Complex sentence: Acidification and temperature increase leads to "dead zones", because it allows for eutrophication to occur and blooms of algae and phytoplankton explode and remove oxygen during their eventual death and decomposition.
Split into simpler sentences: Acidification and temperature increase leads to "dead zones", because it allows for eutrophication to occur. Blooms of algae and phytoplankton explode removing oxygen during their eventual death and decomposition.