An unseasonal red tide in December of last year forced the Mississippi Department of Marine Resources to temporarily suspend all oyster harvesting across the state’s coast. “The blooms are becoming more frequent, they’re covering larger areas, and they’re suddenly happening in places we’ve never seen them before,” said McLean. The phenomenon is called a red tide, and it occurs in places across the globe. “You see a patch of discolored water, and any fish that swims into it will usually die and float to the surface,” McLean said. It also produces a neurotoxin that is deadly to marine life. One species of dinoflagellate, Karenia brevis, turns the surface of the ocean a cloudy red color when enough of it congregates in a single place. We don’t know why or what consequence all that weirdness has.”īut marine microorganisms go beyond making our lives taste better they make our lives possible in the first place. There was a paper that came out in a scientific journal that said, ‘Dinoflagellates are from outer space’ because they are so weird. “They have a ton of DNA inside their cells-more DNA than we have in our cells, sometimes like ten or fifteen times more DNA. “Dinoflagellates are different than basically any other organism,” McLean said. What he found were tiny freaks of nature. McLean was an early investigator of the genetic makeup of phytoplankton, looking at the genes of a specific group called dinoflagellates, single-celled swimmers with little tails that whip them through the water. Other studies estimate that the number is as high as eighty-five percent. Collectively, he said, phytoplankton produces half of the oxygen in our atmosphere. Using the power of the sun, these organisms absorb carbon dioxide, nitrogen, and phosphorus, producing oxygen in the process. McLean’s area of expertise is microscopic marine plants called phytoplankton. All the microorganisms are responsible for that decomposition and as it gets released into the water, other organisms can come in and eat the little bits of plants that are floating in the water-the detritus.” The mud of the wetlands is a twenty-four hour salad bar of this detritus, feeding the oysters, crawfish, crabs, and other bottom-feeding creatures that populate the shallow waters.īut marine microorganisms go beyond making our lives taste better they make our lives possible in the first place. So the only way that actually gets to the animals is when all those plants actually die and start to decompose. “You’ve got all this plant growth, but very few things actually eat those plants to transfer that productivity up the food chain. “The marshes don’t get a lot of appreciation or attention for how productive they are,” McLean said. Much like the flora in our intestines, the microbes in the bayous and bays take the continent’s runoff, break it down, and convert it into nutrients to be reused in the food web. In Louisiana, the microorganisms that populate the coast help make it one of the most productive ecosystems on the planet. Some are terrifying-like flesh-eating Vibrio-but most are pretty magical. Vibrio bacteria, McLean said, are one tiny piece of a massive network of microscopic drifters that power ocean ecosystems-the algae, bacteria, viruses, and fungi that feed the ocean from the bottom of the food chain. When the oysters load up on Vibrio, the bacteria can accumulate in high enough levels to make humans sick. On a hot day towards the end of the last non-r-month, I visited molecular biologist Tim McLean in his office at Tulane University, where he gave me the most straightforward explanation I’ve heard of the rule: “The months without ‘r’-May, June, July, and August-are the warmest months of the year, and that’s when Vibrio bacteria are most abundant in the water and you’re more likely to eat a contaminated or an infected oyster.” He explained that as the water heats up, some microorganisms grow more easily, including these toxic bacteria. If you love oysters, you’ve probably heard the “r-month” rule: steer clear of oysters in months that aren’t spelled with the letter “r.” In all the other months, eat as many as possible. Pictured here: “Phytoplankton: A Studio in the Woods,” 30”x30”, screenprint with watercolor. Part of their mission was to bring attention to the fact that so much of the wetlands’ microscopic worlds have yet to be formally studied. Tim McLean to create artwork on the topic of micro algae. Printmaker Pippin Frisbie-Calder worked with Tulane University’s Dr.
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