Final answer:
Fishing cod at a rate that is greater than natural replacement is not a problem directly associated with the deterioration of the greater Everglades ecosystem, making it the correct answer to the choose the 'EXCEPT' question.
Step-by-step explanation:
The question relates to problems in the greater Everglades ecosystem that have not been identified as a concern. When considering the various activities listed, option (a) fishing cod at a rate that is greater than natural replacement, (b) converting a prairie to a farm field, (c) introduction of an invasive ornamental plant in a new ecosystem, and (d) emission of greenhouse gases increasing the average temperatures of an area, all reflect issues that can contribute to ecosystem deterioration. However, the problems specifically identified with the Everglades include pesticide resistance, increased salts in the soil, nutrient-poor soils, blight, and desertification. Therefore, fishing cod is not directly related to the Everglades ecosystem issues and would be the correct answer to the question presented.