Optimism about the future among business owners and executives in Los Angeles County has plunged in the past eight months, according to a survey by the Los Angeles County Business Federation released Thursday.

The group’s survey, called BizPulse, finds that less than one-third of the 326 respondents believe the economy will get better in the next six months, a significant drop from the beginning of the year. Back then, nearly two-thirds of those surveyed were optimistic about the economy’s future.

Respondents cited lack of market certainty, the regulatory environment, tax and fee burdens, borrowing impediments and the enormous deficits threatening government as influencing their outlook.

“Many have told us at BizFed that, for them, a double-dip recession has already arrived,” David Fleming, BizFed’s founding chairman, said in a statement.

A rare bright spot in the survey is that only 10 percent of respondents plan to lay off workers in the near future, down from 20 percent earlier this year. But only 21 percent believe they’ll be able to increase their workforce in the next few months, down from 33 percent earlier this year. About 69 percent now expect zero growth in their workforce for the next 6 months, compared to only 41 percent earlier.

“This is an alarming and sobering call from L.A. County’s job creators that the struggle to stay afloat is getting sharply more difficult,” said BizFed Chairman Mark Wilbur. “It raises serious questions about how much longer many businesses can hold on.”

BizFed is an alliance of 92 industry trade groups, chambers of commerce and other business associations, representing more than 150,000 businesses and two million employees. Member groups sent the poll to their own individual members, with respondents in the latest survey representing a cross section of businesses by industry, size and location, BizFed said.