Nav: Home

Where river meets ocean

July 09, 2018

They exist all over the world, are among the most productive ecosystems on Earth and are home to a diverse array of wildlife. They also are essential to the global economy. They are estuaries -- coastal embayments where fresh river water and salty ocean water meet.

But this simple definition belies the estuary's complexity, diversity and importance to human sustainability.

"Estuaries are tricky in that they don't fit well with terrestrial science or oceanography," said Nick Nidzieko, a professor in the Department of Geography at UC Santa Barbara. Call them deltas, sloughs, salt marshes, harbors, sounds or bays, estuarine systems are neither fully marine nor fully riverine or riparian. This mixing of characteristics, diversity of habitats and variability in quality have made it difficult for scientists to draw conclusions about how these systems collectively contribute to global processes, particularly with regard to carbon and nutrient cycling through the coastal zone.

"We refer to an ecosystem's metabolism as the total metabolism of everything in an estuary -- all the animals, all the plants," Nidzieko said. "It is an integrated measure of how much organic carbon is being produced or consumed in a place." Estuaries, which are important to fisheries, transportation, shipping and wastewater disposal, have largely been studied on an individual basis, he explained, but their combined impact on the ocean's carbon budget is still something of a black box.

It turns out, according to Nidzieko's observations, that larger estuarine systems are typically less productive per unit size than the smaller ones. The larger-is-more-efficient concept has its roots in evolutionary biology.

"This is well-known with animals," he said. Known as Kleiber's Law, the idea is that an animal's metabolic rate scales to the three-quarters power of its mass. The larger the animal, the slower its metabolism. "A mouse lives for a couple years, its heart beats rapidly and it needs to eat constantly to live. An elephant eats occasionally, its heart beats slower and it lives for decades," Nidzieko explained.

The same three-quarter scaling applies to estuaries. After studying a series of published ecosystem metabolism investigations, Nidzieko determined that the productivity of an estuarine system often does not scale linearly with size; larger, deeper estuarine systems are somewhat less productive per unit size than their smaller, shallower counterparts.

"The explanations for why the elephant has a slower metabolism than a mouse provides the same answer for why San Francisco Bay isn't quite as productive, per unit size, as Goleta Slough," Nidzieko said. "This is basically driven by the physics. This paper shows that metabolism is related to nutrient residence time -- in other words, how fast nutrients move through the system."

The findings may impact the way estuaries are assessed for their benefits and their place in the larger global cycling of carbon, as well as the planning that goes into the uses of these areas. Factoring size and depth into the calculations of an estuary's productivity may also allow scientists to look back into what may have been lost as a result of incursion into coastal wetlands -- historically been targets of development -- such as the San Francisco Bay, ports and harbors around the world, and wastewater treatment systems.

Additionally, these results suggest that multiple remediation projects of smaller estuarine systems may have relatively more impact than a single project in a bigger system. But Nidzieko is quick to point out that larger systems can also do things that smaller systems can't, particularly in the realm of biodiversity.

"But this may provide some guidance into how to design or assess protected areas," he said. In the near future Nidzieko plans to take this concept from the shallow estuary scale to the other extreme -- the ocean basin scale.

"The same pattern holds but we don't yet understand quite why," he said.

University of California - Santa Barbara

Related Metabolism Articles:

A new way to control microbial metabolism
To help optimize microbes' ability to produce useful compounds but also maintain their own growth, MIT chemical engineers have devised a way to induce bacteria to switch between different metabolic pathways at different times.
Parasite manipulates algal metabolism for its own benefit
Researchers from the Max Planck Institute for Chemical Ecology and the universities of Jena and Frankfurt show that a pathogenic fungus alters the metabolism of its host unicellular algae, for its own purposes: the small bioactive substances that are formed in the process benefit the fungi's own propagation while preventing the algae from proliferating.
Lack of sleep affects fat metabolism
A restricted-sleep schedule built to resemble an American work week made study participants feel less full after a fatty meal and altered their lipid metabolism.
Mastering metabolism for shark and ray survival
Understanding the internal energy flow -- including the metabolism -- of large ocean creatures like sharks and rays could be key to their survival in a changing climate, according to a new study.
Rutgers researchers identify the origins of metabolism
A Rutgers-led study sheds light on one of the most enduring mysteries of science: How did metabolism -- the process by which life powers itself by converting energy from food into movement and growth -- begin?
Challenging metabolism may help fight disease
New research by Swansea University academics has shown that harnessing metabolism at a cellular level may help to relieve or heal a range of disorders.
How obesity affects vitamin D metabolism
A new Journal of Bone and Mineral Research study confirms that vitamin D supplementation is less effective in the presence of obesity, and it uncovers a biological mechanism to explain this observation.
Micro-control of liver metabolism
A new discovery has shed light on small RNAs called microRNAs in the liver that regulate fat and glucose metabolism.
Untangling the impacts of gut bacteria on drug metabolism
Individual drugs show variations in how successful or toxic they are, person to person.
Fruit flies help to shed light on the evolution of metabolism
Researchers at the University of Helsinki have discovered that the ability to use sugar as food varies strongly between closely related fruit fly species.
More Metabolism News and Metabolism Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Accessing Better Health
Essential health care is a right, not a privilege ... or is it? This hour, TED speakers explore how we can give everyone access to a healthier way of life, despite who you are or where you live. Guests include physician Raj Panjabi, former NYC health commissioner Mary Bassett, researcher Michael Hendryx, and neuroscientist Rachel Wurzman.
Now Playing: Science for the People

#544 Prosperity Without Growth
The societies we live in are organised around growth, objects, and driving forward a constantly expanding economy as benchmarks of success and prosperity. But this growing consumption at all costs is at odds with our understanding of what our planet can support. How do we lower the environmental impact of economic activity? How do we redefine success and prosperity separate from GDP, which politicians and governments have focused on for decades? We speak with ecological economist Tim Jackson, Professor of Sustainable Development at the University of Surrey, Director of the Centre for the Understanding of Sustainable Propserity, and author of...
Now Playing: Radiolab

An Announcement from Radiolab