Hundreds of schools are missing teachers and support staff two weeks into the school year, with many of the openings in high-poverty districts and struggling schools that are typically the hardest to staff, according to postings on a city database in mid-September.

There were almost 1,700 job postings as of Sept. 19, according to data obtained by Chalkbeat. The listings offer a snapshot of the jobs advertised that day — not an official tally of the total citywide staff openings.

Still, they indicate a critical need for special-education teachers and paraprofessionals, teaching assistants who tend to work with young students and those with disabilities. Many of the unfilled positions were in low-income districts in the Bronx and Brooklyn, and dozens were in schools in the city’s Renewal program for low-performing schools.

The vacancies were posted in the city’s Excessed Staff Selection System, which lists jobs available to teachers in the Absent Teacher Reserve — a pool of teachers who lack permanent positions because they face disciplinary or legal issues, or their schools were closed or downsized. The listings hint at where teachers in the ATR pool may land this year, since the city recently announced it will place such teachers in schools that still have vacancies after Oct. 15.

Education department officials said the data “doesn’t provide accurate or precise information on school vacancies.” In particular, they said there could be a lag in updating the postings, or that schools could post positions that are expected to become available but are currently filled.

In addition, schools may list the same job more than once in order to advertise the position to teachers with different certifications, officials said. For example, a posting for a computer science teacher could also appear as openings for math and science teachers.

Still, the postings suggest where the need for teachers may be greatest — and where ATR teachers could likely end up.

Four out of the five districts with the most postings were in the Bronx. They include Districts 7 and 9 in the South Bronx, along with Districts 10 and 12. District 19 in Brooklyn, which includes East New York, also had dozens of listings.

In District 7, where more than 90 percent of students are poor, there were 60 postings for teachers in subjects ranging from Spanish to physical education and music. That includes 26 listings for paraprofessionals, who are often mandated by students’ special-education plans.

Overall, there were more than 600 listings for paraprofessionals, about half of which were needed to work with students who have disabilities. Almost 400 of the postings were for special-education teachers, who are often in short supply.

Devon Eisenberg knows these staffing challenges well. She is co-principal of The Young Women’s Leadership School of the Bronx in District 9. Despite boasting a staff-retention rate of about 90 percent, the school started the year short one teacher. To plug the hole, Eisenberg relied on substitutes and other teachers to cover the class. She was able to find a permanent hire this week, though the pool of qualified candidates was slim.

“This is definitely not fair for our students as they are not receiving consistent and coherent instruction,” she wrote in an email. “It is also stressful for the teachers covering these holes.”

Starting the school year with a substitute teacher can become a barrier to learning. Research has shown that staff turnover leads to lower test scores, even for students who weren’t in the class that lost its teacher.

Turnover tends to be highest in struggling schools, which often serve the neediest students.

Schools in the Renewal program — which includes 78 low-performing schools — posted about 70 openings, according to the data analyzed by Chalkbeat. The greatest shortage was for special-education teachers, for which there were 16 postings. That was followed by math teachers, with nine openings.

At M.S. 391 The Angelo Patri Middle School, a Renewal school in the Bronx, there were two postings for math teachers. Last year, only 8 percent of students passed state math exams at the school, which has a new principal.

Carmen Marrero teaches special education at M.S. 391 and has worked in other Bronx schools that struggle with staffing.

“We tend to deal with a lot of behavior challenges,” she said, referring to schools in the Bronx. “I guess that keeps some of the aspiring teachers or some of the teachers who are already in the field away from this side of town.”

This year, the openings come with an additional consequence: Schools with vacancies could be prime candidates to receive teachers in the ATR.

Though officials say they will work closely with principals, the department could place teachers even over the objections of school leaders. Some principals have threatened to game the hiring system by simply not posting openings in order to avoid having a teacher from the ATR placed at their school.

Meanwhile, some teachers in the pool dread being assigned to schools whose openings could signal poor leadership or a tough work environment.

Teachers who are in the ATR will not be placed in positions outside of their license areas, which may limit how many of the openings the education department can fill after mid-October.

Critics say the policy will place the least effective teachers in the neediest schools. Education department figures show that only 74 percent of ATR teachers were rated effective, highly effective or satisfactory in 2015-16 — compared to 93 percent of all city teachers.

Education department officials said the city has worked with schools to fill their vacancies well before the start of the school year.

Maria Herrera, principal of Renaissance High School for Musical Theater in the Bronx, said she tries to have all her hires in place by June. That way, she can involve future teachers in end-of-the-year activities that help build a sense of community, and provide training over the summer.

This year, she was able to start school fully staffed. The education department allowed schools to fill positions earlier this year and held numerous job fairs, she said.

“I feel really supported,” she said.