Ch 7 Exam

Aquatic Life Zones

1. saltwater/marine (estuaries,coastlines, coral reeds, coastal marshes, mangrove swamps, oceans)

 

2. freshwater (lakes, ponds, streams, rivers, inland wetlands)

 

cover about 71% of the earth’s surface

;

giant circulatory system transporting water from one place to another as part of the earth’s water cycle

 

play vital roles in biological productivity, climate, biogeochemical cycles, biodiversity

Four Major types of Organisms

1. Plankton: free-floating; 3 types

-phtyoplankton/plant plankton: producers that support aquatic food chains/webs

-zooplanktion/animal plankton: primary consumers that feed on phytoplankton and seconday consumers that feed on other zooplankton

 -ultraplankton: much smaller; photosynthetic bacteria responsible for 70% of primary productivity near ocean surface

 

2. nekton: strongly swimming consumers (fish turtles whales)

 

3. benthos: dwell at bottom (oysters, worms, lobsters)

 

4. decomposers: bacteia that break down waster into sumple nutrient compounds

Aquatic vs. Terrestrial Systems

Aquatic Systems…

 

-have less pronounced and fixed boundaries

-have more complex/longer food chains/webs

-more difficult to monitor and study

 

Depths of Aquatic Life Zones

*temp, access to sunlight, dissolved oxygen, nutrients are factors that determine the types/#s of organims found in layers

 

1. Upper/Euphotic Zone: sunlight can penetrate through; more photosynthesis; dissolved O2 is higher; low levels of CO2

 

2. Deeper zones: Oxygen levels fall ans carbon dioxide levels rise due to aerobic respiration by animals and oxygen gas dissolves less in deep cold water

Coastal Zone

warm nutrient-rish, shallow water that extends from the high-tide mark on land to the gently-sloping, shallow edge of the continental shelf; contains 90% of all marine species; high net primary productivity per unit of area due to ample sunlight and plant nutrients

 

estuaries, coastal wetland, mangrove swamps

estuaries/coastal wetlands/mangrove swamps

estuary: partially enclosed area of coastal water where seawater mixes with freshwater and nutrients from rivers, streams and runoff from land

 

Temperature and salinity levels vary widely in estuaries and coastal wetlands due to tides/seasonal variations in the flow of freshwater into the estuary / unpredictable flows of freshwater after heavy rains and salt water after storms/hurricanes

 

constant water movement stirs up nutient-rich silt; filter toxic pollutants, excess plant nutrients, sediments and other pollutants

 

 Mangrove forest swamps: dominant organisms: trees that can grow in salt water; extensive roots that extend about water to get O2 and for support; nutrient rich forests in sheltered regions along tropical coasts

 

 

Intertidal Zone

area of shoreline between low and high tides

 

its organisms must be able to deal with tides and varying salinity; either hold on, dig in or hide in shells

Barrier Islands

low, narrow, sandy islands that form offshore from coastline; help protect mainland, estuaries, and coastal wetlands from storm waves

 

have one or more rows of natural sand dunes held in place my grass roots which serve as first line of defense against waves

Coral Reefs

form on clear, warm coastal waters; ecologically complex interactions among diverse organisms

 

vulnerable to damage because they grow slowly & disrupted easily; thrive only in clear warm fairly shallow water of constant high salinity

 

sediment runoff and human activities are biggest threats

Open ocean

sharp increase in water depth at the edge of the continental shelf separates coastal zone from vast volume of the ocean

 

divided into three vertical zones

 

1. euphotic zone:lighted upper zone where phytoplanktion photosynthesize; high oxygen low nutrients

 

2. bathyal zone: dimly lit middle zone; zooplankton and smaller fish

 

3. abyssal zone: dark, cold and little O2; enough nutrients on the ocean floor to support 98% of species living in the ocean

 

deposit feeders: take mud in and extract nutrients

 

filter feeders: pass water through/over bodies and extract nutrients

 

average primary productivity and NPP per unit are low except at an occasional equatorial upwelling

Freshwater Life Zones

water with a dissolved salt concentration of less than 1%

 

-standing (lentic) bodies (lakes, ponds, inland wetlands)

 

-flowing (lotic) bodies (streams, rivers)

 

less than 1% of earth’s surface

Lakes

large natural bodies of standing fresh water formed when precipitaion,;runoff or groundwater seepage fill depressions in the earth’s surface

 

depression can be caused by glaciation, crustal displacement, and volcanic activity

 

four distinct zones

 

1. littoral zone: shallow sunlit waters near shore to the depth at which rooted plants stop growing, high biological diversity; adequate nutrients from bottom sediments

 

2. limnetic zone: open sunlit water surface away from the shore that extensd to the depth penetrated by sunlight; main photosynthetic body of the lake

 

3. profundal zone: deep, open water where it is too dark for photosynthesis; low oxygen levels

 

4.benthic zone: bottom of the lake; decomposers, detritus feeders

 

-during the summer and winter the water in deep temperate zone lakes become stratified into different temperature layers which do not mix

 

-fall and spring the waters mix in overturns  that equalize the temp

types of lakes

-oligotropic lake: newly formed; small supply of plant nutrients; deep, steep banks; clear water; low net primary productivity

 

– eutropic lake: large or excessive supply of nutrients; murky water; high net primary productivity; bottom layer is depleted of dissolved oxygen in warm months

 

cultural eutrophication

 

mesotropic lakes: between two extremes

freshwater streams and rivers

surface water: precipitation that dusnt sink/evaporate

 

runoff: flows into streams

 

watershed/drainage basin: land area that delivers runoff, sediment to a stream

 

downward flow of surface water to sea has three dif zones

 

1. source zone:headwaters rush  downwards dissolving oxygen; not productive due to lack of nutrients

 

2. transition zone: wider, deeper streams that flow down gentler slopes; more producers(phytoplankton) and fish

 

3. floodplain zone: wider deeper rivers over flat valleys; higher temperature and less oxygen than first two zones; large amount of producers; muddy and lots of silt

 

inland wetlands

lands covered with fresh water and located away from coastal area

 (marshes, swamps, prairie potholes, floodplains)

human impacts on freshwater systems

1. dams, diversions, canals fragment 60% of worlds largest rivers

 

2. floor control levees alter and destroy habitats

 

3. cities and farmlands add pollutants and exess plant nutrients to streams/rivers

 

4. many inland wetlands have been drained