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Project-based science examples. Book a field trip. Online courses for teens. Teen programs. Teen career resources. See all courses. Learn more and sign up. Search through the site content. Enlarge image. On view at the Aquarium in Kelp Forest. Size Up to feet 30 m ; feet 53 m in ideal conditions. Diet Photosynthesis converts the energy of light to the energy of carbohydrate molecules. Relatives Sea palms, bull kelp; Family: Laminariaceae. Natural history. In Monterey Bay. Sludge, silt or sewage dumped near kelp forests can bury new shoots of giant kelp.
Cool facts. Giant kelp is harvested as a source of algin, an emulsifying and binding agent used in the production of many foods and cosmetics, like ice cream, cereal and toothpaste. Pieces of decomposing kelp known as detritus sink to the depths of the ocean, providing food for deep-sea creatures. As kelp grows, a blade at the tip of each frond separates, producing a series of tiny new blades.
The logo of the Monterey Bay Aquarium represents the tip of a growing giant kelp. Red corallines are algae that have the same rough texture and stony feel as coral.
View plant. Download a beautiful, high-resolution giant kelp wallpaper for your desktop or mobile device. See wallpaper. The researchers conducted experiments on giant kelp in the field, and on kelp blades brought back to the lab. Smith and his colleagues tested whether the seaweed was able to take advantage of urea as a nutrient, and compared growth rates when ammonium and nitrate were used as nutrients.
Scientists know that urea has a persistent presence in the coastal ocean, not only off the coast of California but in coastal oceans globally. The finding helps explain seaweed growth in many places. Less nitrogen available in the warmer surface water diminished phytoplankton growth, while giant kelp growth was steady, thanks to urea as a nutrient source.
Phytoplankton don't make use of urea. Added co-author Dan Reed, principal investigator of the NSF SBC LTER site and a scientist at UCSB, "Knowing that giant kelp uses urea, and that urea isn't related to the availability of nitrate in the ocean, gives scientists a way of understanding the reasons kelp growth seems to differ from that of phytoplankton. Scientists at the NSF SBC LTER site would like to know how nitrogen use is divided between kelp and phytoplankton, and whether ocean warming will have the same effect on giant kelp as on phytoplankton.
A forest of giant kelp off the coast of Southern California. Thanks to data collected over almost two decades, researchers have been able to track patterns of nutrient content, which fluctuate seasonally, and identify significant trends.
Generally, the cooler temperatures bring nutrient-rich waters up from the deep, but during the warmer seasons, nutrients in the shallows and upper ocean -- particularly nitrogen -- become more scarce.
Knowing this pattern, the researchers then sought out how nutrient content might play out over a longer period of time, as ocean temperatures rose. They did so by looking at data from the primary productivity sampling that is conducted in the waters at the SBC LTER on a monthly basis.
This apparent decline in nutritional content does not bode well for the consumers of kelp in and around the Santa Barbara Channel, which include sea urchins and abalone in the water, and intertidal beach hoppers and other invertebrates that consume the kelp wrack that washes up on the shore. Animals that feed on kelp might also expend more energy trying to eat enough to fulfill their nutritional requirements. While urchins have the ability to go searching for more food, Emery added, the consumers on the shore are stuck with what they get.
In both cases, the effects could ripple out to the rest of the food web, the researchers said: Lower-nutrition kelp could mean smaller, fewer, perhaps less healthy beach hoppers, for instance, which would lead to less food for the shorebirds that eat them.
In the water, less nutrition for urchins and abalone could mean less food for their consumers, including fish, lobster, sea otters and humans. Having explored the potential relationships of seawater temperature to nutritional content, the researchers are considering broadening the spatial scale of the study.
Materials provided by University of California - Santa Barbara. Original written by Sonia Fernandez.
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