Over 43,000 aquatic animals estimated dead after Ohio train derailment

• None of the aquatic species that died were believed to be endangered or threatened, per the ODNR.
• Officials believe "the entirety of the impact to the aquatic life" happened within the first 24 hours after the derailment.
• "There is no immediate threat to minnows, fish, or other aquatic species," the department said.

Flashback: Officials first collected samples of dead animals on Feb. 6 and Feb. 7 — just days after the Feb. 3 derailment, ODNR director Mary Merks said in a statement.

• The ODNR estimated at the time that 3,500 aquatic species had died as a result of the derailment.

The big picture: The derailed train was carrying at least five cars with vinyl chloride, which is a hazardous and carcinogenic gas that is used to produce PVC plastic and vinyl products, Axios' Jacob Knutson writes.

• The National Transportation Safety Board's (NTSB) on Thursday released preliminary findings of an investigation into the derailment, which showed — among other things — that the crew of the Norfolk Southern train tried to stop it after they received a "critical" alert about an overheating wheel before the crash.

Go deeper: What we know about the Ohio train derailment