Freshwater diversion projects that have divided environmental advocates are intended to save the coast but may imperil dolphins.
A $20,000 reward is being offered to anyone who can help solve the case.
Someone stabbed an adult male dolphin in Florida, possibly while it was in a "begging posture" at a fishing boat.
The algal bloom has also killed fish, sea turtles and manatees along the Gulf Coast.
Experts say heavy winter rains may be contributing to more beached marine mammals.
Dolphinaris Arizona, which opened a little over 2 years ago, is temporarily closing amid an investigation.
“The mother is grieving and needs space and time to do this,” the New Zealand Department of Conservation said.
A marine animal rescue group is offering a reward of $5,000 for information leading to conviction of the perp.
Noise from ships and boats are causing dolphins to make their calls less complex, according to a new study.