At half past noon, Clark’s Pizza is overflowing with people.

As waiters rush between tables to take orders, the small pizza restaurant on Whitney Avenue seems to be doing well.

But it is not. Clark’s co-owner Costa Mihalakos said business in the past year has declined sharply at his and neighboring restaurants.

The cluster of retail stores and restaurants making up New Haven’s arts district has seen dramatic changes in the past year with the arrival of several new businesses. Most of the businesses were hand-picked by Yale’s Office of New Haven and State Affairs in its effort to revive the area.

Some longtime business owners — like Mihalakos — are resisting the changes.

“There are not enough people for the restaurants,” Mihalakos said. “Instead of bringing in more retail, Yale keeps bringing in more restaurants. It’s a complete mistake. As more restaurants come in, the thinner the slices get for those restaurants that are already here.”

Restaurants are not the only businesses that seem to be suffering, some say.

Larry Panza, manager of Audubon’s in the arts district, said business for his card and gifts shop is down 30 to 40 percent compared to what it was five years ago. He points to the property vacancies in the area as the cause.

“If there were more offices in the vacant area, there would be more people out on the street shopping,” Panza said. Like many other arts district merchants, Panza said he would welcome more businesses that attract customers to the area.

Yale’s Office of New Haven and State Affairs recently attracted Sandra’s, a Southern-style soul food restaurant. Elm City Java, a new coffee and sandwich cafe, opened this May.

Also, a second Gourmet Heaven deli — like the first store on Broadway but without its buffet — will be opening at the end of the year.

Michael Morand, Yale’s associate vice president of the Office of New Haven and State Affairs, praised the new tenants.

“Business is good,” Morand said. “There’s been a tremendous growth in foot traffic on those streets. Businesses like Sandra’s are doing very well. New businesses are coming in. It’s really become a great 24-hour-a-day, 7-day-a-week area to work, eat and play.”

Mihalakos said he disagrees. No one comes to the district at night, he says, forcing him to close down his business early.

Morand said he believes more business is good for the town. Since his office started working to revitalize the arts district in 1995, there has been a push toward attracting a variety of restaurants and retailers in order to increase the number of patrons that come through the area.

But critics like Mihalakos say the number of restaurants has begun to outstrip the demand for food in the district.

Morand places the blame on consumers, not on Yale.

“Businesses that don’t succeed are participating in the great selection by consumers,” Morand said.

Some merchants said they see the recent influx of new business as beneficial.

“I don’t think people looking for the things we serve are going to be completely drawn away from here if new restaurants arrive,” said Nathan Wrann, co-owner of Elm City Java. “People say when [the new] Gourmet Heaven opens it will bring more foot traffic which will bring more business to us.”

Although she acknowledges that most businesses in the area have seen a downturn in business over the past year, Tracy Jackson of Koffee? blames Timothy Dwight College’s recent renovation.

“We’re now getting back some of the business we lost though,” Jackson said. “In general, the more businesses there are, the more people there are who are drawn to the area.”