Seaweed and seaweed harvesting.
Created | Updated Jan 5, 2013
Seaweed harvesting has been going on for centuaries.
The products were important for the chemical industry and for food - the food aspect has largely dissapeared, so its mainly the chemical industry thats involved making food additives and medicines.
internet research has revealed a document, or rather a series of documents detailing huge resources of seaweed around the world.
one in particular was set upon with gusto in Brazil in the early 70s, the industry was huge, seaweed becoming a important resource for cattle feed.
Unfortunatly now Brazil has to import its seaweed because of overharvesting, the seaweed beds have dissapeared. Small communities are now growing seaweed which before they just dragged out of the sea.
The fishing industries dissapeared - and so did much of the sealife.
Here on the Norwegian coast the most important seaweed has dissapeared in the south - nobody quite knows why or are prepared to say, but here on the west coast and further north seaweed harvesting is in full swing.
the methods used are interesting in their simplicity and frightening in their efficiency - a metal sled, much like a comb, some 3 metres in width is dragged across the sea floor scooping up and removing anything not fast enough to escape. This is done in the same area for up to 4 years before they move on;i think the idea is to clean an area completely, then when it grows back it is free of the many of the materials accumulated in older seaweed, and so better for the chemical industry.
Unfortunatly one major predator often moves in and keeps the area completely barren. Echinoderms, or the starfish family. In particular the sea urchin which eats organic matter, be it flesh or plant.
As the operators of the seaweed harvesting rigs say, its not a major problem as sooner or later the overpopulation of sea urchins aquire a sickness and die out - unfortunatly most of the other specis have gone too.
the trawlers are quite large, operated by a 2 man crew, they are supposed to operate within certain areas and have certain quotas but adherence is in doubt.
The average load for a trawler is 130 tons, here they do about 3 loads a day, but 5 or more is possible.
Some 30 years ago the channel coast of france encountered a huge problem for the first time, seaweed. This particular type was washing up in huge quantities and producing a noxious gas. In recent years this problem has become so huge that several animals have died from inhalation, and many people have become ill. The gas mainly produced is hydrogen sulphide.
Hydrogen sulphide has been calculated to be 5 times more poisonous than cyanide gas. this is mainly because of its high solubility.
In the 70s there were large campeigns in the uk over sewage washing up on the coast and beaches. This prompted water companies to install long pipelines into deeper water.
unfortunatly sewage requires oxygen to break down - the areas completely derived of oxygen in the north sea are growing at a very fast rate. In those areas nothing grows, no fish swim -
Seaweed removes up to 90% of nutrients in the water.
All of Europe uses the sea as a dump for its human waste in one way or another.
The problem is if there is not enough seaweed to cleanse the water, what happens to the nutrients?
Part of the answer lies in what happens to fresh water during hot weather.
A good example is Tiverton canal in Devon. The park authorities are very dilligent in removing the higher plants over large areas of the canal. Where they are present, the water is clear and clean, where they are not the water is dark and brown.
Higher water plants are good oxygen generators, the tiny algae use it up. '
if there are no higher plants then the nutrients are taken up by algae. Some are not harmful, but others produce toxins.
over many years areas of the canal have had to be closed to the public, compressors installed from time to time to provide oxygen for the fish which provide a large income, due to anglers.
The same process can be easily seen using a fish tank and fish. If there are no higher plants the water soon turns into a green soup, if the balance is right, no artificial oxygenation is required and the water becomes clear and healthy.
In the sea what is happening is difficult to quantify accuratly. often the research is done by private companies whose interests clash with conservation and other interests.
Evidence of excess of nutrients is the huge algal blooms which occur from time to time. Another worrying possibility is the massive swarms of jellyfish, some up to 30 km long and over 1 km wide have been recorded.
The products were important for the chemical industry and for food - the food aspect has largely dissapeared, so its mainly the chemical industry thats involved making food additives and medicines.
internet research has revealed a document, or rather a series of documents detailing huge resources of seaweed around the world.
one in particular was set upon with gusto in Brazil in the early 70s, the industry was huge, seaweed becoming a important resource for cattle feed.
Unfortunatly now Brazil has to import its seaweed because of overharvesting, the seaweed beds have dissapeared. Small communities are now growing seaweed which before they just dragged out of the sea.
The fishing industries dissapeared - and so did much of the sealife.
Here on the Norwegian coast the most important seaweed has dissapeared in the south - nobody quite knows why or are prepared to say, but here on the west coast and further north seaweed harvesting is in full swing.
the methods used are interesting in their simplicity and frightening in their efficiency - a metal sled, much like a comb, some 3 metres in width is dragged across the sea floor scooping up and removing anything not fast enough to escape. This is done in the same area for up to 4 years before they move on;i think the idea is to clean an area completely, then when it grows back it is free of the many of the materials accumulated in older seaweed, and so better for the chemical industry.
Unfortunatly one major predator often moves in and keeps the area completely barren. Echinoderms, or the starfish family. In particular the sea urchin which eats organic matter, be it flesh or plant.
As the operators of the seaweed harvesting rigs say, its not a major problem as sooner or later the overpopulation of sea urchins aquire a sickness and die out - unfortunatly most of the other specis have gone too.
the trawlers are quite large, operated by a 2 man crew, they are supposed to operate within certain areas and have certain quotas but adherence is in doubt.
The average load for a trawler is 130 tons, here they do about 3 loads a day, but 5 or more is possible.
Some 30 years ago the channel coast of france encountered a huge problem for the first time, seaweed. This particular type was washing up in huge quantities and producing a noxious gas. In recent years this problem has become so huge that several animals have died from inhalation, and many people have become ill. The gas mainly produced is hydrogen sulphide.
Hydrogen sulphide has been calculated to be 5 times more poisonous than cyanide gas. this is mainly because of its high solubility.
In the 70s there were large campeigns in the uk over sewage washing up on the coast and beaches. This prompted water companies to install long pipelines into deeper water.
unfortunatly sewage requires oxygen to break down - the areas completely derived of oxygen in the north sea are growing at a very fast rate. In those areas nothing grows, no fish swim -
Seaweed removes up to 90% of nutrients in the water.
All of Europe uses the sea as a dump for its human waste in one way or another.
The problem is if there is not enough seaweed to cleanse the water, what happens to the nutrients?
Part of the answer lies in what happens to fresh water during hot weather.
A good example is Tiverton canal in Devon. The park authorities are very dilligent in removing the higher plants over large areas of the canal. Where they are present, the water is clear and clean, where they are not the water is dark and brown.
Higher water plants are good oxygen generators, the tiny algae use it up. '
if there are no higher plants then the nutrients are taken up by algae. Some are not harmful, but others produce toxins.
over many years areas of the canal have had to be closed to the public, compressors installed from time to time to provide oxygen for the fish which provide a large income, due to anglers.
The same process can be easily seen using a fish tank and fish. If there are no higher plants the water soon turns into a green soup, if the balance is right, no artificial oxygenation is required and the water becomes clear and healthy.
In the sea what is happening is difficult to quantify accuratly. often the research is done by private companies whose interests clash with conservation and other interests.
Evidence of excess of nutrients is the huge algal blooms which occur from time to time. Another worrying possibility is the massive swarms of jellyfish, some up to 30 km long and over 1 km wide have been recorded.
