Limnology and oceanography: two estranged twins reuniting by global change

The twin fields of limnology and oceanography have been raised apart since birth. Both were born from geology, geography, and biology but were raised separately by the immediate need for water supplies to fuel civilizations (limnology) and by the need for fish and by curiosity about the virgin great unknown (oceanography). I explore differences between inland waters and the sea but conclude that oceans are fast becoming large saline lakes. Two irresistible forces are drawing these twins back together. First, there is a strong and growing realization that many aquatic ecosystems function in similar ways and thus can productively share a common theoretical foundation. Second, there is the growing understanding that most oceans are now suffering the same insults at the hands of civilization as inland waters have been for centuries. I support these ideas with an analysis of the top-10 most important problems and paradigms in these sister fields and gauge their prevalence in the burgeoning published literature. I suggest that in the coming years limnologists will be able to assist oceanographers in learning to understand, manage, and mitigate the impacts of growing global change. Oceanographers will assist limnologists in questions of salinity and physical scale that have been less prevalent topics in inland waters. Limnologists and oceanographers have much more to gain by uniting than by competing. Water is our common strategic resource, and we have much to learn from each other.