Kelp forest
Image credit: Jack Drafahl, Pixabay
Kelp forests are among the most important ecosystems in the world. Along with coral reefs, mangrove coastal zones, and seagrass beds, they represent key environments in the marine puzzle of life.
What is Kelp
Despite its appearance, kelp is not a plant; it is actually a large algae. There are about 30 species of kelp worldwide.
Giant kelp is among the fastest-growing “plants” in the world. It typically grows 28 cm (11 inches) per day, and under ideal conditions, it can grow up to 60 cm (24 inches) per day. This rapid growth is combined with an impressive length of 30 meters (100 feet), although it can reach up to 53 meters (175 feet) in ideal conditions. Once kelp reaches the surface, it spreads horizontally, creating a dense web. The best conditions growth are cold, nutrient-rich waters.
Kelp anatomy
Plants use roots to absorb necessary nutrients, but kelp, being an algae and not a plant, does not have roots. To stay in place, it uses a gripping structure called a holdfast, which anchors it firmly to the rocky ocean floor. To remain upright, it relies on a set of gas filled floats, called pneumatocysts.
Despite these differences, kelp shares a crucial feature with plants: photosynthesis. By converting sunlight, water, and carbon dioxide (CO2) into oxygen and energy, it obtains all the nutrients it needs from the surrounding water.
Image credit: JP Davies, Pixabay
Why is kelp important
Kelp forests form dense ecosystems that protect coastlines and provide a valuable habitat for numerous species. They offer food, shelter, and protection from predators and serve as nurseries for young seals, sea lions, sea otters, and many other marine creatures.
Humans benefit from kelp forests too, as they support local fisheries by sustaining fish populations and act as a very effective natural carbon dioxide (CO2) storage system.
Video credit: Oceana
When things go wrong
Kelp forests have been decimated over the past few decades worldwide. Only a fraction of their former abundance remains. The primary causes of their decline are commercial harvesting, water pollution, climate change, and particularly overgrazing by fish and sea urchins.
In the early 20th century, relentless hunting for pelts drove sea otters to the brink of extinction. The kelp forests lost their natural guardians. Humans decimated this top predator to such an extent that only about 50 otters remained in California. This created a significant opportunity for the local sea urchin population to boom.
Without the otters to prey on sea urchins and control their numbers, the sea urchin population exploded. Even the fast-growing kelp could not keep up with the voracious appetite of this ever-hungry army. As a result, the once-thriving kelp forests were drastically reduced to small pockets, no longer able to fulfill their crucial role as ecosystem providers. The ecosystem collapsed.
When things go right again
This situation is a prime example of the consequences that arise when so-called “keystone species” are removed or their numbers are drastically reduced.
Fortunately, the small population of sea otters that remained, combined with conservation efforts, led to a gradual recovery. The reintroduction of sea otters shifted the odds in favor of the kelp ecosystem’s revival. Sea otters are not the only species supporting kelp; starfish also play a similar role.
There is still a long way to go before the world’s kelp forests are fully restored to their former glory, but with dedicated efforts, we are on the right path. There’s something magical about diving in an underwater forest, don’t you think?
