Sentence:  Devils Lake is where I began my <WSD>career</WSD> as a limnologist in 1964, studying the lake's neotenic salamanders and chironomids, or midge flies. [...] The Devils Lake Basin is an endorheic, or closed, basin covering about 9,800 square kilometers in northeastern North Dakota. 
Meaning of the word marked with <WSD> tags:  One's calling in life; a person's occupation; one's profession.