Hear This: Ship Noise Stresses Whales

Quiet oceans make for calmer right whales, new research suggests. When fewer ships sail the Bay of Fundy, the big baleen whales are less stressed — as evidenced by hormone levels in their poop.

This stress could be one reason the North Atlantic population of right whales, which spend part of their lives in the Bay of Fundy off the East Coast, is having such a hard time reproducing. If the sounds chronically stress them, they could be more prone to disease and it could possibly interfere with their ability to reproduce, the researchers say.

"We know that whales have responded to underwater noise by changing their vocalization, but we didn't know if they responded with physical changes as well," study researcher Rosalind Rolland, of the New England Aquarium in Boston, told LiveScience. "What this study has shown is that they are having a measurable physiological stress response to the noise in their environment."

Calling all whales

Right whales use their calls to communicate across long distances. They use low frequencies because they carry farther, but these are similar to the frequencies made by ocean-going ships. Previous studies have shown that noise levels can impact the whales' behaviors, including where they swim and how they vocalize. It's like trying to talk at a party — often a lot of noise will make you either speak louder or, in the worst cases, wait until later to make your point. What the researchers didn't know is how noise may be impacting the whales physically.

The researchers analyzed noise recordings from September 2001, in areas of the Bay of Fundy where the whales generally reside; they then compared them with samples of whale poop collected by researchers in 2001 through 2005. They were looking for evidence that decreased ship traffic after the tragic events of 9/11 lowered the whales' stress hormone levels.

In the two days before 9/11, nine ships passed through the Bay, but in the two days after, only three ships passed through. This led to a significant decrease in low-frequency noise in the Bay and a drop in the intensity of the noise, they found. This coincided with a drop in stress-hormone levels in the whales' fecal samples: Compared with before Sept. 11, hormone levels were significantly lower after Sept. 11 … only in 2001.

Read on:  http://www.livescience.com/18367-ship-noise-stresses-whales.html

Insects Are Scared to Death of Fish

ScienceDaily (Oct. 27, 2011) — The mere presence of a predator causes enough stress to kill a dragonfly, even when the predator cannot actually get at its prey to eat it, say biologists at the University of Toronto.

"How prey respond to the fear of being eaten is an important topic in ecology, and we've learned a great deal about how these responses affect predator and prey interactions," says Professor Locke Rowe, chair of the Department of Ecology and Evolutionary Biology (EEB) and co-principal investigator of a study conducted at U of T's Koffler Scientific Reserve.

"As we learn more about how animals respond to stressful conditions -- whether it's the presence of predators or stresses from other natural or human-caused disruptions -- we increasingly find that stress brings a greater risk of death, presumably from things such as infections that normally wouldn't kill them," says Rowe.

Shannon McCauley, a post-doctoral fellow, and EEB professors Marie-Josée Fortin and Rowe raised juvenile dragonfly larvae (Leucorrhinia intacta) in aquariums or tanks along with their predators. The two groups were separated so that while the dragonflies could see and smell their predators, the predators could not actually eat them.

"What we found was unexpected -- more of the dragonflies died when predators shared their habitat," says Rowe. Larvae exposed to predatory fish or aquatic insects had survival rates 2.5 to 4.3 times less than those not exposed.

In a second experiment, 11 per cent of larvae exposed to fish died as they attempted to metamorphose into their adult stage, compared to only two per cent of those growing in a fish-free environment. "We allowed the juvenile dragonflies to go through metamorphosis to become adult dragonflies, and found those that had grown up around predators were more likely to fail to complete metamorphosis successfully, more often dying in the process," says Rowe.

The scientists suggest that their findings could apply to all organisms facing any amount of stress, and that the experiment could be used as a model for future studies on the lethal effects of stress.

The research is described in a paper titled "The deadly effects of 'nonlethal' predators," published in Ecology and highlighted in Nature this week. It was supported by grants to Fortin and Rowe from the Canada Research Chairs program and the Natural Sciences and Engineering Research Council of Canada, and a post-doctoral fellowship awarded to McCauley.

http://www.sciencedaily.com/releases/2011/10/111027125241.htm