The microscopic creatures that make up a critical link in the ocean food chain declined dramatically the first half of this year in the North Atlantic as ocean temperatures remained among the warmest on record, U.S. scientists say.
Springtime plankton blooms off the coast of northern New England were well below average this year, leading to the lowest levels ever seen for the tiny organisms, said Kevin Friedland, a marine scientist with the National Oceanic and Atmospheric Administration.
The absence of the normal surge of plankton in the spring is a concern because that's when cod and haddock and many other species produce offspring, Friedland said.
"The first six months of 2013 can be characterized by new extremes in the physical and biological environment," Friedland said.
The findings come after temperatures off the Northeast U.S. hit an all-time high in 2012.
This year, sea surface temperatures during the first six months in the North and Middle Atlantic remained the third warmest on record, Friedland said.
The data remains in line with an overall warming of the ocean. The warming ocean worries many fishermen in the North Atlantic.
Warm water was blamed for lobsters shedding their shells far earlier than usual in 2012, leading to a glut that caused prices to plummet and created turmoil in the industry in Maine and Canada. Fishermen across New England also have reported finding fish in their nets that are normally found far to the south.
Bob Nudd, a lobsterman in New Hampshire, said he's seeing plenty of black sea bass, a species that he used to see only occasionally. He's also seeing more shell disease in lobster, something many fishermen blame on the warmer temperatures.
"I'm not a scientist and I don't know how much temperature change it takes to change the system, but I don't think it's much. And we're definitely seeing a warming trend," said Nudd, 66. "Things are not going to be the way they were in the past. That's about all I can say about that."
Explore further: Environmental conditions and predators affect Atlantic salmon survival in the Gulf of Maine