Zones of the Marine Environment Name: ______________________________________________ The marine environment makes up more than 70% of the Earth’s surface. That and its complexity make it a difficult system to classify. The oceans have two principal life zones: the coastal zone and the open sea. The coastal zone is relatively warm, nutrient-rich shallow water that extends from the high-tide mark on land to the edge of the continental shelf. The continental shelf is the submerged part of the continents. The coastal zone represents less than 10% of the oceans, however, it contains 90% of all ocean species. This zone is the source of most of the ocean’s productivity per acre. The open ocean extends outward from the edge of the continental shelf. The open sea contains about 90% of the world’s ocean area, but has only about 10% of all ocean organisms. Your goal today is to examine and characterize the physical characteristics of these zones in the coastal and open ocean regions. 1. What percentage of the ocean area is considered coastal? What percentage of life is found in the coastal zones? 2. What percentage of the ocean area is considered open ocean? What percentage of life is found in the open ocean? 3. Which area is more productive? The marine environment is a very large and complex system. One way to designate particular marine environments is based on physical characteristics like temperature, depth, light and DO. The environments in which the pelagic and benthic organisms live can be grouped into four major ecological zones: littoral (intertidal) zone, sublittoral zone, bathyal zone and abyssal zone. Examine the location of these zones in Figure 1.1. 4. Describe how the littoral and sublittoral zones are different from the bathyal and abyssal zones based on the physical characteristics listed above. The intertidal zone is part of the seashore located between high and low tide. Organisms of the intertidal zone are covered with salt water at high tide and uncovered at low tide. In addition to withstanding the change in water level, they must also withstand the pounding of the surf. This zone is crowded with life since nutrients and oxygen are readily available. Look at Figures 1.2 and 1.3. 5. Why are nutrients and oxygen in high concentrations in this zone? 6. Why does the intertidal zone have great variation in temperature? 7. Besides the intertidal zone, where else do you see lots of nutrients? Why? 8. Describe where you see high or low concentrations of salts. Why do you think that is? 9. The salinity of the intertidal zones will actually vary depending on several factors: a. How does river run-off affect salinity? b. How does precipitation affect salinity? c. How does evaporation affect salinity? 10. Why is the intertidal zone a region of constant change and how does this affect the organisms that live there? The sublittoral zone is the zone from the low tide mark to the edge of the continental shelf (seen in Figure 1). 11. How is the sublittoral zone different from the intertidal zone? 12. The bathyal zone is the region from the continental shelf to the start of the abyssal zone; down to about 2,000 meters. The abyssal zone refers to the abyssal plains and is about 2,000-6,000 meters. The hadal zone is mainly deep ocean trenches and is deeper than 6,000 meters. What factors likely change as you travel from the bathyal to abyssal to hadal? 13. Fill in the table using the figures that show the abiotic factors and location of the zones. Marine Zone Location Light Salinity Oxygen Nutrients Temperature Organisms Intertidal (littoral) Sublittoral Bathyal Abyssal 14. Some of these zones are located in the photic zone where light intensity is great enough for plants and phytoplankton to perform photosynthesis. Which of the four zones would be included in the photic zone? 15. Which zones are located in the aphotic zone where light is absent? What organisms would not be found in these zones? 16. Marine organisms can be assigned to groups based on depth and lifestyle. For example an animal may be considered bathypelagic. What does this mean? 17. Describe what might be difference about animals that are bathypelagic and bathybenthic. 18. Which of the zones will be most impacted by pollutants from watersheds of rivers?