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Types of aquatic life zones:Types of aquatic life zones:
Saltwater or marine Saltwater or marine Estuaries, coastlines, Estuaries, coastlines,
coral reefs, coastal coral reefs, coastal marshes, mangrove marshes, mangrove swamps, and oceansswamps, and oceans
FreshwaterFreshwater Lakes and ponds, Lakes and ponds,
streams and rivers, streams and rivers, and inland wetlandsand inland wetlands
Major types of organismsMajor types of organisms Phytoplankton – plant planktonPhytoplankton – plant plankton
Free-floating microscopic Free-floating microscopic cyanobacteria and algaecyanobacteria and algae
• The producers and the basis The producers and the basis of the food chainof the food chain
Zooplankton – animal planktonZooplankton – animal plankton Nonphotosynthetic herbivores Nonphotosynthetic herbivores
that feed on phytoplanktonthat feed on phytoplankton Secondary consumers that Secondary consumers that
feed on other zooplanktonfeed on other zooplankton• Range from single-celled Range from single-celled
protozoa to large protozoa to large invertebrates such as jellyfish.invertebrates such as jellyfish.
NektonNekton Fish, turtles, and whalesFish, turtles, and whales
Benthos Benthos Bottom-dwellers – barnacles & Bottom-dwellers – barnacles &
oysters that anchor to one oysters that anchor to one spotspot
Worms – burrow into sand or Worms – burrow into sand or mudmud
Lobsters and crabs – walk on Lobsters and crabs – walk on the bottomthe bottom
Some are filter-feedersSome are filter-feeders Decomposers Decomposers
Bacteria that break down Bacteria that break down organic compoundsorganic compounds
Key Characteristics of aquatic Key Characteristics of aquatic organismsorganisms
Less pronounced and fixed physical Less pronounced and fixed physical boundaries; therefore difficult to count and boundaries; therefore difficult to count and manage populationsmanage populations
More complex and longer food chainsMore complex and longer food chains More difficult to monitor and study More difficult to monitor and study
because of their size and they are hidden because of their size and they are hidden from view.from view.
Limiting FactorsLimiting Factors
Aquatic life zones are divided into three Aquatic life zones are divided into three layers – surface, middle, and bottomlayers – surface, middle, and bottom
Factors are:Factors are: TemperatureTemperature Access to Access to sunlightsunlight for photosynthesis for photosynthesis Dissolved oxygenDissolved oxygen (DO) content (DO) content Availability of Availability of nutrients nutrients such as carbon (COsuch as carbon (CO22),), nitrogen (NOnitrogen (NO33), and phosphorus (PO), and phosphorus (PO44) for ) for
producersproducers
Photosynthesis can take place only as deep as Photosynthesis can take place only as deep as light can penetrate (euphotic zone)light can penetrate (euphotic zone)
Oxygen gets in from photosynthesis and Oxygen gets in from photosynthesis and diffusion for air and is removed by aerobic diffusion for air and is removed by aerobic respiration (includes decomposition)respiration (includes decomposition) OO22 can vary greatly in aquatic ecosystems can vary greatly in aquatic ecosystems Most aquatic organisms cannot survive below 5 ppm Most aquatic organisms cannot survive below 5 ppm
of DOof DO DO and CODO and CO22 concentrations vary with depth concentrations vary with depth
Why are oceans important?Why are oceans important?
Cover 71% of earth’s surfaceCover 71% of earth’s surface Contain about 250,000 known speciesContain about 250,000 known species Provide many ecological and economic Provide many ecological and economic
servicesservices Less that 5% has been explored and Less that 5% has been explored and
mappedmapped
Coastal zoneCoastal zone
Warm,nutrient-Warm,nutrient-rich,shallow water that rich,shallow water that extends from the high tide extends from the high tide mark to the margin of the mark to the margin of the continental shelfcontinental shelf
makes up less than 10% makes up less than 10% of ocean but contains of ocean but contains 90% of all marine species 90% of all marine species and is especially and is especially important to commercial important to commercial fisheries.fisheries.
Gets:Gets: Sunlight and nutrientsSunlight and nutrients
Estuaries – a partially enclosed area where Estuaries – a partially enclosed area where seawater mixes with fresh waterseawater mixes with fresh water An ecotoneAn ecotone
Coastal Wetlands – covered by water all or part Coastal Wetlands – covered by water all or part of the yearof the year river mouths, inlets, bays, sounds, mangrove river mouths, inlets, bays, sounds, mangrove
swamps, and salt marshesswamps, and salt marshes Temperature and salinity vary widely Temperature and salinity vary widely
Tides, seasonal variation in water flow, unpredictable Tides, seasonal variation in water flow, unpredictable flows after heavy rains and floodsflows after heavy rains and floods
VERY PRODUCTIVE AREAS!VERY PRODUCTIVE AREAS!
Intertidal zone – area of Intertidal zone – area of shoreline between high shoreline between high and low tidesand low tides
Very stressful zone for Very stressful zone for organisms:organisms:
Wave stressWave stress Immersed during high tides Immersed during high tides
and dry during low tidesand dry during low tides Changing levels of salinityChanging levels of salinity Organisms usually cling to Organisms usually cling to
something, dig or hide in something, dig or hide in shells.shells.
Barrier IslandsBarrier Islands Long, thin, low Long, thin, low
offshore islands of offshore islands of sedement that sedement that generally run parallel generally run parallel to shoreto shore
Help protect mainlandHelp protect mainland Constantly shiftConstantly shift
Coral reefsCoral reefs
Form in clear, warm, coastal waters in tropics and Form in clear, warm, coastal waters in tropics and subtropicssubtropics
Have many types of organismsHave many types of organisms Attached – corals, algae, and spongesAttached – corals, algae, and sponges FishesFishes Small organisms that bore into or attach themselves to coralSmall organisms that bore into or attach themselves to coral
Easily damaged, grow slowly, can survive only in clear, Easily damaged, grow slowly, can survive only in clear, shallow, warm watershallow, warm water
Have been harmed by global warmingHave been harmed by global warming They face many threats from pollution and other human They face many threats from pollution and other human
activities.activities.
Open SeaOpen Sea Beyond the continental Beyond the continental
shelfshelf Euphotic zone: lighted Euphotic zone: lighted
upper areaupper area PhotosynthesisPhotosynthesis Low nutrient levelsLow nutrient levels High DOHigh DO
Bathyl zone: dimly lit Bathyl zone: dimly lit middle zonemiddle zone
No photosynthesisNo photosynthesis Abyssal zone: dark lower Abyssal zone: dark lower
zonezone Very coldVery cold Little DOLittle DO Many nutrientsMany nutrients
Some open sea organismsSome open sea organisms
Deposit feedersDeposit feeders Take mud into their Take mud into their
bodies and extract bodies and extract nutrients from itnutrients from it
Filter feedersFilter feeders Pass water through or Pass water through or
over their bodies and over their bodies and extract nutrients from itextract nutrients from it
Average primary Average primary productivity & NPP productivity & NPP are low.are low.
Human ImpactHuman Impact
Losing coastal areas to developmentLosing coastal areas to development Housing, marinas, golf coursesHousing, marinas, golf courses
Filling in for agricultureFilling in for agriculture Much beach erosion due to development Much beach erosion due to development
and rising sea levelsand rising sea levels Dredging and heavy nets used in trawling Dredging and heavy nets used in trawling
is destroying bottom habitatsis destroying bottom habitats Coral reefs are being severely damagedCoral reefs are being severely damaged
Freshwater life zonesFreshwater life zones
Found where water with a dissolved salt Found where water with a dissolved salt concentration of less than 1% by volume either concentration of less than 1% by volume either accumulates or flows through the surfaces of accumulates or flows through the surfaces of terrestrial biomes.terrestrial biomes. Standing water – lakes, ponds, inland wetlandsStanding water – lakes, ponds, inland wetlands Flowing water – streams and riversFlowing water – streams and rivers
Covers less than 1% of the earth’s surface but Covers less than 1% of the earth’s surface but ecologically and economically importantecologically and economically important
Are very closely connected to terrestrial biomes Are very closely connected to terrestrial biomes due to nutrient run-offdue to nutrient run-off
Life zonesLife zones Ponds – shallow – light often penetrates to the Ponds – shallow – light often penetrates to the
bottom – usually have only one zonebottom – usually have only one zone Lakes – deeper – generally consist of four zones Lakes – deeper – generally consist of four zones
– defined by depth and distance from shore– defined by depth and distance from shore Littoral zone – shallow water near shore where rooted Littoral zone – shallow water near shore where rooted
plants growplants grow Limnetic zone – open sunlit water away from shore – Limnetic zone – open sunlit water away from shore –
as deep as sunlight penetratesas deep as sunlight penetrates Profundal zone – deep open water that receives no Profundal zone – deep open water that receives no
sunlight – cool so although oxygen is low, some fish sunlight – cool so although oxygen is low, some fish live here.live here.
Benthic zone – bottom of lake – cool temperatures Benthic zone – bottom of lake – cool temperatures and low oxygenand low oxygen
Freshwater Systems
Ecological Services Economic Services
• Climate moderation
• Nutrient cycling
• Waste treatment and dilution
• Flood control
• Groundwater recharge
• Habitats for aquatic and terrestrial species
• Genetic resources and biodiversity
• Scientific information
• Food
• Drinking water
• Irrigation water
• Hydroelectricity
• Transportation corridors
• Recreation
• Employment
© 2004 Brooks/Cole – Thomson Learning
Eutrophication – the natural ageing Eutrophication – the natural ageing of a lakeof a lake
Classify lakes according to nutrient content and Classify lakes according to nutrient content and primary productivityprimary productivity
OLIGOTROPHIC LAKE – low nutrientsOLIGOTROPHIC LAKE – low nutrients Geographically youngGeographically young DeepDeep Blue in colorBlue in color ColderColder Low populations of phytoplanktonLow populations of phytoplankton More desirable fish – bass and troutMore desirable fish – bass and trout Low NPPLow NPP
EUTROPHIC LAKE – many nutrientsEUTROPHIC LAKE – many nutrients Old lakeOld lake ShallowShallow Green or brown in color (algae)Green or brown in color (algae) WarmerWarmer Algal blooms are commonAlgal blooms are common Less desirable types of fish – catfish, carpLess desirable types of fish – catfish, carp High NPPHigh NPP
FigurFigure 7-e 7-2121
Page Page 158158
Sunlight
Little shore vegetation
Limnetic zone
Profundalzone
Oligotrophic lake
Low concentration of nutrients and plankton
Sparse fish population
Narrow littoral zone
Sleepily sloping shorelines
Sand, gravel, rock bottom
Sunlight
Much shore vegetation
Limnetic zone
Profundalzone
Eutrophic lake
High concentration of nutrients and plankton
Dense fish population
Widelittoral zone
Gentlysloping shorelines
Silt, sand, clay bottom
Cultural EutrophicationCultural Eutrophication
Humans add nutrients from the Humans add nutrients from the atmosphere, urban, and agricultural areas atmosphere, urban, and agricultural areas accelerate eutrophication.accelerate eutrophication.
SEASONAL CHANGES IN LAKESSEASONAL CHANGES IN LAKES
Occurs in temperate lakeOccurs in temperate lake Makes use of the property of water that it Makes use of the property of water that it
is less dense as a solid (0is less dense as a solid (0ooC) then it is at a C) then it is at a liquid (4liquid (4ooC);therefore ice floats on water.C);therefore ice floats on water.
This causes THERMAL STRATIFICATION This causes THERMAL STRATIFICATION of deep lakesof deep lakes
SummerSummer
Lakes have three distinct layers:Lakes have three distinct layers: EPILIMNION – upper layer of warm water high levels of EPILIMNION – upper layer of warm water high levels of
DODO THERMOCLINE – layer where the temperature changes THERMOCLINE – layer where the temperature changes
with depth – usually 1with depth – usually 1ooC/meter increase in depth – C/meter increase in depth – moderate oxygen – during summer acts as a barrier moderate oxygen – during summer acts as a barrier between epilimnion and hypolimnionbetween epilimnion and hypolimnion
HYPOLIMNION – bottom layer of cold, dense water – HYPOLIMNION – bottom layer of cold, dense water – low DOlow DO
To keep cool fish would be at the bottom but low DO To keep cool fish would be at the bottom but low DO therethere
Fall OverturnFall Overturn
Water begans to cool, becomes more Water begans to cool, becomes more dense and sinks to the bottom dense and sinks to the bottom
The thermocline disappearsThe thermocline disappears Water mixes – nutrients are carried to the Water mixes – nutrients are carried to the
top and oxygen to the bottom. Fish can be top and oxygen to the bottom. Fish can be found at all depthsfound at all depths
WinterWinter
Lake separates into layers again due to Lake separates into layers again due to difference in density.difference in density.
Warmest (4Warmest (4ooC)water is at the bottomC)water is at the bottom Thermocline is reversedThermocline is reversed Coldest water is at the top and freezes Coldest water is at the top and freezes
forming ice which insulates and protects forming ice which insulates and protects the lake.the lake.
Spring overturnSpring overturn
Water begins to warm upWater begins to warm up Wind blows causing vertical currentsWind blows causing vertical currents Lake overturns again bring nutrients to the Lake overturns again bring nutrients to the
top and oxygen to the bottomtop and oxygen to the bottom
Characteristics of FreshwaterCharacteristics of Freshwater
Surface water forms when precipitation Surface water forms when precipitation that does not sink into the ground or that does not sink into the ground or evaporate becomes run-offevaporate becomes run-off
Watershed – the land area that delivers Watershed – the land area that delivers run-off, sediment, and dissolved run-off, sediment, and dissolved substances to a stream.substances to a stream.
Streams join together to form riversStreams join together to form rivers Rivers flow downhill to the oceanRivers flow downhill to the ocean
Inland wetlands – land covered with water Inland wetlands – land covered with water all or part of the year located away from all or part of the year located away from the oceanthe ocean Marshes – have a few treesMarshes – have a few trees Swamps –dominated by trees and shrubsSwamps –dominated by trees and shrubs Prairie potholes – depressions formed by Prairie potholes – depressions formed by
glaciersglaciers Floodplains – receive water during heavy Floodplains – receive water during heavy
rains or floodsrains or floods Bogs and fens – waterlogged peaty areasBogs and fens – waterlogged peaty areas
Human impactHuman impact
60% of the world’s largest rivers are 60% of the world’s largest rivers are fragmented by dams – destroys wildlife fragmented by dams – destroys wildlife and reduces water flowand reduces water flow
Flood control levees and dikes – destroy Flood control levees and dikes – destroy habitats, disconnect rivers from habitats, disconnect rivers from floodplains,and eliminate wetlandsfloodplains,and eliminate wetlands
In U.S. 53% of the wetlands have been In U.S. 53% of the wetlands have been drained or filled to grow crops – this has drained or filled to grow crops – this has increased floodingincreased flooding