Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification
This master's thesis investigated the effects of acidified conditions on movement behaviors of the harmful algal bloom causing raphidophyte Heterosigma akashiwo. Individual movements of cells (i.e., swimming speed, turning rates, vertical velocity, declination, and diffusivity) were quantified...
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ftunivrhodeislan:oai:digitalcommons.uri.edu:dissertations-2817 2023-05-15T17:51:52+02:00 Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification Kim, Hyewon 2012-01-01T08:00:00Z https://digitalcommons.uri.edu/dissertations/AAI1530885 ENG eng DigitalCommons@URI https://digitalcommons.uri.edu/dissertations/AAI1530885 Dissertations and Master's Theses (Campus Access) Biological oceanography text 2012 ftunivrhodeislan 2021-06-29T19:20:50Z This master's thesis investigated the effects of acidified conditions on movement behaviors of the harmful algal bloom causing raphidophyte Heterosigma akashiwo. Individual movements of cells (i.e., swimming speed, turning rates, vertical velocity, declination, and diffusivity) were quantified using 3-D digital video analysis for a 6-h period and were compared among 3 pCO2 treatments of 280, 380, and 750 ppm reflecting ocean carbonate chemistry in pre-industrial, current, and year 2100 at 2 different pH-acclimation conditions. We discovered that an abrupt decrease in pH levels significantly induced downward swimming of H. akashiwo (all p < 0.001), by exhibiting faster net vertical velocity (-31, -46, -66 µm s-1 at 280, 380, 750 ppm, respectively) and an increase in downward moving fractions (68, 78, 87% at 280, 380, 750 ppm). However, pH-acclimation reduced this strong vertical downward bias, by increasing net vertical velocity (-23, -12, -47 µm s-1 at 280, 380, 750 ppm) and decreased downward swimming populations (59, 56, 75% at 280, 380, 750 ppm) regardless of pCO 2 levels. Pre-acclimation significantly increased swimming speed (144 to 150 um s-1) at all pCO2 levels (all p < 0.001) compared to swimming speed (110 to 119 um s-1) in pH-shock condition and resulted in 2.3 to 2.5 fold higher diffusivity (1.8×105 to 2.2×105 µm2 s-1) compared to diffusivity (8.0×104 to 8.7×10 5 µm2 s-1) in pH-shock. Either pCO2 alteration or acclimation had no effects on turning rates (38.7 to 44.8 deg s-1). Dispersal length of H. akashiwo bloom during 10-h implied a decreasing bloom dispersal in abrupt pH decreases but an increasing bloom dispersal in gradual pH decreases, emphasizing the importance of taking pH-acclimation status into account. Text Ocean acidification University of Rhode Island: DigitalCommons@URI |
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Open Polar |
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University of Rhode Island: DigitalCommons@URI |
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ftunivrhodeislan |
language |
English |
topic |
Biological oceanography |
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Biological oceanography Kim, Hyewon Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification |
topic_facet |
Biological oceanography |
description |
This master's thesis investigated the effects of acidified conditions on movement behaviors of the harmful algal bloom causing raphidophyte Heterosigma akashiwo. Individual movements of cells (i.e., swimming speed, turning rates, vertical velocity, declination, and diffusivity) were quantified using 3-D digital video analysis for a 6-h period and were compared among 3 pCO2 treatments of 280, 380, and 750 ppm reflecting ocean carbonate chemistry in pre-industrial, current, and year 2100 at 2 different pH-acclimation conditions. We discovered that an abrupt decrease in pH levels significantly induced downward swimming of H. akashiwo (all p < 0.001), by exhibiting faster net vertical velocity (-31, -46, -66 µm s-1 at 280, 380, 750 ppm, respectively) and an increase in downward moving fractions (68, 78, 87% at 280, 380, 750 ppm). However, pH-acclimation reduced this strong vertical downward bias, by increasing net vertical velocity (-23, -12, -47 µm s-1 at 280, 380, 750 ppm) and decreased downward swimming populations (59, 56, 75% at 280, 380, 750 ppm) regardless of pCO 2 levels. Pre-acclimation significantly increased swimming speed (144 to 150 um s-1) at all pCO2 levels (all p < 0.001) compared to swimming speed (110 to 119 um s-1) in pH-shock condition and resulted in 2.3 to 2.5 fold higher diffusivity (1.8×105 to 2.2×105 µm2 s-1) compared to diffusivity (8.0×104 to 8.7×10 5 µm2 s-1) in pH-shock. Either pCO2 alteration or acclimation had no effects on turning rates (38.7 to 44.8 deg s-1). Dispersal length of H. akashiwo bloom during 10-h implied a decreasing bloom dispersal in abrupt pH decreases but an increasing bloom dispersal in gradual pH decreases, emphasizing the importance of taking pH-acclimation status into account. |
format |
Text |
author |
Kim, Hyewon |
author_facet |
Kim, Hyewon |
author_sort |
Kim, Hyewon |
title |
Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification |
title_short |
Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification |
title_full |
Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification |
title_fullStr |
Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification |
title_full_unstemmed |
Bloom formation of the toxic raphidophyte Heterosigma akashiwo in response to ocean acidification |
title_sort |
bloom formation of the toxic raphidophyte heterosigma akashiwo in response to ocean acidification |
publisher |
DigitalCommons@URI |
publishDate |
2012 |
url |
https://digitalcommons.uri.edu/dissertations/AAI1530885 |
genre |
Ocean acidification |
genre_facet |
Ocean acidification |
op_source |
Dissertations and Master's Theses (Campus Access) |
op_relation |
https://digitalcommons.uri.edu/dissertations/AAI1530885 |
_version_ |
1766159143229456384 |