Orcas: living with Mom means a longer life

While humans bemoan the current lack of opportunities for young adults, leading to offspring living with their parents long past when it is thought they should be on their own, apparently that is not the case for orcas.

A recent study by scientists from the UK's University of Exeter showed that females can live as much as 50 years after the birth of their offspring and the reason for this extended period of menopause is that the presence of mothers ensured the survival of young adults to breeding age.

Reported in BBC Nature News, "In killer whale society, the young never leave their mothers, remaining in a single group. 'With this close association, older mothers have the opportunity to increase the transmission of their genes by helping their adult offspring survive and reproduce,' said Dr Croft [who lead the study]. Researchers theorized that living longer in order to protect their sons could represent the wisest investment for orca mothers."

The researchers analyzed over 36 years worth of records regarding various orca families or pods.  They determined that orcas who lost their mothers had a 3 to 14 times greater chance, depending on gender, to not survive beyond a year after the mother's death.  
However, the big question still remains: What is it that the mother orcas are doing that increases the survivability of their offspring?

"We simply don't know just how mothers are increasing the survival of their adult male offspring," said Dr Croft. "Anecdotal observations suggest that mothers may help adult sons with foraging or providing support during aggressive interactions. This is one of the things we hope to work on in the future."

So maybe that's why junior continues to bring his laundry home to Mom and raid the fridge.  Survivability.

Source: BBC Nature News

          

Coral Reef Stress Test: researchers develop model to determine survivability

With corals reefs being assaulted, it would seem, from all directions with global warming, pollution, and damage from urban development or tourism pressure all taking its toll; would it not be a valuable tool to have the means to gauge a reef's susceptibility to various environmental pressures, to be able to determine whether one reef has a better chance of survival over another?

Researchers from the Wildlife Conservation Society believe they have developed just such a tool - a "stress test" for coral reefs.

Reviewing the history and the current conditions (coral health, biodiversity) of reefs throughout the western Indian Ocean, the researchers were able to construct a test model with which they could determine which reefs would have a higher possibility of survival based on today's environmental pressures. By identifying specific reefs, the researchers would hope that greater coral reef management could be put in place to protect those particular reefs.

Through their work, which was recently published online in Global Change Biology, the researchers identified coastal regions stretching from southern Kenya to northern Mozambique, northeastern Madagascar, the Mascarene Islands, and the coastal border of Mozambique and South Africa as having the most promising characteristics of high diversity and low environmental stress.

"Reducing human impacts to minimize the multiple stressors on these globally important reefs will give corals a fighting chance in the age of global climate change. These results reveal a window of opportunity for the future conservation of the ocean's most biodiverse ecosystem," said Caleb McClennen, director of the Wildlife Conservation Society's Marine Program.

The unfortunate reality to all of this is that, while it would seem to be advantagous to be able to clearly identify regions that deserve protection based on those that would appear to have a more promising future, the flipside would imply that some regions would be sacrificed, basically written off because limited management resources would only be able to focus on those coral reefs with the best chance of survival in today's conditions.

It is a sad reality that we face; like a mother with two children but only enough food for one. How does she choose who shall survive and who shall perish? Have we cornered ourselves into a similar predicament with our coral reefs?

Read more about the coral reef "stress test" in EurekAlert.