Chemical reduction of Cyanobacteria bloom
Question:

Cyanobacteria are algae that live in body of water, and can manufacture their own food. In certain conditions these algae can proliferate fast. This is called Cyanobacteria bloom, and it can become toxic and damage the ecological balance of the body of water. There are several accepted chemical and biological treatments to reduce the bloom. One of these treatments is the addition of special dye to the body of water, which blocks the light transmission through the water.  


Watch the following video demonstrating the effect of dye addition to water on their light transmission:


During February 2016, Cyanobacteria bloom was observed in Lake Kinnert.

Retrieved from http://www.hayadan.org.il/bad-florish-0303168

How can the blockage of the water light transmission, using a dye, help reduce the Cyanobacteria bloom in lake Kinnert?


0 People tried to answer this question

Blockage of the water light transmission, using a dye, prevents Cyanobacteria respiration, hence reducing their proliferation.


Blockage of the water light transmission, using a dye, prevents Cyanobacteria performing photosynthesis, hence reducing their proliferation.
Blockage of the water light transmission, using a dye, prevents Cyanobacteria from producing toxins, which are essential to their bloom.

Blockage of the water light transmission, using a dye, interferes with the ecological balance which leads to reduced Cyanobacteria proliferation.




Comments:
1.  Ozeri Aya (2021-05-20 16:00:00)
I would like to learn more

 

In your question you describe an interesting phenomenon which is hardly known in Israel. It was nice to learn about it.  

However the question is relatively simple and challenges only few aspects of the student's skills. The background contains description of several facts. The student needs only to deduce a logical deduction, once he is familiar with the term photosynthesis.

The student gains new knowledge. He/she should understand the dye treatment to reduce the bloom of the Cyanobacteria. However, a simple logical analysis of the last sentence: "One of these treatments is the addition of special dye to the body of water, which blocks the light transmission through the water", is enough to understand that it is a different phasing of the correct answer.

All the other possible answers were not so misleading or distracting. It was relatively simple to understand that they are incorrect.

 It was assumed that the student is familiar with the term Photosynthesis, which is reasonable assumption for the defined Piza questionnaire students.    

In addition, the map-point "Reduction of cyanobacteria in domestic aquarium", which is very good and educated, contains the answer: "Reduction of light for 3-7 days. This step reduces the photosynthesis process, thus the cyanobacteria cannot produce nutrients crucial for growing and may starves".  

The background presented prior to the question as literal text, in addition to the student self-knowledge about the term photosynthesis were sufficient for answering the question correctly. The video is nice but does not add new information. The Kinerret photo is a nice addition but doesn't contribute additional data that should assist the learner when answering the question, or maybe I didn't manage to see this data.   

There is no need for higher levels of data processing, such as graph or table analysis, experiencing simulation or observations from watching video or animation.  

Suggestions: 

1.      You can add a graph or a table that shows the relationship between the percentage of the reduction in the Cyanobacteria bloom and the amount of dye per a fixed area. This should emphasis the effect of the amount of the light on the reduction process. Using this table or graph you can also add to your question and answer a relation to the minimal amount of light blocking that is required to stop the algae bloom.    

2.      You can add a video of how cyanobacteria community is being controlled in an aquarium by light reduction.

3.      The question is dealing with reduction of the algae proliferation. However it is not explained in the background in which conditions these algae can proliferate faster. I think this data should be added such that the question directing to photosynthesis is still challenging.

4.      If the Kinerret photo contains algae view then they should be marked with some circles or arrows and additional text.

   

  

2.  akari Nariman (23.05.2016 am 12.09.27)
An exciting phenomenon

 

 

I think there is nothing new that I can add after the things that Aya has said .

I really like the topic , its very interesting and new for me , after I read the question I have done a lot of researches on the internet to read more and to know more in order to add a point on the map and to give a right evaluation for your question , and I really enjoyed that . 

after a lot of researches and looking deeply into the topic , I think that this is an easy question at least for me , it doesn't require thinking and its doesn't take time to know the right answer .so I think you should make it a little bit tricky .

For the video and the picture that you added on the body of the question itself , I think they are bonus and there is no need for them , I didn't get the point of the picture , and the video although its look like its authentic ,it didn't add any new information for the question , its just formatted the formula of the question in other way that the student can see what are you talking about concretely.

The information that you inserted on the map's points , are very useful and interesting and new and related to the main topic of the question  , although it doesn't really help the student to solve the question , its just an addition to the knowledge he has acquired of reading the text of the question.

For me I really don't understand the connection between the points on the map (places) and the information that you wrote on it .

I suggest putting 2 pictures of the same lake one with the Cyanobacteria bloom and the other one is after we treated the bloom and restricted the proliferating of Cyanobacteria for compares .

I also suggesting replacing the video with another one that explain how the Cyanobacteria proliferating and why , and how the dye restrict the proliferation .

I think you  should explain the term photosynthesis aside ,because I think not all the students of junior school know this term and what it does and how it works . In addition , I think you made the question very easy for the student , that there is no need to look on the map's points and read more , so he can solve it by just reading the body of the question , so I think you should put less information on the body of the question and make him look and search on the map's points and read to solve the question .

In general , I really liked this topic , and it was really fun and enjoyable to read about it , and I think you really did a great job .

Well done

Nariman

 

  

 

 

 

3.  Sirhan Manal (29.05.2016 pm 12.55.36)
Chemical reduction of Cyanobacteria bloom

I like the subject that you chose to write a question about, and the video that you added, it shows the relevance of adding dye that influence the light transmission through the water.

You said that there is bloom of the cyanobacteria but you did not mentioned when it is happening and in which circumstances and conditions; like mentioning the lake stratification and that the bloom happens at the summer as a result of the lake stratification.

Also I felt that there was short of the definition of the cyanobacteria, you did not mentioned the properties of this kind of algae, for instance that this kind is characterized in atmospherically nitrogen fixation, you can use this information by this attached link to understand more about this algae;

http://telem.openu.ac.il/courses/c20237/kineret-ee.htm

You mentioned that there are another treatments to reduce this bloom but you did not mentioned just this treatment with dye, I was interested to hear more about the treatments so I can evaluate why you chose to talk about this specific treatment.

Honestly I did not like this treatment because in my own vision I see that this treatment could damage another organisms, that also use the photosynthesis to survive, and the organisms that Nourished of the damaged organisms, I think that this treatment would bring several symptoms to this lake.

I hope you understand my point of view, good luck

4.  Ryder Darian (04.06.2016 pm 10.38.28)
Suggested updates

I will now refer to the updated question as follows:

1. Content grammar.

2. Content clarity/brevity.

3. Content relevance.

4. Question design.


1. Content grammar:

Cyanobacteria are algae that live in body of water water bodies, and can manufacture their own food. InThere are certain conditions in which these algae can proliferate fast. This is called Cyanobacteria bloom, and ita condition that can become toxic and damage the ecological balance of the body of waterwater body. There are several accepted chemical and biological treatments to reduce thethis bloom. One of these treatments is the addition of a special dye to the body of water, which blocks the water’s light transmission through the water.

Please have a look also at the possible answer and consider updating.

2. Content clarity/brevity.

Your question, after the introductory paragraph and associated video and image, was “How can the blockage of the water light transmission, using a dye, help reduce the Cyanobacteria bloom in lake Kinnert?”.

Yet, if I assume correctly, the right answer is the one including photosynthesis, a word that never came up, neither in the introductory paragraph nor the video or the image.


The Question's name is: "Chemical reduction of Cyanobacteria bloom", I find the term "chemical reduction" here rather ambiguous, as it is a well defined chemical term, which you here give a different than normal meaning to.


3. Content relevance.

The content is rather relevant and might be good to associate with climate change if relevant (it seems it is relevant)


4. Question design.

As people before me said, the possible answer alternatives, are for from misleading.




History of edits
Edited BY: Inbal Michael Edit Date: 2016-05-14 19:41:08
Edited BY: Inbal Michael Edit Date: 2016-05-14 19:40:16
Created By: Anastasia Badiyan Edit Date: 2016-05-07 20:42:49
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