Most Coral Reefs Are at Risk Unless Climate Change Is Drastically Limited, Study Shows
ScienceDaily (Sep. 16, 2012) — Coral reefs face severe challenges even if global warming is restricted to the 2 degrees Celsius commonly perceived as safe for many natural and human-made systems. Warmer sea surface temperatures are likely to trigger more frequent and more intense mass coral bleaching events. Only under a scenario with strong action on mitigating greenhouse-gas emissions and the assumption that corals can adapt at extremely rapid rates, could two thirds of them be safe, shows a study now published in Nature Climate Change. Otherwise all coral reefs are expected to be subject to severe degradation.
Coral reefs house almost a quarter of the species in the oceans and provide critical services -- including coastal protection, tourism and fishing -- to millions of people worldwide. Global warming and ocean acidification, both driven by human-caused CO2 emissions, pose a major threat to these ecosystems.
"Our findings show that under current assumptions regarding thermal sensitivity, coral reefs might no longer be prominent coastal ecosystems if global mean temperatures actually exceed 2 degrees Celsius above the pre-industrial level," says lead author Katja Frieler from the Potsdam Institute for Climate Impact Research. "Without a yet uncertain process of adaptation or acclimation, however, already about 70% of corals are projected to suffer from long-term degradation by 2030 even under an ambitious mitigation scenario." Thus, the threshold to protect at least half of the coral reefs worldwide is estimated to be below 1.5 degrees Celsius mean temperature increase.
Full Article Link: http://www.sciencedaily.com/releases/2012/09/120916160926.htm
Reflection
Through this extract of the article, I have realised about the huge threat coral reefs face. If we do not do anything to save these coral reefs, we may never be able to share these nature's beauty with the future generation. The extinction of coral reefs will negatively affect the marine life as many organisms require corals to survive. Coral reefs will also hit certain countries quite severely, as they depend on coral reefs for economic growth. One example is Australia, as they heavily rely on the Great Barrier Reef to boost their tourism sector. Also, extinction of coral reefs will cause a decline in marine life, especially seafood. This will affect the fishing sector as they can no longer fish up enough seafood to make a huge enough profit. The rapid degradation of these coral reefs just goes to show the extent of the negative consequences of global warming. Hence, we should try our best to protect these wonderful reefs so that we can continue to marvel at their beauty.
Long Menopause Allows Killer Whales to Care for Adult Sons
ScienceDaily (Sep. 13, 2012) — Scientists have found the answer to why female killer whales have the longest menopause of any non-human species -- to care for their adult sons. Led by the Universities of Exeter and York and published in the journal Science(Sept. 14, 2012) the research shows that, for a male over 30, the death of his mother means an almost 14-fold-increase in the likelihood of his death within the following year.
The reason for the menopause remains one of nature's great mysteries and very few species have a prolonged period of their lifespan when they no longer reproduce, as in humans. However, female killer whales stop reproducing in their 30s-40s, but can survive into their 90s. While different theories have been put forward for the evolution of menopause in humans, including the well-established 'grandmother' hypothesis, there has been no definitive answer to why females of a small number of other species, including killer whales, also stop reproducing part-way through their lives.
The research team, from the Universities of Exeter and York (UK), the Center for Whale Research (USA) and Pacific Biological Station (Canada) analysed records spanning 36 years, of the members of two populations of killer whales (Orcinus orca) in the North Pacific ocean, off the coast of the USA and Canada.
They found that the presence of a female who was no longer reproducing significantly increased her older offspring's survival. In the case of males over the age of 30, a mother's death meant a 14-fold increase in the likelihood of their death within a year. Females also stay within their mother's group but for daughters of the same age, the difference is just under three-fold. For females under the age of 30, the death of their mothers had no effect on their survival rates.
Killer whales live in unusual social groups, with sons and daughters staying with their mothers in a single group throughout their lives. With this close association, older mothers have the opportunity to increase the transmission of their genes by helping their adult offspring survive and reproduce. When sons mate, their offspring are cared for by females in another group, whereas when daughters reproduce the offspring stay in the group, which increases local competition for resources within the group.
Theory predicts that in order to have the best chance of spreading their genes, without carrying an additional burden, mothers should focus their efforts on their sons. This research backs up this theory and demonstrates the extent to which older sons are dependent on their mothers for survival.
Lead author on the paper University of Exeter PhD student Emma Foster said: "Killer whales are extraordinary animals and their social groups are really unusual in that mothers and their sons are lifelong companions. Our research suggests that they have developed the longest menopause of any non-human species so that they can offer this level of commitment to their older offspring."
Dr Dan Franks, from the Department of Biology at the University of York, said: "Our analysis shows that male killer whales are pretty much mommy's boys and struggle to survive without their mother's help. The need for mothers to care for their sons into adulthood explains why killer whales have evolved the longest post-reproductive lifespan of any non-human animal."
Dr Darren Croft of the University of Exeter added: "Both humans and killer whales are unusual in having a long menopause. Although they share this trait, the way older females benefit from ceasing reproduction differs, reflecting the different structure of human and killer whale societies. While it is believed that the menopause evolved in humans partly to allow women to focus on providing support for their grandchildren, it seems that female killer whales act as lifelong carers for their own offspring, particularly their adult sons. It is just incredible that these sons stick by their mothers' sides their entire lives."
This research was supported by the Biotechnology and Biological Sciences Research Council (BBSRC), the Leverhulme Trust and Earthwatch.
Reflection
It is quite interesting to note that killer whales have the longest menopause of any non-human species. Their sons are extremely reliant on their mother and are not independent at all, unlike their female counterparts. Their mother's death will drastically increase the killer whale's son's likelihood of death as he cannot survive on his own. That sudden loss of their mother deals a huge impact onto the sons, and they can no longer survive on their own. Killer whales have the longest menopause to ensure that their sons are well taken care of and the mother has to spoon feed the killer whales all the time. This fact is quite shocking to me as I always think of killer whales being ruthless predators who mercilessly hunt down their prey and feast on them. I never expected them to be so reliant on their mother's help.
