About what sharks do for the ecosystem and eventuelly for us
These unloved habitants of the oceans are its savers in the same time. They are on top of the underwater food chain and hence are responsible for the balance in the ecosystem "ocean".
As the top predator they have shaped the world around them. They have put on some pressure on their prey so that they evolved ever better strategies of avoiding them. Fish have developed schooling behavior, camouflage, speed, size, communication, ... This race in evolving ever new strategies enabling the animals to occupy new niches, have lead to the diversity of life in the oceans we have today. Hence, the marine world as it looks like today is a product of shark-dominance.
With fish growing ever more effective, it was important that the sharks controlled their number. They hold the underwater world in balance.
Even more so, they mostly eat sick and weak fish, making sure that the fittest ones survive. Like that, sharks ensure the genetic health of the fish stocks. Now that the sharks ensure the qualitative renewal of the populations, they are guarantors of healthy fish stocks... so the quality of our food fish.
Predators control the functioning of the ecosystem.
If you cut off the head, it will ultimately alter the food chain.
Sharks represent the framework of the food chain, down to the phytoplankton. If sharks are not able to controll the plankton eating species anymore, there will be far less phytoplankton.
--> Phytoplankton is responsible for transforming CO2 into oxygen. Between 50 and 85% of the atmosphere's oxygen is produced by phytoplankton. So by killing sharks the humans are risking continuing provision of oxygen (well, a long time from now).
Killing sharks is the greatest ecological timebomb that we're going to face in the near futute!
Sharks are also responsible for the health of coral reefs. In a study of coral reef degradation in the Line Islands, scientists found that a greater number of apex predators like sharks was associated with high cover of reef-building corals and algae, and
low levels of coral disease. Where the ecosystem was left intact, like at the wildlife refuge of Kingman island, the reefs were also better able to recover from disease and warm episodes that
result from global warming.
Source: http://teacheratsea.wordpress.com/tag/food-chain/
Figure: A simplified food chain on the ocean.
In a few short words:
When there are sharks, they are able to control the abundance of the other species that are lower in the food chain than they are.
If the sharks are gone, there will be an over-abundance of their prey, this will lead to the depletion of these species' food sources and so on further down the food chain until the phytoplankton is affected.
There are possible medical uses of sharks, now that their immune system is very strong (but unlike some people believe, they DO get cancer, only a lot less than other groups of animals).
Their cartilage has the ability to suppress the formation of blood vessels. If human cartilage is replaced by shark cartilage, this can prevent arthrosis.
Researchers are using shark skin as a model for creating new coatings that prevent adhesion of algae and barnacles to boats. The new coating is modeled after sharks' placoid scales, which have a rectangular base embedded in the skin with tiny spines or bristles that poke up from the surface that prevent things from attaching to the shark's skin. The US Navy estimated that this coating could save them (less fuel needed with less draft, no costs for paint for all of their ships every year) about 1 billion dollars US.
Copyright December 2014; Olivia Lucie Meier, Sharkworld.