Nutrients From Salmon Carcass Feed Flowers

A new study from Simon Fraser University (SFU) suggests that nutrients obtained from salmon carcasses can affect the growth and reproduction of plants. The research is published in Royal Society Open Science.

Interconnection between ecosystems

The research, led by PhD biology student Allison Dennert with SFU biology Professors Elizabeth Elle and John Reynolds, sought to analyze the impact of cross-ecosystem nutrient subsidies on plant growth and reproduction.

"Understanding the interconnection between ecosystems is incredibly important to our knowledge of how to protect them,” Dennert says.

Previously, a nitrogen isotope – ∂N15 – discovered in terrestrial plant and animal ecosystems had been attributed to nutrients obtained from salmon carcasses that have decomposed. However, “much of the recent work on salmon subsidies in terrestrial habitats has been necessarily observational, with a few notable exceptions,” the authors write. “A potentially powerful and complementary approach to observational studies is to test experimentally for effects of carcass deposition on individual plants living in salmon meta-ecosystems.”

Wildflowers grew larger leaves where a salmon carcass was deposited

Over a three-year field project, the researchers conducted experiments applying four different treatments in a saltmarsh wildflower meadow, located on the banks of an estuary on the central coast of British Columbia (B.C.) in Canada.

The treatments included:

• Addition of a pink salmon carcass
• Addition of the drift seaweed known as rockweed
• Addition of salmon and rockweed
• A control

Dennert and colleagues investigated whether the treatments would affect fitness-associated traits, including leaf area, inflorescence size and seed production in four common wildflowers: silverweed, yarrow, Douglas’ aster and common red paintbrush.

Researchers found that the addition of salmon carcasses led to larger leaves, particularly in yarrow and common red paintbrush, and a greater seed set in yarrow in the third year. Credit: Allison Dennert, Simon Fraser University.

“Following our experiments, we found that some species of wildflower grew larger leaves where a salmon carcass was deposited, and in some years, some species grew larger flowers or produced more seeds,” says Dennert.

Specifically, larger leaves were found in yarrow and common red paintbrush, and in the third year of the study, a greater seed set was also found in the yarrow.

“Currently, lands and waters are managed under separate provincial and federal jurisdictions. Scientifically and management-wise, we think of the land and sea as separate and unconnected entities. This work furthers the idea that ecosystems don’t exist in isolation, and that what happens in one can influence the other,” adds Dennert.

This article is a rework of a press release issued by Simon Fraser University. Material has been edited for length and content.

Reference: Dennert AM, Elle E, Reynolds JD. Experimental addition of marine-derived nutrients affects wildflower traits in a coastal meta-ecosystem. R. Soc. Open Sci. 2023;10(1):221008. doi:10.1098/rsos.221008.