Farming the Ocean Desert

[mistermack]

I had this idea years ago, and I know I'm not the first. Most of the planet is ocean, and most of the ocean is desert. That's because the nutrients sink to the ocean floor, and the surface water is too pure for algae to grow. So all of the Sun's energy goes nowhere, it just warms the water.

There have been trials of seeding the ocean with finely ground iron, or iron ore, not sure which, plus other similar trials, and it did result in a temporary algal bloom, but the effect is soon lost, as the stuff sinks out. 

My idea is a sunken flat plastic sheet, kept at such a depth that the waves and UV don't damage it, trapping the surface layer of water. To get nutrients, you send down a pipe to the ocean floor, with an agitator on the end. Cloudy silty water is pumped up to the trapped layer, and then nature takes it's course. Algae bloom, plankton eats the algae, and you add small fish to grow to a suitable size for the market. 

So with a little one-off cost, and a bit of maintenance, you have a steady crop of fish to sell, from what was previously a pretty sterile ocean desert. 

I think you could probably do it in a more simple form, without the plastic sheeting too, just pumping nutrients to the surface, and catching the resulting fish. There would have to be international agreements, that only those paying for the pumping, could catch fish in the area. 

In a small way, it would remove CO2 from the environment, and provide food from a previously barren source, so it's win win if it worked.

[dimreepr]

51 minutes ago, mistermack said:

I had this idea years ago, and I know I'm not the first. Most of the planet is ocean, and most of the ocean is desert. That's because the nutrients sink to the ocean floor, and the surface water is too pure for algae to grow. So all of the Sun's energy goes nowhere, it just warms the water.

There have been trials of seeding the ocean with finely ground iron, or iron ore, not sure which, plus other similar trials, and it did result in a temporary algal bloom, but the effect is soon lost, as the stuff sinks out. 

My idea is a sunken flat plastic sheet, kept at such a depth that the waves and UV don't damage it, trapping the surface layer of water. To get nutrients, you send down a pipe to the ocean floor, with an agitator on the end. Cloudy silty water is pumped up to the trapped layer, and then nature takes it's course. Algae bloom, plankton eats the algae, and you add small fish to grow to a suitable size for the market. 

So with a little one-off cost, and a bit of maintenance, you have a steady crop of fish to sell, from what was previously a pretty sterile ocean desert. 

I think you could probably do it in a more simple form, without the plastic sheeting too, just pumping nutrients to the surface, and catching the resulting fish. There would have to be international agreements, that only those paying for the pumping, could catch fish in the area. 

In a small way, it would remove CO2 from the environment, and provide food from a previously barren source, so it's win win if it worked.

Why don't we just eat the algae?

[StringJunky]

2 hours ago, mistermack said:

I had this idea years ago, and I know I'm not the first. Most of the planet is ocean, and most of the ocean is desert. That's because the nutrients sink to the ocean floor, and the surface water is too pure for algae to grow. So all of the Sun's energy goes nowhere, it just warms the water.

There have been trials of seeding the ocean with finely ground iron, or iron ore, not sure which, plus other similar trials, and it did result in a temporary algal bloom, but the effect is soon lost, as the stuff sinks out. 

My idea is a sunken flat plastic sheet, kept at such a depth that the waves and UV don't damage it, trapping the surface layer of water. To get nutrients, you send down a pipe to the ocean floor, with an agitator on the end. Cloudy silty water is pumped up to the trapped layer, and then nature takes it's course. Algae bloom, plankton eats the algae, and you add small fish to grow to a suitable size for the market. 

So with a little one-off cost, and a bit of maintenance, you have a steady crop of fish to sell, from what was previously a pretty sterile ocean desert. 

I think you could probably do it in a more simple form, without the plastic sheeting too, just pumping nutrients to the surface, and catching the resulting fish. There would have to be international agreements, that only those paying for the pumping, could catch fish in the area. 

In a small way, it would remove CO2 from the environment, and provide food from a previously barren source, so it's win win if it worked.

I did a thread on this idea quite some time ago for the purposes of reducing atmospheric CO2 but adding your idea increasing food availability makes even more attractive. I wonder if wave power could be utilised to power the pump action, or even solar and tidal by combining the mechanical surface parts that capture wave energy with solar panels on them. Flexible solar film will be commercially available in the near future.

[mistermack]

I can think of problems with the idea, but every industry has problems, and they usually get overcome.
One problem is how whales and sharks would interact with the system. If you had a big unbroken area, whales could drown if they couldn't surface. 
Or they could just drive straight through the plastic to get at the fish. But you could leave gaps, if it was a problem, and choose a thickness 
that didn't get damaged. 

Also, ocean drift would be a problem, and you would have to either anchor in some way, or use up fuel by towing to keep station. 
Maybe solar and wind could make a contribution to the power requirements. No reason why not, although it would have to be custom made stuff.
But if the system worked, it could carry on working for decades just with maintenance, and could easily be expanded. 
After all, you might need special equipment, but you would be paying nothing for the real estate.

With the potential for carbon fixing, it might even be possible for governments to contribute to costs, as part of the carbon trading schemes.
 

[CharonY]

What you describe is basically what is referred to as ocean farming. There are efforts underway to estimate the profitability of establishing aquaculture in oceans. Note that the what you describe in OP ("ocean desert") is not caused by lack of nutrients. Rather, these areas are called dead zones. Those are caused by lack of oxygen. A major driver are algae blooms caused by pollution with nutrients. And are likely go get worse due to climate change because a) warm water retains less oxygen and b) warm top layer reduces mixing of layers.

[mistermack]

16 hours ago, CharonY said:

What you describe is basically what is referred to as ocean farming. There are efforts underway to estimate the profitability of establishing aquaculture in oceans. Note that the what you describe in OP ("ocean desert") is not caused by lack of nutrients. Rather, these areas are called dead zones. Those are caused by lack of oxygen. A major driver are algae blooms caused by pollution with nutrients. And are likely go get worse due to climate change because a) warm water retains less oxygen and b) warm top layer reduces mixing of layers.

Dead zones are totally different. They occur is deep water, at and near the bottom, and are not a feature of surface water, or of the vast areas of open ocean. It's usually run-off from agricultural land and sewage that causes it. The ocean desert areas are vast, and not generally oxygen depleted. In any case, it's the surface layer that would be in use, not the deepest layer at the bottom. 

The seeding experiments proved that it works. But without that, natural upwellings from the deep also show that it works, as you get extremely productive fisheries where that happens.

In the system I'm proposing, it would be very easy to regulate the level of deep-water nutrient that you add to the surface layer, and avoid blooms that could be harmful. 

[CharonY]

Ah, I assume you refer to areas like the subtropical gyres then? They are not entirely devoid of life, but, to my knowledge, are characterized by consistently low chlorophyll amount (which is why I assumed you referred to actual "dead" zones). Many of these areas are not actually nutrient poor per se- they tend to lack one specific micronutrient: iron. In lit you will often find these areas referred to as high-nutrient low-chlorophyll regions. This is where the seeding experiment data are derived from (though not all were successful). However, typically it is done in the context of carbon sequestration, but there are worries regarding the effects of algae bloom. But again, those areas are not actually sterile.

Then there are areas that are limited in more than one macronutrients are missing resulting in low biomass. These areas are a bit more difficult to assess and I am not sure how much data is out there about these. 

[mistermack]

Don't take my word for it :

First paragraph, Wikipedia "Dead Zone" page :

Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water. (NOAA)".^[2] In the 1970s oceanographers began noting increased instances of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated. (The vast middle portions of the oceans, which naturally have little life, are not considered "dead zones".

[CharonY]

Yes, that is what the confusion came from. There are zones with low levels of phytoplankton. But in OP you mentioned "sterile" zones, which implied that it was beyond that, i.e. truly dead.

Edit: this is just an example why precise word usage does matter, as there are quite distinct areas in the ocean with rather complicated transport mechanisms. But the nutrient situation in oceans is far from trivial and there is a lot of research in that area that is far from my expertise.

Edited August 28, 2018 by CharonY

[mistermack]

2 hours ago, CharonY said:

this is just an example why precise word usage does matter, 

But I didn't say sterile, and I didn't say dead zones. 

What I said was that most of the oceans is desert. Which matches pretty well with "(The vast middle portions of the oceans, which naturally have little life,  

I'm sure most people will get the general idea of what I'm saying. You have vast areas that do not produce much life at all, that could be very productive, with a little prodding. Since the oceans account for about 2/3 of the Earth's surface, there is probably about 1/2 of the planet that's just absorbing solar energy, and fixing no carbon, and producing no food. You could be doing both, with this type of system. 

If this type of fish farming could be made to pay, it would reduce the pressure on wild stocks and make cheaper food available to the world. 

[CharonY]

34 minutes ago, mistermack said:

But I didn't say sterile, and I didn't say dead zones. 

I am referring to this: 

 

On 8/24/2018 at 5:15 AM, mistermack said:

surface water is too pure for algae to grow. So all of the Sun's energy goes nowhere, it just warms the water.

 

On 8/24/2018 at 5:15 AM, mistermack said:

from what was previously a pretty sterile ocean desert. 

Both sentences seem to imply an absence of phytoplankton. You also re-iterate that there is no carbon fixation, which is not the same as having lower yields than elsewhere (as the mechanisms are very different). Note that current data on increasing yield (in context of carbon sequestration) was not always successful as nutritional limitations were quite different in various areas.

Aquaculture tends to follow different models and I am pretty sure that there are significant limitations in applying them. There is also the added issue that the nutrient flows in oceans are complex and currently being altered by global warming. Trying to change productivity can also have other consequences (including the danger of expanding dead zones, which is essentially an experiment that we are inadvertently doing with our runoffs) and it is not clear whether it is feasible at all. Again, the various iron seeding experiments were not successful everywhere. 

I.e. the two main challenges are figuring out a) how to increase productivity and b) whether it increases ecological damage and c) whether there are economically and economically sustained means to do so. 

Considering the intensity of research on ocean nutrient fluxes and their changes, it is quite obvious that our current understanding is fairly limited to answers these questions. For example, there are already offshore aquacultures (experimental as well as commercial) , but their ecological impact is still being assessed. That being said, there may be some advantages over inshore aquacultures.

 

Edited August 28, 2018 by CharonY

[mistermack]

To be honest, you are picking nits like a pro. I'm confident most people get what I'm saying. As I mentioned earlier, if you want to pick the nits out of every word, you've got a life's work ahead of you, on a chat forum. When I write no carbon fixation, I'm not claiming absolute zero, I'm opining no significant carbon fixation. 

I operate on a "think post - write post" system, and don't really give a toss if the wording is less than 100 percent. If the average man should get it, that's fine by me. 

As for the other potential problems you pointed out, it would be pointless going into them. In that kind of industry, the only way to find out what works and what doesn't is to try it. Over the years, systems get improved and fine tuned. Farming the land has all sorts of problems. We still do it. The world population the day I was born was 2.5 billion. Today it's 7 billion. So the food requirement has tripled in my lifetime. More so, because people eat more now than they did then. So I think farming the ocean is necessary and inevitable. It's just a question of economics and prices, and supply and demand, that will decide when it happens on a big scale.

[StringJunky]

16 minutes ago, mistermack said:

To be honest, you are picking nits like a pro....

We expect nothing less from him; that's what makes a good scientist.  The devil is in the details and language has to be precise. It is a PITA though when they can't just fluff the gaps and see the brilliance dying to shine out.

Edited August 28, 2018 by StringJunky

[mistermack]

9 minutes ago, StringJunky said:

We expect nothing less from him; that's what makes a good scientist.

So wtf is he doing here ?  

[studiot]

Anyone who has watched the recent BluePlanet2 series would realise how little we know about the ocean and how much more life there is in the deep ocean than we previously thought.

And this is despite the huge gain in knowledge in recent years.

 

1 hour ago, mistermack said:

Since the oceans account for about 2/3 of the Earth's surface, there is probably about 1/2 of the planet that's just absorbing solar energy, and fixing no carbon, and producing no food. You could be doing both, with this type of system. 

The actual situation and figures presented offer quite a different take although they do concur that much of the visible activity take place close to land and offer some reasons for this.

1 hour ago, mistermack said:

Farming the land has all sorts of problems. We still do it. The world population the day I was born was 2.5 billion. Today it's 7 billion. So the food requirement has tripled in my lifetime. More so, because people eat more now than they did then. So I think farming the ocean is necessary and inevitable. It's just a question of economics and prices, and supply and demand, that will decide when it happens on a big scale.

Set against this is the recent news item that over 50% of food is wasted.

Certainly in the same timescale you mention I have seen a massive increase in waste.

 

But yes I agree that more intensive use of the ocean resources will come and economics will play its part.

[CharonY]

On 8/28/2018 at 4:06 PM, mistermack said:

Over the years, systems get improved and fine tuned. Farming the land has all sorts of problems. We still do it. The world population the day I was born was 2.5 billion. Today it's 7 billion. So the food requirement has tripled in my lifetime. More so, because people eat more now than they did then. So I think farming the ocean is necessary and inevitable. It's just a question of economics and prices, and supply and demand, that will decide when it happens on a big scale.

That is not a good argument for ocean farming. Despite the increase in population, world hunger has decreased. Within the timeline you mentioned (i.e. 40s-50s until now) food security has improved, despite higher consumption in developed countries. In fact, the rise of the population can be connected to increased food availability, as well as world poverty (as a side note this is just another indicator that the world is, in fact, not a zero-sum system). As already mentioned, there is also a lot of food waste. I.e. being more efficient in food use alone would massively alleviate caloric deficiencies.

However, there are at least two threats to this situation. One is the well-known threat of wars and major conflicts. The other one is climate change and the changes it will bring to food security. At least the latter threat might benefit from further exploring aquaculture in oceans, which is precisely what folks have started to do. Those that I have heard of must have been around close to a decade by now and I assume that there must be some data somewhere discussing their challenges and benefits. I believe one of the early challenges was nutrient dispersion, for example. Likewise there were worries to the disruption of eco systems, especially the triggering of algal blooms.

[StringJunky]

15 minutes ago, CharonY said:

Likewise there were worries to the disruption of eco systems, especially the triggering of algal blooms.

That's good for reducing CO2 though, isn't it? Would that not be a better use of the ocean and less harmful to the existing oceanic ecosystem?

[CharonY]

32 minutes ago, StringJunky said:

That's good for reducing CO2 though, isn't it? Would that not be a better use of the ocean and less harmful to the existing oceanic ecosystem?

In theory, yes. Sinking phytoplankton could indeed lead to carbon sequestration. There are a few challenges though. A fraction of the biomass is likely to enter the carbon cycle (though it may be in time frame of centuries). In 2009 a study from an European team has shown that following bloom the actual sequestrations was fairly small, the algae were spread and eaten, resulting in a return of much of the CO2 into the atmosphere. The other issue mentioned above is that these blooms can also create dead zones, severely disrupting local ecosystems. 

I cannot say what the current consensus is, but after the initial enthusiasm, a number of subsequent studies have shown significant difficulties in controlling this process. Perhaps there have been new encouraging developments, but I am not sure.

[StringJunky]

3 minutes ago, CharonY said:

In theory, yes. Sinking phytoplankton could indeed lead to carbon sequestration. There are a few challenges though. A fraction of the biomass is likely to enter the carbon cycle (though it may be in time frame of centuries). In 2009 a study from an European team has shown that following bloom the actual sequestrations was fairly small, the algae were spread and eaten, resulting in a return of much of the CO2 into the atmosphere. The other issue mentioned above is that these blooms can also create dead zones, severely disrupting local ecosystems. 

I cannot say what the current consensus is, but after the initial enthusiasm, a number of subsequent studies have shown significant difficulties in controlling this process. Perhaps there have been new encouraging developments, but I am not sure.

I never thought about that:  the fact that the sequestration may not be relatively permanent, like fossil fuels are.

[CharonY]

25 minutes ago, StringJunky said:

I never thought about that:  the fact that the sequestration may not be relatively permanent, like fossil fuels are.

It is quite a complicated system. From a talk I heard years ago, they were discussing the difference in sequestration based on the type of diatoms; some are less buoyant and sink faster and may have affected some studies. In other cases certain temperature and current changes affected dispersion and so on.

[StringJunky]

4 minutes ago, CharonY said:

It is quite a complicated system. From a talk I heard years ago, they were discussing the difference in sequestration based on the type of diatoms; some are less buoyant and sink faster and may have affected some studies. In other cases certain temperature and current changes affected dispersion and so on.

Yes, it's more complicated than I thought. Up 'til now, I thought algae was a good way to get rid of some CO2. Maybe not. It needs a more irreversible/stable process.

[mistermack]

Producing food in this way would reduce both prices and the pressure on land to take more and more wild land into farming, so it would be a good thing, even IF hunger was decreasing. 

Nutrient dispersion would be prevented by the sunken plastic sheet, as mentioned in the OP.

Nutrient levels could easily by monitored and maintained at desired levels, by pumping more in or out, so runaway blooms could be avoided.

And you can hardly have it both ways. Algae being dispersed and eaten, and also creating a dead zone due to sinking in vast quantities. 

Hopefully, most of the Algae WOULD be converted into fish or shellfish, and eaten on land by humans, so neither would arise.

Growing oysters and mussels on ropes or in sacks is a great way to fix carbon, if a suitable environment could be maintained for them.

[CharonY]

4 hours ago, mistermack said:

Nutrient dispersion would be prevented by the sunken plastic sheet, as mentioned in the OP.

That is quite different to how typical ocean aquaculture works. It seems you want to basically trap off a part of the ocean and limit exchange with the outside. What area do you think can you reasonably enclose and would how would you control the mixing. Regular aquaculture depends heavily on the exchange in order to allow production. Limiting exchange would change the equation considerably. How would you address that? Or to put it differently, even smaller experimental aquaculture stations (with only 100 m² in size) are open systems. Have you considered that there may be a reason for that?

[mistermack]

3 hours ago, CharonY said:

That is quite different to how typical ocean aquaculture works.

That's correct. Why would I post a suggestion to employ typical ocean aquaculture?

3 hours ago, CharonY said:

It seems you want to basically trap off a part of the ocean and limit exchange with the outside.

That's obvious from the OP.

3 hours ago, CharonY said:

What area do you think can you reasonably enclose

That's like saying "what size farm could you have?" If it makes money, there's no limit. If it doesn't, then it wouldn't happen.

 

3 hours ago, CharonY said:

and would how would you control the mixing.

With pumps.

3 hours ago, CharonY said:

Regular aquaculture depends heavily on the exchange in order to allow production. Limiting exchange would change the equation considerably. How would you address that? Or to put it differently, even smaller experimental aquaculture stations (with only 100 m² in size) are open systems. Have you considered that there may be a reason for that?

You don't seem to have even read the OP, or understood it. The open oceans are generally nutrient poor at the surface. So there's no point in having the system open. There's very little plankton, like there is in rich coastal waters, so what would be the point of an open system?

This is a repeat from the OP : 

On 8/24/2018 at 12:15 PM, mistermack said:

To get nutrients, you send down a pipe to the ocean floor, with an agitator on the end. Cloudy silty water is pumped up to the trapped layer, and then nature takes it's course. Algae bloom, plankton eats the algae, and you add small fish to grow to a suitable size for the market. 

The point is that in the open ocean, the surface is generally nutrient poor, and the ocean floor has plenty. If it was economic to pump up nutrient rich water, the surface could be made to produce. As happens where there are natural upwellings.

Quote from Wikipedia on their "upwellings" page :   https://en.wikipedia.org/wiki/Upwelling   

 "Approximately 25% of the total global marine fish catches come from five upwellings that occupy only 5% of the total ocean area."

 

 

 

[rangerx]

I run an aquaculture operation. One of the greatest issues with sea farming or other marine operations, is fouling. Regular cleaning is the single most labor intensity. Chronic fouling gives rise to competition for food and space. Hand scrubbing or mechanical washing exacerbates the issue by causing mass proliferation of species such as tunicates and annelids, some of which are deemed invasive. For that reason, power washing is banned. Waste water and manually scraped material cannot be returned to the water unless it's been treated.

Some of the ideas in the OP are theoretically possible, but impractical. The ocean is a dynamic place, with tides, currents, waves and tempestuous weather. Drifting debris, namely rotting or dislodged kelp and grasses entangle gear until it sinks, drags or breaks then otherwise lost at sea.

9 hours ago, mistermack said:

Growing oysters and mussels on ropes or in sacks is a great way to fix carbon, if a suitable environment could be maintained for them.

That may be true on the face of it, but at the cost of carbonates which are already low resulting from the effects of acidic pH.

Ocean Acidification's impact on oysters and other shellfish

CO2 mixed with sea water creates carbonic acid. Harvesting and disposing shell stocks in land fills, gardens etc after marketing removes carbonate from the ecosystem. For every ion of calcium or carbonate that's made available to aquaculture, it subtracts from natural recruitment of numerous other species.