Eating Toxic Algae Might Make Some Plankton Act Drunk

Though it may seem funny, it could have serious environmental consequences

Douglas P. Wilson/FLPA/Corbis

Humans are far from the only animals that get loopy while intoxicated. Now, a new study has found that some plankton that regularly feed on toxic algal blooms can feel a strong effect akin to drunkenness that may make it easier for predators to snap them up.

In recent years, many different variations of harmful algal blooms (HABs) have begun appearing across the world as fertilizer runoff from farms makes its way into the world’s oceans. Red tides, blue-green algae and cyanobacteria are three commons terms for different types of HABs, and according to the Environmental Protection Agency, they are a major threat to aquatic ecosystems, local economies and human health.

But while toxic algae is often seriously harmful to most marine life, a recent study published in the Proceedings of the Royal Society B found that a common species of plankton not only thrives off of red tides, but gets a bit of a buzz, Jennifer Viegas reports for Discovery News.

The plankton in question are a species of copepod—tiny, shrimp-like crustaceans that make up the foundation of the ocean’s food web. Researchers exposed the copepods to a type of poisonous algae that is often found off the New England coast and watched their behavior.

The scientists found that instead of appearing harmed, the plankton thrived on the algae, Traci Watson reports for National Geographic. Even so, this steady diet of toxic algae caused the tiny crustaceans to behave oddly. After chowing down, the plankton began swimming faster and straighter.

While this might seem like the opposite effect that intoxicants like alcohol have on humans, the study's lead author Rachel Lasley-Rasher says this behavior is just as risky for the tiny critters as lurching and weaving is for drunken people. When not munching on toxic algae, copepods swim slowly and in odd patterns, so as not to attract the attention of larger predators. However, by swimming faster and in straight lines they not only have a higher risk of catching the eyes of a fish or shrimp, but are more easily caught thanks to their predictable paths, Watson reports.

“When you move faster in the water you create a larger fluid wake,” Lasley-Rasher tells Viegas. “This is why you drive your boat slowly in a ‘no-wake zone.’”

Being easy prey could have lasting effects on the ocean’s ecosystems. Larger creatures feasting on the algae-munching plankton allows the toxin to travel up the food chain, Watson reports. And as the plankton are consumed, fewer remain to slow the spread of red tide algae.

But despite thriving on the algae, after eating the poisonous food, the plankton acted as if they were running away from something and not as if they had just had a satisfying meal, Watson reports.

“If [the algae] doesn’t hurt them, it’s kind of strange that they’d want to get away,” Lasley-Rasher tells Watson.

The researchers still aren’t sure how the copepods developed the ability to ingest the toxic algae, but it’s possible that years of coexistence have made the tiny critters resistant to its effects.

While it may be amusing to think of these plankton as getting soused, their tippling could have serious effects on the ocean’s ecosystems.

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