Using huge hoses, researchers are vacuuming up marsh bugs along the oiled Gulf coast. By comparing their samples to bugs collected before the spill, teams hope to determine the effects of oil on creatures near the bottom of the food web.
© 2010 National Geographic; partially funded by NSF; field producing & videography - Fritz Faerber
WHEN PEOPLE THINK OF SALT MARSHES, THEY USUALLY THINK OF THE GRASSES, THE BIRDS, AND ANIMALS. BUT PEOPLE DON’T ALWAYS THINK ABOUT THE SMALLEST CREATURES LIVING THERE.
AS SCIENTISTS TRY TO MEASURE THE ENVIRONMENTAL IMPACT OF THE WORLD’S LARGEST ACCIDENTAL OIL SPILL, SOME ARE STUDYING THE SMALLEST ANIMALS---NAMELY THE ARTHROPODS --NEAR THE BOTTOM OF THE FOOD CHAIN. ARTHROPODS ARE ANIMALS LIKE INSECTS, SPIDERS AND CRUSTACEANS, AND THE FOOD WEB THEY FORM IS A VITAL COMPONENT OF THIS ECOSYSTEM.
MORE THAN 200 MILLION GALLONS OF OIL GUSHED INTO THE GULF OF MEXICO, AND SOME OF THAT OIL CREPT INTO THE MARSHES OF THE GULF COAST, CONTAMINATING HUNDREDS OF MILES OF COASTLINE – FROM TAR BALLS TO THICK OIL.
A TEAM FROM THE UNIVERSITY OF HOUSTON CONDUCTED A STUDY LOOKING AT THE COASTAL FOOD WEB ALONG THE GULF AND THE ATLANTIC COAST LAST YEAR- BEFORE THE SPILL.
NOW THE RESEARCHERS HOPE THEY CAN SHED LIGHT ON THE OIL’S IMPACT ON THE FOOD WEB.
Soundbite: Steven Pennings, Ecologist, University of Houston
“So we have 22 sites, and at each site we make a collection of the arthropod food web, and we do this by vacuum sampling. So we have a backpack with a lawnmower engine, and it connects to a big hose, and the students basically vacuum the insects out of the marsh and collect them.”
PENNINGS’ TEAM VISITS EACH SITE FROM TEXAS TO NEW ENGLAND, CAREFULLY SURVEYING ANIMAL AND PLANT HEALTH.
AS BRITTANY DELOACH-MCCALL SUCKS UP ARHTROPODS AT THIS COLLECTION SITE IN NEW JERSEY, HER COLLEAGUES CHECK THE MARSH GRASS AND LOOK FOR OTHER SMALL ANIMALS.
“A food web consists of a variety of species that play different roles. There are plants, which are eaten by a variety of insects that eat plants, we call those herbivores and then they’re eaten by other things –predators like spiders. With reference to the oil spill, it might be that some members of this food web are more vulnerable to oil than others, and so you might end up with a food web that is distorted in some way.”
BY TAKING LIGHT READINGS FROM UNDER THE MARSH GRASS, TAKING CORES OF THE ROOTS AND COUNTING SNAILS AND OTHER CRITTERS, THE TEAM CAN GET A HEALTH SNAPSHOT. BY COMPARING OILED AND UNOILED AREAS THEY GET AN IDEA OF THE IMPACT.
Soundbite: Pennings “One of the things ecologists are doing a lot of work on now is how much a food web changes if one species gets pulled out. And under certain circumstances, that can have a big impact and in other cases, not that much, because the other species can compensate … and in this case we’re likely to see the oil won’t just affect one or two species but might affect a large portion and that could perturb the food web in novel ways.
THE TEAM SAMPLED 5 HEAVILY OILED SITES. THEY ADDED SOME LOCATIONS TO THEIR ORIGINAL 22, SINCE THEIR LOCATIONS WEREN’T HEAVILY OILED. THE TEAM FOUND A DRAMATIC DIFFERENCE IN MARSHES AFFECTED BY THE CRUDE.
Soundbite: Brittany DeLoach McCall, University of Houston Researcher
“In the oiled sites we saw a lot of dead plant material, we saw a lot of mud flats, where the plants have died and eroded away. We also saw a lot of oiled crabs and snails. And it didn’t seem like as much insects as in the control plots.”
THE CURRENT YEAR OF THIS STUDY IS FUNDED THROUGH THE NATIONAL SCIENCE FOUNDATION.
PENNINGS HOPES TO CONTINUE HIS RESEARCH TO MONITOR ANY LONG-TERM IMPACT OF THE SPILL. AND WHILE SOME SCIENTISTS SAY MUCH OF THE OIL HAS ALREADY BROKEN DOWN, MARSHES ARE PRONE TO LONG TERM CONTAMINATION.
Soundbite: Pennings “The nature of a salt marsh is that the sediments retain organic matter for a very long time, and decomposition is very slow. So what we’ve learned from previous oil spills is that if oil gets in the marsh, it can stay in those marsh sediments for decades. What that is likely to mean is that the small animals, whether fiddler crabs or insects are likely to be exposed to oil for decades to come.
PENNINGS SAYS HE WILL FOCUS ON TRACKING THIS EFFECT TO LEARN MORE ABOUT THE MARSH FOOD WEB AND HELP UNDERSTAND THE OIL’S IMPACT.