The man-made noise also affects fish

The oceans are no longer the haven of peace we imagined. Noise pollution caused by humans is increasingly affecting the inhabitants. Several investigations had already warned that the noise emitted by ships mislead marine mammals like whales and dolphins, leading to cause death.



However, a new study has analyzed the impact of noise from ships, offshore oil and gas in fish and has demonstrated that affects them as well as vehicle traffic to terrestrial animals.

"The fish make sounds to communicate (for example, to attract mates and deter rivals), bearings, find food and avoid predators. The man-made noise may be masking important sounds and threaten biological reproduction and survival ", explains Hans Slabbekoorn email, the main author of the research, published in 'Trends in Ecology and Evolution'.
Animals clueless

And that noise pollution can confuse animals and away from the best areas to find food or reproduce. And not only that. We also produce stress, which in turn may adversely affect their growth and reproductive ability.

And what are the most affected? Many fish, but not all, emit sounds. Scientists have known about 800 species, although their hearing sensitivity is different. In addition, fish that do emit have been little investigated. Among the best known are the perch, herring and cod. Researchers believe that the eel also occurs even if the reality is as yet unknown details about its ability to emit and receive sounds.

In general, fish detect sounds better in the range of 30 to 1000 Hz, although some may do so at rates of 3,000 Hz and 5,000 Hz, according to this study. For example, Atlantic cod has an average hearing sensitivity while the golden carp or goldfish can hear high frequencies.

Scientists have observed that herring, cod and tuna are developed worse in noisy environments and seek refuge elsewhere.

Feces of sperm whales 'help' the oceans to absorb atmospheric CO2

Australian scientists have discovered that the faeces of whales 'help' the oceans to absorb carbon dioxide from the atmosphere, because they are released about 50 tons of iron annually.

The work, published in the journal Proceedings B 'of the British Royal Society, explains that in this way stimulates the growth of small marine plants known as' phytoplankton', whose mission is to absorb carbon dioxide during photosynthesis.

This is obtained by the absorption of 400,000 tons of carbon, more than double what the whales 'manufactured' for their breath. Researchers have also seen that, with this stimulation, the plants produce more food for the whale, about 12,000 tons.

As the BBC explains, the phytoplankton is part of the base of the food chain of marine animals and the growth of these small plants is limited by the amount of available nutrients, including iron.
Fertilize plants

Recently, scientific groups have made some tests to try to alleviate the effects of climate change by injections of iron in the ocean, but not all the experiments have proved successful. For example, in 2008 a German expedition inserted tons of iron in the Southern Ocean without success.

The total numbers of sperm in the world is hard to tell, although it is known that in the same way they do in the Southern Ocean, fertilize the plants and the process is repeated in different parts of the world.

These animals feed mainly on squid in the deep sea and defecate in the surface waters where phytoplankton grows, the access of sunlight finally the scientists suggest that this mechanism could also be repeated with the "krill."