In marine mammals, a clear vector is difficult to identify due to confounding variables such as inability to confirm exposure and complicated pathological testing measures. One way to suggest a pathway into the marine mammal food web, is to examine what their primary food source is. A 2009 study examines a possible avenue of exposure though fish in cetaceans, mostly bottlenose dolphins, and sea grass in manatees. In this study, scientists also examine by what category they were exposed, by aerosols or ingestion, which is analyzed by measuring the levels of brevetoxin in the lungs versus in the stomach contents. They found that the majority of stomach contents in manatees were seagrass, and of those seagrass, the brevetoxin accumulation in the epiphytes was as high as 87%. In dolphins, the vector was more challenging to test for, because it was thought that fish die off before they can be eaten by larger animals, but this study also showed that fish can bioaccumulate brevetoxin and survive long enough to poison cetaceans. This is important because while a bloom might not be currently occurring, wildlife still could potentially die from exposure due to brevetoxin moving through the food web. Another way of assessing a pathway for exposure is the location of lesions and hemorrhaging, for example lesions in the lungs from inhalation.