12.23.25

Growing kelp for community

A grow line on a kelp farm in Prince William Sound, Alaska.

The activities are as follows:

When thinking about farming, many people imagine fields of corn or soybeans, or even their own vegetable garden. All of these crops are grown on land, but what about growing food in the ocean? Alaska Natives who live along the coast have been harvesting kelp, a group of seaweeds, from the wild for thousands of years. Kelp is very nutritious and is full of vitamins and minerals. It is used in a variety of dishes, from soups to salads. Kelp also provides structure for herring to lay their eggs, another traditional food source that coastal Alaska Native communities harvest. Kelp has other purposes too, including soil fertilizer and food additive applications.

Recently, there has been a surge of interest in farming kelp at a larger scale along the Alaskan coast. Farming kelp involves cultivating kelp at a site to grow larger for harvest. Caitlin is a biologist who works for the Native Village of Eyak within the Prince William Sound of Alaska. The Tribe wants to start a kelp farm to provide a nutritious food source for its community members. Caitlin was tasked with designing the farm setup and testing how much kelp can be grown. Her first step was to find a site. She had to consider environmental factors that help the kelp grow. Kelp need particular nutrients and cool water temperatures. She also had to make sure the site was easy to get to and that it was protected from intense weather like high winds and large waves. 

Left: seed line one week after planting in November. Middle: kelp at the farm in April. Right: kelp blades after the harvest in June. 

To get started, Caitlin talked to the members of the Eyak community to learn where they have historically found kelp, called Traditional Knowledge. She listened to their suggestions, which were based on current and long-term connections with the local environment. This helped her identify a site that is a short boat ride. Caitlin also had discussions with other kelp farmers in Alaska and read scientific research articles to learn more about how to set up a kelp farm and which species would be a good fit. She decided to grow sugar kelp because it has a sweeter taste and grows well in other places with similar conditions. 

She designed the farm to grow the kelp vertically in the water. To do this, she would place lines vertically in the water for kelp to attach and grow at different depths. This design maximizes the amount of kelp grown below the surface, which is good to minimize interference with boats and animals. While vertical lines have benefits, there could be drawbacks too. Kelp needs sunlight for photosynthesis, which it uses to grow. But the deeper you go in the water, the less sunlight there is. The kelp at the surface will get plenty of light, but the kelp attached to the line in deeper water might not get enough. The kelp at the bottom could also get blocked or shaded by the kelp above it. 

Caitlin wanted to know if there is a time of year when kelp had the fastest growth rates. This information would help her know when to harvest kelp from the site. She also wanted to know whether depth affected the kelp growth. If it turned out that kelp didn’t grow on her vertical lines in deeper water, she may have to try another design. She predicted that kelp grown in the first 1-2 meters from the surface would grow more over a season because it would receive the most sunlight. 

To assess her kelp farm plan, Caitlin worked with partners to seed lines with fertilized sugar kelp spores. Each of these spores can grow into a large kelp blade that can be up to 5 meters long. The seeded lines were then installed vertically at the farm site in the fall of 2022. Caitlin and her colleagues set up 532 vertical lines that were each 10 meters long. In total, over 2 miles of seeded line were installed on the farm! The lines were attached to a horizontal line to secure them in place and were spaced out so they had room to grow. 

Each month, Caitlin and her colleagues monitored the kelp growth by measuring the length of kelp blades, or leaf-like structures, on 5-8 of the seeded lines. On each line, they measured kelp blades at different depths so they could see how the kelp was growing at different depths.

Featured scientist: Caitlin McKinstry (she/her) from the Native Village of Eyak. Written with Rosel Burt and Melissa Kjelvik from Prince William Sound College.

Flesch–Kincaid Reading Grade Level = 7.4

Additional teacher resource related to this Data Nugget:

This Data Nugget created with funding from the NSF Alaska EPSCoR Interface of Change.

8.27.25

Can kelp help the plovers? 

Beach hopper on a sidewalk

The activities are as follows:

It’s a beach day! You’re walking through the sand on a southern California beach, looking for a place to put your things. You notice there are clumps of dried-up seaweed everywhere. As you brush aside some of these clumps to lay out your towel, a shrimp-like bug jumps out at you and bounces off your hand! With smelly dried seaweed, small birds skittering across the sand, and hopping bugs, you wonder, is this beach healthy? Yes! These are all parts of a thriving food web.

Beaches are home to many important species that each play a role in the ecosystem. On the Pacific Coast of California, the dried-up seaweed is typically made up of several species of kelp. Kelp captures the sun’s energy through photosynthesis. Beach hoppers, the little jumping “bugs”, are actually small crustaceans
that feed on the kelp. In turn, these beach hoppers are the main food source for birds.

Snowy plovers are a type of bird that loves to eat beach hoppers. This shorebird species is threatened in California due to habitat loss. The sandy beaches where the plovers live and nest are also places where people like to walk and play. Scientists want to better understand what makes up the base of the food web that supports plovers to help their populations recover.

High school seniors, Mari and Azra, visited beaches in Lompoc, a coastal city in California, many times with their science classes. They wanted to learn more about the sandy beach ecosystem, so they read an article from a local research group at the University of California-Santa Barbara. On one of their field trips, they learned about a scientist named Jenny Dugan. Jenny and members of her lab study the beach hoppers’ important role in the sandy beach ecosystem. The Dugan lab had done a series of experiments to see what types of kelp beach hoppers liked to eat.

Azra (left) and Mari (right) working with kelp.

Mari and Azra wanted to set up a similar experiment to see if the beach hoppers in the Lompoc area preferred the same species of kelp. Their teacher, Ms. Moore, collected beach hoppers, sand, and kelp on her way to school one day. Mari and Azra set up ten plastic containers by measuring an equal amount of damp sand and punching holes in the lids. Then they tried to put 10 beach hoppers into the container. But it was hard to know the exact number until the very end of the experiment because some would hop out before the lid was on! At the end of the study, the number ranged from 8-15 beach hoppers in each container. Finally, Mari and Azra weighed out 15.0 grams of kelp and put it on top of the sand in the containers. They put one type of kelp in each container. Four containers had feather boa kelp, Egregia, four containers had giant kelp, Macrocystis, and two containers had Laminaria, another type of kelp. Mari and Azra also set up controls for each type of kelp with sand and kelp, but no beach hoppers. This container would tell them how much kelp weight was lost to water evaporation over the 3 days of the experiment, and not due to being eaten.

Trial 1: Mari and Azra placed the containers outside in a shady spot for three days. On the third morning, they opened up the containers to weigh the kelp that remained. Before weighing the kelp, they rinsed it to remove excess sand and dried it gently to remove excess water. Finally, they counted the beach hoppers that were in the container.

Trial 2: After reviewing their results from this experiment, Mari and Azra realized the beach hoppers did not like Laminaria at all. They decided to repeat the experiment using kelp and beach hoppers from a different beach, and did not include Laminaria as a food source.

Featured scientists: Mari and Azra from Lompoc High School, California. Jenny Dugan from the University of California-Santa Barbara. Written by: Melissa Moore from Lompoc High School.

Flesch–Kincaid Reading Grade Level = 8.1