FIGURE 4.6 Pollution of the seas. Chlorophyll concentration is one measure of pollution levels in large bodies of water. Europe’s exceptionally long and convoluted coast affords easy access to the world’s oceans. However, pollution of the nearly landlocked Baltic, Black, and Mediterranean seas (red and yellow dots) is causing increasing concern. Lesser concentrations of chlorophyll are significant in the Atlantic and Arctic oceans and in the Mediterranean and Black seas. For this map, chlorophyll was used to measure the amount of algae in bodies of water. Excessive algae growth is an indicator of pollution from fertilizers and sewage that fuel the growth of those organisms.