Lisa Hildebrand of Oregon State University and Kathleen Hunt of George Mason University collecting whale poop off the Oregon Coast. Credit: GEMM Lab, Oregon State University
Key points:
- Microparticles were found in all analyzed samples of gray whale prey and feces
- The particles were mostly fibers and included microplastics
- Food chain contamination could lead to health problems like malnourishment
Analyses of zooplankton and feces from gray whale habitats revealed that a single whale may consume 6.5 to 21 million human-made microparticles daily. The findings raise safety concerns about the marine food chain and human seafood consumption.
The estimates, calculated based on caloric requirements of pregnant or lactating gray whales, are likely conservative as they only account for zooplankton consumption. The Oregon State University researchers discovered microparticles in whale feces that are too large for zooplankton to eat, which could come from water during filter feeding or sediment while suction feeding on the seafloor.
Microparticles, including microplastics, were found in all of the samples analyzed. The most common microparticles were fibers, accounting for more than half of the particles in both zooplankton and feces.
The study in Frontiers in Marine Science focused on the Pacific Coast Feeding Group, which comprises about 230 gray whales that spend winters near Baja California, Mexico and forage between northern California and southern British Columbia from June to November. The researchers analyzed 26 zooplankton samples from the group’s feeding areas as well as five gray whale fecal samples.
A total of 418 suspected microparticles were identified in the zooplankton samples and microparticle loads were extrapolated to predict consumption rates. Previous studies of the Pacific Coast Feeding Group, using drones and other tools, found these whales to be smaller than gray whales from other groups, possibly due to pollution and high boating activity.
“That all can lead to being poorly nourished and having poor health,” said first author Leigh Torres, an associate professor at Oregon State. “That can lead to stunted growth, smaller body size, lower ability to have calves and animals not using this habitat anymore.”
The researchers continue to investigate the impact of marine microparticle pollution, noting that fish eaten by humans likely consume the same contaminated zooplankton.