Before I started writing this blog, I asked myself: Should I do this? Am I just becoming a fear mongering sensationalist? But eventually I decided that these stories are important and need to be told. Today I will present to you two tragic case studies, which hopefully will show to you the relevance of global water concerns, and the outcomes that come with apathy towards our environment.
Death of the River Goddess
In 2007, Turvey et al. published a paper in the journal Biology letters, entitled “First Human caused extinction of a cetacean species?” They had just returned from an intensive six week survey of the Yangtze River, China, looking for Lipotes vexillifer, known as the Yangtze River Dolphin or baiji.
The baiji was said to be the reincarnation of a beautiful princess, thrown into the Yangtze after she refused to marry a man she did not love. The earliest surviving description of the baiji was in the Erya, a Chinese dictionary dating from approximately 3 BC, with the population estimated at 5000.
During the six week study, covering 1669 km, Turvey et al. did not once see a baiji. As a result of this, the baiji was declared functionally extinct. Functional extinction means the population is no longer viable, and can no longer sustain itself.
The article states that the last authenticated sightings of the baiji were a stranded female found in 2001, and a live animal photographed in 2002. Subsequent to the publication of this article, in August 2007, A Chinese businessman photographed one further baiji in the Yangtze River.
Chinas huge population has put pressure on the Yangtze River basin, increasing pollution, but the primary cause is harmful fishing practices by local fisherman, with baijis being killed by hooks, nets and electro fishing.
The extinction is the end of the line for the family Lipotidea, which are thought to have diverged from other river dolphins 20-25 million years ago.
For more information on the baiji, and its journey to extinction, I would highly recommend Samuel Turvey’s book, Witness to Extinction, How We Failed to Save the Yangtze River Dolphin.
This case study is based on an article published in Environmental Health, “Cancer in Wildlife, a Case Study: Beluga from the St. Lawrence Estuary, Québec, Canada” by Martineau et al. (2002).
This article describes how researchers studying the Beluga whale population in the Saint Lawrence Estuary (a population of approximately 650 whales), discovered extreme cancer rates, especially in the intestinal tract. These cancers can be attributed to water contaminants, likely from aluminium smelters in the region.
The authors examined 129 whale carcasses found stranded in the Saint Laurence estuary between the years 1983-1999, and found that 27% of the dead animals had cancer. This rate of 163/100 000 is on par with human cancer rates. Intestinal cancer in the whales was estimated at 63/100 000, which is higher than rates observed in humans and other mammals worldwide.
Furthermore, only 33 cases of cancer have been reported globally in cetaceans (whales dolphins and porpoises), both in the wild and captivity outside the studied Saint Laurence Beluga population. And only one of these was in a beluga whale. This information strongly indicates that there is something unfortunately unique about the Saint Laurence Beluga whale population.
The Saint Lawrence belugas were found to have high concentrations of heavy metals, polycyclic aromatic hydrocarbons (PAHS), PCBS and DDT in their metabolic systems. These are all extremely toxic compounds, and are released into the environment as by products from industry.
The authors suggest that the high cancer rates can be attributed to the PAH’s found in the water in the Saint Laurence Estuary. These PAH’s contaminate invertebrates living in the sediment, which the belugas then feed on.
The presence of the contaminants has been attributed to the aluminium smelters in the region. Workers in these plants also display a high prevalence of cancers, as do residents who do not work in the plants. It is suggested that this is due to the high levels of PAH’s in drinking water, sourced from local rivers and lakes.
If hearing about the baiji made you sad, why not try to stop it happening here? The Maui dolphin population, found only in New Zealand is estimated at 55 individuals. To find out more, and what you can do to help, visit the Department of Conservation (DOC) fact page on Maui dolphins. If dolphins aren’t your thing, what about the damaging effect of mice on seabirds? For more information on what is being done to stop this, see Sub Antarctic Science.
I found both the story of the baiji, and of the belugas incredibly upsetting. The lesson I will take from this is that while we may not be able to influence the outcome of things happening half a world away, we can certainly take a strong stance in our own back yard.