Fertilizer and other agricultural waste pouring into the Gulf of Mexico creates a larger and larger patch of lifeless ocean each year. Finally, the EPA has a plan of attack. Is it enough?
The abbreviation et al. means and others. It is most often used when a work you are citing in your paper has multiple authors. When a work has two authors, cite both names every time the reference occurs in the text.
The abbreviation et al. is used both in parenthetical citations and in running text citations. Chapter 6 of the Publication Manual is devoted to how to cite references in the text. Among other places in that chapter, you can see the use of et al. in Table 6.1 on page 177.