Porpoises Have to Be Careful in the Eastern Scheldt in the Netherlands

Mar. 7, 2013 — The unexpected conclusion of the doctoral research project on the feeding ecology of porpoises by Okka Jansen at Wageningen University is that the Eastern Scheldt in the Netherlands may be an ecological trap. She also discovered that more than just examining stomach contents is required to find out what porpoises eat. The analyses of stable isotopes and fatty acids provide different and more complete data.

Coastal waters are rich marine ecosystems. Porpoises are the most common small cetacean species in the Netherlands' coastal waters. The numbers and distribution of porpoises have considerably changed in recent decades. The question is: what is driving these changes? Within this context, doctoral candidate Okka Jansen studied the feeding ecology of the porpoise in the Netherlands' coastal waters. 

"Most studies of the feeding ecology of porpoises are based on examinations of stomach contents," says Okka Jansen. "But this method falls a long way short of the mark in telling us everything about what they eat. I performed additional research using two other techniques: analysis of stable isotopes and analysis of fatty acids in porpoises and their prey. These three methods combined give the most accurate reflection of the diet of porpoises." The analysis of stable isotopes (from bone and muscle tissue) mainly provides information about the location in which and how high in the food chain the animals have foraged. Fatty-acid analysis indicates the most probable composition of the diet of porpoises in recent months.

"The combination of these three techniques is unique in sea-mammal research," says doctoral thesis supervisor Prof Peter Reijnders. "Examination of the stomach contents only enables you to see recent food ingestion, whereas fatty-acid analyses allow you to trace back what animals have eaten over a slightly longer period, and analyses of stable isotopes (extracted from bone tissue) indicate what they have eaten over a much longer period. In this way, Okka's research showed that the diet of porpoises in the Netherlands' coastal waters consists of inshore fish species, such as gobies, smelt, and dragonet as well as schooling species from deeper waters further from the coast, which were eaten a longer time ago, such as mackerel and herring. The porpoise is in essence an opportunistic predator. By contrast, the white-beaked dolphin, which she also studied, turned out to be much more of a specialist; with the exception of extremely young animals, the staple part of their diet always consists of cod and whiting, irrespective of their habitat."

Read more:  http://www.sciencedaily.com/releases/2013/03/130307092330.htm

Python Study May Have Implications for Human Heart Health

ScienceDaily (Oct. 27, 2011) — A surprising new University of Colorado Boulder study shows that huge amounts of fatty acids circulating in the bloodstreams of feeding pythons promote healthy heart growth, results that may have implications for treating human heart disease.

CU-Boulder Professor Leslie Leinwand and her research team found the amount of triglycerides -- the main constituent of natural fats and oils -- in the blood of Burmese pythons one day after eating
increased by more than fiftyfold. Despite the massive amount of fatty acids in the python bloodstream there was no evidence of fat deposition in the heart, and the researchers also saw an increase in the activity of a key enzyme known to protect the heart from damage.

After identifying the chemical make-up of blood plasma in fed pythons, the CU-Boulder researchers injected fasting pythons with either "fed python" blood plasma or a reconstituted fatty acid mixture they developed to mimic such plasma. In both cases, the pythons showed increased heart growth and indicators of cardiac health. The team took the experiments a step further by injecting mice with either fed python plasma or the fatty acid mixture, with the same results.

"We found that a combination of fatty acids can induce beneficial heart growth in living organisms," said CU-Boulder postdoctoral researcher Cecilia Riquelme, first author on the Science paper. "Now we are trying to understand the molecular mechanisms behind the process in hopes that the results might lead to new therapies to improve heart disease conditions in humans."

The paper is being published in the Oct. 28 issue of the journal Science. In addition to Leinwand and Riquelme, the authors include CU postdoctoral researcher Brooke Harrison, CU graduate student Jason Magida, CU undergraduate Christopher Wall, Hiberna Corp. researcher Thomas Marr and University of Alabama Tuscaloosa Professor Stephen Secor.

Previous studies have shown that the hearts of Burmese pythons can grow in mass by 40 percent within 24 to 72 hours after a large meal, and that metabolism immediately after swallowing prey can shoot up by fortyfold. As big around as telephone poles, adult Burmese pythons can swallow prey as large as deer, have been known to reach a length of 27 feet and are able to fast for up to a year with few ill effects.

There are good and bad types of heart growth, said Leinwand, who is an expert in genetic heart diseases including hypertrophic cardiomyopathy, the leading cause of sudden death in young athletes. While cardiac diseases can cause human heart muscle to thicken and decrease the size of heart chambers and heart function because the organ is working harder to pump blood, heart enlargement from exercise is beneficial.

Read on ...