Bull Kelp (Nereocystis luetkeana)


Galiano Island Status: 57 observations around Galiano Island


Bull Kelp (Nereocystis luetkeana) is a common variety of Phaeophyceae (brown algae). It can be easily identified by its bulbous floating structure known as a ‘pneumatocyst’, which contains gasses that aid in keeping it afloat at the surface. Attached to the pneumatocyst are a number of ‘fronds’, which are comparable to leaves on a tree. At the surface, these fronds photosynthesize, contributing to the algae’s astonishing growth rate of up to half a metre in a day. Under the surface, the kelp’s pneumatocyst connects to a ‘stipe’, which, like the stem of a plant, can be traced downwards to its base. Instead of roots, however, bull kelp is secured to rocky areas of the seafloor with what’s known as a ‘holdfast’. 


Anchors to rocky substrates typically in areas with moderate wave action. Prefers cold nutrient-rich waters.


The Aleutian Islands to central California.


Anthropogenic threats include boating, overfishing, pollution and climate change. Urchins are highly efficient kelp grazers and can decimate kelp forests when left unchecked.

Photo Credit

kathawk, Sherry Kirkvold

Comments are closed.