Choose to view chapter section with a click on the section heading. Ecology and Ecosystems

1. Choose to view chapter section with a click on the section heading. • Ecology and Ecosystems • Ecosystems in the Open Sea • Coastal Ecosystems - Estuaries, Salt Marshes, Mangrove Swamps, Seagrasses • Coastal Ecosystems - Intertidal Zones, Beaches, Kelp and Seaweed, Coral Reefs • Polar Ecosystems • Deep-Sea Ecosystems Chapter Topic Menu

2. Ecology and Ecosystems Ecology and Ecosystems Chapter 16 Pages 16-3 to 16-9

3. The Science of Ecology • With the rise of environmental awareness, the term ecology has become a buzzword thrown about by the media and politicians. • You may already have a general idea of what ecology is, but to discuss marine ecology clearly it’s important to be precise and specific. Ecology and Ecosystems Chapter 16 Page 16-3

4. The Science of Ecology • Ecology is the science that studies how organisms relate to each other and their environment. • Ecology embraces the broad range of disciplines, including biology, physics, geology, climatology, oceanography, paleontology, and even astronomy. • Beyond biotic (living) factors, the study of ecology considers the abiotic (nonliving) aspects of the environment. Ecology and Ecosystems Chapter 16 Page 16-3

5. The Science of Ecology • Abiotic aspects include temperature, wind, pH, currents, minerals, and sunlight. • Ecology also examines the biological factors, such as the quantity and type of organisms in an environment. • Ecology studies the relationships and interactions of the abiotic and biotic aspects of the environment. • The goal is to understand how, through relationships and interactions, changes in an environment will affect those organisms in the environment. • In marine ecology, the four branches of oceanography come together. Ecology and Ecosystems Chapter 16 Page 16-3

6. Ecology Terminology • At some level you’re probably familiar with the concept of an ecosystem. • Definition: A distinct entity usually with clearly defined physical boundaries, distinct abiotic conditions, an energy source, and a community of interacting organisms through which energy is transferred. • No ecosystem exists entirely in isolation (except under artificial conditions). The ocean is composed of interacting, complex ecosystems. Ecology and Ecosystems Chapter 16 Pages 16-3 to 16-5

7. Ecology Terminology • A community is a collection of different organisms living and interacting in an ecosystem. This includes all species and types of organisms. • A population is a group of the same species living and interacting within a community. • The interaction is part of the definition because sometimes two populations of the same species live in a single community. • Can you think of examples? Ecology and Ecosystems Chapter 16 Pages 16-3 to 16-5

8. Ecology Terminology • A habitat includes the area and conditions in which you find an organism. • Some species are adapted to or occur in very specific habitats, whereas others range over a variety of habitats. • Chitons, for example, live in the rocky intertidal zone, whereas octopuses live in a wide depth range and in many different parts of a reef. The chiton has a narrowly defined habitat compared to the octopus. Ecology and Ecosystems Chapter 16 Pages 16-3 to 16-5

9. Ecology Terminology • A microhabitat exists on a very small scale. For example, tiny crustaceans and worms live in the spaces between sand grains on the sea floor. • Organisms in this microhabitat are a type of infauna called meiofauna. Ecology and Ecosystems Chapter 16 Pages 16-3 to 16-5

10. Ecology Terminology • An organism’s role in its habitat is called itsniche. • Very different species can occupy the same niche. On coral reefs, for example, cleaner-shrimp and cleaner-fish both survive by feeding on the parasites and dead or injured skin of reef fish. • To avoid confusing habitat and niche, think of the habitat is an organism’s address, and the niche as it’s job. Ecology and Ecosystems Chapter 16 Pages 16-3 to 16-5

11. Energy Flow and Nutrient Cycles • Trophic relationships and nutrient cycles are concepts fundamental to ecology. • They describe how energy and matter form the basis for interaction among organisms and between organisms and the environment. • Recall that photosynthesizers and chemosynthesizers bring energy from the sun and chemicals into the food web. • This energy transfers up through the food web, but most of the energy gets lost as heat in the process. • Only about 10% of the available energy passes from one trophic level to the next. Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

12. Energy Flow and Nutrient Cycles Energy flow. This illustration shows how energy flows through a functioning ecosystem. Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

13. Energy Flow and Nutrient Cycles • The energy flow through the food web affects an ecosystem by determining how much energy is available for organisms at higher trophic levels. • In all ecosystems, there are fewer high-level predators than low-level prey. • The amount of primary production shapes the ecosystem. • High primary production creates the potential for more organisms at high trophic levels, and the potential for more trophic levels. • Anything that affects energy flow will also affect the ecosystem. • Even with ample primary production the ecosystem would lose many of the high-level organisms in its community. Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

14. Energy Flow and Nutrient Cycles Interrupted energy flow. A substantial decline in an ecosystem’s primary consumers disrupts energy flow to higher trophic levels. Here we see a reduction of the amount and types of prey available to killer whales. The whale population will suffer in this ecosystem unless they move on to an area with more productivity, or more primary consumers to transfer energy to higher trophic levels. Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

15. Energy Flow and Nutrient Cycles • Energy flows through an ecosystem, eventually being lost as heat into the water, atmosphere, and space. • Nutrients, on the other hand, aren’t lost. • Carbon, nitrogen, phosphorus, and other crucial elements cycle through the Earth’s ecosystems. Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

16. Energy Flow and Nutrient Cycles • The nitrogen nutrient cycle is thought to be more limited in marine ecosystems than in terrestrial ecosystems. • Because: Inorganic nitrogen must be fixed into organic compounds before it can be used by organisms. • Nitrogen-fixing bacteria that do this live primarily in terrestrial ecosystems. • Seabird droppings, erosion, and runoff carry organic nitrogen compounds (and phosphorus) from terrestrial environments into the marine environment. • This is an example of how ecosystems don’t exist entirely in isolation. Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

17. Energy Flow and Nutrient Cycles Nitrogen Cycling Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

18. Energy Flow and Nutrient Cycles • The ecological significance of nutrient cycles is usually greater than that of energy flow. • Why? Nutrients are usually a limiting factor, whereas energy is usually not. Compare many warm, tropical marine ecosystems with cold, temperate marine ecosystems. • Tropical ecosystems generally have more energy (sunlight) available, yet oceanic conditions don’t supply as many nutrients to tropical regions. • One of the few highly productive marine ecosystems found in tropical waters is the coral reef. • Temperate coastal waters, by comparison, have less overall sunlight, but receive far more nutrients. For this reason, the most highly productive marine ecosystems are found in colder water. Ecology and Ecosystems Chapter 16 Pages 16-6 to 16-8

19. Ecosystems in the Open Sea Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-14

20. Euphotic Zone Ecosystems • The euphotic zone comprises only 1% of the ocean, yet the majority of marine life lives there. • Extends as deep as 200 meters (656 feet), but in coastal waters with more turbidity, light may only penetrate to about 30 meters (100 feet). • The euphotic zone is where photosynthetic organisms live, and light energy transfers through food webs as chemical energy. Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-12

21. Euphotic Zone Ecosystems • The neuston are the plankton that live in the uppermost layer of the ocean. • This ecosystem is very thin – only a few millimeters in many instances. • It receives the maximum sunlight and because it covers about 71% of the Earth’s surface. Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-12

22. Euphotic Zone Ecosystems • There have been surprisingly few studies to compare the neuston layers to the water layers below. • It is known that the first few millimeters to a few centimeters of water differ substantially from the water below. • Generally, neuston layers hold significantly more nutrients, chlorophyll a, and carbon compounds. • Surface tension supports eggs, larvae, and microscopic life on the top film of the water. • Cyanophyte, diatom, and dinoflagellate populations in the neuston ecosystem may be 10,000 times more numerous than in the water just a few millimeters deeper. • This makes the neuston zone an important ecosystem for worldwide primary productivity. Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-12

23. Euphotic Zone Ecosystems • This isn’t true globally, however. In some places, photosynthesis and primary productivity are higher below the neuston ecosystem. • One reason may be photoinhibition. Photoinhibition seems to be prevalent in tropical seas. • Because there’s little water to protect neuston organisms, ultraviolet light may account for some of the photoinhibition. • If this is true, ozone depletion may make photoinhibition worse as even more UV light makes it to the Earth’s surface. Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-12

24. Euphotic Zone Ecosystems • An important factor reducing primary productivity in the neuston ecosystem may be pollutants. • A variety of pollutants from the atmosphere and runoff enter the euphotic zone. • How pollutants affect the neuston ecosystems concerns scientists with respect to global climate change. • The ocean plays an important role in moderating global climate - particularly removing CO2. • Many oil-based chemicals, float on water, creating a barrier that slows or stops carbon dioxide (and other gases) from dissolving into the water below. By affecting the euphotic zone ecosystems, these pollutants may contribute to global climate change. Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-12

25. Euphotic Zone Ecosystems • Floating debris, whether natural or human-produced, acts as potential shelter and attracts marine life. • This creates distinct neustonic ecosystems that thrive around floating material in the water. • The world’s largest floating ecosystem is the Sargasso Sea - a complex community. • Sargassum mat organisms include tiny fish of many species, crustaceans, and other organisms. • On the other hand, the Sargassum fish is a species of frogfish adapted specifically to this ecosystem. It blends in with the Sargassum, preying on small crustaceans and fish. Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-12

26. Euphotic Zone Ecosystems • The Sargasso Sea and other euphotic zone ecosystems found around floating debris provide another example of how ecosystems interact. • Predatory fish hide under Sargassum or debris, feeding on fish and other neustonic organisms that live there. • These predators in turn provide food for pelagic fish, sharks, dolphins, and other large predators. Ecosystems in the Open Sea Chapter 16 Pages 16-10 to 16-12

27. Continental Shelf Ecosystems • The neritic zone consists of the water between the low-tide mark and the edge of the continental shelf. • This zone can range from only a few to several hundred kilometers or miles wide. • The neritic zone is a significant marine ecosystem because it is the most productive region in the ocean. • The area tends to keep nutrients in the shallow, photic zone and helps retain heat from the sun. • Being near the shoreline - the neritic zone benefits from nutrients in river runoff also. • Nutrients rising with currents from deep water at the shelf edges also make this zone biologically rich. • All of these factors combine to make the neritic zone a highly productive ecosystem. Ecosystems in the Open Sea Chapter 16 Pages 16-12 to 16-14

28. Continental Shelf Ecosystems Ecosystems in the Open Sea Chapter 16 Pages 16-12 to 16-14 Neritic Zone Productivity

29. Continental Shelf Ecosystems • Upwelling plays a significant role in the balance of coastal ocean ecosystems. • This is because upwelling brings nutrients from deeper water to shallow, more productive depths. • This is especially significant with respect to fecal pellets and other nutrients that sink to the relatively less productive bottom in the abyssal zone. • Wind causes upwelling that returns nutrients to the upper ocean depths. Ecosystems in the Open Sea Chapter 16 Pages 16-12 to 16-14

30. Continental Shelf Ecosystems • The role of upwelling is unmistakable. • Areas with the highest upwelling activity also have the highest nutrient levels. • These correspond with many of the ocean’s highest productivity regions. • Examples include the waters offshore of Peru, the Bering Sea, the Grand Banks in the Atlantic, and the deep water surrounding Antarctica. Ecosystems in the Open Sea Chapter 16 Pages 16-12 to 16-14

31. Continental Shelf Ecosystems Ecosystems in the Open Sea Chapter 16 Pages 16-12 to 16-14 Areas of Coastal Upwelling

32. Coastal Ecosystems - Estuaries, Salt Marshes,Mangrove Swamps, Seagrasses Coastal Ecosystems - Part 1 Chapter 16 Pages 16-15 to 16-22

33. High Productivity Marine Environments • Coastal ecosystems are generally highly productive ecosystems for several reasons. • They benefit from nutrient-rich runoff from land. Because they’re shallow, the benthic organisms in these ecosystems live in the upper photic zone, instead of the bottom as in the open sea. • Salt-tolerant plants can grow in the well-lit shallows, providing shelter. These plants act as the foundation for several different types of ecosystems that cannot exist in the open ocean. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-15

34. High Productivity Marine Environments • The combination of nutrients, ample light, and shelter make coastal ecosystems diverse and rich. • While you don’t commonly find large organisms here (though there are some), these ecosystems provide a haven for juveniles of open ocean species. • Mangrove swamps contribute to the health of coral reefs in this way. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-15

35. High Productivity Marine Environments • Human activities have wide-ranging potential effects on coastal ecosystems. • The effects are varied and immediately at hand. • People have always tended to live near water, putting humans in proximity with these ecosystems - this causes problems. • Agriculture, for example, can alter these ecosystems when excess fertilizer washes seaward with rain runoff. Can you name more? • The variety of human activities is so wide we can’t always anticipate all the consequences to ecosystems. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-15

36. High Productivity Marine Environments • Because the effects are immediately at hand, coastal ecosystems may experience the consequences more severely. • Pollutants, for example, often reach coastal ecosystems in concentrated form. • Open ocean ecosystems, by contrast, benefit from a diluting effect. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-15

37. High Productivity Marine Environments • One particular concern with coastal ecosystems is eutrophication, which is an overabundance of nutrients that causes an ecological imbalance. • Eutrophication is a stimulus to some species and a detriment to others. • Fertilizer runoff can dump excess nutrients in the water, stimulating excessive algae growth or algae blooms. When the algae die, degradation of biomass consumes available oxygen. • The depletion of oxygen kills fish and other sea life. • Although there are other causes of harmful algae blooms (HABs), eutrophication is the most conspicuous. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-15

38. Estuaries • Estuaries exist where the tides meet rivers. • They’re not found where all rivers enter the sea, but they’re common where the tidal range is high. • This allows high tide to push well up river, often flooding large land areas. • Estuaries may be large, complex deltas with multiple inlets, lagoons, and islets or they may be simple wide stretches of river entering the sea. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

39. Estuaries Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

40. Estuaries • Estuaries tend to trap and accumulate runoff sediments, so they’re rich with nutrients and biologically productive. • Most of the major North American rivers flowing into the Atlantic flow first into estuaries. • This is why the North Atlantic doesn’t have as much sediment flowing in to it as other ocean basins have with comparable rivers. • Estuaries trap much of the sediment. This also makes estuaries sensitive to eutrophication because the same process traps excess nutrients such as fertilizer runoff. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

41. Estuaries • Estuaries act as a dumping ground, filter, and absorber of nutrients (and pollutants). • Estuaries are the kidneys of the biosphere because of their cleansing function. • The continuous replenishment of nutrients results in ecosystems with high primary productivity from algae and halophytes - saltwater plants. These, in turn, support a large community of primary and secondary consumers. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

42. Estuaries • Some factors limit productivity in estuaries. • One is that organisms in this ecosystem must tolerate wide salinity ranges. • The osmotic stress caused by the rising and falling tides mixing with fresh water proves fatal to many organisms. • Organisms that tolerate wide salinity ranges are called euryhaline organisms. Therefore, variations in salinity tend to reduce the variety of species. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

43. Estuaries • Another productivity limit results from the tendency of decomposition to deplete the oxygen in the nutrient-rich sediments. • This limits the benthic organisms that can thrive in estuaries. • The rotten eggs smell common to these areas comes from sulfides released by thriving anaerobic sulfur bacteria. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

44. Estuaries • Estuaries provide a region of shallow, sheltered water and nutrients, making them excellent nurseries. • By providing a rich haven, larvae and juveniles of open ocean species can elude predation and grow before venturing out to sea. • Estimates show that estuary ecosystems serve as nurseries for more than 75% of commercial fish species. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

45. Estuaries • Estuaries contribute to the productivity of adjacent marine ecosystems in at least two ways. • First, surviving juveniles migrate from the estuaries as they grow and mature. They increase the number of individuals that survive the hazardous larval and juvenile stages. • Second, estuaries provide a steady stream of nutrients to adjacent marine ecosystems, while trapping sediment and other materials in runoff from rain and storms. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-16 to 16-17

46. Salt Marshes • Salt marshes exist in estuaries and along the coasts. • They are found where flat, gently sloping shore are washed by the tides with nutrient-rich sediments. • Rivers provide a source of sediments and nutrition. • Conditions within a salt marsh vary, which affects the types of organisms inhabiting different areas within the ecosystem. • The upper marsh includes the areas only rarely flooded by the tides. • The lower marsh includes areas flooded by salt water as a regular part of the tidal cycle. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-17 to 16-19

47. Salt Marshes Salt Marsh Plant Community Coastal Ecosystems - Part 1 Chapter 16 Pages 16-17 to 16-19

48. Salt Marshes • Most plants can’t live in seawater because osmosis dehydrates them. • Halophytes, on the other hand, have adaptations that allow them to survive in salt water. • Thanks to these adaptations, halophytes occupy a niche with little competition from other plants, and become the dominant species. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-17 to 16-19

49. Salt Marshes • Halophytes in the lower marsh deal with constant osmotic stress. • The hollow reed Spartina sp., called cordgrass, is a good example of halophyte adaptation to this part of the ecosystem. • Spartina sp. excludes salt from its tissues and moves oxygen it produces by photosynthesis to its roots. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-17 to 16-19

50. Salt Marshes • Plants in the upper marsh don’t have to deal with daily tides. • In addition, the inflow of fresh water dilutes salt water, reducing osmotic stress. • Organisms thriving in this part of the ecosystem adapt differently. One example is Salicornia sp., or pickleweed. Coastal Ecosystems - Part 1 Chapter 16 Pages 16-17 to 16-19