Just another thought...

I think it is also important to draw attention to the fact that a major part of the diet of the coastal populations included aquatic fauna that are rich in amino acids, something that was available in only relatively small quantities further inland. Thus, diets were probably better and agricultural failure wouldn't have led to such food shortages as it is thought to have done in the Lowland parts. Could this be a factor in explaining the differential collapse of the Maya area?  It is possible- the coastal areas did not experience a demographic crash to the same extent as the landlocked cities...