Chapter 7 Biodiversity in Aquatic Systems. Key Concepts Factors that influence aquatic systems Saltwater life zones Freshwater life zones Human.

Chapter 7Chapter 7Biodiversity in Aquatic Biodiversity in Aquatic

SystemsSystems

Key ConceptsKey Concepts

Factors that influence aquatic Factors that influence aquatic systemssystems

Saltwater life zonesSaltwater life zonesFreshwater life zonesFreshwater life zonesHuman activities that affect Human activities that affect

aquatic systemsaquatic systems

Mangroves

Coral reefs

Rivers

Lakes

Aquatic Life ZonesAquatic Life Zones

Aquatic life zones = aquatic biomes Aquatic life zones = aquatic biomes

2 major types2 major types

1. 1. saltwater or marinesaltwater or marine: estuaries, : estuaries, coastlines, coral reefs, coastal coastlines, coral reefs, coastal marshes, mangrove swamps, oceansmarshes, mangrove swamps, oceans

2. 2. freshwaterfreshwater: lakes, ponds, streams, : lakes, ponds, streams, rivers, inland wetlandsrivers, inland wetlands

What lives in water?What lives in water? PhytoplanktonPhytoplankton: plant plankton; : plant plankton;

producersproducers ZooplanktonZooplankton: animal plankton; : animal plankton;

herbivoresherbivores NektonNekton: consumers; strong swimmers; : consumers; strong swimmers;

fish, whales, turtlesfish, whales, turtles BenthosBenthos: bottom-dwellers; barnacles, : bottom-dwellers; barnacles,

worm that burrow, lobsters, crabsworm that burrow, lobsters, crabs DecomposersDecomposers: bacteria: bacteria

Advantages Advantages

Water buoyancy

Constant temperature

Nourishment from dissolved nutrients

Easy dispersal

Less exposure to UV radiation

Dilution ofpollutants

Disadvantages

Can tolerate a narrow range of temp.

Exposure to pollutants

Fluctuating population size

Aquatic offspring separated from parents

© 2004 Brooks/Cole – Thomson Learning

What Factors Limit Life?What Factors Limit Life? TemperatureTemperature

Access to sunlight for photosynthesis Access to sunlight for photosynthesis (mainly (mainly euphotic zoneeuphotic zone))

Dissolved oxygenDissolved oxygen: high near surface : high near surface (photosynthesis), low in deep, cool water (photosynthesis), low in deep, cool water

Availability of nutrients: fewer nutrients Availability of nutrients: fewer nutrients available in deep area (lower available in deep area (lower net primary net primary productivityproductivity))

Saltwater Life ZonesSaltwater Life ZonesOceans cover 71% of the planetOceans cover 71% of the planet

Oceans contain 250,000 Oceans contain 250,000 species of plants and animalsspecies of plants and animals

Oceans provide many Oceans provide many ecological and economic ecological and economic servicesservices

Figure 7-6Figure 7-6Page 147Page 147

Marine Systems

Ecological Services

• Climate moderation

• CO2 absorption

• Nutrient cycling

• Habitats and nursery areas for marine and terrestrial species

• Biodiversity

Economic Services

Animal and pet feed

Pharmaceuticals

Harbors and transportation routes

Recreation

Employment

Offshore oil and natural gas

Minerals

Marine Systems

Ocean Life ZonesOcean Life Zones1.1. Coastal ZoneCoastal Zone: shallow, nutrient-rich, : shallow, nutrient-rich,

warm, extends to warm, extends to continental shelf, continental shelf, 90% all ocean species (high or low 90% all ocean species (high or low NPP?)NPP?)

2.2. Euphotic ZoneEuphotic Zone: upper zone, : upper zone, photosynthesis, low nutrient levels, photosynthesis, low nutrient levels, dissolved Odissolved O2 2 highhigh

3.3. Bathyal ZoneBathyal Zone: dimly lit, no producers: dimly lit, no producers4.4. Abyssal ZoneAbyssal Zone: dark, deep ocean, : dark, deep ocean,

dissolved Odissolved O2 2 lowlow

Coral ReefsCoral Reefs Form in clear, coastal watersForm in clear, coastal waters Oldest, most diverse ecosystemsOldest, most diverse ecosystems Complex interaction between organismsComplex interaction between organisms Vulnerable to damage because:Vulnerable to damage because:

1.1. Grow slowlyGrow slowly

2.2. Disrupted easilyDisrupted easily

3.3. Thrive only in warm, clear, shallow waterThrive only in warm, clear, shallow water

Coral Reef

Ocean warming

Algae growth from fertilizer runoff

Rising sea levels

Increased UV exposure from ozone depletion

Using cyanide and dynamite to harvest coral reef fish

Coral removal for building material, aquariums, and jewelry

Damage from anchors, ships, and tourist divers

Threats to Coral Reefs

Coral BleachingCoral Bleaching: whitening of corals, due : whitening of corals, due to stress or death of their symbiotic to stress or death of their symbiotic protozoa (zooxanthellae), or due to the protozoa (zooxanthellae), or due to the loss of pigmentation within the protozoaloss of pigmentation within the protozoa

Under stress, corals may expel their Under stress, corals may expel their zooxanthellae, which leads to a lighter or zooxanthellae, which leads to a lighter or completely white appearance (“bleached”)completely white appearance (“bleached”)

Coral bleaching can be induced by:Coral bleaching can be induced by:

increased (most commonly) or reduced water increased (most commonly) or reduced water temperaturestemperatures

increased solar radiation increased solar radiation changes in water chemistry changes in water chemistry starvation caused by a decline in zooplanktonstarvation caused by a decline in zooplankton increased sedimentation (due to runoff) increased sedimentation (due to runoff) pathogen infections pathogen infections changes in salinity changes in salinity windwind low tide air exposurelow tide air exposure fishingfishing

Highly Productive AreasHighly Productive Areas EstuariesEstuaries: where saltwater mixes with : where saltwater mixes with

freshwater (ecotone)freshwater (ecotone) Coastal wetlandsCoastal wetlands: land areas covered with : land areas covered with

water (river mouths, inlets, bays)water (river mouths, inlets, bays) MangrovesMangroves: forest swamps; protect coastlines : forest swamps; protect coastlines

and coral reefs; important habitatand coral reefs; important habitat

* constant water movement stirs up nutrients, * constant water movement stirs up nutrients, making making estuariesestuaries and and wetlandswetlands very productive very productive areasareas

EstuaryEstuary

MangroveMangrove

Intertidal ZoneIntertidal Zone Area of shoreline between low and high Area of shoreline between low and high

tidestides Stressful zoneStressful zone Animals may be crushed or swept awayAnimals may be crushed or swept away

may be immersed during high tidemay be immersed during high tide

may be left to dry during low tidemay be left to dry during low tide Salinity is constantly changingSalinity is constantly changing ExampleExample: rocky shores, barrier beaches: rocky shores, barrier beaches

Rocky Shores and Barrier BeachesRocky Shores and Barrier Beaches

Intertidal ZonesIntertidal Zones Both have great variety of species, Both have great variety of species,

lots of available nicheslots of available niches Rocky shores have lots of pools in Rocky shores have lots of pools in

rocks where animals liverocks where animals live Barrier Beaches-most animals Barrier Beaches-most animals

survive by burrowing, digging, survive by burrowing, digging, tunneling in the sandtunneling in the sand

Rocky Shore Beach

Barrier BeachBarrier Beach

Barrier IslandsBarrier Islands Long, thin, low offshore islands of sedimentLong, thin, low offshore islands of sediment Parallel to the shoreParallel to the shore Protect mainland by dispersing storm waves Protect mainland by dispersing storm waves

(“barrier”)(“barrier”)

Human Impact on Marine Human Impact on Marine SystemsSystems

½ world’s original wetlands (91% Ca) have ½ world’s original wetlands (91% Ca) have been destroyed been destroyed

35% mangroves destroyed 35% mangroves destroyed 70% beaches eroding rapidly70% beaches eroding rapidly Boats with chains/nets destroy ocean bottom Boats with chains/nets destroy ocean bottom

habitatshabitats 27% coral reefs severely damaged27% coral reefs severely damaged 11% coral reefs destroyed11% coral reefs destroyed Prediction: 70% coral reefs destroyed by 2050Prediction: 70% coral reefs destroyed by 2050

Megalodon SharkMegalodon Shark

Miocene Period-20 myaMiocene Period-20 mya 60 ft long; jaws 5 ft long60 ft long; jaws 5 ft long

Freshwater Life ZonesFreshwater Life Zones Less that 1% salt concentrationLess that 1% salt concentration 2 types:2 types:1.1. StandingStanding: lakes, ponds: lakes, ponds2.2. FlowingFlowing: streams, rivers: streams, rivers Freshwater systems cover less than Freshwater systems cover less than

1% of earth’s surface1% of earth’s surface Runoff from land provides FW zone Runoff from land provides FW zone

with organic matter, nutrients, with organic matter, nutrients, pollutionpollution

Freshwater Systems

Ecological Services Economic Services

• Climate moderation

• Nutrient cycling

• Waste treatment and dilution

• Flood control

• 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

Freshwater Life ZonesFreshwater Life Zones Littoral zoneLittoral zone: shallow, sunlit water : shallow, sunlit water

surface surface near near shoreshore Limnetic zoneLimnetic zone: open, sunlit water : open, sunlit water

surface surface away away from shore; main from shore; main photosynthetic partphotosynthetic part

Profundal zoneProfundal zone: deep, open water; too : deep, open water; too dark for photosynthesisdark for photosynthesis

Benthic zoneBenthic zone: bottom of the lake, cool : bottom of the lake, cool temp, low oxygen levels (why?)temp, low oxygen levels (why?)

How do Plant Nutrients affect How do Plant Nutrients affect Lakes?Lakes?

Lakes are classified according to: Lakes are classified according to: nutrient content and productivitynutrient content and productivity

Newly-formed lake = Newly-formed lake = oligotrophicoligotrophic lake lake (poorly nourished); clear water(poorly nourished); clear water

Established lake= Established lake= eutrophiceutrophic lake (well- lake (well-nourished); murky waternourished); murky water

Cultural eutrophicationCultural eutrophication: human inputs : human inputs of nutrients accelerates eutrophicationof nutrients accelerates eutrophication

Seasonal Changes in LakesSeasonal Changes in Lakes Thermal stratificationThermal stratification: three distinct layers : three distinct layers

with different temperatureswith different temperatures

1.1. EpilimnionEpilimnion: upper layer of warm water, high : upper layer of warm water, high dissolved oxygen (warm water on top, less dissolved oxygen (warm water on top, less dense)dense)

2.2. ThermoclineThermocline: cooler “middle” layer, moderate : cooler “middle” layer, moderate levels of dissolved oxygenlevels of dissolved oxygen

3.3. HypolimnionHypolimnion: lower layer of cold water, low : lower layer of cold water, low concentration of dissolved oxygen (more dense)concentration of dissolved oxygen (more dense)

Seasonal Changes in LakesSeasonal Changes in Lakes

Seasonal Changes in Lakes, Seasonal Changes in Lakes, contcont..

FallFall: surface water cools, thermocline : surface water cools, thermocline disappears as warm water becomes colder disappears as warm water becomes colder (and more dense)(and more dense)

fall overturnfall overturn: brings nutrients from : brings nutrients from bottom to top, brings dissolved oxygen from bottom to top, brings dissolved oxygen from surface to bottomsurface to bottom

WinterWinter: cold temp, water separates into : cold temp, water separates into different densitiesdifferent densities

SpringSpring: surface water sinks (becomes more : surface water sinks (becomes more cold dense)cold dense)

spring overturnspring overturn: brings nutrients from : brings nutrients from bottom to top, brings dissolved oxygen from bottom to top, brings dissolved oxygen from surface to bottomsurface to bottom

Streams and RiversStreams and Rivers

Remember hydrologic cycle!Remember hydrologic cycle! RunoffRunoff: precipitation that does not sink : precipitation that does not sink

into the ground or evaporate--flows into into the ground or evaporate--flows into streamsstreams

WatershedWatershed: land area that delivers runoff : land area that delivers runoff to a streamto a stream

Small streams join to form rivers; rivers Small streams join to form rivers; rivers flow downhill to the ocean (hydrologic flow downhill to the ocean (hydrologic cycle)cycle)

Stream and River--Life ZonesStream and River--Life Zones

1.1. Source zoneSource zone: cold, clear water (from : cold, clear water (from mountains) rushes over waterfalls and mountains) rushes over waterfalls and rapids; dissolves large amounts of oxygen rapids; dissolves large amounts of oxygen with turbulence; cold water fish and lots of with turbulence; cold water fish and lots of algae and mosses on rocksalgae and mosses on rocks

2.2. Transition zoneTransition zone: streams merge to form : streams merge to form wider streams; fewer obstacles; warmer wider streams; fewer obstacles; warmer water supports more producerswater supports more producers

3.3. Floodplain zoneFloodplain zone: streams move across : streams move across valleys; slow-moving; warmer temp; less valleys; slow-moving; warmer temp; less dissolved oxygen; muddy, lots of silt dissolved oxygen; muddy, lots of silt

Rain and snow

Water

Sediment

Lake Glacier Rapids

WaterfallTributary

Flood plain

Oxbow lake

Salt marsh

Delta Ocean

Depositedsediment

Source Zone

Transition Zone

Floodplain Zone

Inland WetlandsInland WetlandsLand covered with freshwater all Land covered with freshwater all

or part of the timeor part of the time IncludesIncludes: marshes, swamps, : marshes, swamps,

prairie potholes (from glaciers), prairie potholes (from glaciers), floodplains, bogsfloodplains, bogs

Important for flood controlImportant for flood control

Freshwater marshFreshwater marsh

Cypress SwampCypress Swamp

Prairie PotholesPrairie Potholes

Human Impact of Freshwater Human Impact of Freshwater SystemsSystems

60% of world’s rivers are fragmented by 60% of world’s rivers are fragmented by dams and canals (destroys wildlife dams and canals (destroys wildlife habitats by reducing water flow)habitats by reducing water flow)

Flood control levees destroy habitats, Flood control levees destroy habitats, eliminate wetlands (fish breeding eliminate wetlands (fish breeding grounds)grounds)

In U.S., 53% of inland wetlands have In U.S., 53% of inland wetlands have been drained or filled and covered with been drained or filled and covered with asphalt/concrete for buildingsasphalt/concrete for buildings

How Sustainable are Aquatic How Sustainable are Aquatic Ecosystems?Ecosystems?

Most pollutants end up in the oceanMost pollutants end up in the ocean Aquatic life zones are constantly renewed Aquatic life zones are constantly renewed

because:because:

1. water is purified by hydrologic cycle1. water is purified by hydrologic cycle

2. nutrients cycle in and out2. nutrients cycle in and out

3. populations can be replenished3. populations can be replenished However, this can happen ONLY if over-However, this can happen ONLY if over-

polluting and over-fishing do not occur!! polluting and over-fishing do not occur!!