It’s not unusual for old tires — or even remnants of war — to degrade and wash ashore during storms, said Art Trembanis, a professor of oceanography and geology at the University of Delaware.

However, the abundance of tires recently discovered on Delaware’s beaches is alarming, he said.

“Sadly, I think what we’re seeing play out is the sins of the fathers are being brought on to our beaches — although, all well-intentioned at the time,” Trembanis said. “It’s a matter of trying to think of how far ahead is one really trying to consider our stewardship of the environment. I think we need to have a much longer viewpoint of that as we assess these kinds of programs.”

These man-made marine habitats can become marine debris during storms, and impact the environment, if not designed with sturdy materials.

“Smaller little tires are relatively light, so they’re going to tend to want to stay up on the surface, and then they’re going to get moved around by these waves and currents, and they’re going to take out everything in their path — and that means further disturbance to seabed environments,” Trembanis said.

Loose tires could also become a hazard for people swimming in the water, he added.

Small vehicle tires are no longer used for artificial reefs. Instead, agencies use industrial-sized tires that are weighed down with concrete, he said.

Other kinds of materials can prove just as hazardous. Following Hurricane Sandy in 2012, subway cars used as a part of an artificial reef site off the Delaware coast were smashed.

Artificial reefs have evolved over time, however, and agencies are beginning to use more environmentally-friendly materials, such as natural rock and concrete, Trembanis said.

DNREC said many of the tires it has collected have strap-like markings, suggesting they may have been tied with metal cable — a method Delaware never used, according to the agency. In Delaware, stacked tires filled with concrete were dropped onto the ocean floor as structures, DNREC said.

The last time the state’s reefs were surveyed, tires were in place and covered in coral, the agency said. However, DNREC is working to get updated imagery of its artificial reefs.

The agency also plans to get new SONAR scans of any debris fields in locations with tire reefs to help confirm the sources of the tires that washed ashore.

Although the source of the tires is still being investigated, illegal dumping is not suspected, DNREC said.

Trembanis advises residents and beachgoers to avoid touching the tires if they see them, because there may be wire, glass or other hazardous materials inside them. Instead, they should report the sighting to DNREC, he said.