Not just the Sting

Jellyfish stinging humans isn't the only concern out there. They are causing harm to industries such as tourism, fishing, and direct harm to certain power plants across the globe as well.

The Jellyfish Population is Increasing!:
The jellyfish population is always increasing naturally, but there is speculation that its increasing at an alarming rate. There are several factors that can cause this, and some of these factors are tied back to the impact of humans on an ecosystem. ³

Human Activity:
There is much speculation that human activities are the cause of the rise of the jellyfish and taking over the oceans.
♠ Overfishing allows jellyfish to inhabit the areas previously inhabited by fish, now able to consume larger scales of eggs and larvae of fish, shrimp and crabs. ¹
♠ Human-induced eutrophication or the addition of excessive nutrients (from fertilizer runoff and sewage) cause algae and plankton blooms, giving a larger food source for jellyfish. The reduction of oxygen is also not   as much a problem to jellyfish as it is to other sea creatures since jellyfish don't need a lot of oxygen. ¹

Jellyfish Activity?:
Jellyfish have costed much to industries as well (possible speculation).
♠ Over $350 million in losses in the Black Seas's fishing and tourism industry from the invasion of the comb jelly. ² 
♠ November 2007, jellyfish blooms wipe out Northern Ireland's salmon farm killing over 100,000 fish. ² 
♠ Coastal power plants are acquiring damage from jellyfish blocking the cooling vents. ² 

Again, it is still speculation that jellyfish are reproducing at unnatural rates, and there is even more speculation that the jellyfish populations must be controlled in some manner. Further research and examination is needed by scientists.


---------------------------------------------------------------------------

Resources: 
¹ Explosion in jellyfish numbers may lead to ecological disaster, warn scientists by Tracy McVeigh
² Jellyfish 'may benefit from ecosystem instability' by Mark Kinver
³ Jellyfish: On the Rise or Not? by Neel Patel