Toxic death?

Had a lovely couple of dives on the Manchester Merchant yesterday along with the two Shanes, Brendan, Kevin, Martin, Ben & Lisa. Only trouble was that the fish-life appears to be in big trouble.... No sign of the big schools of pollack and over-sized congers. Instead we saw many, many dead fish and crabs. When I said during the brief that we would see lots of tompot blennies, I wasn't wrong, but I didn't expect them to all be dead. The only things that seemed to be thriving were huge schools of juvenile bib and some monstrous lobster (obviously lots of food available). At first I thought someone had been using explosives to fish, but the wreck was still in good shape. It seems that the 'red tide' may be responsible - a highly toxic algal bloom, but I haven't been able to find out anything about the grey coating that is covering every surface and slowly smothering all the anemones and dead man's fingers. It looks like a nuclear winter down there. Not sure about the cause but it seems to de-oxygenate the water and particularly affects shellfish. There is not much info around about it killing off all the fish. If anyone has seen this before or knows anything about it, we would love to hear about it.
Jacquie