Is UV light responsible for Ocean dead spots?, page 1

I think that, Increases in solar UV light are causing the massive ocean die offs. And here is why

As the light kills microbial life it disengages the food chain from the bottom up

For years the food chain in seawater has been misunderstood, and consequently aquaculturists have often followed the wrong direction. Until recently, scientists had considered that the food chain's primary producers (microalgae, which fix light energy and yield organic materials), were consumed by the zooplankton as soon as they were produced. However, recent studies have shown that several other food transfer pathways exist as well. For example, it was reported that the dominant species in zooplankton communities, which have been considered to be typical herbivores, feed on detritus and bacteria. Maeda (1999) also outlined the significant role of bacterial aggregates as food for the zooplankton.

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UV kills all known spoilage microorganisms, including bacteria, viruses, yeasts and moulds (and their spores).