The Maine Department of Marine Resources says it’s monitoring a large, unusual bloom of phytoplankton in the Casco Bay area.

The department says the bloom isn’t a threat to human health, unlike other toxic blooms it typically monitors. The species is called Karenia mikimotoi and it can have harmful effects on fish, shellfish and other marine life.

The marine resources department says the bloom has been associated with fish die offs in places such as Alaska, Japan and Ireland. The department says the toxicity of the species is not fully understood. Die offs associated with the species appear to be due to a combination of low oxygen caused by the bloom and some kind of toxin that harms fish and shellfish.

The department is also informing industry about the bloom.