Ch. 6 Aquatic Biodiversity and Life Zones

75% of Earth is covered with water 71% is Saltwater Salinity of the water determines the type of life that can survive

Marine LIFE ZONES ESTUARIES COASTAL MARSHES (WETLANDS) MANGROVE SWAMPS (FORESTS) CORAL REEFS COASTLINES OCEANS

Estuary and Coastal Wetlands Estuaries are rivers that meet the sea where seawater mixes with freshwater (brackish water). Coastal wetlands are land areas covered with water some or all of the year. river mouths, inlets, bays, sounds, salt marshes=temperate zones Mangrove forests=tropical zones

Estuaries and Coastal Wetlands: Centers of Productivity Estuaries include river mouths, inlets, bays, sounds, salt marshes in temperate zones and mangrove forests in tropical zones. Figure 6-7

WETLANDS Fig. 6-7b, p. 131 Figure 6.7 Natural capital: some components and interactions in a salt marsh ecosystem in a temperate area such as the United States. When these organisms die, decomposers break down their organic matter into minerals used by plants. Colored arrows indicate transfers of matter and energy between consumers (herbivores), secondary or higher-level consumers (carnivores), and decomposers. Organisms are not drawn to scale. The photo below shows a salt marsh in Peru. Fig. 6-7b, p. 131

Mangrove Forests Are found along about 70% of gently sloping sandy and silty coastlines in tropical and subtropical regions. Figure 6-8

Estuaries and Coastal Wetlands: Centers of Productivity Estuaries and coastal marshes provide ecological and economic services. Filter toxic pollutants, excess plant nutrients, sediments, and other pollutants. Reduce storm damage by absorbing waves and storing excess water produced by storms and tsunamis. Provide food, habitats and nursery sites for many aquatic species.

CORAL REEFS Where does the color of the coral come from? Video- polyps and zooxanthellae

What are benefits of coral reefs? Remove Carbon Dioxide from water (too much CO2 can form (carbonic acid) Ca2CO3!!) Protects coastlines from waves=erosion Habitat for marine life Supports fishing and tourism

What causes this?

THREATS TO CORAL REEFS

The Coastal Zone (COASTLINE): Where Most of the Action Is The coastal zone: the warm, nutrient-rich, shallow water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf. The coastal zone makes up less than 10% of the world’s ocean area but contains 90% of all marine species. Provides numerous ecological and economic services. Subject to human disturbance.

High tide Coastal Zone Open Sea Sun Low tide Sea level Photosynthesis Euphotic Zone Estuarine Zone Continental shelf Bathyal Zone Twilight Abyssal Zone Figure 6.5 Natural capital: major life zones in an ocean (not drawn to scale). Actual depths of zones may vary. Darkness Fig. 6-5, p. 130

Rocky and Sandy Shores: Living with the Tides Organisms experiencing daily low and high tides have evolved a number of ways to survive under harsh and changing conditions. Gravitational pull by moon and sun causes tides. Intertidal Zone: area of shoreline between low and high tides.

Rocky and Sandy Shores: Living with the Tides Organisms in intertidal zone develop specialized niches to deal with daily changes in: Temperature Salinity Wave action Figure 6-9

Levels of Open ocean feeders: Plankton- 70% of primary productivity from Phytoplankton Zooplankton Ultraplankton Nekton Turtles fish Benthos- bottom dwellers Oysters, lobsters, crabs, worms Decomposers Specialized bacteria

Ocean Layers Euphotic zone: brightly lit surface layer. Nutrient levels low, dissolved O2 high, photosynthetic activity. Bathyal zone: dimly lit middle layer. No photosynthetic activity, zooplankton and fish live there and migrate to euphotic zone to feed at night. Abyssal zone: dark bottom layer. Very cold, little dissolved O2.

NPP is highest near surface where sun is abundant. Nitrates and Phosphates are limiting factors in open oceans and limit NPP. How do you think algal blooms affect NPP?

Benefits of a marine ecosystem.

FRESHWATER LIFE ZONES Freshwater life zones include: Standing (lentic) water such as lakes, ponds, and inland wetlands. Flowing (lotic) systems such as streams and rivers. Figure 6-14

Lakes: Water-Filled Depressions Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, and groundwater seepage consisting of: Littoral zone (near shore, shallow, with rooted plants). Limnetic zone (open, offshore area, sunlit). Profundal zone (deep, open water, too dark for photosynthesis). Benthic zone (bottom of lake, nourished by dead matter).

Lakes: Water-Filled Depressions Figure 6-15

Effects of Plant Nutrients on Lakes: Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. Oligotrophic (poorly nourished) lake: Usually newly formed lake with small supply of plant nutrient input. Eutrophic (well nourished) lake: Over time, sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant growth.

Effects of Plant Nutrients on Lakes: Too Much of a Good Thing Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. Figure 6-16

Effects of Plant Nutrients on Lakes: Cultural eutrophication: Human inputs of nutrients from the atmosphere and urban and agricultural areas can accelerate the eutrophication process.

Freshwater Inland Wetlands: Vital Sponges Inland wetlands act like natural sponges that absorb and store excess water from storms and provide a variety of wildlife habitats. Figure 6-18

Freshwater Inland Wetlands: Vital Sponges Filter and degrade pollutants. Reduce flooding and erosion by absorbing slowly releasing overflows. Help replenish stream flows during dry periods. Help recharge ground aquifers. Provide economic resources and recreation.

River Zones Source zone- cold water, clean, high DO (trout) Transition zone- somewhat stagnant deep water, lower DO, warmer (bass) Floodplain- algae, rooted aquatic plants, low DO, very warm, more stagnant water

Water flowing from mountains to the sea creates different aquatic conditions and habitats. Figure 6-17

Impacts of Human Activities on Freshwater Systems Dams, cities, farmlands, and filled-in wetlands alter and degrade freshwater habitats. Dams, diversions and canals have fragmented about 40% of the world’s 237 large rivers. Flood control levees and dikes alter and destroy aquatic habitats. Cities and farmlands add pollutants and excess plant nutrients to streams and rivers. Many inland wetlands have been drained or filled for agriculture or (sub)urban development.