I believe its marine & freshwater ecosystems
Seawater/Freshwater
Benthic/Pelagic
Littoral/Abyssal
Do you get the idea? there are MORE than just 2.
Aerial, and Aquatic
what are the two main systems in a plant
the two major river systems are the Amazon and the Parana.
Capitalism, socialism, and communism are major economic systems.
it rains
Plankton
what are the two main systems in a plant
The nervous system and the endocrine system are the two major regulatory systems in the body.
POLLUTION!
Enterprise-wide knowledge management systems and knowledge work systems
they are aquirum aquatic
doodoo head