Most of us would have never realized it, unless we knew where to look, but there is an invasion taking place in Northern California waters.
John Cruger-Hansen is harbormaster of Spud Point Marina in Bodega Bay. He sees this invasion beneath his docks and on the bottoms of boats.
"Well to really keep the bottom clean you need to scrape once a month and it used to be three months. It's a big difference," he said.
It's an observation measured, quantified, explained and now published by Dr. Susan Williams, an ecologist at the UC Davis Bodega Marine Lab. She is worried about the long-term effects.
"We expect this to be general across the world's oceans," she said.
The study found that, in these waters, temperatures have warmed by one degree Fahrenheit in the last 50 years. This might not sound like much, but it has allowed the number on invasive species to double.
"Warm water favors these invasive species over native ones. So the heat is on, now," Williams said.
The non-native species come from places like Australia and Japan. They are transported on the hulls of ships or in their bilge water and they grow fast.
"It can be completely covered in a month," Williams said. "They probably grow twice as fast as native species, and as the ocean warms, they will grow even faster."
Slowing ships cost more fuel and threaten some of our favorite foods like mussels and oysters.
"Shellfish that we like to eat sometimes mussels or oysters are sometimes so completely covered that the animal will die," Williams said.
When Williams took her latest sample to the laboratory, she counted 12 invasive species in one community alone. They have layered and live on top of each other.
"These species have no natural predators or very few in these waters, so nothing keeps them in check," she said.
So it's not good news. It is just another example of how small changes in climate could lead to big ones a few years from now.