Dubai Municipality has put a post on Instagram addressing the issue. The post reads – “We have noticed yesterday morning that the sea colour in some areas of Jumeirah beaches have changed. A specialized technical team from the Environment Department conducted the required tests and it turned out that this is one type of Algal Blooms (Trichodesmium Erythraeum Bloom) which is not harmful and will fade within the next two days.
Algal blooms, according to our online search, is a rapid increase in the population of algae in water that is recorgnised by the discolouration in the water from their pigments.
As the Dubai Municipality has mentioned in their post, it is not harmful and will gradually fade away.
Full article: http://www.khaleejtimes.com/nation/dubai/have-you-noticed-change-in-sea-colour-at-dubais-jumeirah-beach