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Cesar Jung-Harada 🌏
Tolo Filtering Lab 吐露港生物自淨實驗號

Tolo Filtering Lab 吐露港生物自淨實驗號

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  1. Poor water quality in Tolo Harbour

Tolo Harbour is a region that is most vulnerable to red tides in Hong Kong. Because of the landlocked situation and narrow exit to the open sea, the water circulation in Tolo Harbour is weak. Red tides refer to a harmful algae booms caused by excess nitrogen in the sea. Red tides have caused threats to fish farmers in Tolo harbour due to a toxicity of algae and lack of oxygen. Can filter feeders help consume the excess nitrogen in the waters and prevent red tides?

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  1. Feasibility of polyculture in Tolo Harbour

Polyculture has become a new trend in marine farming. Oysters, mussels and kelps are the common trios. However, there are still many unknowns to be explored. The design soughts to answer the question mentioned in the following.

Can a polyculture marine farm clean Tolo Harbour?

Symbiosis:

Do different species live well together? What is the optimal proportion of different species? Do different species compete for food?

Effect on water current:

Water current is essential to marine farms to ensure a constant supply of food and the removal of faeces. Is it possible to set up a marine farm in an area of low water circulation like Tolo? What is the optimal density to minimize the effect on water flow?

Design:

How to minimize the efforts in controlling the density of the farming structure, thus the species?

What is the most efficient way to document and compare the filtering ability of different species?

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The ultimate goal of the design is to clean the waters in Tolo Harbour with polycuture farms.

The vision is to inspire and encourage fish farmers in Tolo harbour to convert their monoculture fish farms into a more sustainable polyculture marine farms that filter water in Tolo Harbour with the findings of the intervention. The findings include - the optimal density of oysters, mussels and kelp, the optimum proportion and placing of species.

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Half of the raft is occupied with oysters and the other half is occupied with mussels. Kelp are placed in between to provide oxygen. To monitor the filtering ability of oysters and mussels individually and together, sensors are place around the periphery of the raft. The sensors measures pH value, oxygen level. The orientation of the raft does not change while the water current does. To compare the filtering performance, researchers can obtain the reading from sensors during periods of different water current.
Half of the raft is occupied with oysters and the other half is occupied with mussels. Kelp are placed in between to provide oxygen. To monitor the filtering ability of oysters and mussels individually and together, sensors are place around the periphery of the raft. The sensors measures pH value, oxygen level. The orientation of the raft does not change while the water current does. To compare the filtering performance, researchers can obtain the reading from sensors during periods of different water current.
the laboratory can be expanded and collapsed to investigate the effect of density of farming structure to the growth of the filter feeders and the water current. The device can be adjusted on the 4 corners of the raft, saving the effort to move row by row.
the laboratory can be expanded and collapsed to investigate the effect of density of farming structure to the growth of the filter feeders and the water current. The device can be adjusted on the 4 corners of the raft, saving the effort to move row by row.
low density
low density
medium density
medium density
high densit
high densit
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Research Log

Research Log

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Filtering ability of different filter feeding animals

SpeciesFiltering abilityNatural Habitat
Clams
4.5 gallons per day
Sand
Mussels
15 gallons per day
sand and gravel bottoms of streams and rivers
Oysters
30 gallons per day
Sea bed  salty or brackish waters on all U.S. coasts, lower portion of the intertidal area
Kelp
Absorb CO2 produced by other species
subtidal rocky reefs, cold, nutrient-rich waters
Scallop
Scallops can be found living within, upon, or under either rocks, coral, rubble, sea grass, kelp, sand, or mud.

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Questions driving the design process

Research & Development

  1. What is it? What does it do?

A seafarm that acts as a natural sea water filter created by a range of sea creatures in polluted regions. It can farm specific species that only grows in clean seawater.

  1. What are the questions this work is asking? What new knowledge are you creating?

How to organise a multitude of sea creatures together that can clean the sea. How much sea water can sea creatures filter? How to make it profitable besides cleaning the seawater?

  1. How are you going to test your assumptions?
  2. Test the cleaning performance: install pH meter in the beginning and the end of the chain. The survival rate of the species that rely on clean water.
  3. How to maintain your device?

It is an offshore device therefore ships are required for harvesting the whole chain of seafood. Farmers only need to get to the closer edge of the

The farmers would harvest in the closer edge of the chain which is closest to the shore.

  1. What do you think are the strongest and the weakest points in your project now?

3Weakest: costly and not very profitable

  1. What construction technique are you using?

Modular gyroid units that form a chain.

User, community

  1. Who uses it? Can you draw a particular user? Can you describe to me that user, how they look, your assumption on their backgrounds, abilities, preferences, and what drives them?

Sea farmers, environmentalists. Willing to invest in boats

Use

  1. What are the benefits users can get from the device?

Farm safer and species that require clean water.

  1. What problems does your design cause?

Excretion created by the sea creatures.

Will it kill the existing biodiversity by competing food with them?

  1. How do you operate and maintain this installation?

Off shore

  1. How do people get on board?

Since it is an offshore device, sea farmers need to take a boat to harvest

  1. How much weight can you carry?
  2. How to maximum efficiency and convenience for the user
  3. Are there simpler ways to achieve the objective?
  4. Are there other possible use for clean seawater filtered by oysters?

To grow organisms that only grow in clean seawater. Ie, abalone

  1. How long will it be in the water?

Can be forever.

Health & Safety

  1. Is it stable? Safe? ship survivability？
  2. Is the device safe and environmental friendly to the ocean

use environmentally friendly material.

Materials, process, scale

  1. What is the scale and materials? Where and how is it built? Where do the materials come from? Where do the materials go after it’s used/broken?
  2. What materials would you use? Where do you source it? Once used, where does it go?
  3. is it recyclable？

it can be reused after the seafood are harvested.

  1. How long does the project take to be complete: build, bring on site and board?
  2. How to mass produce the device?

print/ cast the gyroid modules

Energy, Waste

  1. Where does the installation get its energy from?

It utilises the water current and wind current to rotate.

  1. Is it sustainable and how?

Ecology

  1. Is your installation amicable to all marine lives?
  2. How does it work? Especially the biology of it?
  3. Which other species will naturally be attracted to the oyster reef there, such as crabs, fish, mussels, algae and other species?

Geography

  1. Where do you think this installation would be? Choose a very specific site in Hong Kong waters. Why there? Tell me the characteristics of the place: water depth, tide, current, wave, closest port, fauna and flora, people and industries nearby.
  2. Will it be influenced by the weather condition?
  3. Does your device perform differently when in different geographic environments(for instance, near shore, in shallow water, and in distant seawater)?

Money

  1. Is it cost-effective?
  2. Is it possible to be mass-produced?
  3. What is the product / outcome of this installation? Who benefits from it? What is the business model of this?

Questions to reflect on

  • How to harvest oysters on the periphery?
  • How to reduce maintenance of the centre part (fish tank?
  • Are there other ways to utilize the clean water filtered by oysters? other than