How come when you need food the most and your builders are building the dam and your water is populated with Algae and there are no more coconuts It seems there are no mushrooms either or else there are and you let ur person down and it's gone. My Tribe couldn't survive.

That happened to me too - AND the birds kept eating all my crops as well. My first tribe all died very quickly :(.

I have a few building the dam, 1 collecting coconuts, kids looking for 'shrooms and collectibles, and 1 fishing. no algae yet.

As soon as the farm gets built, you need to make the scarecrow. I've found the best way to last until you get the ocean clean is to mass harvest the food quickly so you have a stockpile, then get the dam built. Have like one or two harvesting the crops while everyone else researches and you should be fine.