Ari Levy

Whether you're a start-up, family-owned, or publicly traded, there's danger in letting your business rely too heavily on Google search for site traffic.

One morning in May, Linda Stradley woke up to find her online recipe and cooking business in crisis. The number of visitors to the site, which had reached around 5 million a month, was suddenly down by 44 percent, cutting ad earnings by 56 percent.

Google periodically, and without notice, upgrades its service to push spammy websites and content farms lower down in search results. The goal is to create a better Internet, where users are more likely to find the best and most relevant websites based on their search terms.

Google said the latest algorithm change, announced in a tweet from the head of its webspam team on May 20, would affect about 7.5 percent of English queries that are noticeable to users.

While the updates are targeted at bad actors, for people like Stradley, who aren't trying to game the system, they can be devastating. At 72, Stradley works at least eight hours a day and relies on the income from her website and its more than 3,000 pages. She says the costs will be in the tens of thousands of dollars.

Whether in food, travel, personal finance or e-commerce, any website that needs to be discovered needs Google. The company controls 68 percent of the US search market, according to ComScore, and reeled in more than $50 billion in advertising sales in 2013.

Sites like Stradley’s whatscookingamerica.net use Google's ad-serving technology and share revenue with the search engine. Google has made over 890 such improvements in 2013, Jason Freidenfelds, a company spokesman, said.