@ Shivam, I think it is due to dissolved organic materials because bacteria do not tint the water yellowish-green. Generally water rich in phytoplankton and other algae usually appears green.
Shallowness, the presence of suspended particles and dissolved organic matter and most importantly, high abundance of phytoplankton change the colour to greenish and yellowish depending of which group of microalgae are dominating.
It is the pollution caused by human waste (treated/untreated sewage) discharged into the sea. Its richness in phosphorous (among other macro and micronutrients) fosters the growth of microrganisms (algae, bacteria, cyanobacteria) that proliferate while removing oxygen in great quantity from the water, causing eutrophication. Is this phenomenon occurring with a lot of dead fish on the shore? In this case it is water pollution, otherwise it could be diatoms (protozoa) that stain the water with the colors you described.
There are many reasons posible, but first let me say that this is not a global situation, In some place you wont see any effect on water color.
As some people said the most likely reason is nutrient addition that cause development of microorganisms.
In some places it can be cause by suspended inorganic material
In other places it can be caused by colored organic matter (CDOM). I have seen that Eucalyptus trees are very potent CDOM manufacturers.
Hope this helps
This is due to the increase in the level of nutrients in the shore area; this is due to the discharge of sewage from cities. The results of eutrophication is the growth of algae which leads into yellowish-green coloration in these areas.
Pollution caused by bacteria & algae depending on the pigment produced by the algae that will determine the color of water.
Probably eutrophication caused by the sewage discharge from cities can be one of the reason for yellowish-green color of costal water near cities .
Generally, this type of phenomenon not seen in every coastal water of near cities. It's a localised activities which varies with place and topography of the ocean. Still, I agree and satisfied with the answer made by Dr. Biswas ma'am.
this might be due to the effluent of heavy metals,several nutrients and the response of phytoplankton to the condition from near by industry,flower culture,sewage treatment,agriculture, and other ditches.
Probably eutrophication of specific microalgae due to sewage discharge from cities
I think, it could be due to sewage containing a lot of iron iii oxide.
If there are any particles suspended in the water, they will increase the scattering of light. In coastal areas, runoff from rivers, resuspension of sand and silt from the bottom by tides, waves and storms and a number of other substances can change the color of the near-shore waters. Some types of particles (in particular, the cells of phytoplankton, also referred to as algae) can also contain substances that absorb certain wavelengths of light, which alters its characteristics.
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