Harbour in two separate studies (in 2006 and 2010) for the
temporal assessment while reference mussels were transplanted to two other harbours along the South African coastline (2010). The transplanted mussels were removed after an exposure period of
7 weeks and together with resident mussels from the harbour, were analysed for metal concentrations. The mussels were analysed using standard microwave digestion and ICP-MS techniques. The results indicated that for both the spatial and temporal studies the transplanted mussels had higher metal concentrations than the resident mussels. This was attributed to two reasons. Long term exposure of the resident mussels probably resulted in adaptation through metal regulation and excretion. It would also seem that even though the control mussels that were used for the transplantation studies were collected from below the low tide level, their continuous emersion in the harbours presented a different exposure scenario than exposure under tidal influences. The choice of whether to make use of transplanted (no adaptation) or resident mussels (site specific
exposure scenario) would therefore be dependent on the objective of the monitoring programme.
Since the general trends in spatial and temporal bioaccumulation were similar (even though absolute levels differed) it is recommended that resident mussels be utilised for a national monitoring programme.
Recently, a regional field validation of the AM was completed along the coastline of China, covering both tropical and temperate coastal environments. AMs were deployed at four sites along a pollution gradient within six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) in China. Both temporal and spatial changes in the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) in the AM were analyzed and compared.
Results of this field study show significant temporal and spatial differences in metal concentrations between the six cities. In a direct city to city comparison to determine pollution hotspots, the results indicate that Qingdao contains the highest concentrations of Cr (1245 ug/g), Hg (0.152 ug/g) and Cu (234 ug/g), while Cd and Pb were highest in Shanghai (0.183 ug/g and 21.8 ug/g respectively). Overall, this field validation has shown that the AM provides relevant and complementary information on the dissolved, bioavailable metal concentrations along the entire China’s coast. Most importantly, the metal concentrations in the AM reflect the level of pollution of the sites selected in all the six cities, demonstrating once again, the effectiveness and reliability of the AM as a monitoring tool.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Global Artificial Mussel program now extended to 16 countries worldwide.
We have initiated a global “Artificial Watch” program with collaborators from Australia, Brazil, Canada, China, and India, to name a few. To date, this program includes 18 countries worldwide. .
Recently, a field validation of the AM was completed along the coastline of China. A temporal and spatial comparison of the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) among six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) along the Chinese coast, and among four sites along a pollution gradient within each of these cities.
Results of this study show that significant temporal and spatial differences could be observed between cities. Furthermore, this project has shown that the data obtained reflects the pollution status of the sites selected within the cities.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Artificial Mussel program
This study primarily aimed to investigate the effects of two commercial AgNPs on ovarian follicular cells of marine medaka (Oryzias melastigma) utilising a primary cell culture. Since these cells play an important role in maintaining ovarian function and reproductive health, it was hypothesized that exposure to nanoparticles may potentially interfere with the production of sex steroid hormones and therefore have an effect on steroidogenesis.
After exposing the follicular cells to the AgNPs for 48 hours, dose-dependent cytotoxicity was evaluated by an MTT assay. Modulations of the expression of the steroidogenic genes were determined by measuring the mRNA concentrations by real-time polymerase chain reaction (Q-RT-PCR). Additionally, the level of mRNA expressions of the apoptotic and anti-apoptotic proteins (bax and bcl-2) were measured. At least three independent experiments were conducted.
The results not only indicate that changes in gene expression are elicited by AgNPs, but differences between the two commercial AgNPs can also be observed. The data presented here provides insight into the toxicological effects that AgNPs elicit on ovarian follicular cells of marine medaka and further contributes to the effects of nanoparticles on marine organisms.
Key words: marine medaka; silver nanoparticles, steroidogenesis, ovarian follicular culture
for six weeks at five localities along the South African coastline ranging from temperate to sub-tropical environment. Two-way analysis of variance, Pearson correlation and Discrimination Function Analysis were used to compare the concentrations of contaminants
in AMs and mussels across sites and exposure periods. While uptake patterns between the AM and transplanted mussels were significantly comparable for majority of the analysed metals, no positive correlations were observed at the reference site. The results indicated
positive correlations for Cd, Cu, Pb and Zn in Cape Town; Cd and Pb in Port Elizabeth; Pb in Saldanha Bay; Cd, Cu, Pb and Zn in Richards Bay and no positive relationships from the reference site in Tsitsikamma National Park.
Similar field study was carried out at nine locations along the Chinese coastal line with different levels of metal pollution. Results showed very high concentrations of Cu, Cr and Hg at Qingdao, an industrial city with heavy traffic (194-202, 3610-5010 μg/g and 85-139 ng/g.
respectively). The concentration of Pb in this location was nearly double of other locations. The second high concentrations by metal pollution were found in Shanghai (Cu, Zn, Cr and
Pb: 21.2-36.7, 20.9-37.7, 4.44-13.1 and 3.85-8.61 μg/g respectively). High concentrations of Zn was identified at Dalian and Shantou, which can be attributable to industrial pollution at these two sites.
The overall field results in South Africa and China showed that the AM can provide a good estimate on metal levels in the marine environment, and the uniformity in biomonitoring which mussels cannot.
With the support from the International Atomic Energy Agency (IAEA), our “Global Artificial Mussel Watch” has now extended to eight African countries.
It was hypothesised that exposure to nanoparticles may potentially interfere with steroidogenesis and hence reproduction in the marine medaka (Oryzias melastigma). This study has looked into the effects of AgNPs in vitro and in vivo and has made comparisons between the effects of AgNPs and AgNO3. Modulations of the expression of the steroidogenic genes and sex hormone levels were quantified by real-time polymerase chain reaction (Q-RT-PCR) and Enzyme-linked Immunosorbent Assays (ELISAs) respectively.
Our results indicate that changes in the gene expression pattern are elicited by AgNP treatment groups, and differences between the AgNO3 and AgNP treatments were clearly evident. It was also found that exposure to AgNPs affects the levels of estradiol and testosterone, thus disrupting the balance of the sex hormones.
The data presented here provides insight that exposure to these particles may affect steroidogenesis and sex hormone production in medaka, which subsequently compromises reproduction. Findings from this study suggest their potential to cause endocrine disrupting effects with implications that may extend beyond the marine environment.
Using SPMDs, this study was carried out to investigate and compare the levels of endocrine disrupting chemicals (EDCs) in coastal waters of six cities (i.e. Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) along the entire coast of China, with a view to identify spatial and temporal variations and potential pollution hotspots. Within each of these six cities, four additional sites were selected along a pollution gradient.
4-Nonyl phenol, Bisphenol A, 17β-Estradiol and 17-α-Ethynylestradiol were measured in the SPMD, and significant temporal and spatial differences of these EDCs were found both within and between the six selected cities, and levels of which conform to the expected pollution levels within the cities.
Overall, the data acquired indicates that coastal waters of Shenzhen contains the highest recorded levels of the EDC’s measured (2309 ng/g lipid 4-Nonyl phenol; 584 ng/g lipid 17β-Estradiol; 361 ng/g lipid 17-α-Ethynylestradiol), with Dalian and Shantou showing the lowest concentrations, and the data obtained in this study revealed the contamination level and pattern of EDCs in China’s coastal waters.
Recently, a regional field validation of the AM was completed along the coastline of China, covering both tropical and temperate coastal environments. AMs were deployed at four sites along a pollution gradient within six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) in China. Both temporal and spatial changes in the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) in the AM were analyzed and compared.
Results of this field study show significant temporal and spatial differences in metal concentrations between the six cities. In a direct city to city comparison to determine pollution hotspots, the results indicate that Qingdao contains the highest concentrations of Cr (1245 ug/g), Hg (0.152 ug/g) and Cu (234 ug/g), while Cd and Pb were highest in Shanghai (0.183 ug/g and 21.8 ug/g respectively). Overall, this field validation has shown that the AM provides relevant and complementary information on the dissolved, bioavailable metal concentrations along the entire China’s coast. Most importantly, the metal concentrations in the AM reflect the level of pollution of the sites selected in all the six cities, demonstrating once again, the effectiveness and reliability of the AM as a monitoring tool.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Global Artificial Mussel program now extended to 16 countries worldwide.
As a result, the burden of metals is now a serious environmental concern. The focus of these concerns is focused particularly on estuaries and harbours due to their highly productive nature and
their close proximity to the point sources of pollution. Mussels are one of the organisms that are used worldwide to monitor pollution in harbours due to their ability to take up contaminants and the
ease at which they can be transplanted. Mussels were collected from a reference site (Sheffield Beach) and transplanted in Richards Bay Harbour in two separate studies (in 2006 and 2010) for the
temporal assessment while reference mussels were transplanted to two other harbours along the South African coastline (2010). The transplanted mussels were removed after an exposure period of
7 weeks and together with resident mussels from the harbour, were analysed for metal concentrations. The mussels were analysed using standard microwave digestion and ICP-MS techniques. The results indicated that for both the spatial and temporal studies the transplanted mussels had higher metal concentrations than the resident mussels. This was attributed to two reasons. Long term exposure of the resident mussels probably resulted in adaptation through metal regulation and excretion. It would also seem that even though the control mussels that were used for the transplantation studies were collected from below the low tide level, their continuous emersion in the harbours presented a different exposure scenario than exposure under tidal influences. The choice of whether to make use of transplanted (no adaptation) or resident mussels (site specific
exposure scenario) would therefore be dependent on the objective of the monitoring programme.
Since the general trends in spatial and temporal bioaccumulation were similar (even though absolute levels differed) it is recommended that resident mussels be utilised for a national monitoring programme.
Recently, a regional field validation of the AM was completed along the coastline of China, covering both tropical and temperate coastal environments. AMs were deployed at four sites along a pollution gradient within six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) in China. Both temporal and spatial changes in the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) in the AM were analyzed and compared.
Results of this field study show significant temporal and spatial differences in metal concentrations between the six cities. In a direct city to city comparison to determine pollution hotspots, the results indicate that Qingdao contains the highest concentrations of Cr (1245 ug/g), Hg (0.152 ug/g) and Cu (234 ug/g), while Cd and Pb were highest in Shanghai (0.183 ug/g and 21.8 ug/g respectively). Overall, this field validation has shown that the AM provides relevant and complementary information on the dissolved, bioavailable metal concentrations along the entire China’s coast. Most importantly, the metal concentrations in the AM reflect the level of pollution of the sites selected in all the six cities, demonstrating once again, the effectiveness and reliability of the AM as a monitoring tool.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Global Artificial Mussel program now extended to 16 countries worldwide.
We have initiated a global “Artificial Watch” program with collaborators from Australia, Brazil, Canada, China, and India, to name a few. To date, this program includes 18 countries worldwide. .
Recently, a field validation of the AM was completed along the coastline of China. A temporal and spatial comparison of the concentrations of trace metals (Pb, Cu, Zn, Hg, Cd, Cr) among six cities (Dalian, Qingdao, Shanghai, Xiamen, Shantou, and Shenzhen) along the Chinese coast, and among four sites along a pollution gradient within each of these cities.
Results of this study show that significant temporal and spatial differences could be observed between cities. Furthermore, this project has shown that the data obtained reflects the pollution status of the sites selected within the cities.
Data collected from the coastline of China will be discussed, as well as the recent progress of the Artificial Mussel program
This study primarily aimed to investigate the effects of two commercial AgNPs on ovarian follicular cells of marine medaka (Oryzias melastigma) utilising a primary cell culture. Since these cells play an important role in maintaining ovarian function and reproductive health, it was hypothesized that exposure to nanoparticles may potentially interfere with the production of sex steroid hormones and therefore have an effect on steroidogenesis.
After exposing the follicular cells to the AgNPs for 48 hours, dose-dependent cytotoxicity was evaluated by an MTT assay. Modulations of the expression of the steroidogenic genes were determined by measuring the mRNA concentrations by real-time polymerase chain reaction (Q-RT-PCR). Additionally, the level of mRNA expressions of the apoptotic and anti-apoptotic proteins (bax and bcl-2) were measured. At least three independent experiments were conducted.
The results not only indicate that changes in gene expression are elicited by AgNPs, but differences between the two commercial AgNPs can also be observed. The data presented here provides insight into the toxicological effects that AgNPs elicit on ovarian follicular cells of marine medaka and further contributes to the effects of nanoparticles on marine organisms.
Key words: marine medaka; silver nanoparticles, steroidogenesis, ovarian follicular culture
for six weeks at five localities along the South African coastline ranging from temperate to sub-tropical environment. Two-way analysis of variance, Pearson correlation and Discrimination Function Analysis were used to compare the concentrations of contaminants
in AMs and mussels across sites and exposure periods. While uptake patterns between the AM and transplanted mussels were significantly comparable for majority of the analysed metals, no positive correlations were observed at the reference site. The results indicated
positive correlations for Cd, Cu, Pb and Zn in Cape Town; Cd and Pb in Port Elizabeth; Pb in Saldanha Bay; Cd, Cu, Pb and Zn in Richards Bay and no positive relationships from the reference site in Tsitsikamma National Park.
Similar field study was carried out at nine locations along the Chinese coastal line with different levels of metal pollution. Results showed very high concentrations of Cu, Cr and Hg at Qingdao, an industrial city with heavy traffic (194-202, 3610-5010 μg/g and 85-139 ng/g.
respectively). The concentration of Pb in this location was nearly double of other locations. The second high concentrations by metal pollution were found in Shanghai (Cu, Zn, Cr and
Pb: 21.2-36.7, 20.9-37.7, 4.44-13.1 and 3.85-8.61 μg/g respectively). High concentrations of Zn was identified at Dalian and Shantou, which can be attributable to industrial pollution at these two sites.
The overall field results in South Africa and China showed that the AM can provide a good estimate on metal levels in the marine environment, and the uniformity in biomonitoring which mussels cannot.
With the support from the International Atomic Energy Agency (IAEA), our “Global Artificial Mussel Watch” has now extended to eight African countries.