Complex sentence: Organisms such as oysters and mussels have been extensively used as biomonitors in marine and estuarine environments, e.g. the'Mussel Watch' programme is a world-wide project using mussels to assess environmental impacts on coastal waters.
Split into simpler sentences: Organisms such as oysters and mussels have been extensively used as biomonitors in marine and estuarine environments. For example, the'Mussel Watch' programme is a world-wide project using mussels to assess environmental impacts on coastal waters.