Seal teeth offer glimpse into the environmental past of Russia’s Lake Baikal

March 21 marks World Water Day — and a fitting time to consider one of the most unique mammals in Earth’s waters.The nerpa, also known as the Baikal seal, is the only seal that lives exclusively in fresh water. This earless seal can be found in just one place, Russia’s Lake Baikal, where it is at the top of the food web. And now, Wellesley scientists have found that the teeth of this particular seal may hold the strongest evidence of the effects of decades of environmental pollution, nuclear testing, and climate change on Lake Baikal — the deepest, oldest, and most bio-diverse lake in the world.”The Baikal seal teeth are a chemical record of the lake,” said Marianne Moore, Wellesley Professor of Biological Sciences. By analyzing the chemical composition of hundreds of seal teeth, Professor Moore and her co-researchers, post-doctoral fellow Ted Ozersky and Wellesley student Xiu Ying (Annie) Deng ’15, are working to reconstruct the Baikal seal’s diet and contaminant burdens over the last 80 years. The teeth were collected from ice harvested in the area by fellow scientists in Russia.Baikal seals can live up to 40 and 50 years, and much like the rings of a tree trunk, the layers of dentine within their teeth can be studied and linked to environmental patterns and changes over a period of time. Moore, Ozersky, and Deng are looking for evidence of toxic metals such as uranium, mercury, cadmium, and zinc inside the teeth samples, which date back to the period before industrialization in the region.Why not just measure these toxic elements in the water? Professor Moore explained that these metals show up at extremely low levels in the water. The teeth of the nerpa are actually better indicators due to biomagnification, the process by which the concentration of a substance increases with each level of the food chain. Because the Baikal seal is at the top of its food web, their teeth hold the best clues into the lake’s environmental past.”Ultimately, the goal of our project is to study contamination levels in Lake Baikal as reflected by the seals, and to tie these patterns to changes in the watershed, such as the introduction of mining in the area, an increase in coal burning, and other environmental events,” said Dr. Ozersky.Still early in the project, the Wellesley researchers have already made a surprising discovery: levels of some toxic metals such as uranium were higher in the mid 1970’s than in seals today. …

Read more

Killer fish with teeth? Danish swimmers escape waters fearing killer fish

Aug. 12, 2013 — The capture in the Danish/Swedish strait of Oresund of a fish some twenty centimeters in size and with long sharp teeth has caused Danish swimmers to leave the water fearing an invasion of meat eating killer fish, Piranhas. There is however no cause for panic say experts. The fish, though exotic, is a Pacu, not a piranha. None the less they caution male swimmers to protect their privates when swimming in the sound.”Discovering whether this fish is a lone wanderer or a new invasive species will be very exciting. And a bit scary. It’s the first time this species has been caught in the wild in Scandinavia,” says Associate Professor and fish expert Peter Rask Møller of the National History Museum of Denmark, University of Copenhagen.Caught by hobby fishermanThe frightening fish was caught by hobby fisherman Einar Lindgreen on August 4. As he emptied his nets north of Danish isle Saltholm in the strait Oresund which seperates Denmark and Sweden he saw the red-bellied bigtooth among eels and perch. Back in the harbour the exotic fish caused quite an uproar, as several of Lindgreens colleagues were convinced that they were staring at a South American Piranha. Fortunately the fish was sent for study at the Natural History Museum of Denmark. …

Read more

Utilizzando il sito, accetti l'utilizzo dei cookie da parte nostra. maggiori informazioni

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close