The mystery surrounding the deaths of at least 877 dolphins in Peru deepened on Wednesday as the government said human activity was not to blame but failed to pinpoint a natural cause for the massive die-off.

A final report from the Peruvian government's Ocean Institute, which manages one of the world's richest marine ecosystems, said the dolphins did not die from a lack of food, hunting by fishermen, poison from pesticides, heavy metal contamination, an infection or a virus.

Environmental scientists have known that high levels of the toxic element, mercury, have been accumulating in the Arctic Ocean for some time. It was believed to be mostly caused by atmospheric sources stemming from the combustion of coal. However, a new study from the Harvard School of Engineering and Applied Sciences and the Harvard School of Public Health has found that the great majority of Arctic mercury arrives via circumpolar rivers. Some of the largest rivers in the world flow north into the Arctic in Eurasia and North America.

Sharks have a reputation of being apex predators of the sea. But even they have their weak points. Many shark populations have plummeted in the past three decades as a result of excessive harvesting — for their fins, as an incidental catch of fisheries targeting other species, and in recreational fisheries. This is particularly true for oceanic species. However, until now, a lack of data prevented scientists from properly quantifying the status of Pacific reef sharks at a large geographic scale.

A Peruvian minister has denied claims that explosions used in oil exploration are to blame for the deaths of hundreds of dolphins.

Fisheries Minister Gladys Triveno said a government investigation showed that natural causes were to blame.

She contradicted a study by an environmental group which suggested that explosions had caused the deaths.

The animals have washed up along Peru's northern coastline since the beginning of the year.

A huge swath of the waters off Antarctica must be protected from fishing and other industries, environmental groups said on Monday.

More than 40% of the region needs to be given protection before one of the world's last true frontier areas is damaged irreparably by human activity, the Antarctic Ocean Alliance (AOA) said.

All are aware of the tragic loss of biodiversity that this planet is current going through in various ecosystems. However, a new National Oceanic and Atmospheric Administration (NOAA) report shows that when good policies are in place, natural ecosystems can sustain themselves and thrive. NOAA has released its annual report, stating that a record six fish populations have been rebuilt to healthy levels in 2011.

With melting sea ice opening up previously inaccessible parts of the Arctic Ocean, the fishing industry sees a potential bonanza. But some scientists and government officials have begun calling for a moratorium on fishing in the region until the true state of the Arctic fishery is assessed. When scientists with the Circumpolar Biodiversity Monitoring Program began tracking 323 vertebrate species across the entire Arctic several years ago, most assumed that many fish and animals would not fare well in a region where rapid warming is causing such profound changes.

The vast swirl of plastic waste floating in the North Pacific has grown 100-fold over the last 40 years, according to a research paper published Wednesday.
And scientists warned the killer soup of microplastic — particles smaller than five millimetres – threatened to alter the open ocean’s natural environment.
In the period 1972 to 1987, no microplastic was found in the majority of samples taken for testing, said the paper in the Royal Society journal Biology Letters.

The Biodiversity Management Committees of the coastal local bodies will be actively involved in the campaign. Information on declining marine biodiversity, threats faced by the marine ecosystem, sustainable livelihood and conservation measures will be highlighted, he said.

The Kerala campaign will be led by the district coordinators of the board in association with experts in conservation, ecology and environment. The programme is funded by the National Biodiversity Authority.