Fred Jacobs, the SeaWorld spokesman, did not say whether the change in policy had been prompted by the health-care law.
"The move is intended to bring consistency to the part-time designation across the SeaWorld Parks system," Jacobs wrote in an statement.
According to Fitzpatrick, the theme park employs 1,650 people and brings $75 million in economic activity to the county each year. He called it the number-one tourist destination in Bucks County.
Fitzpatrick wrote that Sesame Place had cut back on health care and weekly hours "presumably" because of Obamacare.
He enclosed a letter SeaWorld sent to seasonal and part-time employees announcing that their health coverage would end in 2014. Their current health-care plan, Starbridge Limited Medical, does not comply with the minimum coverage level mandated by the Affordable Care Act, the letter said.
SeaWorld advised workers in the letter that by January, they should find their own plan through one of the new state or federal online marketplaces.
A spokesman for Fitzpatrick said the congressman received the letter from a constituent who worked at Sesame Place.
Jacobs did not say how many workers would be affected by the reduction in hours or the insurance change. He said that SeaWorld would add 1,100 full-time positions across its 11 parks and that those new hires would receive health insurance.
He did not respond to a request for further comments.
Fitzpatrick voted last week with most House Republicans for a bill that would defund Obamacare.
"I continue to believe it must be repealed," he wrote in the letter, "and replaced with a sustainable solution that promotes affordable access to world-class health care for which our nation is recognized."
It's the second time in barely a year that national politics have wandered down Sesame Street. During last year's presidential election, Obama and presidential rival Mitt Romney tussled over whether the Republican would cut funds for public broadcasting and leave Big Bird unemployed.