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Environmental concentrations and risk assessment of microplastics in selected echinoderms in rocky shores of the Western Cape, South Africa
Author(s)
Julius, Daniélle Reneé
Date Issued
2023
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Plastic debris is accumulating in all environments globally and South Africa’s
poor waste management plan has led to an increase in plastic contamination
throughout the country. Microplastics (MPs) are defined as plastic particles
smaller than 5 mm . Information about MPs in coastal environments and biota in
South Africa is poor. The aim of this study was to determine coastal MP
concentrations in water (MPs/L) and sediment (MPs/kg) and ingested MP in
echinoderm species (MPs/g and MPs/I). Sampling took place during in summer
2020 during low at 14 sites along the coast of the Western Cape, South Africa.
Water (n= 5 per site), sediment (n= 5 per site) and echinoderms (n= 20 per site)
were sampled at each site. Sampling efforts for echinoderms were subject to
availability, but at least two echinoderm species were analysed. Environmental
and biological samples were digested in 10% KOH at 60 oC (24 hours). MPs were
extracted and analysed based on visual type, colour, size and polymer type (using
an FTIR-ATR). A risk assessment was done to assess the risks posed by MPs in
all sample types. The results showed a higher mean concentration in sediment
(185.07 MPs/kg; ± 15.25 SE) samples followed by echinoderms (1.44 ± 0.12
MPs/g) and water (1.33 ± 0.15 MPs/L) samples, suggesting sediment is a MP
sink. Gordan’s Bay (site 12) had the highest concentration in sediment samples
(360 ± 36.74 MPs.kg), identifying harbours as a source for MP contamination.
Kalk Bay (site 9) displayed the highest concentration in both water and
echinoderm samples (4.97 ± 0.18 MPs/L and 2.90 ± 0.38 MPs/g respectively),
suggesting the source of MPs are from stormwater outfall pipes. In addition MPs
present in the water column are ingested directly by echinoderms based on
feeding strategy. Filaments were the most dominant MP type (89.33%) with
black/grey being the most dominant colour (41.12%). PET was the most
dominant polymer type (41.33%). Based on the risk assessment, MPs recorded at
Mouille Point (site 6) poses the greatest risk associated with polymers. MP
concentrations reported in this study provide a baseline for future studies, with a need for investigations to focus on the effects of MPs on echinoderms in rocky
shores environments along the Western Cape coastline, South Africa.
poor waste management plan has led to an increase in plastic contamination
throughout the country. Microplastics (MPs) are defined as plastic particles
smaller than 5 mm . Information about MPs in coastal environments and biota in
South Africa is poor. The aim of this study was to determine coastal MP
concentrations in water (MPs/L) and sediment (MPs/kg) and ingested MP in
echinoderm species (MPs/g and MPs/I). Sampling took place during in summer
2020 during low at 14 sites along the coast of the Western Cape, South Africa.
Water (n= 5 per site), sediment (n= 5 per site) and echinoderms (n= 20 per site)
were sampled at each site. Sampling efforts for echinoderms were subject to
availability, but at least two echinoderm species were analysed. Environmental
and biological samples were digested in 10% KOH at 60 oC (24 hours). MPs were
extracted and analysed based on visual type, colour, size and polymer type (using
an FTIR-ATR). A risk assessment was done to assess the risks posed by MPs in
all sample types. The results showed a higher mean concentration in sediment
(185.07 MPs/kg; ± 15.25 SE) samples followed by echinoderms (1.44 ± 0.12
MPs/g) and water (1.33 ± 0.15 MPs/L) samples, suggesting sediment is a MP
sink. Gordan’s Bay (site 12) had the highest concentration in sediment samples
(360 ± 36.74 MPs.kg), identifying harbours as a source for MP contamination.
Kalk Bay (site 9) displayed the highest concentration in both water and
echinoderm samples (4.97 ± 0.18 MPs/L and 2.90 ± 0.38 MPs/g respectively),
suggesting the source of MPs are from stormwater outfall pipes. In addition MPs
present in the water column are ingested directly by echinoderms based on
feeding strategy. Filaments were the most dominant MP type (89.33%) with
black/grey being the most dominant colour (41.12%). PET was the most
dominant polymer type (41.33%). Based on the risk assessment, MPs recorded at
Mouille Point (site 6) poses the greatest risk associated with polymers. MP
concentrations reported in this study provide a baseline for future studies, with a need for investigations to focus on the effects of MPs on echinoderms in rocky
shores environments along the Western Cape coastline, South Africa.
Additional information
Thesis (Master of Marine Science)--Cape Peninsula University of Technology, 2023
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