The Kelp Forest
A tropical rain forest comes to mind when we think of plentiful and interesting environments. However, the kelp forests right off our coast rival rain forests in both abundance and biodiversity. The kelp beds off the Piedras Blancas Elephant Seal Translate/Rookery are one of the reasons that stretch of ocean was chosen to be Marine Protected Area. Over 800 animals, from tiny one celled creatures to whales, use the kelp forest as a home, refuge, nursery and hunting ground. There are about 10,000 different kinds of seaweeds worldwide, broken down into three main groups: red, green and brown. Only 600-700 seaweeds can be found in California. Of the brown seaweeds about 20 of the largest are referred to as kelps. Kelp forests like the ones off our coast occur in few places: the west coasts of North & South America, small areas of South Africa, Australia, New Zealand and islands near the Antarctic.
Kelps along with all seaweeds are algae and as such are primitive plants with no root structure. There is a holdfast that looks like a root system but is merely an anchor holding the plant to the seabed. Nutrients needed for growth are absorbed by all parts of the plant directly from the surrounding seawater. Giant Kelp (Macrocystis) has become the dominant species on the central coast by out-competing other seaweeds for available sunlight. Giant Kelp has long stems, called stipes, with blades attached along them. Where each blade attaches to the stipe there is a float or pneumatocyst filled with gas that provides the buoyancy needed to lift the blades closer to the surface and more sunlight. The blades use energy from sunlight along with nutrients from the ocean in photosynthesis to provide food for growth. The stipes and the attached blades are called fronds. There are 6-12 fronds on each plant and under ideal conditions they can grow up to a foot a day, reaching a length of over 100 feet.
The reproductive cycle for Giant Kelp is similar to all seaweeds. There are specialized reproductive blades called soporophylls that are attached just above the holdfast and have no float. They produce spoors of both male and female gender. These free floating spoors attach to the bottom and grow to become gametophytes. The female produces an egg that is fertilized by the sperm from the male and starts to grow into the mature plant.
Giant kelp is a perennial that can live up to 7 years; however changing environmental conditions can affect its health, growth and coverage. Like most forests there is a growing season for kelp. The springtime prevailing winds push the surface water down the coast but because of the earth’s rotation the surface water ends up moving offshore. This phenomenon, called the Coriolis Effect allows subsurface water with all its stockpiled nutrients to come to the surface near the shore. This water shift called upwelling along with the longer days of abundant sunshine cause a growth spurt in the kelp forest. The fall brings lighter winds, shorter days and slower growth. The storms of winter can bring large wave action that will dislodge holdfasts. After strong storms we often see huge piles of seaweed on the beach. An overabundance of herbivores like the Sea Urchin can also deplete kelp beds. Sea Otters eating Sea Urchins will provide the balance needed for a healthy kelp forest and are considered a keystone creature for that environment.
Besides being a very important ecosystem the kelp forest is also of great economic value. Algin, extracted from harvested kelp is an emulsifying agent used to keep combined liquids in suspension and make them smoother. Over 500 different products from pharmaceuticals and lotions to paints and beer have algin in them. It is likely that not a day goes by that we all don’t use something with seaweed in it. The abalone farm north of Cayucos leases the kelp beds off the Estero bluffs from Fish & Game and pays a per pound harvest fee to gather kelp to feed its abalone.