Nav: Home

Salmon provide nutrients to Alaskan streambanks

March 18, 2020

Adult Pacific salmon spend a great portion of their life in the ocean. But their life began along the banks of freshwater streams. Their life will end there, as well. These important steps in the lifecycle of salmon play a role in the health of streambank ecosystems.

David D'Amore and a team of scientists studied how different soils respond to the delivery of "salmon-derived nutrients." These nutrients come from adult salmon returning to their home streams, known as spawning. The study sites were forested ecosystems in Alaska's coastal temperate rainforest.

Aquatic and terrestrial scientists have studied salmon derived nutrients in these systems, but D'Amore set out to see if there was a difference in how these nutrients worked with varying soil types along the streambanks.

"The fate of salmon-derived nutrients will be influenced by the soil type in the riparian zone," says D'Amore. "These soils play an important role in the transfer of material and energy between terrestrial and aquatic environments. The nutrients provided by salmon can support microbial and plant growth. In turn, these organisms support the salmon and other animals that rely on food from the streambank ecosystems."

"Soils along the streams resulted from a series of alluvial deposits after the glaciers retreated," says D'Amore. "Two alluvial deposits were formed during the last ice age, resulting in two different soils. An older terrace formed Spodosols, rich in organic matter. They also have highly enriched organic-metal complexes. But there are also younger floodplain soils with little development. These two soil types offer a stark contrast in attributes such as acidity, cation exchange capacity, and organic matter - all which affect how well nutrients are absorbed and held in soil."

This difference in how the two soil types worked with salmon-derived nutrients added the novel twist for the research done by D'Amore's team.

Salmon begin life along the banks of streams that flow past the alluvial soils of the coastal rainforests. Once the salmon emerge from their egg nests, they are nurtured by the nutrients that support the food web in the stream. There, they are also protected by the woody debris of large conifers that fall into the stream. Once they are large enough to survive in the ocean, the salmon depart the freshwaters to spend 2-4 years in the nutrient-rich waters of the North Pacific. The adult salmon then return to their natal streams from the ocean to close the life cycle loop.

"Our study found that both nitrogen and phosphorus decreased over time, but were retained in the soils and could be available to plants in the riparian zone over the duration of the spawning cycle," says D'Amore. "Although the extractable nitrogen and phosphorus amounts did not differ between soil types, the way the nutrients were processed did. We also found that over time - and location - there were differences in the way these salmon-derived nutrients were used."

The findings in this study revealed the potential for contrasting nutrient cycling pathways between the two soil types. "Future research work will focus on the fate of nitrogen through leaching and denitrification," says D'Amore.

"In addition, we plan to look at nitrogen and phosphorus, along with their physical and biological compartments, to determine the ultimate fate of the salmon-derived nutrients. The link between the nutrient subsidy and increased plant growth needs to be more closely examined, especially in the spatial context of the soils and their different nutrient retention characteristics."
-end-
This study was recently published in the Soil Science Society of America Journal. The research was funded by USDA-CREES National Research Initiative (Managed Ecosystems Program 2006-35101-16566).

American Society of Agronomy

Related Nitrogen Articles:

'Black nitrogen'
In the periodic table of elements there is one golden rule for carbon, oxygen, and other light elements.
A deep dive into better understanding nitrogen impacts
This special issue presents a selection of 13 papers that advance our understanding of cascading consequences of reactive nitrogen species along their emission, transport, deposition, and the impacts in the atmosphere.
How does an increase in nitrogen application affect grasslands?
The 'PaNDiv' experiment, established by researchers of the University of Bern on a 3000 m2 field site, is the largest biodiversity-ecosystem functioning experiment in Switzerland and aims to better understand how increases in nitrogen affect grasslands.
Reducing reliance on nitrogen fertilizers with biological nitrogen fixation
Crop yields have increased substantially over the past decades, occurring alongside the increasing use of nitrogen fertilizer.
Flushing nitrogen from seawater-based toilets
With about half the world's population living close to the coast, using seawater to flush toilets could be possible with a salt-tolerant bacterium.
We must wake up to devastating impact of nitrogen, say scientists
More than 150 top international scientists are calling on the world to take urgent action on nitrogen pollution, to tackle the widespread harm it is causing to humans, wildlife and the planet.
How nitrogen-fixing bacteria sense iron
New research reveals how nitrogen-fixing bacteria sense iron - an essential but deadly micronutrient.
Corals take control of nitrogen recycling
Corals use sugar from their symbiotic algal partners to control them by recycling nitrogen from their own ammonium waste.
Foraging for nitrogen
As sessile organisms, plants rely on their ability to adapt the development and growth of their roots in response to changing nutrient conditions.
Inert nitrogen forced to react with itself
Direct coupling of two molecules of nitrogen: chemists from Würzburg and Frankfurt have achieved what was thought to be impossible.
More Nitrogen News and Nitrogen Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.