Key Concepts: Ch. 7

1. Key Concepts: Ch. 7 • Factors that influence aquatic systems • Saltwater life zones • Freshwater life zones • Human activities that affect aquatic systems

2. Aquatic Life Zones: Types • Marine systems: Contain high salinity: particularly estuaries, coastlines, coral reefs, coastal marshes, mangrove swamps,and oceans. • Freshwater systems: Very low or no salinity: particularly lakes and ponds, streams and rives, and inland wetlands.

3. Aquatic Life Zones: Types Fig. 7-2 p. 145

4. Aquatic Life Zones: Components • Plankton: free floating microscopic organisms. May be autotrophic (phytoplankton ) or heterotrophic (zooplankton) • Nekton: free swimming organisms • Benthos: bottom dwelling and attached organisms • Decomposers:mostly bacteria, breakdown waste and dead organisms and make available to producers.

5. Aquatic Life Zones: Limiting Factors • Aquatic zones are divided into three layers: surface, middle and bottom • Limiting Factors:determine types and numbers of organisms found in each layer are temperature, sunlight, dissolved oxygen, nutrient availability. • Euphotic zone: Light penetrating zone, maximum of 200m deep. Major limiting factor • Dissolved oxygen: major limiting factor in aquatic environments

6. Dissolved Levels of Oxygen and Carbon Dioxide

7. Saltwater Life Zones • The oceans cover 71% of the earth surface • Makeup 99.5% of world’s habitable volume • Contain 250,000 known species • Provide economic and ecological services. • Divided into the coastal zone and open sea.

8. Saltwater Life Zones: Coastal Zones • Coastal zone: warm nutrient rich shallow water that extends from the high-tide mark on land to the edge of the continental shelf. • Less than 10% of ocean area but 90% of all marine species • Very high NPP per unit area

9. Saltwater Life Zones: Coastal Zones • Estuaries: Partially enclosed area of coastal water where seawater mix with fresh water and nutrients from rivers, streams and runoff from land • Coastal wetlands: land area covered with water all or part of the year. Associated with estuaries • Examples include: 1. mangrove forest swamps in tropical waters, 2. salt marshes in temperate zones, 3. River mouths, 4. Bays, 5. Inlets, and 6. Sounds.

10. Coastal Wetlands and Estuaries Temperature and salinity are influenced by tides, seasonal variations in the flow of freshwater, and unpredictable freshwater from rains and saltwater from storms

11. Intertidal Zones: Rocky Shores and Sandy Shores • Intertidal zone: shoreline between the high tide and the low tide • Very stressful zone and organisms must avoid being swept away or crushed by waves, immersed during high tides, left high and dry (and hot) at low tides, and changing salinity. • Rocky shore: tide pools, rocky intertidal, waves crashing and organisms stick to the rocks to prevent from being washed away • Sandy shore (barrier beaches): organisms burrow to prevent from exposure, also lots of birds to feed on burrowed organisms.

12. Rocky Shore Organisms

13. Sandy Shore Organisms

14. Sandy Shore Organisms

15. Intertidal Zones: Barrier Islands • Barrier Islands: long, thin, low offshore islands of sediment that generally run parallel to the shore. Found along the Atlantic and Gulf coasts of the U.S. • Mainly protect the mainland and the estuaries and wetlands from wave energy. • Constantly eroding and shifting sand.

16. Coral Reefs • Form in clear warm coastal water in the tropics and subtropics. • Most diverse marine environment (1/4 of all marine species) and very productive. • Organisms fall into three main groups: attached, that give the reef its structure; fishes; and small organisms that bore into, attach to, or hide within the reef. • Very vulnerable ecosystem because it grows slowly, disrupted easily, thrive only in clear warm and fairly shallow water of constant high salinity, narrow temperature range (cause coral bleaching with just an increase of 1 degree Celsius. (see fig. 7-17)

17. Coral Reefs Fig. 7-16 p. 154

18. Ocean Zones Fig. 7-7 p. 148

19. Open Ocean Zones • Euphotic Zone: upper 200m where light penetrates for photosynthesis, low nutrient levels, high dissolved oxygen • Bathyal zone: dimly lit middle zone zooplankton and small fishes that migrate to euphotic zone for food. • Abyssal zone: dark lower zone very cold, little dissolved oxygen, and has enough nutrients on the ocean floor to support 98% of the identified species. Many are deposit feeders or filter feeders. • Low avg. and NPP but overall largest contribution to the earth’s total NPP (due to size)

20. Human Impact on the Marine Life Zones • Salt marshes, mangrove forests, and sea grass meadows– marine nurseries– are being lost or degraded by real estate developments • Loss of wetlands (more than half worldwide) by filling in for development and agriculture • 35% of original mangrove forests have disappeared for development, rice fields nad aquaculture. • 70% of world’s beaches have eroded • Ocean bottom habitats are degraded by dredging and trawlers • Coral reefs severely damaged or destroyed.

21. Freshwater Life Zones Freshwater life zones occur where water with a dissolved salt concentration of < 1% by volume accumulates on or flows through the surfaces of terrestrial biomes. • Standing water (Lentic):standing bodies of freshwawter sucha s lakes ponds, and inland wetlands. • Flowing water (Lotic): flowing systems such as streams and rivers.

22. Freshwater Life Zones • Ponds are shallow and light will penetrates to the bottom therefore there is only one life zone. • Lakes are normally characterized by having four distinct zones based on depth and distance from shore. • Littoral zone: sahllow sunlit waters near the shore to the depth of rooted plants. • Limnetic zone: the open sunlit water surface layer away from the shore that goes as deep as the sunlight photosynthetic layer • Profundal zone: the deep open water, too dark for photosynthesis. Cooler and darker water with low DO. • Benthic zone: the bottom of the lake. Cool temperatures and low DO.

23. Freshwater Life Zones Fig. 7-20 p. 158

24. Fig. 7-21 p. 158 Types of Lakes: Oligotrophic Poorly nourished lake. Usually a newly formed lake with a small supply of nutrients and is deep with steep banks. Low NPP and crystal clear blue or green water small populations of phytoplankton and fish

25. Fig. 7-21 p. 158 Types of Lakes: Eutrophic A lake with a large or excessive supply of nutrients (N and P). Usually murky brown or green, poor visibility, high NPP. Bottom layer may become deoxygenated and life will die. Human inputs of nutrients causes Cultural Eutrophication. Mesotrophic lakes are in between oligotrophic and eutrophic.

26. Thermal Stratification in Temperate Lakes • Epilimnion: upper layer of warm water with high levels of DO. • Thermocline: where the water temperature changes rapidly with depth and with moderate levels of DO. Acts as a barrier during the summer to preventtransfer of nutrients and DO between the hypolimnion and the epilimnion • Hypolimnion: Lower layer of colder, denser water. Usually with low DO due to not being exposed to the atmosphere.

27. Fig. 7-22 p. 159 Seasonal Changes in Lakes • Fall overturn: surface water cools and becomes denser and sinks. The thermocline disappears. • Spring overturn: surface water teaches max. density and sinks through the lower layers Both bring nutrients from the bottom and DO from the top and cause even mixing and distribution of temperature and life.

28. River Systems • Surface water: precipitation that does not sink into the ground or evaporate • Runoff: water that flows into streams • Watershed or drainage basin: The land area that delivers runoff, sediment and dissolved substances to a stream

29. Water movement downward • Water travels from mountain areas and flows downward through three life zones: • Source zone: narrow head water or mountain highland streams of cold, clear water rushing over waterfalls and rapids. High DO, plants attached to rocks, cold-water fish which need lots of DO. • Transition zone: the headwater streams merge to form wider, deeper streams that flow down gentler slopes. Warmer water helps to support more producers and cool-water and warm –water fish with low DO needs. • Floodplain zone: streams join into wider and deeper rivers that meander across broad, flat valleys. Higher temperatures, low DO. Slow moving meandering rivers with large populations of phytoplankton, muddy, and lots of silt, fish like carp and catfish.

30. Fig. 7-23 p. 160 River Systems

31. Inland Wetlands • Lands covered with fresh water all or part of the time (excluding rivers, lakes and reservoirs and streams) located away from the shore • They include: • Marshes (with few trees) • Swamps (dominated by trees and shrubs) • Prairie potholes (depressions carved by glaciers) • Floodplains (receive excess water from runoff) • Bogs and fens (waterlogged soils which tend to contain Peat and may or may not have trees) • Wet Artic Tundra (summer)

32. Inland Wetlands Fig. 7-25 p. 162

33. Human Impact on Freshwater Ecosystems • Large rivers are strongly or moderately fragmented by dams, diversions, or canals. This alters or destroys the habitats along rivers and coastal deltas and estuaries by reducing flow. • Flood control levees and dikes built along rivers alter and destroy habitats, disconnect rivers from their floodplains, and eliminate wetlands and backwater for spawning. • Wetlands have been drained for development or agriculture. Causes an increase in flood and drought damage.

34. Sustainability of Aquatic Life Zones • Coral reef destruction • Loss of biodiversity • Pollution • Sedimentation • Renewability • Natural purification