Dead salmon can boost the growth of wildflowers

A new study led by the Simon Frasier University (SFU) has found that nutrients from salmon carcasses can significantly alter the growth and reproduction of plant species in the surrounding habitats, even causing some flowers to grow larger and more plentiful. This is the first study documenting the connection between salmon and coastal plant growth and reproduction, while shedding light on how the impact of climate change on the rivers and streams traveled by salmon could help inform ecosystem planning and management.

During a three-year field study, the scientists experimentally added pink salmon carcasses into the estuary of a small river from British Columbia’s central coast, a region featuring a large meadow of grasses and wildflowers. 

“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,” reported study lead author Allison Dennert, a PhD student in Biology at SFU.

The researchers undertook similar experiments with drift seaweed rockweed, a plant that provides a different set of nutrients than salmon carcasses. In addition, they also experimented with a combination of salmon carcasses and rockweed – along with a control group – and examined their impact on four widespread wildflower species (silverweed, yarrow, Douglas’ aster, and common red paintbrush).

The experiments revealed that the addition of salmon carcasses led to larger leaves, especially in yarrow and common red paintbrush, along with a greater seed set in yarrow in the third year of the study.

“Understanding the interconnection between ecosystems is incredibly important to our knowledge of how to protect them,” said Dennert. “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,” she concluded.

The study is published in the journal Royal Society Open Science.

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By Andrei Ionescu, Earth.com Staff Writer

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