Complex sentence: This rich ecological diversity has benefited from a relative lack of pollution during the history of human habitation around the gulf, but environmental groups fear that the lack of a coordinated effort to control pollution may jeopardize the gulf's ecosphere.
Split into simpler sentences: This rich ecological diversity has benefited from a relative lack of pollution during the history of human habitation around the gulf. However, environmental groups fear that the lack of a coordinated effort to control pollution may jeopardize the gulf's ecosphere.