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Response of Daphnia magna from Natural Populations to Ultraviolet Radiation

Zheng, Luo (2018) BIOM02 20172
Degree Projects in Biology
Abstract
Diel vertical migration (DVM) is performed by various zooplankton taxa. The general movement pattern of DVM has been well studied while the possible clonal differences of this movement largely remain unknown. My master thesis focus on investigating the effects of environmental stressors on Daphnia magna strains isolated from natural populations. Here I maintained 11 strains of Daphnia magna originating from natural populations from lakes and ponds in southern Sweden. Their response under three consecutive treatments of UV radiation (UV turned off; UV turned on; UV turned off) was observed and the swimming speed and depth were analyzed. Results showed that D. magna from natural populations may respond to UV radiation with increasing... (More)
Diel vertical migration (DVM) is performed by various zooplankton taxa. The general movement pattern of DVM has been well studied while the possible clonal differences of this movement largely remain unknown. My master thesis focus on investigating the effects of environmental stressors on Daphnia magna strains isolated from natural populations. Here I maintained 11 strains of Daphnia magna originating from natural populations from lakes and ponds in southern Sweden. Their response under three consecutive treatments of UV radiation (UV turned off; UV turned on; UV turned off) was observed and the swimming speed and depth were analyzed. Results showed that D. magna from natural populations may respond to UV radiation with increasing swimming speed and depth. After UV exposure the swimming behavior remained similar to the phase when UV radiation exists. Difference in swimming behavior among strains under neutral environmental conditions was found. Furthermore, this difference disappeared under UV threat and all strains then performed a similar pattern of movement. (Less)
Popular Abstract
Zooplankton usually perform a daily movement that they swim up to the surface at afternoon, and swim down to deep water at early morning. This behavior of zooplankton, also known as diel vertical migration (DVM), was affected by sunlight and worked as a predator-avoiding strategy. Many studies had concluded that ultraviolet radiation in sunlight was one of the factors triggering the diel vertical migration of zooplankton.

This brought up the questions for my master thesis: If diel vertical migration was triggered by UV in sunlight, would zooplankton perform a similar movement when they are exposed to short-term UV radiation? For individuals from same species, would they perform exactly the same DVM, or there would be a difference... (More)
Zooplankton usually perform a daily movement that they swim up to the surface at afternoon, and swim down to deep water at early morning. This behavior of zooplankton, also known as diel vertical migration (DVM), was affected by sunlight and worked as a predator-avoiding strategy. Many studies had concluded that ultraviolet radiation in sunlight was one of the factors triggering the diel vertical migration of zooplankton.

This brought up the questions for my master thesis: If diel vertical migration was triggered by UV in sunlight, would zooplankton perform a similar movement when they are exposed to short-term UV radiation? For individuals from same species, would they perform exactly the same DVM, or there would be a difference between different strains (clones) due to genetic difference? In order to solve these questions, I recorded responses of Daphnia magna from different strains under certain UV radiation and analyzed their swimming speed and depth.

Results showed that when exposed to UV threat, D. magna would not perform the DVM-type movement but swim swiftly to stay at deeper water instead. Unlike typical DVM that individuals swim back to the surface when sunlight is gone, D. magna still kept the similar evasive movement in deep water when short-term UV was off. I also found that D. magna from different strains would have different swimming speed under normal conditions. When UV threat appeared, this difference between strains broke down, indicating that UV threat would be a bigger factor than strain differences. Despite some flaws in statistics, my findings not only provided evidence of strain difference in swimming behavior of zooplankton taxa, but also deepened the knowledge of their vertical movement under UV threats. (Less)
Please use this url to cite or link to this publication:
author
Zheng, Luo
supervisor
organization
course
BIOM02 20172
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8958658
date added to LUP
2018-09-13 14:40:04
date last changed
2018-09-13 14:40:04
@misc{8958658,
  abstract     = {Diel vertical migration (DVM) is performed by various zooplankton taxa. The general movement pattern of DVM has been well studied while the possible clonal differences of this movement largely remain unknown. My master thesis focus on investigating the effects of environmental stressors on Daphnia magna strains isolated from natural populations. Here I maintained 11 strains of Daphnia magna originating from natural populations from lakes and ponds in southern Sweden. Their response under three consecutive treatments of UV radiation (UV turned off; UV turned on; UV turned off) was observed and the swimming speed and depth were analyzed. Results showed that D. magna from natural populations may respond to UV radiation with increasing swimming speed and depth. After UV exposure the swimming behavior remained similar to the phase when UV radiation exists. Difference in swimming behavior among strains under neutral environmental conditions was found. Furthermore, this difference disappeared under UV threat and all strains then performed a similar pattern of movement.},
  author       = {Zheng, Luo},
  language     = {eng},
  note         = {Student Paper},
  title        = {Response of Daphnia magna from Natural Populations to Ultraviolet Radiation},
  year         = {2018},
}