Transcript Euphotic zone

Aquatic
Biodiversity
Core Case Study:
Why Should We Care About
Coral Reefs?
Coral
Bleaching
AQUATIC ENVIRONMENTS
• Saltwater and freshwater aquatic life
zones cover almost three-fourths of the
earth’s surface
Figure 6-2
AQUATIC ENVIRONMENTS
Figure 6-3
Red = most productivity and
Purple = nearly empty of life
Nutrients trapped on
ocean floor move up
with an upwelling
Winds blowing across the ocean surface often push
water away from an area. When this occurs, water
rises up from beneath the surface to replace the
diverging surface water. This process is known as
“upwelling.”
Nutrients brought to the
euphotic zone used by
phytoplankton
The thermocline blocks
the upwelling and
prevents nutrients from
reaching the euphotic
zone (this is observed to
occur during an El Niňo)
Why is there more
nutrients available in
the cold arctic waters
than the warm tropical
waters?
Warm water (less density
than cold water)
Cold water (more density
than warm water
Red = most productive
Purple = least productive
Notice the
connection
between SST and
primary productivity
Infra Red radiation, Visible Light, and UV radiation as
its wavelengths are absorbed as depth increases
What Kinds of Organisms Live in
Aquatic Life Zones?
• Aquatic systems contain floating, drifting,
swimming, bottom-dwelling, and decomposer
organisms.
– Plankton: important group of weakly swimming,
free-floating biota.
• Phytoplankton (plant), Zooplankton (animal),
Ultraplankton (photosynthetic bacteria)
– Nekton: fish, turtles, whales.
– Benthos: bottom dwellers (barnacles, oysters).
– Decomposers: breakdown organic compounds
(mostly bacteria).
Life in Layers
• Life in most aquatic systems is found in
surface, middle, and bottom layers.
• Temperature, access to sunlight for
photosynthesis, dissolved oxygen content,
nutrient availability changes with depth.
– Euphotic zone (upper layer in deep water
habitats): sunlight can penetrate.
Marine Ecosystems
• Scientists estimate
that marine systems
provide $21 trillion in
goods and services
per year – 70% more
than terrestrial
ecosystems.
Figure 6-4
The Coastal Zone:
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.
The Coastal Zone
Biological Zones in the Open Sea:
Light Rules
• 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.
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
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.
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
Barrier Islands
• Low, narrow, sandy islands that form offshore
from a coastline.
• Primary and secondary dunes on gently
sloping sandy barrier beaches protect land
from erosion by the sea.
Figure 6-10
Threats to
Coral Reefs:
Increasing
Stresses
• Biologically
diverse and
productive coral
reefs are being
stressed by
human activities.
Figure 6-11
Natural Capital Degradation
Coral Reefs
Ocean warming
Soil erosion
Algae growth from fertilizer runoff
Mangrove destruction
Bleaching
Rising sea levels
Increased UV exposure
Damage from anchors
Damage from fishing and diving
Fig. 6-12, p. 135
Effects of Human Activities on
Marine Systems: Red Alert
• Human activities
are destroying or
degrading many
ecological and
economic services
provided by the
world’s coastal
areas.
Figure 6-13
Natural Capital Degradation
Marine Ecosystems
Half of coastal wetlands lost
to agriculture and urban
development
Over one-third of mangrove
forests lost to agriculture,
development, and
aquaculture shrimp farms
Beaches eroding because of
coastal development and
rising sea level
Ocean bottom habitats
degraded by dredging and
trawler fishing
At least 20% of coral reefs
severely damaged and 30–
50% more threatened
Fig. 6-13, p. 136
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
Natural Capital
Freshwater Systems
Ecological
Services
Economic
Services
Climate moderation
Food
Nutrient cycling
Drinking water
Waste treatment
Irrigation water
Flood control
Hydroelectricity
Groundwater
recharge
Transportation
corridors
Habitats for many
species
Recreation
Genetic resources
and biodiversity
Employment
Scientific
information
Fig. 6-14, p. 136
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
• During summer and winter in deep
temperate zone lakes the become
stratified into temperature layers and will
overturn.
– This equalizes the temperature at all depths.
– Oxygen is brought from the surface to the
lake bottom and nutrients from the bottom are
brought to the top.
Sunlight
Green
frog
Painted
turtle
Blue-winged
teal
Muskrat
Pond
snail
Littoral zone
Limnetic zone
Diving
beetle
Plankton
Profundal zone
Benthic zone
Yellow
perch
Bloodworms
Northern
pike
Fig. 6-15, p. 137
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:
Too Much of a Good Thing
• 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
• Cultural eutrophication:
– Human inputs of nutrients from the atmosphere
and urban and agricultural areas can accelerate
the eutrophication process.
Freshwater Streams and Rivers:
From the Mountains to the Oceans
• Water flowing from mountains to the sea
creates different aquatic conditions and
habitats.
Figure 6-17
Rain and
snow
Lake Glacier
Rapids
Waterfall
Tributary
Flood plain Oxbow
lake
Salt marsh
Delta Deposited
sediment
Ocean
Source Zone
Transition Zone
Water
Sediment
Floodplain Zone
Fig. 6-17, p. 139
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.
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.
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.
The End
Guess
what I am
thinking.