Figure 10-8 Diagram illustrating some of the work done by both nature and man’s economic system in developing recreational values for man from natural ecosystems. Numbers are for the complex of marine bays near Corpus Christi, Texas with an area of 228,480 acres. Economic activity was evaluated by Anderson  with recreation, tourism, and fishing $166/ (acre) (year) and oil, gas, shell, cooling waters, and savings on shipping $203/ (acre) (year). Using $10,000 kcal/dollars work equivalents were calculated. Energy contributions of personal activity by 13,914 visitors per day was converted using 3000 kcal/ (person) (day). Management by state and federal agencies was estimated as $1 million annually.