Like a detective tailing a suspect, marine ecologist Tom Adam lurked in the turquoise waters of the Florida Keys National Marine Sanctuary a few years ago trying to spot parrotfish, rabbitfish, and surgeonfish, feeding on algae that grow on the reef. When Adam spotted one, he followed it, but not too close. He didn\u2019t want to scare the fish away, yet needed to be near enough to see precisely where it nibbled.<\/p>\n
\u201cWe watched very carefully to see exactly where [each] fish was taking a bite,\u201d says Adam, who along with a colleague from the University of California, Santa Barbara, logged more than 1,000 bites. They then identified the exact types of algae living in those spots.<\/p>\n
Their work is part of a recent study<\/a> that shows each fish species eats different types of algae on different parts of the reef, and that each species has a unique set of microorganisms\u2014or microbiome\u2014in its gut.<\/p>\n The team used DNA sequencing and computational analysis to identify and sort the millions of gut microbes taken from fish harvested in the same waters, zeroing in on the 59 that were most dominant. Each species harbored a unique subset of that 59. The bacteria Lachnospiraceae, which is known to ferment diverse plant carbohydrates<\/a>, was only found in the surgeonfish, for example, and the bacteria Erysipelotrichaceae, which has been linked to protein digestion<\/a>, was only found in the parrotfish.<\/p>\n The researchers hope to use the data in future studies that examine the microbes\u2019 genetic interactions to see if a fish\u2019s unique gut microbiome may drive it to select different algae. \u201cThat\u2019s sort of the big burning question,\u201d says Douglas Rasher, a marine ecologist at the Bigelow Laboratory for Ocean Sciences in Maine and coauthor of the paper. \u201cTo what degree are these microbes playing a role in shaping the feeding behavior of the fish, versus responding to the feeding activities of the fish?\u201d<\/p>\n Rasher has previously published research<\/a> showing reefs need a diversity of fish species that forage on different types of algae to stay healthy.<\/p>\n Microbes are essential for every living creature, allowing plants and animals to take energy from food and to fight against pathogens. As DNA sequencing gets ever cheaper and more accurate, research on human microbiomes has exploded. Researchers have found that human bodies host 100 trillion microbes<\/a>, which could affect everything from autism to obesity. Ecologists are increasingly recognizing that these colonies could shed new light on why different organisms behave the way they do.<\/p>\n