What divides our planet into the northern hemisphere and southernhemisphere

I believe your answer is the equator.
Hope this helps, have a wonderful day!
Stay smart, ~{Dunsforhands}

When a lake, river or other aquatic  system  becomes  eutrophic, it can have serious negative effects on other organisms like fish, birds and even people.if an algal bloom is so bad that it causes wide-spread death  in  the  water, the organisms that die will all sink to the bottom and start to decompose.

Most of the land is used for housing/commercial uses