March 20, 2009 -- Known for poisoning coastal waters, decimating local fisheries, and even affecting air quality, red tides are a stunning testament to the power single-celled organisms wield over ocean life. Now a new study of nutrients in the oceans has found that red tide outbreaks -- which routinely contain trillions of cells, and can stretch for miles -- do more than just blight ecosystems. They feed off the fish they kill, harvesting nitrogen that helps them replicate and expand their reach throughout the sea. Off the coast of the southeastern United States, red tide blooms are common in the summer. Harmless bacteria pull nitrogen out of the air, and when they die they dump it into the water column. The phytoplankton that make up the tide, Karenia brevis, feast on that recycled nitrogen. This is an advantage for K. Brevis -- unlike most phytoplankton, which require iron to reproduce, the species thrives on nitrogen and phosphorous, allowing it to take over local ecosystems whenever those nutrients are abundant. As the small, toxic critters multiply, they use up nitrogen first. Smaller tides peak when supplies run out. Related Content:
But John Walsh of the University of South Florida and a team of researchers found that when a tide is big enough to start killing fish, K. brevis can get about half of its nitrogen from schools of decomposing herring, sardines and mackerel. "Fish dissolve about 50 percent in the first 24 hours after they die, giving off organic nutrients," said Jason Lenes of the University of South Florida, a co-author on the study, which was published this month in the journal Progress in Oceanography. "It's hard to say how long fish can sustain the blooms. But small ones can last one to three months, and large ones go on eight to 12 months before they're washed away by the currents." Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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