It could be anything that changes how the light is reflected off the surface, so it could be oil of some sort, or a smoother surface, as Bob suggested. Did it look a different colour when you were close or just in the photo? Could also be different microorganisms in the water.
It looked the same as I moved around – there was definitely something different about that area, whether it was colour or texture, not just an illusion caused by a reflection… Hmm, different texture does actually support Bob’s idea about the wind, or maybe a current in the water? A currant in the water? Pulled under by a strong currant :o)
Greene Island 
Notwithstanding, not being there, I would suggest wind ‘shade’ from the seawall :o)
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I don’t think so – wind not from that direction – but I get your drift ;o)
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It could be anything that changes how the light is reflected off the surface, so it could be oil of some sort, or a smoother surface, as Bob suggested. Did it look a different colour when you were close or just in the photo? Could also be different microorganisms in the water.
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It looked the same as I moved around – there was definitely something different about that area, whether it was colour or texture, not just an illusion caused by a reflection… Hmm, different texture does actually support Bob’s idea about the wind, or maybe a current in the water? A currant in the water? Pulled under by a strong currant :o)
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