On July 19, NRDC, Oceana, and Mote Marine Laboratory launched “Waldo” – an ocean robot designed to help defend the Florida Keys’ environmental and economic resources from impacts from the Gulf oil spill. Waldo is armed with an array of instruments, including a fluorometer that measures the light emitted – or fluorescence – of the water. If the water sampled contains fluorescence, this indicates that oil may be present. Researchers look for corroborating signals, such as a change in salinity, and may conduct water sampling tests to confirm the presence of oil. If oil is found, local government officials are alerted so that emergency resources and response plans can be activated to help to protect the area’s important ecological resources.
The autonomous underwater vehicles (AUVs) like Waldo run for approximately 30 days at a time and NRDC’s sponsored run of Waldo ended on day 28 – after he had transmitted roughly a ½ million water sample points – when a shark bit into and damaged Waldo’s rudder and his left wing was lost. Since then, the robot has been recovered and hopefully will soon be out for another run with 7 other gliders to monitor for the oil from the submerged plumes of oil droplets in the Gulf. Just yesterday, scientists at Woods Hole Oceanographic Institution confirmed the existence of a submerged oil plume from the Gulf spill that’s at least 22 miles long – an AUV was critical to this discovery. Additional AUV runs should help us keep track the route of this oil.
Data: SIO, NOAA, U.S. Navy, NGA, GEBCO; Image: U.S.G.S.
Thankfully, the best thing about Waldo’s run is what we didn’t find – oil. Waldo didn’t turn up any strong indications of oil on the continental shelf to the north and northwest of the Florida Keys during this run.
He did, however, teach us more about hurricanes. Waldo operated throughout Tropical Storm Bonnie – something that manned research vessels are unable to do because of the need to ensure the safety of their crews. Waldo was able to monitor the heat content of the water column over the continental shelf, which is deeper than satellite can reach (being able to identify the heat at the surface only). How much heat is in the water determines hurricane force and the measurements Waldo captured during this time will help advise future forecasting of hurricane strength.
AUVs searching for oil in the Gulf have also taught us more about the area’s water currents – and about global climate change. At a depth of about 180 to 300 feet below the surface, thick layers of chlorophyll extend from approximately 60 miles offshore to 80 miles offshore and even beyond. Chlorophyll is an indicator of algal growth and algae needs carbon dioxide to grow. Just like plants on land help absorb carbon dioxide, so too does plant life (e.g., algae) in the ocean. Satellites can only measure surface chlorophyll; they cannot reach the deep layers that these AUVs can. Until now, researchers have supplied guesstimates of the undersea extent of plant life, and hence carbon dioxide absorption by the ocean. The AUV data can be folded into climate change models to help more accurately report on the extent of plant life and resulting extent of carbon dioxide uptake by the ocean.
NRDC and Oceana decided to help fund Waldo’s mission because we want to ensure that the ecological treasures off of Florida’s west coast and the Florida Keys are protected – and the path of the oil plumes is still a huge question that remains from the spill.
We know that as much as half the Gulf disaster’s oil (over 100 million gallons) may still be in the system. That’s an enormous amount of oil, the equivalent of nine Exxon Valdez-sized oil spills. While most of the underwater oil has been found in the deeper waters of the Gulf, natural upwelling can bring deep waters to the shallower shelf – and the Florida Keys and other areas so far safe from the spill are not out of the woods just yet. We are pleased that NOAA may be continuing this important effort by funding another run of the AUV gliders and using Waldo to help answer “where is the oil?”. With Waldo and the rest of his team, we can hopefully better determine the fate and impacts of this remaining oil.