Rafael is preparing to speak about the degradation of salt marshes. As he prepares he writes, “After listening to my speech, my audience will be able to identify the causes of over-salination and degradation of salt marshes.” He begins his speech by saying, “Coastal salt marshes are a safe harbor for plant and animal life, but the over-salination of these marshes is degrading them.” He then transitions to a detailed discussion about the pH levels needed for certain life forms to thrive. He adds, “Now this is an important point.” He then tells them, “Salt marshes have receded by 10 percent in the past five years.” What is his thesis statement?