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Toxic cyanobacterial blooms, is prediction the new solution?

Chen, Ying (2012) BIOM25 20121
Degree Projects in Biology
Abstract
Abstract
Toxic cyanobacterial blooms can form in both freshwater and marine environments, which could threaten the health of human beings and animals. The genera that are
known for causing the scums in freshwater are Anabaena, Microcystis, Cylindrospermopsis and Planktothrix. In order to control lake water quality and
minimize the potential health risk associated with the cyanobacterial blooms, the EWACS (Early Warning against Cyanobacterial Scums) model and the competition
theory were established. As a part of the EWACS model, buoyancy rates for different species were investigated in this study. A Percoll gradient experiment was performed
to measure the floating velocities of those species with a two-tank method. However, none of the... (More)
Abstract
Toxic cyanobacterial blooms can form in both freshwater and marine environments, which could threaten the health of human beings and animals. The genera that are
known for causing the scums in freshwater are Anabaena, Microcystis, Cylindrospermopsis and Planktothrix. In order to control lake water quality and
minimize the potential health risk associated with the cyanobacterial blooms, the EWACS (Early Warning against Cyanobacterial Scums) model and the competition
theory were established. As a part of the EWACS model, buoyancy rates for different species were investigated in this study. A Percoll gradient experiment was performed
to measure the floating velocities of those species with a two-tank method. However, none of the species floated up in this experiment. In order to find out the best
competitors for light and nutrients, in other words, the dominant phytoplankton species in a lake, another competition experiment was conducted with chemostats
between a nitrogen-fixing species Anabaena and a non-nitrogen fixer Planktothrix. Monoculture experiments were performed to determine the lowest critical
requirements (R*) for nutrients and light. Unfortunately, the stable state was not reached for both species. Anabaena died after three weeks of monoculture experiment
and Planktothrix did not grow in the chemostat. These results suggest that the prediction models are not always workable. And it leaves us questions for further research.

Popular science summary:

Cyanobacteria, also known as blue-green algae, are famous for their extensive and highly visible blooms. Most of them are harmful, which can threaten the health of humans and animals. Researches about the predictions of the cyanobacterial blooms are considerable. Are these methods and models truly workable? In this study, we investigated two models to explore the question.

The first model we tried to apply is EWACS (Early Warning against Cyanobacterial Scums) model. The accurate measurement of buoyancy rate is essential for this model. The culture collections we used in this experiment were from Amsterdam and Wageningen. Unfortunately, all the species we used in this experiment did not float up. Since the lack of data, we could not continue with the following-up calculations. Thus we came up with a proposal for a new experiment.

The second model we tried to explore is the competition model between two cyanobacterial species Anabaena and Planktothrix. One is nitrogen-fixing species (Anabaena) and the other one is non nitrogen fixing species (Planktothrix). We tried to compare the competition abilities for nutrients and light between the two species under phosphorous-limited, nitrogen-limited and light-limited conditions. Chemostat is the main way we used to examine the questions. Three chemostats were used and light, population densities were measured three times per week (Monday, Wednesday and Friday).

In order to find out the lowest critical light requirements, the monoculture experiments of Anabaena lasted for two months. However, the stable state was never reached even after 60 days. Instead, the cultures were dying during the last two weeks. The same situation happened to the non-nitrogen fixer Planktothrix. They were not growing in the chemostat. That is why the monoculture experiment for Planktothrix only last for four days. Since the lack of data, this model could not be applied to our study.

Due to the lack of data, neither of the models was used in this study. Our results suggest that the prediction models are not always practicable. Moreover, our work raised new questions for future study: can prediction models actually solve the harmful cyanobacterial blooms?


Advisor: Anne Immers
Master´s Degree project: 30 credits in Aquatic Ecology. 2012
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Chen, Ying
supervisor
organization
course
BIOM25 20121
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3627075
date added to LUP
2013-03-28 14:19:23
date last changed
2013-03-28 14:19:23
@misc{3627075,
  abstract     = {Abstract
Toxic cyanobacterial blooms can form in both freshwater and marine environments, which could threaten the health of human beings and animals. The genera that are
known for causing the scums in freshwater are Anabaena, Microcystis, Cylindrospermopsis and Planktothrix. In order to control lake water quality and
minimize the potential health risk associated with the cyanobacterial blooms, the EWACS (Early Warning against Cyanobacterial Scums) model and the competition
theory were established. As a part of the EWACS model, buoyancy rates for different species were investigated in this study. A Percoll gradient experiment was performed
to measure the floating velocities of those species with a two-tank method. However, none of the species floated up in this experiment. In order to find out the best
competitors for light and nutrients, in other words, the dominant phytoplankton species in a lake, another competition experiment was conducted with chemostats
between a nitrogen-fixing species Anabaena and a non-nitrogen fixer Planktothrix. Monoculture experiments were performed to determine the lowest critical
requirements (R*) for nutrients and light. Unfortunately, the stable state was not reached for both species. Anabaena died after three weeks of monoculture experiment
and Planktothrix did not grow in the chemostat. These results suggest that the prediction models are not always workable. And it leaves us questions for further research.

Popular science summary:

Cyanobacteria, also known as blue-green algae, are famous for their extensive and highly visible blooms. Most of them are harmful, which can threaten the health of humans and animals. Researches about the predictions of the cyanobacterial blooms are considerable. Are these methods and models truly workable? In this study, we investigated two models to explore the question. 

The first model we tried to apply is EWACS (Early Warning against Cyanobacterial Scums) model. The accurate measurement of buoyancy rate is essential for this model. The culture collections we used in this experiment were from Amsterdam and Wageningen. Unfortunately, all the species we used in this experiment did not float up. Since the lack of data, we could not continue with the following-up calculations. Thus we came up with a proposal for a new experiment. 

The second model we tried to explore is the competition model between two cyanobacterial species Anabaena and Planktothrix. One is nitrogen-fixing species (Anabaena) and the other one is non nitrogen fixing species (Planktothrix). We tried to compare the competition abilities for nutrients and light between the two species under phosphorous-limited, nitrogen-limited and light-limited conditions. Chemostat is the main way we used to examine the questions. Three chemostats were used and light, population densities were measured three times per week (Monday, Wednesday and Friday). 

In order to find out the lowest critical light requirements, the monoculture experiments of Anabaena lasted for two months. However, the stable state was never reached even after 60 days. Instead, the cultures were dying during the last two weeks. The same situation happened to the non-nitrogen fixer Planktothrix. They were not growing in the chemostat. That is why the monoculture experiment for Planktothrix only last for four days. Since the lack of data, this model could not be applied to our study. 

Due to the lack of data, neither of the models was used in this study. Our results suggest that the prediction models are not always practicable. Moreover, our work raised new questions for future study: can prediction models actually solve the harmful cyanobacterial blooms? 


Advisor: Anne Immers
Master´s Degree project: 30 credits in Aquatic Ecology. 2012 
Department of Biology, Lund University},
  author       = {Chen, Ying},
  language     = {eng},
  note         = {Student Paper},
  title        = {Toxic cyanobacterial blooms, is prediction the new solution?},
  year         = {2012},
}