Complex sentence: Whilst originally created to be a research station it has evolved into a Learned Society whose mission is to "promote the sustainable management of freshwater ecosystems and resources, underpinned by the best available science".
Split into simpler sentences: Whilst originally created to be a research station it then evolved into a Learned Society. Our mission is to "promote the sustainable management of freshwater ecosystems and resources, underpinned by the best available science".