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.
Ecosystem - Metabolism - Metabolism - Everything - Animals
"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.
Animals - Kleiber - Law - Idea - Animal
"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...
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