In the past two weeks, 6 dolphins have become stranded on Southern California beaches and have left animal rescue organizations puzzled as to why. As the Pacific Marine Mammal Center said, this is a drastic uptick in stranded animals as during this time last year they only responded to one incident of a stranded dolphin. The LA Times reported that one potential cause are the recent storms that can make ocean water toxic as a result of runoff.

Kristen Sakamaki, a veterinarian at the Pacific Marine Mammal Center told KTLA that “There are a variety of potential reasons as to why these dolphins are stranding. These include, but are not limited to, viral infections, bacterial infections, and toxins. We may not always get a definitive answer, but we consider our research with these dolphins to be a very important piece to the puzzle in providing clues as to what is going on in our nearshore habitats.” The LA Times explained further that “recent heavy rains may also be to blame. The rain runoff from the land can result in excess nutrients and harmful toxins in the ocean, the organization said. But officials won’t know the real answer until their studies and the necropsies are complete. The center said it is working with agencies, including NOAA, and academic universities across the country to try and understand the unusual increase of beached dolphins.

• Officials warned the public that the marine mammals can carry zoonotic diseases that can be transmitted to pets and humans, especially young children. Attempting to push beached marine mammals back into the ocean “may actually be doing more harm than good.”

Why This Matters: While marine mammals are resilient animals they can serve as indicators of changes in their ocean environment. When epidemics of beached marine mammals occur, it’s a red alert that some sort of pathogen or environmental disruptor is harming coastal waters. In recent years one particular diatom, Pseudonitzchia australis, has been responsible for producing a toxin called Domoic acid toxicosis, that could have dramatic effects on marine mammal populations as it causes sickness and death in animals and results from algal blooms made worse by climate change.

Go Deeper: An atmospheric river has been drenching California and parts of Southern California haven’t seen this much rain in decades. While this rain is generally welcome in a drought-prone state, there is too much of a good thing as increased rain can cause mudslides and all sorts of toxins to wash into the ocean as we’ve seen from this story. Additionally, climate change is thought to make these atmospheric rivers more potent.