Tag: salinity | Data Nuggets

The activities are as follows:

With so much coastline, Alaska has many opportunities for mariculture, which is the farming of food in the ocean. Large-scale mariculture is still new in Alaska, but interest is growing quickly because it can provide jobs and food for small coastal communities.

Alaska’s cold, clean waters are ideal for growing oysters. Oysters usually stay on a farm for several years until they are large enough to sell. Farmers want oysters to grow as quickly as possible so they can sell them sooner. Because oyster farming is still fairly new in Alaska, research needs to be done to find the best ways to grow oysters successfully.

Amanda is a marine researcher who lives and works in Valdez, Alaska. She wants to figure out which methods are most effective for oysters to grow. She can then share her findings with farmers to help them. Amanda partnered with members of the Valdez Native Tribe who were interested in growing oysters in the area.

Amanda started monitoring the oysters every year to document their growth. A few years after the farm was set up, she visited the site and noticed that the oysters had not survived the summer season. Amanda wanted to find out why this happened so they could prevent it from happening again in the future.

Amanda had a few ideas about what might be affecting the oysters. She noted that the oysters were all in surface baskets, which float at the top of the water. She also observed that the year that all the oysters perished, Valdez had heavy rainfall. Amanda knew that rain can lower salinity, or the amount of salt in ocean water, near the surface. Freshwater from rain flows into the ocean and can stay on top if it does not mix well with saltwater below. When salinity becomes too low, oysters close their shells and stop feeding and growing.

Amanda asked one of her students, Jane, if she wanted to do an independent research project to test a new type of home for oysters. They explored the use of lantern nets, which are a different setup that holds oysters below the surface of the water instead of floating on top. These nets hang straight down and are about 3 meters long. They also have several levels, allowing oysters to be placed at different depths so Amanda and Jane could see where the oysters grew best.

To test salinity levels and oyster growth at different depths, Amanda and Jane set up a new study at the Valdez farm site. In April 2025, they brought very small, young oysters to the farm. They weighed out equal amounts of oysters and placed some into three surface baskets and some into different levels of two lantern nets.

Over the summer, Jane visited the oyster farm every two weeks to measure salinity. She looked at four different depths: surface (0 meters), 1, 2, and 3 meters deep. This way, she could see whether the freshwater inputs make the surface water less salty. In October 2025, Jane and Amanda measured the oyster size at the end of the summer to see how much they had grown. They compared the length of oysters from the surface baskets and from the different levels of the lantern nets.

Featured scientists: Amanda Glazier (she/her) and Jane Churchill (she/her) from Prince William Sound College. Written by Melissa Kjelvik.

Flesch–Kincaid Reading Grade Level = 7.8

Additional teacher resource related to this Data Nugget:

Student research spotlight featuring Jane Churchill, one of the researchers featured in this activity:
Video series by Alaska SeaGrant “Meet your Alaskan farmer” offering a glimpse into what it is like growing oysters in remote Alaska communities and how farmers are working together:
- “Shucking barriers: Developing the Alaska oyster cooperative”
- “Seawan Gehlbach, Simpson Bay Oyster Farm:”
- “Meta Mesdag, Salty Lady Seafood Co.”
Short articles on Alaska oyster farming:
- NOAA Fisheries: “Exploring the Upsides and Obstacles of Growing Pacific Oysters in Alaska’s Cold Waters”
- Alaska Public Media: “Alaska oyster farmers refine growing techniques to meet high demand”
- Read an overview of Alaska mariculture at the following site.
Video with interviews from students and faculty about the collaborative education and training programs in Alaska.

This material is based upon work supported by the National Science Foundation under award #OIA-2344553 and by the State of Alaska.

Seagrass survival in a super salty lagoon

A researcher in the Dunton Lab measures seagrasses underwater using a mask, snorkel, and a white PVC quadrat.

The activities are as follows:

Seagrasses are a group of plants that can live completely submerged underwater. They grow in the salty waters along coastal areas. Seagrasses are important because they provide a lot of benefits for other species. Like land plants, seagrasses use sunlight and carbon dioxide to grow and produce oxygen in a process called photosynthesis. The oxygen is then used by other organisms, such as animals, for respiration. Other organisms use seagrasses for food and habitat. Seagrass roots hold sediments in place, creating a more stable ocean bottom. In addition, the presence of seagrasses in coastal areas slows down waves and absorbs some of the energy, protecting shorelines.

Unfortunately, seagrasses are disappearing worldwide. Some reasons include damage from boats, disease, environmental changes, and storms. Seagrasses are sensitive to changes in their environment because they have particular conditions that they prefer. Temperature and light levels control how fast the plants can grow while salinity levels can limit their growth. Therefore, it is important to understand how these conditions are changing so that we can predict how seagrass communities might change as well.

Ken is a plant ecologist who has been monitoring seagrasses in southern Texas for over 30 years! Because of his long-term monitoring of the seagrasses in this area, Ken noticed that some seagrass species seemed to be in decline. Kyle started working with Ken during graduate school and wanted to understand more about what environmental conditions might have caused these changes.

Manatee grass (*Syringodium filiforme*) located within the Upper Laguna Madre.

Texas has more seagrasses than almost any other state, and most of these plants are found in a place called Laguna Madre. During his yearly seagrass monitoring, Ken noticed that from 2012 – 2014 one of the common seagrasses, called manatee grass, died at many locations across Laguna Madre. Since then, the seagrass has grown back in some places, but not others. Kyle thought this would be an opportunity to look back at the long-term dataset that Ken has been collecting to see if there are any trends in environmental conditions in years with seagrass declines.

Each year, Ken, Kyle, and other scientists follow the same research protocols to collect data to monitor Laguna Madre meadows. Seagrass sampling takes place 2 – 4 times a year, even in winter! To find the manatee grass density, scientists dig out a 78.5 cm² circular section (10 cm diameter) of the seagrass bed while snorkeling. They then bring samples back to the lab and count the number of seagrasses. While they are in the field, they also measure environmental conditions, like water temperature and salinity. A sensor is left in the meadow that continuously measures the amount of light that reaches the depth of the seagrass.

Kyle used data from this long-term monitoring to investigate his question about how environmental conditions may have impacted manatee grass. For each variable, he calculated the average across the sampling dates to obtain one value for that year. He wanted to compare manatee grass density with salinity, water temperature, and light levels that reach manatee grass. He thought there could be trends in environmental conditions in the years that manatee grass had low or high densities.

Featured scientists: Kyle Capistrant-Fossa (he/him) & Ken Dunton (he/him) from the U-Texas at Austin

Flesch–Kincaid Reading Grade Level 9.8

Additional teacher resources related to this Data Nugget:

There is another Data Nugget that looks at these seagrass meadows! Follow Megan and Kevin as they look at how photosynthesis can be monitored through the sound of bubbles and the acoustic data they produce.

Follow this link for more information on the Texas Seagrass Monitoring Program, including additional datasets to examine with students.

There are articles in peer-reviewed scientific journals related to this research, including:

Capistrant-Fossa, Kyle A., and Kenneth H. Dunton. 2024. Rapid sea level rise causes loss of seagrass meadows. Communications Earth & Environment 5.1: 87.
Wilson, Sara S., and Kenneth H. Dunton. 2018. Hypersalinity during regional drought drives mass mortality of the seagrass Syringodium filiforme in a subtropical lagoon. Estuaries and Coasts 41: 855-865.

National Park Service information about the Gulf Coast Inventory and Monitoring.

Texas Parks and Wildlife information on seagrass:

Testing the waters for oyster farming

Seagrass survival in a super salty lagoon