Humans use giant kelp for food and use chemicals derived from this species as components in several other products. It is rarely harvested from natural forests, however, and is instead often grown in aquaculture operations. Its fast growth rate and natural means of generating energy from the sun make it an ideal species to grow in these sea farms.
Giant kelp grow to feet 30 m on average but can reach lengths of feet 53 m in ideal conditions. Giant kelp grow at an average rate of 11 inches 28 cm a day but can grow 24 inches 61 cm a day in ideal conditions. Decomposing kelp that sinks to the seafloor provides food for animals in the deep sea. Sea otters wrap themselves in giant kelp to keep from floating away while sleeping. Home Ocean Facts What is a kelp forest? What is a kelp forest? Kelp forests provide food and shelter for thousands of species.
Search Our Facts. Did you know? For years, scientists debated whether it was nutrient availability or grazers not human harvesters, but sea urchins that had the most influence over kelp forest health, size, and longevity.
After using Landsat to look at long-term trends, and comparing those trends to known differences between Central and Southern California waters, Cavanaugh and LTER lead Daniel Reed found that a third force—wave disturbance—was the kingmaker of kelp dynamics. Strong waves generated by storms uproot the kelp from their holdfasts and can devastate the forests far more than any grazer. The data they collected from the LTER study sites off Santa Barbara became a tremendous resource for kelp researchers.
But that work covered four discrete locations for a species found all over the world. Giant kelp can grow anywhere there are cold, shallow, nutrient-rich waters and a rocky seafloor.
Conditions for kelp growth have historically been ideal along the west coast of North America, as well as Chile, Peru, the Falkland Islands, South Africa, and around Australia, New Zealand, and the sub-Antarctic islands. More and more often these days, though, the conditions are less ideal. Climate change has brought a trifecta of kelp scourges: warmer waters with fewer nutrients; new invasive species; and severe storms.
After a recent meeting on kelp forests and climate change, Byrnes, Cavanaugh, and other colleagues set out to consolidate all of the available kelp forest data from around the world. They wanted to take a step toward understanding how climate change is affecting kelp globally, but they quickly discovered they had a sparse patchwork of information. Byrnes was struck with a thought. They had used Landsat to expand their studies across time, so why not use Landsat to expand their studies around the world?
Could Landsat be used to establish global trends in kelp forest extent? The answer was yes, but the problem was eyeballs. Unlike research on terrestrial vegetation—which uses Landsat data and powerful computer processing arrays to make worldwide calculations—distinguishing kelp forests requires manual interpretation. While kelp forests pop out to the human eye in near-infrared imagery, computers looking at the data numerically can confuse kelp patches with land vegetation.
Programs and coded logic that separate aquatic vegetation from land vegetation can be confounded by things like clouds, sunglint, and sea foam. Clouds, sunglint, and sea foam make it difficult for computer programs to detect the location of forests. So far, human eyes work better.
Byrnes, now based at the University of Massachusetts—Boston, realized that the best way to study global kelp changes was to turn to citizen scientists. Byrnes and Cavanaugh put together a science team and joined with Zooniverse, a group that connects professional scientists with citizen scientists in order to help analyze large amounts of data. The result was the Floating Forests project. The Floating Forest concept is all about getting more eyeballs on Landsat imagery. Like those systems, though, kelp forests provide important three-dimensional, underwater habitat that is home to hundreds or thousands of species of invertebrates, fishes, and other algae.
Some species aggregate and spawn in kelp forests or utilize these areas as juvenile nursery habitat. Large predatory species of sharks and marine mammals are known to hunt in the long corridors that form in kelp forests between rows of individual plants. Though kelp forests are important ecosystems wherever they occur, they are more dynamic than the other systems mentioned above. In other words, they can disappear and reappear based on the oceanographic conditions and the population sizes of their primary herbivores.
Warmer than normal summers and seasonal changes to currents that bring fewer nutrients to kelp forests both sometimes occurring naturally combine to weaken kelps and threaten their survival in some years. Strong individual storms can wipe out large areas of kelp forest, by ripping the kelp plants from the seafloor.
Large gatherings of sea urchins a primary herbivore in kelp forests can prevent kelp plants from growing large enough to form forests.
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