Bull kelp forest
Come with me on my dive today into the remarkable bull kelp forest (Nereocystis luetkeana) “alive” in the current.
Bull kelp is so beautiful, especially right now. It is growing at an insanely fast rate (apparently up to 60 cm a day) and is an intense colour green unlike anything else I know. When older, it will become more olive coloured.
Kelp is not a plant but rather, it is an algae. It makes food from sunlight, like plants do (by photosynthesis), but it has simpler structures and different chemical pathways.
Bull kelp is growing so fast to allow the leaf-like parts, called “fronds”, to be closer to the sun so more food can be made. The round part of the kelp, is the “pneumatocyst” and it is for floatation, letting the fronds drift at the surface to catch the sun’s rays. This bladder-like structure is completely hollow and is filled with carbon monoxide (NOT carbon dioxide). Apparently, there is enough carbon monoxide in the bladder of bull kelp to kill a chicken! Now that’s valuable information.
The stem-like part is called the “stipe” and it is also hollow. It can be 36 metres long! Since it is hollow, bull kelp can be played like a trumpet or didgeridoo!
The kelp does not have roots but rather a “holdfast”, a mess of woody structures that holds onto rocks. The kelp will actually change the ocean bottom by carrying off rocks that are too small to be a counter force to the floatation of the kelp’s bladder.
The stipe gets thinner near the holdfast which is why this kelp likely got its name. “Bull kelp” because the stipe is shaped like a “bull whip”.
This kelp forest is life-giving. Like plants, the algae produce oxygen, use carbon dioxide (reducing the amount causing climate change) and are food for animals. Sea urchins love to mow down on bull kelp. Humans can also eat it. I love pickled young bull kelp!
When there is lots of large kelp like this, it truly is – a forest, providing habitat for some 750 species of fish and animals without backbones (invertebrates).
Bull kelp is also an aid to navigation as boaters should know it is shallower where you see kelp.
And yes, you can do puppet shows with bull kelp, cutting a face into the bladder like you would into a jack-o-lantern. The fronds even look like two pig-tails!
We divers have yet an additional reason to value kelp. Since it is so strong, we can hold onto it if we need to during our safety stop (3 minutes at 5 metre depth).
There will be more on kelp here in the future. Wait till you find out how bull kelp reproduces!
But for now, come underwater with me. Come into the forest, breath in, breath out and worship the kelp!
Click this link for the short videos and images of bull kelp from the fronds down to the holdfast.
