Native SpeciesKnotted wrack

Ascophyllum nodosum
FOUND by Kings of Kettle Cove
Cape Elizabeth
ID Confirmed
Quality checked by Mrs. Moniz
Peer reviewed by Kettle Cove Kelp Club
Field Notes
The moment we stepped off the bus at Kettle Cove we were greeted by the smell of the beach and a cool, damp wind that cut straight through our fleeces like a knife. It was 9:30 in the morning a very warm and grey day for October 24, the wind and flood tide lapping water up onto the shore. You could barely see a sliver of sky and a cool 16 mph Atlantic wind blew from the northeast over Richmond making it hard to hear as the teachers briefed us on the boundaries. After that we were off, bounding down the sand enjoying the 60º F weather to the slimy rocks coated with many types of algae, both invasive and native until we found our species. The Knotted Wrack we found was growing in abundance, sheets of it dominating most of the rocks. The great thing about this is that knotted wrack is native to Maine and should be thriving in its natural habitat.
Supporting Evidence
Photo of my evidence.
In this photo you can see how the small receptacles (air bladders) branch off of the stems. Some are darker and larger (½ cm wide) and some are smaller (¼ cm wide) and yellow. The olive green ones are female and the yellow ones male. This trait is specific only to Knotted Wrack and therefore shows what plant this is.
Photo of my evidence.
We believe that we found a Knotted Wrack because, as you can see in this photo, olive green/yellow Knotted Wrack stems branch off of our specimen’s main stem at random times. This is called axial growth and is a specific characteristic of this alga.
Photo of my evidence.
In this photo you can see the yellow (male) and olive green (female) air bladders of the Knotted Wrack compared to the reddish/brown bladders of Bladder Wrack. Also, the Bladder Wrack has a different growth pattern than the Knotted Wrack and also has thinner stems.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Ascophyllum nodosum
Common name:
Knotted wrack
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.561254 °
W -70.218504 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Kettle Cove
Trip date: 
Tue, 2017-10-24 09:30
Town or city: 
Cape Elizabeth
Type of investigation: 
Species Survey
Time of low tide: 
Tue, 2017-10-24 08:26


You made some great observations, and provided very detailed evidence to support you claim that the species you found is Knotted Wrack. Your annotations of the photos were also very helpful as well as the comparison you made between the Balder Wrack and Knotted Wrack.