Executive Summary for August 25th

In our weekly oceans news roundup, scientists find that subtropical and temperate coral reefs are at risk from climate change, a rise in disease in dolphins is a sign of poor ocean health and blue whales may be changing their songs in response to increasing ocean noise.

Published on Aug. 25, 2017 Read time Approx. 2 minutes

Not Just the Great Barrier Reef: Temperate Corals Also at Risk

Australian scientists have found that corals in subtropical and temperate waters south of the Great Barrier Reef on the country’s east coast are also vulnerable to climate change and have a limited ability to adapt to warming waters.

Researchers have assumed that corals at the Great Barrier Reef would migrate to cooler waters as temperatures rise. But a study conducted by the University of Queensland scientists that investigated 17 reefs south of the Great Barrier Reef concluded that conditions there could hinder such expansion. The study was published on August 23 in the Proceedings of the Royal Society B.

“In the subtropical-to-temperate transition zone south of the Great Barrier Reef, corals are at the limits of their distribution and environmental tolerances, as the water is cooler,” Brigitte Somme, a researcher at the University of Queensland School of Biological Sciences, said in a statement. “There is less light and conditions are more seasonal and variable than on the Great Barrier Reef.”

“Our results suggest that species that occur in these subtropical and temperate reefs south of the Great Barrier Reef are more closely related to each other and have more similar characteristics than the coral species that occur on the Great Barrier Reef,” she added. “This suggests that environmental tolerance is important for coral persistence in these marginal environments and that species with unsuitable traits cannot persist in these cooler and more light-limited environments.”

Rise in Dolphin Disease Bad Sign for Ocean Health

The growing prevalence of disease in two populations of Atlantic bottlenose dolphins is a worrisome indicator of ocean health, according to researchers.

study published in the journal Diseases of Aquatic Organisms found that infections and disease in 360 dolphins rose from 9 percent in 2003 to 33 percent of the marine mammals in 2015.

Scientists captured and performed health examinations on a population of dolphins living offshore of Charleston, South Carolina, and a population living in the Indian River Lagoon in Florida.

“When we look at more than a decade of research, analyzing long-term health data and trends and a variety of environmental factors, we see a number of red flags about the health of our oceans and what it could potentially mean for human health,” Gregory Bossart, chief veterinary officer at Georgia Aquarium, said in a statement.

“Today, fewer than half of the dolphins we are seeing as part of our health assessments can be classified as healthy,” he added. “It is clear these populations are experiencing a health burden largely driven by infectious disease and environmental exposures.”

Blue Whales Changing Frequency of Songs as Ocean Noise Increases

Researchers who study blue whales have discovered that the massive marine mammals are communicating on a lower frequency, possibly in response to a growing underwater noise from ships and industrial activities in the ocean.

“Northeastern Pacific blue whale songs … have been exhibiting a long-term linear downward trend and are now 31 percent lower in frequency than they were in the 1960s,” scientists from Oregon State University wrote in the study published in the journal Scientific Reports.

That suggests, they added, “this downward shift is related to increased population size post commercial whaling, modified by trade-offs between short- and long-distance communication and global ambient noise increases due to shipping.”

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