DIY Algae Bioreactor


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Hong Kong is currently experiencing a lot of red tides. And mass killing of fish as a consequence.

"Since last winter, rare but deadly red tides containing harmful algae have resulted in the deaths of more than 36 tonnes of cultured fish, with the impacted areas extending from Tolo Harbour to Long Harbour.The red tides have caused the mariculture industry an estimated loss of HKD100 million in one month alone, SCMP reports." Source HK Coconuts TV

What are red tides? What causes them? Are they naturally occurring or caused by human activity? Are there any benefits to red tides? In this workshop we will explore these questions together.

A red tide is made of algae or phytoplankton. And plankton is generally plankton is good. Why? Because plankton feeds on CO2 (carbon dioxide) and produces O2 (oxygen). And it's the very base of the food chain. We like anything that reduces CO2 in the atmosphere, because it is good for our climate. So why should we worried about red tides?

“Where does the oxygen we breath come from? […] Rainforests are responsible for roughly one-third (28%) of the Earth’s oxygen but most (70%) of the oxygen in the atmosphere is produced by marine plants. The remaining 2 percent of Earth’s oxygen comes from other sources. The ocean produces oxygen through the plants (phytoplankton, kelp, and algal plankton) that live in it. These plants produce oxygen as a byproduct of photosynthesis, a process which converts carbon dioxide and sunlight into sugars the organism can use for energy.”

In this workshop, we will:

  1. try to collect plankton from the port with simply a bottle, and with a DIY plankton net
  2. observe plankton with different microscopes.
    1. A DIY microscope build in the Philippines by the Awesome lab
    2. the Foldscope , invented by Dr Manu Prakash, Assistant Professor, Stanford University ,CA, Department of Bioengineering, TED Senior Fellow
    3. A conventional microscope with a USB output
  3. build a DIY bioreactor to grow plankton "in the lab"

In other words we will investigate our immediate environment, the ocean surrounding Hong Kong, and will focus primarily on microscopic, oxygen-producing organisms. We will learn to image, describe, identify and classify them. We will learn to compare sites, species and environmental influences on them.

We hope that all these activities will help us better understand red tides, what causes them, how to prevent them and what we can do to mitigate their impact on our local marine ecosystem.

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Step 1: Collecting Water Samples With a Bottle


So we wanted to see if there was a trace of red tide algae in our local waters. Are the red tide a "latent beast" waiting for the right circumstances? Can we find red tides algae in small quantity in our local waters, or are these red tides coming from upstream ( Pearl River Delta)? First step for us was to go and collect with bottles from the nearest port, in our case Sam Ka Tsuen Typhoon Shelter (Lei Yun Mun) in Hong Kong.

Sample 1

Sample 2

Sample 3

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Step 2: First Encounter With Microscopy


The 3 samples on videos on the previous step came from Sam Ka Tsuen Typhoon Shelter (Lei Yun Mun). Not very much life there. So we practiced using the microscope on many other samples (below).

Why did we not see plankton?


  1. Not enough water
  2. Too dirty, everything died
  3. Location, should go at sea
  4. Microscope is not great
  5. What does the plankton need? CO2, Nutrients, Light. Maybe one of these is missing?
  6. Maybe we should have scooped more water with fine plankton nets? Let's do that (next step)

Where does red tides happen in Hong Kong?

"Dr Johnny Chan Chun-yin, clinical assistant professor of the medicine department at the University of Hong Kong's Li Ka Shing Faculty of Medicine, warned that close contact with toxic algae could lead to pain in the limbs and reversed temperature sensations. Consuming marine life that had eaten the toxins could cause serious headaches, nausea and loss of balance. Professor Ho Kin-chung, a red-tide expert and dean of science and technology at the Open University, said the city should remain alert for a possible repeat of the 1998 disaster. However, there was no crystal ball to show when the next outbreak would happen and whether it would be as lethal, he said. "Definitely, this is something we don't know but we can't rule out," Ho said. "This is just like infectious diseases. The virus is always there; it just explodes … in the right conditions." "In the past, red tides might stem from a local fish farm's discharge, but now the whole sea has been almost completely eutrophicated," said Ho. Eutrophication refers to excess nutrients in the water, and their composition - dominated by nitrogen and phosphorous - was key in defining the nature of a red tide. Warmer weather and slow currents also favoured the formation of red tides, according to the experts. Ho hypothesised that the El Nino phenomenon - weather events resulting from the warming of the Pacific - tended to create slower currents." two algae have been said to be toxic red tides. Gymnodinium sp. Alexandrium catenella Karenia digitata

How to predict the likelihood of red tides?

Our plan to find plankton

Go the dock and get more samples. Go the aquarium shop / pet shop.

Fish for plankton

Other samples

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Step 3: Building a Plankton Net


We found some synthetic fabric that we coud use as plankton net. We saw 2 plankton nets and attacjed them to two copper wire hoops. We attached bottles to the end of the nets fastened with copper wire.

I found Later that the government has really nicely made instructions.

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Step 4: Collecting Plankton and Algae With the Plankton Net


We walked up to Lei Yun Mun fish market and tried to find algae either by:

  • fishing with our plankton nets on the side of the dock
  • scrapping the inside of fish tanks in the market
  • collecting some stones in the intertidal zone and cutting out algae from the surface of the rocks

Most algae we sampled came from rocks.

This is what we found in the water and the algae.


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Step 5: Let's Build a Bioreactor to Keep the Algae Alive!


The big question became: once we have collected these algae, how can we keep them alive to change their environments and find out what triggers them to reproduce at a high rate (algal bloom)? What could prevent these algal bloom from happening? We would have to create a mini stable enclosed system to have a baseline. How would we build that? The students found many interesting references of how to build a DIY bioreactor and produced this list.

Our machine was simple:

  1. Individual brainstorm and drawing
  2. Everyone presents their own ideas, get questions, feedbacks and suggestions
  3. We take the best of each student's ideas into one single design that we will build
  4. We build the prototype together, often broken down into small groups

We ended up building 57x30x60 (WxLxH) wood frame, aluminium rod suspending three one gallon bottles filled with sea water, 2 LED neons, one air pump, a long silicone tube and straw system to make sure the bubbles are coming from the bottom.

According to literature, algae grows better with a lot of

  1. CO2
  2. Nutrients
  3. Sunlight

We will need to be able to measure these variables and study the effects of it on the algae. Currently, the system does not provide more of any of the above 3 main variables and we just circulate air through the air pump. The LED lamp is not optimised for algae / leafy vegetable growth but we will play with these parameters in the next stage of the experiment.


Step 6: First Week: Conclusion


What did we learn?

Some plankton are toxic to fish. There is zooplankton living around algae. Maybe they need each other. Plankton need CO2, Sunlight, nutrients (like all living forms). Plankton likes bubbles apparently. We learnt to use a microscope. We learnt to build a plankton net and catch plankton. Plankton can move fast (at their scale). We learnt the difference between zooplankton and phytoplankton. Some plankton glow in the dark and that's really cool.

What did we like?

We like making, drilling, cutting, screwing, sewing. We like to use the microscope. We like to get samples of algae, shells, sea water.

What do we wish?

We didn’t have time to put the fish in the algae tanks. We didn’t the time to see the effects of the nutrients with the algae. We wish that we did not cover ourselves in mud collecting samples.

Why does it matter?

Plankton is important because it absorbs CO2 (carbon dioxide), and produces 02 (oxygen). This means that without plankton... we would all die. Plankton is really important because it is the base of our food chain and because it regulates the climate.

The questions that remain

In this instructable we have not answered the questions we asked at the very beginning. We even have more questions now:

  1. What kind of fish would be poisoned by these algae?
  2. Can algae survive A LOT of sunlight and nutrients? Would it trigger blooming?
  3. How can we measure the growth of the plankton?
  4. Can we attach a microscope to our bioreactor?
  5. How can we monitor the evolution of our bioreactor conditions?
  6. What are red tides?
  7. What causes them? Why do they happen in some places and not others?
  8. Are they naturally occurring or caused by human activities?
  9. Are there any benefits to red tides?

We will continue to expand this instructable trying to answer these questions.Thank you for bearing with us. :)

Step 7: The Investigation Continues... Ask a Scientist!


As we continue investigating, we ask around and we got this answer:

"This year is probably going to break a new record for red tides in Hong Kong. I recently provided some feedback to someone in Clearwater Bay who contacted SWIMS about this a few weeks ago. Now those comments are posted to the Friends of Hoi Ha Facebook group:

In case you are wondering what causes a Red Tide, here is an explanation by Professor David Baker, PhD, HKU/ Swire Marine Institute. Red tides are caused by the right combination of light, temperature and nutrients. In Hong Kong, we typically see the worst red tides during the seasonal transitions in the Autumn and Spring, when temperature and light are just right for these algae to bloom. Unfortunately, we have a major problem with nutrients in Hong Kong, so the “fuel” for these algae is quite abundant which is why we have so many blooms in recent years. If we can cut off the nutrients, we can end the blooms.

IS THE SEA LIFE DYING THROUGH TOXINS OR LACK OF OXYGEN?It can be either or both. Most red tide blooms in Hong Kong are not classified as “harmful” because the HK government is primarily concerned with human health and protecting fish farms. Thus, the only species deemed toxic are those that produce toxins that can affect vertebrates such as people and fish. This year, there have been such species blooming in HK, which has led to huge losses in the fish mariculture industry. Otherwise, the so-called “non-toxic” species can cause harm to the environment. These red tides are very unnatural, high concentrations of algae that have a limited life span. When they die at the end of their life cycle they sink to the seafloor en masse, where they decompose. In that process, the bacteria digesting the algae consume oxygen, and can deplete the bottom water layers of so much oxygen that it suffocates everything that cannot escape.

ARE THERE ANY LONG-LASTING EFFECTS?Rarely. In some parts of the world, toxic algae are naturally abundant, and their toxins can accumulate in the food web (Kiribati Island is an example). This is extremely rare. Of course, a single red tide can be very dangerous to ocean and human health, but far more serious in my opinion is the recurrent, chronic nature of these phenomena. Singularly, they may have limited impacts, but in synergy a long chain of red tides can cause great environmental harm if nature cannot recover.

IS IT DANGEROUS FOR DOGS/CHILDREN TO SWIM IN A RED TIDE?If you see a red tide, you can report it to the government and they will investigate. They take this quite seriously. AFCD maintains a red tide monitoring website, where reported red tides are identified, and appropriate recommendations made for avoiding recreational swimming, etc. if necessary. From the website (…/fish…/hkredtide/update/update.html

RED TIDE REPORTING NETWORKWe welcome your assistance in reporting red tide to us. Please record the following information: (1) location of red tide (2) colour of the seawater (3) extent of the red tide (4) occurrence of dead fish and any other abnormal features observed around the red tide. Please report to: 2150 7124 (office hours) OR 1823 (non-office hours) OR via Hong Kong Red Tide Information Network Mobile Apps.


David M. Baker, Ph.D.Assistant Professor The Swire Institute of Marine Science, School of Biological Sciences & Department of Earth Sciences The University of Hong Kong Kadoorie Biological Sciences Building Pokfulam Road, Hong Kong, PRC

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Step 8: Ask the Kids


After being presented with all the previous documentation and experiments, we asked the kids what are the questions they feel are most critical. Here is a list of the question in the order of complexity (IMHO).">" are the number of times students have expressed interest in the topic, or asked a question related to that topic.

A> BiologyWe simply describe the red tides, what they are made of, what they do, where they live. What are red tides?

B >> Environmental science / chemistryWe study the environmental conditions in which red tides happen. We use many sensors to quantify the environment. We study the interactions between red tides and other species. Are there any benefits to red tides? How can we predict and reduce red tides? What causes them? Why do they happen in some places and not others? Are they naturally occurring or caused by human activities?

C >> MaricultureWe try to grow as much algae as possible. And remove as many disrupting factors to maximise their growth. How can we measure the growth of the plankton? Can we grow plankton, and make it huge? Can we attach a microscope to our bioreactor?

How can we monitor the evolution of our bioreactor conditions? We can catch the bad ones

D >>> Marine toxicologyWe study what either kills algae, or what algae kills. How do red tides kill fish? If we find out they kill fish, we could stop it. How do red tides affect the human brain? Can algae survive A LOT of sunlight and nutrients? Would it trigger blooming? What kind of fish would be poisoned by these algae?

E >>>> Evolutionary biology. Mutations. GMOWe study how algae evolve, mutate. We engineer algae for specific purpose, either by selection or genetic intervention. How can we turn people into plankton? It’s an interesting question, it’s weird. Because maybe in the future we could turn plankton into people. It’s interesting because when machines are getting smarter, people would become more stupid, evolving towards plankton. Can we use red tides and turn them into something else? Can we create a new organism? Can new people evolve again from plankton?

If we could be plankton, we could actually be there and understand it from the inside, like Ant Man - or shall we say “Plankton Man”!!!!

F>> BioethicsWhy is it bad to kills animals and humans? We discuss high-level questions about which living organism should or should not be alive in order to fulfil our ethical and cultural agenda. This level requires us to have some understanding about all the above concepts and is perhaps, the most critical, yet most subjective / cultural.

closed windows:

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Step 9: Expedition on a Fish Farm Affected by Red Tides


11 More Images

We decided to go to find out ourselves where red tides were happening and perhaps

Location: Coordinates: 22.274800, 114.295088

  • Gonyaulax polygramma 多紋膝溝藻
  • GroupDinoflagellates
  • Class:Dinophyceae
  • Named by:Stein
  • Year:1883
  • Shape: Pear
  • Form of colony:Solitary
  • Size(um):Length: 29-66;
  • Width: 26-54
  • Frequency of occurrence in Hong Kong:Medium
  • Region of occurrence:Northeast,South,Southeast,West, Tolo Harbour
  • Potentially harmful to fish:Caused fish kill in Hong Kong
  • Toxin produced:N/A

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Step 10: The Concept: a Scientific Experiment and a Business Experiment


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Step 11: Building Version 2


5 More Images

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Step 12: Growing Algae in Our Bioreactor