South Africa coast Archives - One Earth - One Ocean e. V. https://oneearth-oneocean.com/en/category/south-africa-coast-en/ Eine weitere WordPress-Website Tue, 20 Dec 2022 21:28:51 +0000 en-US hourly 1 https://wordpress.org/?v=6.5.5 https://oneearth-oneocean.com/wp-content/uploads/2022/08/cropped-oeoo-logo-unterzeile-blau-1-32x32.jpg South Africa coast Archives - One Earth - One Ocean e. V. https://oneearth-oneocean.com/en/category/south-africa-coast-en/ 32 32 Biofouling on buoyant marine plastics: An experimental study into the effect of size on surface longevity https://oneearth-oneocean.com/en/research-en/2016/biofouling-on-buoyant-marine-plastics-an-experimental-study-into-the-effect-of-size-on-surface-longevity/ https://oneearth-oneocean.com/en/research-en/2016/biofouling-on-buoyant-marine-plastics-an-experimental-study-into-the-effect-of-size-on-surface-longevity/#respond Sun, 03 Apr 2016 10:16:53 +0000 https://oneearth-oneocean.com/2016/04/03/biofouling-on-buoyant-marine-plastics-an-experimental-study-into-the-effect-of-size-on-surface-longevity/ Francesca M.C. Fazey, Peter G. Ryan, Biofouling on buoyant marine plastics: An experimental study into the effect of size on surface longevity, Environmental Pollution, Volume 210, March 2016, Pages 354-360, ISSN 0269-7491, http://dx.doi.org/10.1016/j.envpol.2016.01.026. (http://www.sciencedirect.com/science/article/pii/S0269749116300264) Abstract: Recent estimates suggest that roughly 100 times more plastic litter enters the sea than is found floating at the sea surface, despite the buoyancy and durability of many plastic polymers. Biofouling by marine biota is one possible mechanism responsible for this discrepancy. Microplastics (<5 mm in diameter) are more scarce than larger size classes, which makes sense because fouling is a function of surface area whereas buoyancy is a function of volume; the smaller an object, the greater its relative surface area. We tested whether plastic items with high surface area to volume ratios sank more rapidly by submerging 15 different sizes of polyethylene samples in False Bay, South Africa, for 12 weeks to determine the time required for samples to sink. All samples became sufficiently fouled to sink within the study period, but small samples lost buoyancy much faster than larger ones. There was a direct relationship between sample volume (buoyancy) and the time to attain a 50% probability of sinking, which ranged from 17 to 66 days of exposure. Our results provide the first estimates of the longevity of different sizes of plastic debris at the ocean surface. Further research is required to determine how fouling rates differ on free floating debris in different regions and in different types of marine environments. Such estimates could be used to improve model predictions of the distribution and abundance of floating plastic debris globally. Keywords: Marine plastic debris; Buoyancy; Biofouling; Fragment size; Microplastics

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]]> Francesca M.C. Fazey, Peter G. Ryan, Biofouling on buoyant marine plastics: An experimental study into the effect of size on surface longevity, Environmental Pollution, Volume 210, March 2016, Pages 354-360, ISSN 0269-7491, http://dx.doi.org/10.1016/j.envpol.2016.01.026. (http://www.sciencedirect.com/science/article/pii/S0269749116300264) Abstract: Recent estimates suggest that roughly 100 times more plastic litter enters the sea than is found floating at the sea surface, despite the buoyancy and durability of many plastic polymers. Biofouling by marine biota is one possible mechanism responsible for this discrepancy. Microplastics (<5 mm in diameter) are more scarce than larger size classes, which makes sense because fouling is a function of surface area whereas buoyancy is a function of volume; the smaller an object, the greater its relative surface area. We tested whether plastic items with high surface area to volume ratios sank more rapidly by submerging 15 different sizes of polyethylene samples in False Bay, South Africa, for 12 weeks to determine the time required for samples to sink. All samples became sufficiently fouled to sink within the study period, but small samples lost buoyancy much faster than larger ones. There was a direct relationship between sample volume (buoyancy) and the time to attain a 50% probability of sinking, which ranged from 17 to 66 days of exposure. Our results provide the first estimates of the longevity of different sizes of plastic debris at the ocean surface. Further research is required to determine how fouling rates differ on free floating debris in different regions and in different types of marine environments. Such estimates could be used to improve model predictions of the distribution and abundance of floating plastic debris globally. Keywords: Marine plastic debris; Buoyancy; Biofouling; Fragment size; Microplastics

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]]> https://oneearth-oneocean.com/en/research-en/2016/biofouling-on-buoyant-marine-plastics-an-experimental-study-into-the-effect-of-size-on-surface-longevity/feed/ 0 The effect of fine-scale sampling frequency on estimates of beach litter accumulation https://oneearth-oneocean.com/en/research-en/2014/the-effect-of-fine-scale-sampling-frequency-on-estimates-of-beach-litter-accumulation/ https://oneearth-oneocean.com/en/research-en/2014/the-effect-of-fine-scale-sampling-frequency-on-estimates-of-beach-litter-accumulation/#respond Thu, 18 Sep 2014 17:41:25 +0000 https://oneearth-oneocean.com/2014/09/18/the-effect-of-fine-scale-sampling-frequency-on-estimates-of-beach-litter-accumulation/ Peter G. Ryan, Annerie Lamprecht, Debbie Swanepoel, Coleen L. Moloney, The effect of fine-scale sampling frequency on estimates of beach litter accumulation, Marine Pollution Bulletin, Available online 16 September 2014, ISSN 0025-326X, http://dx.doi.org/10.1016/j.marpolbul.2014.08.036. (http://www.sciencedirect.com/science/article/pii/S0025326X14005888) Abstract: The effect of sampling frequency on estimates of the rate of litter accumulation was determined for two South African sandy beaches. After initial cleaning, all manufactured items >10 mm diameter were collected in alternating bouts of daily or weekly cleanups. Daily sampling collected 2.5 (range 2.1?3.4) times more litter items than weekly samples and 1.7 (1.3?2.3) times more litter by mass. Low density items such as foamed polystyrene showed a greater differential (4?5 times more items from daily sampling), presumably due to faster turnover of lightweight litter items. Variation in weekly samples was not consistently less than daily estimates, suggesting that less frequent samples only partly integrate short-term fluctuations in litter dynamics. Researchers using beach accumulation data to infer trends in nearshore marine litter, or to assess the efficacy of litter mitigation measures, need to ensure consistency in sampling frequency. Keywords: Stranded debris; Plastics; Sample rate; Accumulation; Meta-analyses; South Africa

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]]> Peter G. Ryan, Annerie Lamprecht, Debbie Swanepoel, Coleen L. Moloney, The effect of fine-scale sampling frequency on estimates of beach litter accumulation, Marine Pollution Bulletin, Available online 16 September 2014, ISSN 0025-326X, http://dx.doi.org/10.1016/j.marpolbul.2014.08.036. (http://www.sciencedirect.com/science/article/pii/S0025326X14005888) Abstract: The effect of sampling frequency on estimates of the rate of litter accumulation was determined for two South African sandy beaches. After initial cleaning, all manufactured items >10 mm diameter were collected in alternating bouts of daily or weekly cleanups. Daily sampling collected 2.5 (range 2.1?3.4) times more litter items than weekly samples and 1.7 (1.3?2.3) times more litter by mass. Low density items such as foamed polystyrene showed a greater differential (4?5 times more items from daily sampling), presumably due to faster turnover of lightweight litter items. Variation in weekly samples was not consistently less than daily estimates, suggesting that less frequent samples only partly integrate short-term fluctuations in litter dynamics. Researchers using beach accumulation data to infer trends in nearshore marine litter, or to assess the efficacy of litter mitigation measures, need to ensure consistency in sampling frequency. Keywords: Stranded debris; Plastics; Sample rate; Accumulation; Meta-analyses; South Africa

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