Seaweeds And Kelp

CopyRight @ 1997

I was on a night dive in Hawaii with a guide who had been the head diver for the Hilton for 10 years and had certifications for just about everything, ratcheda, ratcheda, ratcheda... I asked him if he had been kelp diving. "Ya and I'll never do that again". Huh? I love the kelp beds.

The cold nutrient rich waters of California support a wide variety of seaweeds. Seaweeds, as they are called, are Algae. There are basically 3 kinds of Algae that make up the seaweeds. A fourth, the Golden Algae, are actually types of plankton. The seaweed type of Algae are called the Reds, Greens and Browns. The big kelps are a type of Brown Algae called the Laminareas. The Reds and Greens are smaller and tend to be more common in the shallower waters.

In the intertidal areas, the Red and Green Algae make strange shapes and colors growing everywhere on all the rocks. Different species have characteristic depths and conditions where they are found. Past about 30 feet, it is the Browns that give the characteristic golden color to California reefs.
Have you ever wondered what those little pink articulated things are that grow on just about every shallow rock in California. Those are the Red Algae, Rhodocladia and Rhodophera. Their hard outer shell is made of calcium taken from the seawater.

The term kelp can mean a number of things depending on where you are. From the Arctic to Antarctic it is commonly used to refer to the large local algae, whatever that is. In California it is used to refer to the big brown algae, primarily Macrocystis pyrifera. It is the fastest growing plant in the world. Up to 24 inches a day has been claimed. It has air bladders to make it float and can form thick mats on the surface in up to about 100 feet of water. It can have heavy thick rope like "stalks" with fronds 5 inches wide by 36 inches long. Its growing end produces delicate beautiful patterns of miniature leaves.

Talk California Kelp and you are talking the language of Wheeler J. North. He was the researcher awhile back that made what is considered the definitive study of kelp forest ecology. It is a big book you can skip unless you are really interested. He did make some points to note though.
Kelp only grows on rock, except above Santa Barbara, where it seems to grow in the mud. It is used for food by only about 3 fish. Indirectly it is used by other fish to allow them to extend their range by letting them know where the rocks are. They follow the kelp down to the rocks like divers do. Fish population is dependent on the rocks under the kelp, not the kelp. In a rocky kelp forest, the fish population may be up around 35 pounds per acre. This is also true in a rocky reef where there is no kelp such as Guadeloupe Island. In the Santa Barbara area, where the bottom under the kelp is not rocky, the fish are about 3 pounds per acre. Fish need hiding places from predators and kelp helps, but is just not what it takes.
The invertebrates, urchins and mollusks (abalone) are the ones that really eat the kelp. They mostly eat the kelp leaves that have broken off and drifted to the bottom. Over populations of urchins may destroy a kelp bed by attacking the holdfasts of the kelp plants.

Kelp beds provide incredibly beautiful diving. Only silliness will get you stuck in them. They may grow like multi-stalked huge trees from a single large holdfast or they may grow distributed as single strands coming up every 6 inches from the rock. The single strand ones are the beds that get the thickest. It is true that they have great tensile strength to resist wave action, but they are really not individually strong. They will give a panicked diver a good opportunity to kill themselves, but a common practice in classes is to teach students how easy it is to break them by folding them over. Some instructors make the students bite the kelp to show how fragile it really is. Simple swimming skill will make it rare that you get a strand entangled on your gear. If I cannot easily pull kelp off of my gear, I tend to keep swimming to break it. Divers in kelp areas learn to wear their knife on the inside of their leg, tape their fin straps together and set up the rest of their gear so that it is not likely to catch on the kelp.
When returning to a boat, it is easiest to save enough air to swim under the kelp, but a "kelp swim" will allow a person to easily cross the densest paddy. A kelp swim is basically a "dog paddle" where you bring your hands out of the water to shove the kelp down in front of you as you go over it.
Kelp grows the entire length of the California coast, where there are rocks to anchor to. Warm water and pollution has thinned out the kelp some. It used to be common to find paddies that were 2 or more feet thick and covering miles. Dense beds like this are unusual now. Normally, it does not get too dark under the kelp, but it can, especially if it is where many single strands grow on flat rocks. It is beautiful and calm under the kelp. When the evening wind blows, it flips over the fronds on the surface, making it glisten in the sunset.

Kelp is a kind of Laminarea. That is, it is a member of the family of Brown algae, Laminarealis. (sp) More common than the large Bull Kelps are other species of Laminareas that are much smaller. They tend towards cooler water than the Macrocystis. The typical Laminarea is a holdfast, a strong stalk (commonly 18 inches tall) and then leaves (called stipes) on top. I have seen them 6 feet tall near Point Buchon, but those were extraordinary. They loosely look like a small tree in design, except that instead of branches and many leaves, it has essentially no branches and one or two large leaves. These may grow in fields above flat rocks such that you must look carefully to see anything under the canopy. It is exotic to drop right onto the bottom and swim through these fields. Swimming above them, look carefully as they move in the surge and you may see a kelp bass that is trying to hide.
In many areas of boulders and broken rocks, the Laminareas grow singly, well spaced on rocks, such that they make the perfect things to grip while you relax as the surge pushes against you. They also can be used as a pull handle to spring forward against whether there is a surge or not. It is easier to pull against something solid than it is to use fins to push against fluid water. With hands and fins, you can really travel. It is best to grab the bottom of the stipe and pull constantly, so as not to break the plant. I like to brachiate when under water. These laminareas are beautiful in the way a healthy garden is.

In areas where swell is generally negligible, like on the inside of the islands starting at about 60 feet, is another Laminarea called Elephant Ear kelp. This has a small stipe, perhaps 6 inches long, but it has huge leaves. The single leaf, may be 2 feet wide and 30 feet long. Obviously, any sizable surge would rip this loose. These sit in a mat no more than 2 feet off the bottom. You cannot see anything under them. Because it is so impenetrable, few divers go under it. It makes for a fascinating dive though. Vis is usually no more than 4 feet, because at that distance, you see either rock or kelp no matter how clear the water is. It can be a good place to hunt lobster, especially at night, but grabbing a lobster that is resting on kelp is near impossible, even with two hands. Often, Sculpin hang out in the calm water under this kelp.
Above the central coast, another kind of Laminarea found commonly in the lower intertidal zone, is the Sea Palm, Palmifera californica. These greenish golden plants grow in dense groups on the top of rocks, to a height of about 16 inches. Instead of just a couple of leaves on the top, these have an abundant mop. They look like a small palm tree. Their coloration and shape are pretty enough that I always look forward to seeing them.

Kelp makes for wonderful diving.

Feather Boa

To be continued...

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