Microplastics affect sand crabs' mortality and reproduction: study

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Oregon (U.S.), Jan 17 (Canadian-Media): Sand crabs, a key species in beach ecosystems were found to have increased mortality rates and decreased reproductive success when exposed to plastic microfibers,  according to a new Portland State University (PSU) study, media reports said.

A Pacific mole crab, or a sandcrab, in an aquarium. You can see the feeding appendages are out feeling for food in the water. PSU researcher Dorothy Horn examined the effects of exposure to microfibers on adult mortality, reproductive output and embryonic development of the sand crab. Credit: Dorothy Horn

Sand crabs eat by filtering small particles from the water. The effects of exposure to microfibers on adult mortality, reproductive output and embryonic development of the sand crabs were examined by Dorothy Horn, a Ph.D. candidate in PSU's Earth, Environment and Society program as sand crabs are considered indicator species because their health reflects the health of the ecosystem.

"When pollutants affect sand crabs, it's also affecting most organisms around it in that ecosystem," Horn said. "We don't eat them, but they're a bright blinking light for 'There's a problem in this area.'"

The study found that with an increasing number of microplastic fibers internalized, crab mortality increased, and the number of days that a crab held viable eggs decreased. Exposure to microplastics also caused variability in a crab's embryonic development rates.

A Pacific mole crab, or sand crab, in an aquarium jar with PSU researcher Dorothy Horn in the background. Horn examined the effects of exposure to microfibers on adult mortality, reproductive output and embryonic development of the sand crab. Credit: Dorothy Horn

Sand crabs, said Horn are prey for shorebirds, nearshore fish and some marine mammals, and their increased mortality and decreased reproductive performance following exposure to microplastics could have potential effects on species higher up on the food chain.

"We've proved it's causing them harm, and it can have harmful effects on these other organisms," Horn said.