As fish swam across the screen and snowy egrets and raccoons appeared, classical music washed over an audience in a demonstration showing the connection between ecosystems — in this instance salt marshes — and music.

Animals on the screen embodied the role of each melody, accompaniment, and bass line instruments in the piece, ultimately forming a single ecosystem and song.

In a classical piece, there is a melody, which is considered the “star” of the song, accompaniment, which supports the melody, and the bass line, which is the bottom support for both of the latter, said music educator Terry Wolkowicz.

Wolkowicz and New Bedford Symphony Orchestra CEO David Prentiss paired the animals and the musical components together for a presentation on balance in music and ecosystems.

The presentation is a part of a greater program Prentiss and Wolkowicz are putting on at several local schools, but on Thursday, Nov. 7, it was a standalone event held at the DNRT Center at Helfand Farm.

The relationship between the different instruments in a classical piece is similar to relationships seen in ecosystems, Wolkowicz said during the presentation.

Rabbits, for example, can be considered the melody, the plants they eat the accompaniment and the microbes in soil the bottom support.

Other examples in ecosystems include secondary succession, which often occurs after natural disasters, such as wildfires.

Using the 1988 wildfires in Yellowstone National Park as an example, Wolkowicz explained how ecosystems rebound and why balance is necessary.

Secondary succession began immediately after the wildfires with the return of pioneer species, such as grasses and beetles, Wolkowicz said. The soil is considered the bass line.

Next come the small mammals and birds that feed on the grasses and insects, and as time passes, small trees and saplings will grow and larger herbivores and predators will return, followed by larger trees and forest species until the ecosystem becomes a climax community, Wolkowicz said.

Ecosystems, like songs, can have multiple melodies, but there is always one that is slightly more important than the rest, and when this one is taken out of the picture, the song becomes off balance, Wolkowicz said.

In an ecosystem, these crucial melodies are known as keystone species, which are species that many others rely on and are essential for keeping balance in an ecosystem.

Keystone species in Massachusetts include oak trees and woodpeckers.

During the presentation, Wolkowicz played a song that has several melodies by composer Aaron Copland to demonstrate how melodies work together and what happens when the main melody is removed.

The Thursday night presentation was part of a music series that Prentiss and Wolkowicz organized in several local schools.

Partnering with several school districts across surrounding communities, Prentiss and Wolkowicz learn how they can help teachers teach their students and then center their program around that topic.

“We talk to teachers and schools [and ask] what can we do to help you, and balance and ecosystems is a next generation science standard,” Prentiss said.

Wolkowicz and Prentiss started the program, which has three phases, in the beginning of October with student assemblies. They will soon start making classroom visits.

“It also helps them learn these scientific topics,” Wolkowicz said. “So one builds upon the other.”

Going into classrooms and giving presentations is part of the New Bedford Symphony Orchestra’s effort to introduce music to new people.

“We believe a symphony orchestra should really be in the community, not just in the concert hall,” Prentiss said. “We bring our music and we bring our programs through communities all over.”