Hi,

The pictures are not the best and I don't know the zoom but in a quick check it looks a lot with Phormidium sp. and Oscillatoria sp.

Hi Loïc,

True. I'm sorry for the bad image quality. 

The cyanobacteria seem to be Phormidium sp. and Oscillatoria sp. But can't it be Lyngbya sp. as well?

P.S: Specimens collected in mangrove areas.

The image looks like a Schizothrix species. Filaments in thick sheats with many branches.

Yes, the image quality could have been better, but I believe it’s Lyngbya with a thick sheath similar to Lyngbya majuscule.  See if these descriptions match.

http://dbmuseblade.colorado.edu/DiatomTwo/sbsac_site/species.php?g=Lyngbya&s=majuscula

http://www.inaturalist.org/taxa/208549-Lyngbya-majuscula

With this pictures it is hard for me to distinguish Lyngbya sp. from Oscillatoria sp. The movement and how sometimes the filament breaks is important for that. I really think the smallest ones are very similar to a Phormidium sp. culture I used to have but 1000x zoom with video and picture should help by looking at the ending of the filament.

bad slide preparation..

Thanks loads for the info guys.