Washington State University scientists have developed a new method for classifying diverse ocean environments, shedding new light on how marine biomes are defined and changed by nature and humans.
Recently published in Global Environment and BiogeographyResearch by Alli Cramer, a 2020 PhD graduate from the WSU School of the Environment, now at UC Santa Cruz, and WSU Professor Stephen Katz, has revealed a new approach that categorizes biomes based on their life-supporting potential and sea-level stability.
Kramer and Katz reviewed more than 130 studies weighing variables such as light, depth and nutrients across seven biomes comprising dozens of environments, including coral reefs, kelp layers, ocean ice and deep abyssal plains.
Analyzing the data in extrapolation, rather than starting from an initial hypothesis, they found that the biomes were clearly classified by two powerful variables: total primary production, which is a measure of energy in the food web. Substrate movement, or ocean floor movement and formation.
“This means that energy flow and mobility are common regulatory forces across a wide range of marine ecosystems,” said Kramer. Despite their differences, coral reefs and deep-sea deserts respond to the same processes.
While biomes on Earth have long been delineated by climate, marine biomes have evaded the explicit classification.
“Oceans are a big black box,” Katz said. Scientists have traditionally held that depth, temperature, and light are important. But we found that they do not possess every society. The sea’s energy economy works in other ways than just sunlight. “
As a PhD student, Kramer set out to develop a more effective method for screening marine biomes.
After analyzing several variables, Katz said, “There were really only two variables at the end revealing the large pattern.”
Gross primary production measures the energy flowing through the marine community – whether it is fueled by sunlight, a recycled “brown food web” from the depths, or chemicals flowing from hydrothermal vents. Coral reefs, sea ice, and mangrove swamps have high primary production, while deep, deep muddy plains are low-productivity marine deserts.
The other powerful variable, substrate transport, biomes classified according to the nature of the substrate – what are its components, and how much it is moved and flipped by waves and currents. The often stable sandy bottom defines a different biome from one that is constantly moving.
“These two axes are two important forces in determining ocean ecosystems and driving their formation,” Katz said.
He added, “One of the new things about this classification system is that it is simple – so simple that no one botheres.” “When our colleagues told us about this, they were surprised that no one had tried it before.”
The new method could help scientists, fisheries managers and conservationists reconsider the richness and diversity of ocean biomes as well as the value of highly productive areas to which humans are affected.
“Previous work examined the marine environment on an ecosystem-by-line basis,” said Kremer. “By integrating data from many ecosystems, we found the common thread that binds them together. This allows us to see the ocean in new ways and sheds light on some of the key places where our actions may change the function of the ecosystem.”
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