European rivers are stuffed with barriers, but a movement grows to remove them nationalgeographic.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from nationalgeographic.com Daily Mail and Mail on Sunday newspapers.
The works of Franz Kafka often describe people trying to reach a goal but never arriving – all ways are blocked, any possible detours turn out to be impassable. Migratory fish and invertebrates in European rivers today are in a similarly Kafkaesque situation. New research in the journal
Nature, published December 17, reveal that on average, there are at least 0.74 barriers per kilometre of European waterway. This means that an organism can hardly travel more than 1,000 meters without being stopped by a dam, weir, culvert, sluice or ramp.
The movement of flowing water is the essential nature of all running water systems, from small rivulets to large rivers. But this natural movement, and especially its pulsing nature, with flood events and droughts, is too dynamic for human beings who have sought to become “master and possessor of nature” (Descartes,
The Hidden Fruits of the Deep
Vast meadows sprawl far beyond the old boundaries drawn for seagrasses. They may provide a unique refuge for biodiversity.
By Georgina Wood
In the sheltered lagoons of the Great Barrier Reef lie sandy flats the size of Switzerland where reef-building corals refuse to grow. Much of the seafloor here resembles a moonscape hewn with small eruptions the modest houses of timid crustacean architects.
Each year, however, when the sunlight filters through in just the right way, thousands of stout, spoon-shaped leaves encrusted with silvery hairs begin to emerge. Linked by spindly runners, they cover the seafloor within a few weeks, forming a fine herbage that dots the sediment. For several months they cling to the seabed, blossoming with tiny flowers that fruit and float below the tide. Soon they will shed their seeds into the sandy banks and lay in wait for the right sunlight to filter through once again.