Gray whales eating millions of microparticles per day

Researchers from Oregon State University have discovered that gray whales feeding off the Oregon Coast ingest an estimated 21 million microparticles daily, as revealed by analyzing whale fecal samples. The study, recently published in the journal Frontiers in Marine Science, highlights the alarming increase in microparticle pollution, including microplastics and other human-generated materials such as clothing fibers. Leigh Torres and Susanne Brander, the researchers behind the study, predict that this pollution will continue to rise exponentially in the coming decades.

The presence of microparticles poses a significant threat to the health of gray whales, adding to the challenges they already face due to increased boat traffic and declining prey availability. Leigh Torres, an associate professor at Oregon State University, expresses concern over these findings, emphasizing the need for greater awareness of microplastic pollution’s impact on the marine environment and human exposure. She explains that the pervasive presence of microplastics is unavoidable and affects all ecosystems, including the Oregon coast.

Susanne Brander, an associate professor and ecotoxicologist at Oregon State, stresses that the study underscores the urgency of reducing the release of microparticles due to their adverse effects on organisms and ecosystems. While some states, like California, have taken steps to address the issue, Brander emphasizes the necessity for further action in Oregon and globally, as this problem will persist without intervention.

The study focused on a specific subgroup of around 230 gray whales called the Pacific Coast Feeding Group. These whales migrate from their wintering grounds in Baja California, Mexico to coastal habitats stretching from northern California to southern British Columbia, where they forage between June and November.

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.

Since 2015, Leigh Torres and her team at the Geospatial Ecology of Marine Megafauna Laboratory in the OSU Marine Mammal Institute have been utilizing drones and other tools to study the health and behavior of the gray whale subgroup off the Oregon Coast. As part of their research, they collect fecal samples from these whales.

For their recent study, the researchers collected samples of zooplankton, a vital food source for gray whales, as well as commercial and recreational fish. The team wanted to determine the microparticle loads in the zooplankton to gain a comprehensive understanding of the prey’s quality. The microparticle analysis conducted by Lisa Hildebrand, Susanne Brander, and members of Brander’s Ecotoxicology and Environmental Stress Lab revealed microparticles in all 26 zooplankton samples collected from whale feeding areas. Out of 418 suspected microparticles identified, over 50% were fibers.

Torres and Hildebrand combined this data with known estimates of energetic requirements for pregnant and lactating female gray whales to calculate the daily consumption of zooplankton and microparticles. The estimates indicated that lactating and pregnant whales ingest between 6.5 million and 21 million microparticles per day.

Leigh Torres emphasized the significance of the findings, stating that it serves as a wake-up call to the amount of microplastics that whales consume through their diet. She further suggests that humans are likely exposed to a considerable amount of microplastics through their consumption of fish.

The researchers note that the microparticle consumption estimates are likely conservative as they only considered the particles obtained from zooplankton. Gray whales, being filter feeders that engulf large volumes of water while feeding, are also likely ingesting microparticles directly from the water and seafloor sediment.

Analysis of the fecal samples provided insights into the types of microparticles being ingested by gray whales. Fiber was the predominant microparticle found in the five analyzed samples. The researchers observed that the microparticles in the fecal samples were significantly larger than those found in the zooplankton, suggesting that the larger particles originated from the water or sediment and were not part of the prey consumed by the whales.

These findings raise concerns for Torres, as her previous research has indicated that this subgroup of gray whales is thinner compared to other groups. She expresses worry about the whales’ already stressful conditions due to boat traffic and reduced prey availability, combined with the poor quality of prey due to high microplastic loads.

Torres and Brander plan to continue their investigations by studying the effects of microfibers on zooplankton, which are an essential food source for whales and fish in Oregon waters. The researchers are particularly interested in understanding the potential consequences of microplastic ingestion, including inadequate nutrition, poor health, stunted growth, reduced reproductive success, and habitat avoidance.

Source: Oregon State University

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