Tag Archives: nutrient

Whales eat much more than we assumed, and it has huge ecological implications

Baleen whales eat a lot more food than previously assumed: three times as much, to be exact, according to new research. The findings are not meant to shame these animals into going on a diet. Rather, they shed light on the key ecological role whales play in the ocean.

Image via Pixabay.

The sheer size and appetite of whales make them important players in the ocean. In particular, they serve as key drivers of nutrient recycling in the ocean. They consume vast amounts of food, releasing important nutrients back into the water following digestion. A new paper refines our understanding of just how much food whales as a group can consume, and take a look at the ecological implications of the decline in whale numbers since the onset of the 20th century.

Big eaters

“While it may just seem like a fun trivia fact, knowing how much whales eat is an important aspect of ecosystem function and management,” Matthew Scott Savoca, a Postdoctoral Research Fellow at Stanford University and corresponding author of the paper, told ZME Science. “If we want to protect whales and make sure they are thriving in modern oceans, then knowing how much food they need to survive and reproduce is critical.”

“There are implicit benefits of having whales on the planet — isn’t it cool to think that we live at a time when we’re alongside the largest animal in the history of life on Earth? Beyond that, whales have direct value as carbon sinks (e.g., sequestering carbon in their bodies and exporting it to the deep sea when they die and sink – which we did not discuss in this study). In addition, whale watching is a multi-billion dollar per year global business that is expanding as whales are recovering.”

Previous estimates of just how much whales eat were built upon data obtained from metabolic models or direct analysis of the stomach contents of whale carcasses. Such data can give us a ballpark figure but, according to the new paper, they are quite inaccurate.

Savoca and his colleagues directly measured the feeding rates of 321 baleen whales across seven species in the Atlantic, Pacific, and Southern oceans. They tracked foraging behavior and estimated prey consumption by tracking the whales using GPS tags. Location data was then combined with sonar measurements of prey density, of the quantity of prey consumed per feeding, and current estimates of how much each species typically eats per feeding event.

Overall, the results suggest that we’ve underestimated how much food baleen whales ingest by a factor of three. On average, these animals consume between 5% and 30% of their body weight per day, depending on species, across all the investigated regions. In total, blue, fin, and humpback whales in the California Current Ecosystem consume over two million tonnes of krill every year per species.

The study also puts into perspective just how massive an impact whaling and other stressors have placed on whales and, by extension, on the ecosystems they inhabit. Prior to the 20th century, the team estimates, whales in the Southern Ocean were consuming around 430 million tonnes of Antarctic krill per year. This figure is twice the total estimated biomass of Antarctic krill today.

Whales, the paper explains, serve an important ecological role as nutrient recyclers, tying into that last tidbit of information. Prior to the 20th century, before whales were hunted in meaningful numbers, these animals consumed a massive amount of biomass, releasing much of the nutrients in their food back into the ocean as waste. This, in turn, allowed for much greater productivity in the ocean (as they made large quantities of nutrients freely-available for krill and other phytoplankton to consume).

“In brief, if whales eat more than we thought, then they also recycle more nutrients (i.e., poop) than we thought. If that is the case then limiting nutrients may have been used more effectively and efficiently in a system that had many more whales,” Savoca said for ZME Science. “It’s not that these whales add more iron (or other nutrients) to the system, they just [move] it from within the bodies of their prey, to in the seawater itself where it could, in theory, fertilize phytoplankton — the base of all open ocean food webs.”

To put things into perspective, the authors estimate that today, baleen whales in the Southern Ocean recycle around 1,200 tons of iron per year; prior to the 20th century, this figure was likely around 12,000 tons of iron per year. In essence, whaling has led to a 90% decrease in the amount of essential nutrients whales can recycle in their ecosystems.

I asked Savoca whether there is any overlap between the decline in baleen whale populations and the detrimental effects of industrial fishing on today’s ocean ecosystems. Should we expect trouble ahead as we’re removing key nutrient recyclers from one side of the equation, and taking more fish out of the sea on the other?

“You are hitting on a major issue,” he admitted. “We have noticed that oceans have become less productive after removing millions of large whales in the 19th and 20th centuries. The same is true of ongoing industrial fishing. The collapse of predatory fish communities have the same detrimental impacts on marine communities as the wholesale decimation of the whales did.”

“I am not against fishing, but we have to do so as sustainably as possible if we want to maintain essential ocean productivity into the future.”

Whales and their extended family — cetaceans — have been experiencing immense pressures ever since the onset of industrial-scale whaling in the early 20th century. Commercial whaling only slowed down in the 1970s, which is a very, very short time ago from an ecological perspective. This has allowed whales and other cetaceans some much-needed respite, but they are still struggling. Over half of all known cetacean species today are inching towards extinction, 13 of which are listed as “Near Threatened”, “Vulnerable”, “Endangered”, or “Critically Endangered” on the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species. Besides the lingering effects of whaling, this family is still struggling under the combined effects of (chemical and noise) pollution, loss of habitat, loss of prey, climate change, and direct collisions with ships.

Research such as this study and many others before it can raise an alarm that not all is well with the whales. But actually doing something about it hinges on us and governments the world over taking the initiative to protect them. Understanding just how important whales are for the health of our oceans and, through that, for our own well-being and prosperity definitely goes a long way towards spurring us into action.

But Savoca’s conclusion to our email discussion left an impression on me. There is great beauty in natural ecosystems that we’re destroying, oftentimes unaware. Beyond the practical implications of conserving whale species, we have a chance to conserve these for our children and all future generations.

“I remember one day in Monterey Bay when we were surrounded by blue whales (likely over a dozen), each about twice the size of the boat we were on. I will also never forget the sound and scale of the ice in Antarctica,” Savoca wrote for ZME Science.

“My life’s work is devoted to making sure people and animals have these (and ideally ever better) ecosystems of awe and plenty well into the future.”

The paper “Baleen whale prey consumption based on high-resolution foraging measurements” has been published in the journal Nature.

Cold sandwiches are calorie traps — don’t fall for it

For some reason, we tend to feel that cold food isn’t as filling as hot food, and it’s tricking us into overeating.

When you’re tempted to conclude that the human species is rational, you may want to slide over to marketing research and check out a journal called Appetite. The journal looks at sensory and other influences on people’s selections of food and drinks. It doesn’t take long to understand the selections we make don’t exactly scream common sense.

A recent research effort in the journal examines our practice of adding orders “on the side” if our main item on order is a cold sandwich. They found that customers who bought cold sandwiches were twice as likely to order a la carte extras such salty crisps and cookies, as if the sandwich, just for its being cold, could not possibly satisfy them without companion sides.

Imagine customer Raph telling the waiter what he wants. After studying his lunch menu, he pats on cold crabmeat sandwich. He wants to know, “What will it come with?” Raph looks at the sides list on the menu and taps on stuffed olives and plantain chips. Was Raph’s sandwich (580 calories and 26 grams of fat, but who’s counting) was not enough to sustain him for a few hours?

If we look at the research in focus, we know that Raph or customers standing at takeout counters think they need more than just the sandwich to complete a sit-down eating experience, because it’s just a cold sandwich, and that’s not much. They simply feel that the cold sandwich alone will not offer ample satiety.

“We show that the temperature at which foods and beverages are served impacts consumers’ complementary purchases, defined as additional foods and beverages purchased for a consumption episode.” wrote Sara Baskentli, Lauren Block, Maureen Morrin in their journal article, “The serving temperature effect: Food temperature, expected satiety, and complementary food purchases.”

Somebody cared

Anyone hunting for explanations for this behavior might remember all the family memories of steaming food on a table marking religious holidays and celebrations. A psychological add-on is that the hot food is a reminder that somebody in the household cared enough to stand, mix, pour, bake, braise, and simmer so that you could be pleased and nourished. Translation: Hot food equals caring. Cold food? Not so much.

To test the hypothesis, researchers examined customers’ café orders over a two-week period. The researchers saw 123 customers’ orders at a New York City café with sandwiches on their menu. People buying cold sandwiches were twice as likely to buy other food items. As for cold beverage orders? Calorie and money traps were evident, too.

“When a customer purchased a cold beverage, they were three times more likely to also buy food items, such as a croissant or a muffin,” said the news release from Rutgers.

The authors in their paper nailed the good news for restaurant business and the caution for the rest of us.

“Serving temperatures that increase complementary purchasing may enhance the firm’s bottom line, but could add unnecessary calories to the meal, and thus is of interest to both consumers and managers.”

In the bigger picture, this is a research discussion that indicates the important difference between appetite and hunger. Scientists like to point out the difference between the two words. Appetite is not hunger, plain and simple. According to the Aspen Clinic, for example, “appetite” involves a “conditioned response to food” and the word is more closely linked to behavior and emotional connection to food. Appetite “can increase/decrease due to hormones, emotional state, and taste preferences.”

Dairy has been greatly underestimated and is an “excellent” protein source for children, study finds

Dairy holds a controversial position in our modern diets. It used to be a go-to recommendation for kids, but nowadays, many recommend avoiding giving dairy to children — or even adults. A new study takes a pretty clear position in that debate, naming dairy an excellent protein source using a new calculation method.

Dairy might be better for us than we preivously thought. Image via Pixabay.

Researchers from the University of Illinois have been using pigs as a model for the protein uptake of children. This isn’t a new approach, it’s something that was suggested by the Food and Agriculture Organization (FAO) of the United Nations in 2011.

“Plant proteins are the primary sources of amino acids in many parts of the world, whereas animal proteins are the primary sources in other parts of the world. However, the composition and digestibility of these types of proteins differ,” says Dr. Hans H. Stein, professor of animal sciences at U of I and principal investigator of this research.

Researchers in Stein’s lab calculated the protein score for eight different sources of protein, derived both from plants and animals. The protein scores are a reflection of the amount of digestible amino acids in a food with a “reference protein,” a theoretical protein which contains all the fully digestible amino acids in the proportions required for human nutrition at a particular stage of life. They calculated how digestible the proteins are through this standard method which has been used for 20 years. However, researchers argue, this method is not complete and has significant flaws, failing to take significant factors into consideration.

“The total tract digestibility fails to take into account nitrogen excretion in the hindgut,” Stein says. “The PDCAAS also assumes that all amino acids in a foodstuff have the same digestibility as crude protein, but in reality, amino acid digestibilities differ.”

So they also used a new calculation, which they called digestible indispensable amino acid score (DIAAS). They calculated DIAAS on the same eight different proteins — whey protein isolate, whey protein concentrate, milk protein concentrate, skimmed milk powder, pea protein concentrate, soy protein isolate, soy flour, and whole-grain wheat. They found that all dairy proteins met Food and Agriculture Organization (FAO) standards as “excellent/high” quality, while soy protein isolate and soy flour qualified as “good” sources of protein. With this approach, dairy scored much better than it did with traditional methods. This would mean that dairy has been greatly underestimated as a protein source for children, though researchers concede that this method also has its limitations.

“The protein sources used in this experiment were fed raw, and foods processed as they typically are for human consumption might well have different protein values.”

Still, Stein and his team believe this is a significant step forward compared to previous approaches. Although lots of time and effort is being invested into understanding how the human body deals with nutrients, we still know surprisingly little about these interactions. Of course, more research is needed to validate this method, but small shifts like this go a long way towards expanding our understanding — and enabling us to eat healthier.

“The results of this pilot study indicate that dairy proteins may be an even higher quality source of protein compared to vegetable-based protein sources than previously thought,” said Dr. Greg Miller, chief science officer at NDC. “While using DIAAS is a newer concept and more research will be needed, one thing rings true — milk proteins are high quality and milk as a beverage has protein plus eight other essential nutrients, which is especially important when it comes to kids, because they need quality nutrition to help support their growth and development.”

The paper, “Values for digestible indispensable amino acid scores (DIAAS) for some dairy and plant proteins may better describe protein quality than values calculated using the concept for protein digestibility-corrected amino acid scores (PDCAAS)” was published in the February 2017 issue of the British Journal of Nutrition.

Rising CO2 poses significant threat to human nutrition

Image via Harvard University.

If current trends continue, by 2050, the elevated levels of CO2 in the atmosphere will cause many crops around the world to produce a reduced amount of nutrients, especially zinc and iron. Considering that about almost 1 in 3 people in the world (2 billion people) suffer from iron or zinc deficiencies resulting in a loss of 63 million life years annually from malnutrition, the reduction of these nutrients is one of the biggest threats associated with climate change.

“This study is the first to resolve the question of whether rising CO2concentrations — which have been increasing steadily since the Industrial Revolution — threaten human nutrition,” said Samuel Myers, research scientist in the Department of Environmental Health at HSPH and the study’s lead author.

The study appeared yesterday, 7 May, in Nature.

Some studies have already shown, in greenhouses or controlled conditions, that an increase in CO2 leads to a decrease in nutrients in the plants, but those studies were criticized for using artificial conditions, and some claimed that in reality, the situation would be different.  Experiments using free air carbon dioxide enrichment (FACE) technology became the gold standard recently, as it allowed scientists to juggle with CO2 levels and observe the changes in a natural environment.

The researchers analyzed 41 different types (genotypes) of rains and legumes from seven different FACE locations in Japan, Australia, and the United States. The level of CO2 across all seven sites was in the range of 546 to 586 parts per million (ppm) – more or less the projected values for 2050. The results showed a significant decrease in the concentrations of zinc, iron, and protein in the grains. In the grains, zinc concentrations went down, on average by 9.3 percent, iron by 5.1 percent and protein by 6.3 percent. The results for zinc and iron were similar for the legumes, but protein levels remained similar.

The problems this could cause are huge! Some 3 billion people of the world get 70 percent of their dietary zinc and iron from grains, especially in the developing world – where iron and zinc deficiencies are already major problems. The raise in CO2 will almost certainly have devastating effects.

While the reduction of CO2 levels in the atmosphere is almost a utopia at this stage, there are still things we can do to protect ourselves from this incoming disaster – breeding cultivars with reduced sensitivity to CO2, biofortification of crops with iron and zinc, and nutritional supplementation for populations most affected could all play a role in reducing the human health impacts of these changes. However, these are all temporary solutions – the true long term goal is to reach sustainable levels of CO2 emissions.

“Humanity is conducting a global experiment by rapidly altering the environmental conditions on the only habitable planet we know. As this experiment unfolds, there will undoubtedly be many surprises. Finding out that rising CO2 threatens human nutrition is one such surprise,” said Myers.

Scientific Reference: Increasing CO2 threatens human nutrition. Nature  doi:10.1038/nature13179

Ecosystems still feel the pain of ancient extinctions

The more researchers study ecosystems, the more we learn that an ecosystem behaves, in many ways, just like a living organism: thousands of years after human hunters wiped out big land animals like giant ground sloths, the ecosystems they lived in are still suffering from the effects, much like a body suffers from past trauma.

The giant sloth, imagined in happier days. Image: Jaime Chirinos/SPL

The giant sloth, imagined in happier days. Image: Jaime Chirinos/SPL

Humans wiping out species (directly through hunting or indirectly through habitat destruction) is not really a new thing. Early human hunters have posed a stress on environments for thousands if not tens of thousands of years, because they were so successful and the prey didn’t have enough time to adapt.

Most ecosystems rely on big animals to supply them with nutrients (read: dung fertilizing).

“If you remove the big animals from an ecosystem, you pretty much stop nutrients moving,” says Chris Doughty of the University of Oxford.

In order to understand the impact of this extinction, Doughty and his colleagues studied the distribution of phosphorous – a nutrient that plants need to grow; he analyzed the Amazon basin in South America, an area which was once the home of fantastically large animals, such as elephant-like gomphotheres and giant ground sloths.

Unfortunately for these spectacular animals though, some 12.500 years ago, humans moved to South America, and shortly after this, these animals went extinct due to extensive hunting and climate change. Today, the Amazon basin is home to a huge biodiversity, but there are no more truly big animals – and their extinction still has a massive effect on the distribution of phosphorous throughout the basin.

Using the relationship between animal size and phosphorous distribution, Doughty estimated how much phosphorus South America’s larger extinct animals would have transported 15,000 years ago. His model concluded that megafauna would have spread nutrients 50 times faster than today’s fauna. This happens because big animals carry more food around in their bellies and they also travel more searching for food. It’s just like blood vessels in the body:

When you get rid of big animals, it’s like severing the nutrient arteries.”, says Doughty. He thinks the same thing happened in North America, Europe and Australia, where most big animals have also been wiped out. “The idea that herbivores redistribute nutrients is not new, but the scale of this thinking is much, much bigger,” says Tim Baker at the University of Leeds in the UK.

If his model is correct, than it’s quite safe to assume that the Amazon is still recovering from this drastic event which severely altered the circuit of nutrients. With large herbivores gone from the area, it’s up to the humans to take their role – but we’re doing the complete opposite of what they’re doing.

amazon basin

“These megafauna would disperse nutrients, whereas humans concentrate them,” says Doughty. We spread fertiliser on small plots of productive farmland, and keep large animals like cows fenced rather than letting them roam freely. “There are probably more nutrients because of people, but they are very poorly distributed.”