Many more animals were attracted to the freshly thawed bait than the rotten fish. "So we assumed that had to do with palatability," Hay said. "It could have been that the predators didn't smell the rotten fish, but that's not consistent with what we know about carrion on the roadway. It could have been that the predators smelled it, but didn't want it."
Counting the species found in the traps confirmed the level of attraction to the various forms of the bait, but it didn't necessarily test feeding, Hay noted. "It could be that the rotten food is just as good, but a lot of the good smells have leached out in the water, so maybe it's just food that's harder for predators to find," he explained.
Researchers assessed their questions about feeding by conducting laboratory experiments.
To eliminate food avoidance because of texture, they fed stone crabs, lesser blue crabs and striped hermit crabs noodle-like test foods made from pureed forms of either the freshly thawed menhaden or the rotten bait. Researchers found that, no matter the rotten bait's texture, stone crabs avoided eating the rotted, microbe-laden food, but readily consumed the freshly thawed menhaden containing few microbes.
"Even when the stone crabs were handed the rotten fish, they didn't want to eat it," Hay said.
Next, researchers tested whether microbes directly affected the palatability of microbe-laden, rotting food. They placed menhaden in two different pools for two days -- one group in seawater where microbes were allowed to grow naturally and the other in seawater with the antibiotic
Source:Georgia Institute of Technology Research News