Aquatic Biodiversity

1
Chapter 6

• Aquatic Biodiversity

2
Chapter Overview Questions

• What are the basic types of aquatic life zones
  and what factors influence the kinds of life they
  contain?
• What are the major types of saltwater life zones,
  and how do human activities affect them?
• What are the major types of freshwater life
  zones, and how do human activities affect them?

3
Updates Online

• The latest references for topics covered in this
  section can be found at the book companion
  website. Log in to the books e-resources page at
  www.thomsonedu.com to access InfoTrac articles.
• InfoTrac Down the bayou a marine biologist, a
  community, and the resolve to preserve an ocean's
  bounty. Taylor Sisk. Earth Island Journal, Autumn
  2006 v21 i3 p27(6).
• InfoTrac A scourge of the '70s returns to Great
  Lakes. The Christian Science Monitor, March 30,
  2006 p14.
• InfoTrac The fate of the ocean. Julia Whitty.
  Mother Jones, March-April 2006 v31 i2 p32(15).
• National Oceanic and Atmospheric Administration
  Fisheries
• Amazon Conservation Association Amazon Rivers
  Project

4
Core Case StudyWhy Should We Care About Coral
Reefs?

• Coral reefs form in clear, warm coastal waters of
  the tropics and subtropics.
• Formed by massive colonies of polyps.

Figure 6-1
5
Fig. 6-1a, p. 126
6
Fig. 6-1b, p. 126
7
Core Case StudyWhy Should We Care About Coral
Reefs?

• Help moderate atmospheric temperature by removing
  CO2 from the atmosphere.
• Act as natural barriers that help protect 14 of
  the worlds coastlines from erosion by battering
  waves and storms.
• Provide habitats for a variety of marine
  organisms.

8
AQUATIC ENVIRONMENTS

• Saltwater and freshwater aquatic life zones cover
  almost three-fourths of the earths surface

Figure 6-2
9
Landocean hemisphere
Ocean hemisphere
Fig. 6-2, p. 127
10
AQUATIC ENVIRONMENTS
Figure 6-3
11
There are four major types of organisms in
aquatic systems

• Plankton are free-floating, weakly swimming,
  generally one-celled organisms.
• There are three major types of plankton
• phytoplankton (plant plankton)
• zooplankton (animal plankton) they may be
  single-celled protozoa to large invertebrates
  such as jellyfish
• ultraplankton that are no more than 2 micrometers
  wide and are photosynthetic bacteria.
• Ultraplankton may be responsible for as much as
  70 of the primary productivity near the ocean
  surface.

12
There are four major types of organisms in
aquatic systems

• Nekton is a second group of organisms.
• These are fish, turtles and whales
• Benthos are bottom dwellers
• barnacles, oysters, worms, lobsters and crabs
• Decomposers
• These organisms break down organic matter into
  simple nutrients for use by producers.

13
Three layers of aquatic life zones

• Surface
• Middle
• Bottom
• Factors that determine types and numbers of
  producers
• Temperature
• sunlight availability
• dissolved oxygen
• nutrient availability

14
Biological Zones in the Open SeaLight Rules

• The open sea is divided into three vertical zones
  based primarily on penetration of light.
• Low average primary productivity and NPP occurs,
  but oceans are so large they make the largest
  contribution to NPP overall.

15
Open Sea

• Euphotic zone brightly lit surface layer.
• Nutrient levels low, dissolved O2 high,
  photosynthetic activity.
• Large, fast-swimming predatory fish like
  swordfish, shark and bluefin tuna live in this
  zone.

16
Open Sea

• Bathyal zone dimly lit middle layer.
• No producers are in this zone (No photosynthetic
  activity)
• Zooplankton and smaller fish live in this zone
  and migrate to euphotic zone to feed at night

17
Open Sea

• Abyssal zone dark bottom layer.
• Very cold, little dissolved O2.
• The nutrients on the ocean floor support about
  98 of species living in the ocean.
• Organisms in this area are deposit feeders, or
  filter feeders.
• Hydrothermal vents are present in some areas with
  specialized bacteria that feed on chemical
  nutrients and are food for other organisms

18
Effects of Human Activities on Marine Systems

• About 40 of the world population lives along
  coasts.
• Over half of US population lives with 62 miles of
  the coast.

19
Effects of Human Activities on Marine Systems
Red Alert

• Human activities are destroying or degrading many
  ecological and economic services provided by the
  worlds coastal areas.

Figure 6-13
20
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 3050 more threatened
Fig. 6-13, p. 136
21
Euphotic Zone

• Euphotic zone describes the upper layer where
  sunlight can penetrate.
• Clouding or excessive algal growth reduces depth
  of euphotic zone.
• Dissolved oxygen levels are higher near the
  surface due to photosynthesis in this area
• Conversely, O2 levels are lower in deeper, dark
  layers due to aerobic respiration and because
  less O2 gas dissolves in deeper and colder water.

22
Nutrients

• Open oceans tend to have limited amounts of
  nitrates, phosphates, iron, and other nutrients
  that limit productivity.
• Conversely, shallow waters are generally well
  supplied with nutrients for growth.
• Deep dwelling species depend on animal and plant
  material that die/ sink to bottom.
• Large fish are vulnerable to overfishing
  depletion.

23
Saltwater Life Zones

• Oceans have two major life zones
• the coastal zone
• the open sea

24
The Coastal Zone Where Most of the Action Is

• The coastal zone interacts with the land so, it
  is greatly affected by human activities.
• The coastal zone extends from the high-tide mark
  on land to the edge of the continental shelf.
• Ecosystems in coastal zones have a high net
  primary productivity per unit area.
• They constitute 10 of the oceans and contain 90
  of all marine species.
• There is ample sunlight and nutrients flow from
  land and wind/currents

25
The Coastal Zone

• Estuaries and coastal wetlands are subject to
  tidal rhythms, runoff from land, and seawater
  that mixes with freshwater and nutrients from
  rivers and streams.
• Mangrove forest swamps grow in sheltered regions
  of tropical coasts.
• They collect mud and anaerobic sediment.

26
The Coastal Zone

• Coastal wetlands/ estuaries make nutrients
  available due to constant stirring of bottom
  sediment.
• These areas filter toxic pollutants, excess plant
  nutrients, reduce storm damage and provide
  nursery sites for aquatic species.
• Humans are destroying/degrading these ecosystems
• 1/3 have already been lost.

27
The Coastal Zone
Figure 6-5
28
High tide
Sun
Coastal Zone
Open Sea
Sea level
Low tide
Photosynthesis
Euphotic Zone
Estuarine Zone
Continental shelf
Bathyal Zone
Twilight
Abyssal Zone
Darkness
Fig. 6-5, p. 130
29
SALTWATER LIFE ZONES

• The oceans that occupy most of the earths
  surface provide many ecological and economic
  services.

Figure 6-4
30
Natural Capital
Marine Ecosystems
Economic Services
Ecological Services
Climate moderation
Food
CO2 absorption
Animal and pet feed
Nutrient cycling
Pharmaceuticals
Waste treatment
Harbors and transportation routes
Reduced storm impact (mangroves, barrier islands,
coastal wetlands)
Coastal habitats for humans
Recreation
Habitats and nursery areas
Employment
Genetic resources and biodiversity
Oil and natural gas
Minerals
Scientific information
Building materials
Fig. 6-4, p. 129
31
Marine Ecosystems

• Scientists estimate that marine systems provide
  21 trillion in goods and services per year 70
  more than terrestrial ecosystems.

Figure 6-4
32
Fig. 6-6, p. 130
33
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
34
Herring gulls
Peregrine falcon
Snowy Egret
Cordgrass
Short-billed Dowitcher
Marsh Periwinkle
Phytoplankton
Smelt
Zooplankton and small crustaceans
Soft-shelled clam
Clamworm
Bacteria
Producer to primary consumer
All consumers and producers to decomposers
Secondary to higher-level consumer
Primary to secondary consumer
Fig. 6-7a, p. 131
35
Fig. 6-7b, p. 131
36
Mangrove Forests

• Are found along about 70 of gently sloping sandy
  and silty coastlines in tropical and subtropical
  regions.

Figure 6-8
37
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.

38
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.

39
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
40
Rocky Shore Beach
Hermit crab
Sea star
Shore crab
High tide
Periwinkle
Sea urchin
Anemone
Mussel
Low tide
Sculpin
Barnacles
Kelp
Sea lettuce
Monterey flatworm
Nudibranch
Fig. 6-9, p. 132
41
Barrier Beach
Beach flea
Peanut worm
Tiger Beetle
Clam
Blue crab
Dwarf Olive
High tide
Sandpiper
Ghost Shrimp
Low tide
Silversides
Mole Shrimp
Moon snail
White sand macoma
Sand dollar
Fig. 6-9, p. 132
42
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
43
Primary Dune
Secondary Dune
Bay or Lagoon
Ocean
Beach
Trough
Back Dune
No direct passage or building
Limited recreation and walkways
Most suitable for development
No direct passage or building
Intensive recreation, no building
Intensive recreation
Grasses or shrubs
Bay shore

No filling
Taller shrubs
Taller shrubs and trees
Fig. 6-10, p. 133
44
Barrier Islands

• The islands help protect the mainland, estuaries,
  and coastal wetlands from heavy storm damage.
• Sand is constantly shifting due to winds and
  parallel currents along the islands.
• Undisturbed beaches have one or more rows of sand
  dunes on them. Grass roots hold the sand in
  place and the dune is a first line of defense
  against storms. It is safer to build behind the
  second set of dunes if any building occurs.

45
Barrier Islands

• People want to live on these islands, but they
  are subject to damage.
• In spite of this, almost one-fourth of barrier
  islands are developed.
• Developers want to build on the islands and do
  not consider the protective services that the
  dunes provide.
• Large storms can and have swept away or severely
  damaged seaside buildings.

46
Barrier Islands

• Governments often provide funds for rebuilding
  and insurance at fairly low rates for building on
  the dunes.
• Some people think that persons building in such
  risky places should accept all responsibility for
  repair or replacement due to storm damage.

47
Threats to Coral ReefsIncreasing Stresses

• Biologically diverse and productive coral reefs
  are being stressed by human activities.

Figure 6-11
48
Gray reef shark
Green sea turtle
Sea nettle
Fairy basslet
Blue tangs
Parrot fish
Sergeant major
Brittle star
Hard corals
Algae
Banded coral shrimp
Phytoplankton
Coney
Symbiotic algae
Zooplankton
Blackcap basslet
Sponges
Moray eel
Bacteria
All consumer and producers to decomposers
Secondary to higher-level consumer
Primary to secondary consumer
Producer to primary consumer
Fig. 6-11, p. 134
49
Coral Reefs

• Coral reefs in shallow coastal zones of tropical
  and subtropical oceans support a very diverse,
  complex ecosystem.
• They grow slowly and are vulnerable to damage.
• They thrive in clear, warm, fairly shallow water
  with a high salinity.
• The ideal water temperature is between 18-30oC
  and will bleach if the water warms above this by
  so much as 1oC.

50
Coral Reefs

• Severe storms, freshwater floods, and invasions
  of predatory fish adversely affect the reefs.
• They have survived natural disturbances for a
  long geologic history.
• The greatest threats today are due to sediment
  runoff and other human activities.
• Coral reef systems may not have enough time to
  adapt to these rapidly changing conditions.

51
Coral Reefs

• There are indications that recovery is possible
  when restrictions are imposed and pollution is
  reduced.

52
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
53
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
54
Natural Capital
Natural Capital
Freshwater Systems
Economic Services
Ecological Services
Climate moderation Nutrient cycling Waste
treatment Flood control Groundwater
recharge Habitats for many species Genetic
resources and biodiversity Scientific information
Food Drinking water Irrigation
water Hydroelectricity Transportation
corridors Recreation Employment
Fig. 6-14, p. 136
55
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).

56
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.
• What causes this overturning?

57
Lakes Water-Filled Depressions
Figure 6-15
58
Sunlight
Painted turtle
Green frog
Blue-winged teal
Muskrat
Pond snail
Littoral zone
Limnetic zone
Diving beetle
Plankton
Profundal zone
Benthic zone
Northern pike
Yellow perch
Bloodworms
Fig. 6-15, p. 137
59
Effects of Plant Nutrients on LakesToo Much of
a Good Thing

• Plant nutrients from a lakes environment affect
  the types and numbers of organisms it can support.

Figure 6-16
60
Effects of Plant Nutrients on LakesToo Much of
a Good Thing

• Plant nutrients from a lakes 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.

61
Effects of Plant Nutrients on LakesToo Much of
a Good Thing

• Cultural eutrophication
• Human inputs of nutrients from the atmosphere and
  urban and agricultural areas can accelerate the
  eutrophication process.
• Mesotrophic lakes
• Lakes between these two extremes

62
Freshwater Streams and RiversFrom the Mountains
to the Oceans

• Water flowing from mountains to the sea creates
  different aquatic conditions and habitats.

Figure 6-17
63
Rain and snow
Glacier
Lake
Rapids
Waterfall
Tributary
Oxbow lake
Flood plain
Salt marsh
Deposited sediment
Delta
Ocean
Source Zone
Transition Zone
Water
Sediment
Floodplain Zone
Fig. 6-17, p. 139
64
Case StudyDams, Wetlands, Hurricanes, and New
Orleans

• Dams and levees have been built to control water
  flows in New Orleans.
• Reduction in natural flow has destroyed natural
  wetlands.
• Causes city to lie below sea-level (up to 3
  meters).
• Global sea levels have risen almost 0.3 meters
  since 1900.

65
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
66
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.

67
Human activities have four major impacts on
freshwater systems

• Dams, diversions, of canals fragment 60 of
  worlds large rivers and destroys habitats.
• Flood control dikes and levees alter rivers and
  destroy aquatic habitats.
• Cities and farmlands add pollutants.
• Wetlands have been drained or covered with
  buildings. The U.S. has lost more than 50 of
  its wetlands since the 1600s.
• These systems are able to recover when
  destructive practices are stopped or reduced

68
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 worlds 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.

69
Impacts of Human Activities on Freshwater Systems

• These wetlands have been ditched and drained for
  cropland conversion.

Figure 6-19
70

• Critical Thinking 1 and 2
• Do in class if time