(Kelp) Forests of the Sea
Tyler Sims
Most people are familiar with a forest. They come in all shapes and sizes but generally there consist of lots of trees and many fauna and flora call these habitats their home. Kelp forests are similar to forests found on land - just substitute the squirrels and birds for fish and crabs, switch the trees for large kelp species, and put the whole habitat under the ocean.
Giant kelp (Macrocystis spp.) are one of the best-known kelp species which make up kelp forests in the Pacific Ocean, and for good reason. They are massive organisms that grow to an average of 30m, and under the best conditions 53m. This species is known to grow up to 30.5 cm a day, meaning in just over 3 months you will have full grown giant kelp, that will live in that spot for up to 7 years. In addition to giant kelp, laminaria, bull kelp, common kelp, and lessonia are other species that make up these underwater forests around the world.
General location of kelp forests around the world. Kelp will usually keep close to shorelines where there is an excess of ocean movement from currents and tides. Although it can be found further from shores where the ocean is not too deep, to allow adequate sunlight for photosynthesis. They are rarely found deeper than 40 meters. Map: World Map Clipart. Kelp forest distribution: Parley.
However, another important question is: what is kelp? Kelp is a species of macroalgae (as opposed to microalgae, think phytoplankton) and despite appearances, kelp is not a plant. Vascular plants, from trees and flowers to shrubs and grasses, all have distinct tissue types like roots, a trunk or stem, leaves and some sort of flowering body. Kelp has different parts, but they do not function the same way the different parts of a plant do. An algae’s holdfast simply holds it in place and unlike roots, will not absorb nutrients. The stipe (rather than a stem) does not transport nutrients and water throughout the kelp, it is a structural support system for the fronds (also known as blades). The fronds are similar to the leaves of plants in that they are the photosynthetic factories of the organism. Kelp also has a special air bladder called a pneumatocyst that fills with gas and helps the blades to float near the surface where there is better access to sunlight. All other water and nutrients the kelp need get absorbed from the water around them. Lastly, kelp reproduce by spores that are transported in ocean currents.
Sea otters floating amongst floating bull kelp. Photo: Unsplash
Much like terrestrial forests, there are many organisms that live in the kelp forest for the protection it offers and the availability of food. Some species inhabit the ocean floor, eating the scraps of other animals and fallen kelp. Some species live among the fronds of the kelp, and lay eggs or raise young there. One of kelp forests’ most popular residents, the sea otter, will wrap themselves in kelp blades to stay anchored while they sleep. These forests are hubs for biodiversity and host a wide variety of animals including whales, seabirds, seals, fish, urchins and many more.
Kelp bass swimming between kelp stipes. Photo: Water Frame, Alamy.
Kelp forests are beautiful places and many organisations around the world are working tirelessly to better understand them and their complex ecosystems. The more that is known about them, the better they can be protected and enjoyed by generations to come.
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