Which British county has the longest coast

Marine ecologySeagrass dieback on the coasts

Seagrass is probably the most important ecosystem you've never heard of! This is what the ecologist James Bull of the University of Swansea in Wales says about the underwater plants growing off many coasts:

"People know coral reefs and rainforests and have heard how important they are. But I'm sure: They don't know that about seaweed! It occurs all over the world, around the coasts of all continents with the exception of Antarctica. The grass carpets protect the coastlines from erosion, absorb the greenhouse gas carbon dioxide from the air, and provide a nursery for important edible fish such as cod. "

"Seagrass - The Most Important Ecosystem You've Never Heard Of"

But the green carpets are thinning out more and more. The British researcher does not consider it absurd to speak of a "seagrass death". Hardly anyone has heard of this:

"There are around 70 different species of seaweed around the world. They are declining everywhere."

Bull's working group can also confirm this trend. Your study area is off the south-western tip of England, around the archipelago of Scilly:

"We have been going out there every summer for 23 years and take a close look at the seagrass carpets. I believe it is the longest series of tests in the world. The seaweed has decreased by a total of 20 to 30 percent in this period. In some In places it has almost completely disappeared. "

Seagrass species are declining worldwide

The main reason for this is the increasing shipping traffic near the coast. On the one hand, seaweed can be directly injured or torn out by anchors. On the other hand, ships stir up the sediment on the sea floor so that the water becomes cloudy and so much sunlight no longer penetrates to the plants, which do photosynthesis.

And then there is a mysterious parasite with the Latin generic name Labyrinthula: a unicellular, microscopic slime mold that causes the so-called sore throat. Infested grasses first get black spots and then die:

"In the years after 1930 there was a major epidemic of disease disease in the whole of the North Atlantic. 90 percent of all seagrasses are said to have fallen victim to it. Whether this is really true, we do not know for sure. In any case, it was a mass extinction, and in some places, which we know better, the seagrass stocks are not even half as large today. Why this epidemic? Why was the disease so devastating 80 years ago and never again later? All of this is a mystery. "

Sickness disease has caused mass deaths before

The findings of researchers at Cornell University in the USA are also mysterious. They examined almost 20 seaweed stocks off the North American Pacific coast and discovered that there are apparently two forms of the pathogen: an aggressive and a rather harmless one. Both variants occur together. We do not yet know why this is so. Only one thing: the more aggressive form of the parasites seems to benefit from higher water temperatures, which means that the damage to plants is greater.

Because seaweed is dwindling across the fields, there are now attempts to artificially reintroduce the plants. But what is tricky, as James Bull says:

"There's a restoration program in place in Chesapeake Bay on the US east coast, and it's been very successful. You can plant seaweed. However, it's extremely labor-intensive. You can also make it easier and just sow the seeds. But that's it many are lost. "

Seagrass stocks continue to decline and a pathogen that could become more dangerous if sea temperatures continue to rise - not a good prospect for the ecosystem, which hardly anyone has any idea how important it is.