Mission: Codium

Research Question

Is Codium fragile marching up Maine's coast?


You're invited

Codium (Codium fragile subspecies tomentosoides) has been found and documented as far east as South Bristol. Scientists Pete Thayer (Maine Department of Marine Resources) and Anita Klein (University of New Hampshire) want you to look for codium in tide pools and along beaches to help monitor established populations, detect new occurrences, and track its potential spread up the coast of Maine. Check out this VIDEO of UNH's Larry Harris that highlights codium and other threats to the Gulf of Maine.

Mission steps

1. Print the Species ID card for codium

2. Print a Coastal Species Survey datasheet

3. Go out and look for codium in tidepools or washed up on beaches

4. If you FIND codium, collect a sample to send to Anita Klein at UNH for DNA analysis!

  • Cut a 1” segment near the growing tips
  • Remove all visible epiphytes (often red alga Neosiphonia harveyi)
  • Label date, location and habitat with a Black Sharpie pen, on a snack size, Ziploc type bag
  • Place the 1” segment of fresh tissue inside the bag and cover the sample in > 3X volume of silica (Activa Flower Drying Art-Silica Gel is easily found at craft and hobby stores like Michael's!)
  • Seal tightly. Make sure the tissue is fully coated and covered. Silica dried tissue is stable for years, for later DNA extraction!
  • Mail to:
    1. Anita Klein
      Assoc. Prof. Biological Sciences
      Biochemistry and Molecular Biology Graduate Coordinator
      University of New Hampshire
      Room 383 Rudman Hall
      46 College Rd.
      Durham, NH 03824-2618

5. Go to your My Vital Signs page (link at top right) to add your "codium found" or "not found" observation

6. Check out Mission: Analysis - Change Over Time to make sense of your observations in context of the larger VS database of codium observations!

Why this Mission matters

Scientists and fishermen are increasingly concerned about codium's impact on native marine communities. It is notorious for altering native habitats in the Gulf of Maine. It has disrupted native kelp forests that provide young fish food and protection from predators. Fish are unable to move through and live in codium’s dense, low growth like they can in between kelp fronds.

Codium continues to cause problems for shellfish and the Gulf of Maine’s shellfish industry:

    It grows over large shellfish and decreases their ability to filter
    It can lift shellfish out of their beds in stormy, turbulent water
    It interferes with fishermen’s shellfish harvesting and processing practices

It is also responsible for changing Maine’s sandy beaches into rocky shores by washing up still attached to rocks, gravel, or shellfish. It piles up on beaches, rots, and stinks. Nobody likes a smelly beach.


I'm sad to report that I HAVE seen this seaweed -- both attached to rocks in the intertidal zone and washed ashore on the beach. Not just one beach, but several. If there's anything I can do to help, please be sure to let me know!

- Katie