As Oceans Warm, Marine Life Moves Poleward, Changes Breeding Patterns

As the temperature of Earth increases, a number of behavioral shifts and broad changes across the landscape of marine life have been observed over the course of a three year study that examined decades worth of data from all of the world's oceans. These behavioral changes indicate that warming ocean temperatures affect breeding and lifestyle patterns of marine life, according to the study authors.

In the journal Nature and Climate Change, researchers from CSIRO, Australia's national science agency, analyzed whether the gradual warming of the oceans -- where surface temperatures rise at about one-third the rate as surface temperatures on land -- is acting as a buffer to marine life.

The international research team pooled the results from more than 1,700 peer-reviewed studies and established a large databasef of marine life and climate records.

"Just as the medical profession pools information on the symptoms of individual patients from surgeries and hospitals to reveal patterns of disease outbreaks, we pooled information from many studies to show a global fingerprint of the impact of recent climate change on marine life," the study authors wrote in a news release.

Each of Earth's oceans were included in the study, with an average of 40 years worth of data among them.

The researchers write that while there is a public perception that the impacts of climate change are an issue for the future, there are already "stunning" and "pervasive" observable changes to the world's oceans that can be linked with climate change. From coastal shores to open water, from tropical warm seas to chilly polar waters and across a range of species from very tiny to the most massive, the researches contend "climate change has already had a coherent and significant fingerprint across all ecosystems."

Two of the most observable changes in marine life are that species are breeding earlier and shifting their geographic distribution toward the poles.

What's most intriguing about the distribution shift, the researchers note, is that while the waters are warming at only one-third the speed of land surface temperatures, the redistribution of marine species to cooler waters is happening much faster at sea than on land.

"The leading edge or front-line of marine species distributions is moving toward the poles at an average of 72 km per decade -- considerably faster than species on land that are moving poleward at an average of 6 km per decade," the authors said. "Plankton and bony fish, many of which are commercially important, showed the largest shifts."

Changing water temperatures are also changing the way marine animals breed. There were observable changes in the timing of breeding, feeding and migration events across a range of marine life, the researchers report, noting the largest shifts in breeding patterns were again observed in plankton and larval bony fish.

The researchers conclude that their findings "indicate that changes in life events and distribution of species indicates we are seeing widespread reorganization of marine ecosystems, with likely significant repercussions for the services these ecosystems provide to humans."