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Title: Corals and Coral Reefs


1
Corals and Coral Reefs
Black Forest dive site, San Salvador Island
2
Discussion Topics
  • 1. What are corals and how do they form coral
    reefs?
  • 2. Why are most coral reefs restricted to
    tropical regions?
  • 3. Primary productivity and species diversity of
    coral reefs
  • 4.Threats to coral reefs

3
What is a coral reef?
4
What is a coral reef?
  • An erosion-resistant marine ridge or mound that
  • develops in tropical and subtropical waters by
  • the growth of hermatypic corals, coralline
    algae, and other calcifying marine organisms,
    plus
  • geochemically precipitated magnesium and
    calcium carbonates.

5
Hermatypic
  • From the ancient Greek, herma, meaning rock, or
    stone.
  • Hermatypic corals are those that contribute to
    coral reef structure, i.e., reef-building species.

6
Classification of Corals
  • Phylum Cnidaria (Greek stinging thread)
  • (formerly Coelenterata Greek hollow gut)
  • Includes anemones, corals, jellyfish,
    hydrozoans
  • ca. 9000 living species

7
Key Features of Cnidarians
  • Strictly aquatic
  • Radial symmetry with tentacles surrounding
    mouth
  • Mouth is only opening to gut (gastrovascular)
    cavity
  • Two body plans polyp (benthic) medusa
    (planktonic)
  • Tissue-level of organization (no organs)
  • Two tissue layers epidermis (outer)
    gastrodermis (inner)
  • Note mesoglea (middle layer) is not a true
    tissue
  • Specialized feeding or defensive cells with
    nematocysts
  • Many species host symbiotic algae in gastrodermal
    cells
  • Ciliated, planktonic "planula" larva

8
Class Anthozoa (Greek flower animals)
anemones, corals Features a. solitary or
colonial polyp b. no medusa stage
9
Subclass Hexacorallia ( Zoantharia) sea
anemones, hard corals Features a. polyps
with more than eight tentacles b. solitary or
colonial
10
Order Scleractinia ( Madreporaria)
hard, or stony,
corals Features polyps secrete heavy,
calcareous external skeleton (
corallum) Hermatypic corals reef-building
species
Source Stanley, G.D. (2006) Science 312 857-858
(May 12, 2006)
11
Order Scleractinia ( Madreporaria) hard or
stony corals Ahermatypic corals
non-reef-building species
12
Sublcass Octocorallia ( Alcyonaria)
soft corals (sea fans, sea pens, sea rods,
etc)Features a. tiny polyps with eight pinnate
tentacles b. most are colonial a few are
solitary c. secrete soft, internal
skeleton of protein (gorgonin collagen)
often with calcareous spicules
13
Class Hydrozoa hydra, Portugese
Man-of-War, stinging corals Order
Hydrocorallina (Milleporina) stinging corals
Features a. colonial polyps b.
numerous defensive polyps with stinging
nematocysts c. secrete
internal calcareous skeleton
14
Cnidarian Polyp Body Plans
Mouth
Tentacles
Gut
Skeleton (corallum)
15
Formation of Coral Skeleton (Corallum)
Gut Cavity
CO2
Gastrodermis
Mesoglea
Epidermis
Extra-Cellular Fluid
Skeleton
Primary Reaction (simplified) Ca2 2 HCO3-
CaCO3? CO2 H2O
16
Coral Growth Forms
Lateral Budding of Single Polyp
Apical Growth With Lateral Budding
Radial Growth and Branching
17
Major Reef Types
  • Fringing Reef
  • Barrier Reef
  • Atoll Reef

18
Fringing Reef
19
Fringing Reef at Puako, Big Island of Hawaii
http//coralreefnetwork.com/reefs/ecology/default.
htm
20
Formation of Fringing Reef 2-3,000 years
ago Fringing reef develops in shallow water
along shoreline expands to keep pace with rising
sea level.
Sea Level Present
2000 yr ago
3000 yr ago
10,000 yr ago
21
Current Fringing Reef Will it continue to
keep pace with rising sea level?
Sea Level Present
2000 yr ago
3000 yr ago
10,000 yr ago
22
Fringing Reef(Moorea, French Polynesia )
23
Barrier Reef(Great Barrier Reef, Australia)
24
Barrier Reef
25
Formation of Barrier Reef 8-10,000 years ago
Fringing reef developing along shoreline
expands to keep pace with rising sea level.
Sea Level Present
8,000 yr ago
10,000 yr ago
26
Formation of Barrier Reef 5,000 years ago Reef
has expanded to keep pace with rising sea level
lagoon has formed behind reef
Sea Level Present
5,000 yr ago
Lagoon
8,000 yr ago
10,000 yr ago
27
Current Barrier Reef Separated from shore by
very wide lagoon with patch reefs. Will reef
continue to keep pace with rising sea level?
Sea Level Present
Patch Reefs
Lagoon
Lagoon
Barrier Reef
5,000 yr ago
8,000 yr ago
10,000 yr ago
28
Barrier Reef(Moorea, French Polynesia )
29
Barrier Reef (Belize Barrier Reef)
30
Belize Barrier ReefSouthwater Cay and Tobacco
Reef
Deep Ocean
Lagoon
31
Atoll Reef(Enewetak Atoll, Marshall Islands)
32
Charles Darwin (1842) Coral ReefsProposed 3
stages for atoll formation
  • 1. Circular fringing reef forms
  • along island shoreline
  • 2. As island subsides,
  • or sea level rises, circular
  • barrier reef, or atoll, develops
  • 3. Island may become fully submerged-
  • only circular atoll reef remains

33
Enewetak (Eniwetok) Atoll Marshall Islands,
Western PacificDeep drilling here in 1950s
confirmed Darwins theory of atoll formation
Evidence of a volcanic cone found under 1,500
meters of coral reef limestone.
Deepest reef fossils are about 50 million years
old.
Photo Source http//strata.geol.sc.edu/EniwetokGa
llery/pages/013-Eniwetok-Reef-Flat.html
34
Bora Bora Atolls, French Polynesia
35
Bikini AtollMarshal Islands, Western Pacific
36
July 25, 1946 Bikini
Atoll, U.S. Pacific Proving Ground
Atomic Bomb Test Baker 21 kiloton bomb
detonated at a depth of 27 meters.
http//www.bikiniatoll.com/history.html
37
Enewetak Atoll, U.S. Pacific Proving Ground43
nuclear tests (including first hydrogen bomb)
were conducted here from 1948 to 1958.
H-Bomb Test at Enewetak, 1952
http//www.youtube.com/watch?vkdPwTUp4-VA
38
Enewetak Atoll, U.S. Pacific Proving Ground360
Kiloton Atomic Bomb Mohawk July 2, 1956
Time Life Pictures/Time Life Pictures/Getty
Images Jul 02, 1956 http//www.life.com/gallery
/33842/terrible-beauty-a-bomb-testsindex/0
39
Patch Reef
  • Small, isolated reef formations
  • Located in shallow water (3-6 m)
  • Outer edge ringed by sand
  • Often dominated by large star coral and brain
    coral colonies

Florida
40
Patch Reefs Great Barrier Reef, Australia
41
Patch Reef Moorea, Western Pacific
Photo by Dr. Josh Idjadi
42
Most coral reefs (black symbols) are found in
shallow tropical and semitropical waters,
between 30? north and 30? south latitudes.
43
Why are (Most) Coral Reefs Restricted to Shallow
Tropical (and Sub-Tropical) Waters?
44
Why are (Most) Coral Reefs Restricted to Tropical
(and Sub-Tropical) Waters?
  • Bright sunshine

45
Within the tropics (23.5N 23.5S), the sun is
directly overhead all year long.
Summer Solstice Sun directly overhead at
23.5N Winter Solstice Sun directly overhead at
23.5S
46
Why are (Most) Coral Reefs Restricted to Tropical
(and Sub-Tropical) Waters?
  • Bright sunshine
  • Warm water

47
Temperature-Depth Profiles in the Ocean
Temperate
Tropical
Polar
48
Why are (Most) Coral Reefs Restricted to Tropical
(and Sub-Tropical) Waters?
  • Bright sunshine
  • Warm water
  • Low nutrient levels in water

49
Nutrient Levels Typically Decrease With Distance
from the Mainland
50
Why are (Most) Coral Reefs Restricted to Tropical
(and Sub-Tropical) Waters?
  • Bright sunshine
  • Warm water
  • Low nutrient levels in water
  • Clear water

51
Water Clarity and ColorBahamas New England
52
Why are (Most) Coral Reefs Restricted to Tropical
(and Sub-Tropical) Waters?
  • Bright sunshine
  • Warm water
  • Low nutrient levels in water
  • Clear water
  • High, stable salinity (gt 30 ppt)

53
Exception to the Rule Coral Reefs Can be Found
in Cold (4-12º C) and Deep (100s -1000s of
meters) Ocean Waters
Source Roberts et al (2006) Science 312 543-547
54
Global Distribution of Cold Water Coral Reefs
Source Roberts et al (2006) Science 312 543-547
55
Reef Structure Belize Barrier Reef
56
Belize Barrier Reef
Photo Credit Jörne Geister, www.reefbase.org
57
  • Major Features of Barrier Reef Complex
  • Outer reef (reef proper) exposed to ocean waves
  • Wide lagoon (sheltered by outer reef) with
  • Patch reefs and/or mangrove islands.

Outer Reef
Sea Level Present
Patch Reefs / Mangrove Islands
Lagoon
Lagoon
5,000 yr ago
8,000 yr ago
10,000 yr ago
58
Zonation of Belize Barrier Reef
Reef Crest
Reef Flat
Back Reef
Fore-reef
Lagoon
Sand Trough
Spur and Groove
Fore-reef slope the wall
59
Zonation of Belize Barrier Reefoblique aerial
view
60
Coral Reefs Characterized by
  • High productivity
  • High species diversity

61
Productivity
62
Productivity
  • Rate at which new biomass is formed.

63
Productivity
  • Rate at which new biomass is formed.
  • Typically expressed as
  • Amount of carbon (C) incorporated into organic
    molecules in cells/tissues per unit area per unit
    time,
  • e.g., grams of C / m2 / day
  • kilograms of C / m2/ year

64
Primary Productivity
  • Rate at which new biomass is formed by primary
    producers photosynthetic organisms (e.g.,
    cyanobacteria, algae, plants).

65
Primary Productivity
  • Two components

66
Primary Productivity (PP)
  • Two components
  • a) Gross Primary Productivity Rate at which CO2
    is fixed during photosynthesis and assembled
    into carbohydrates, lipids, and/or proteins.
  • These molecules may be oxidized during cell
    respiration released as CO2, or
  • excreted as unwanted by-products.

67
Primary Productivity (PP)
  • Two components
  • a) Gross Primary Productivity Rate at which
    CO2 is fixed during photosynthesis and
    assembled into carbohydrates, lipids, and/or
    proteins.
  • - Rate of C excretion as CO2 or by-products

b) Net Primary Productivity Rate at which
organic molecules build new cells and tissues,
i.e., rate of new biomass formation.
68
Net Primary Productivity of Marine and
Terrestrial Communities
69
Coral Reef Primary Productivity (g C/m2/d)
  • Zone Gross Net
  • Ocean Water 0.01-0.7 0.01-0.65
  • Fore Reef 2.0-7.0 0-5.1
  • Reef Crest 2.0-7.0 0.3-1.5
  • Back Reef 2.6-40.0 0-27.0
  • Sand/Patch Reefs 0.9-12.9 0-3.4
  • Lagoon Water 0.01-2.0 0-1.4
  • Entire Reefs 2.3-6.0 0-0.17

70
Coral Reef Primary Productivity (g C/m2/d)
  • Assemblage Gross PP
  • Corals/Zooxanthellae 0.77-20
  • Coralline Algae 0.8-2.8
  • Algal Turfs 0.9-12.1
  • Macroalgae 2.3-39.4
  • Microalgae 0.08-3.7
  • Seagrass 3.0-16.0

71
  • Why is Primary Productivity
  • So High on Coral Reefs?

72
High Primary Productivity on Coral Reefs due to
  • Abundant sunlight

73
High Primary Productivity on Coral Reefs due to
  • Abundant sunlight
  • Clear, shallow water with stable temperature

74
High Primary Productivity on Coral Reefs due to
  • Abundant sunlight
  • Clear, shallow water with stable temperature
  • N2 fixation by bacteria and cyanobacteria on
    surfaces and in sediments

75
Nitrogen A key limiting nutrient in the ocean
  • Required by organisms for making
  • Amino acids and proteins
  • Nucleotides and nucleic acids
  • Et al.

Most nitrogen in the ocean is N2 gas unusable
by cells
76
Major Sources of Nutrients for Coral Reefs
N2
Air
Ocean
N-Fixation
N2
Ammonia Nitrate
Bacteria Algae Plants
N-Fixing Bacteria
On and in sediments on animals and plants
Primary Producers
77
High Primary Productivity on Coral Reefs due to
  • Abundant sunlight
  • Clear, shallow water with stable temperature
  • N2 fixation by bacteria and cyanobacteria on
    surfaces and in sediments
  • Nitrogen (and Phosphorus?) input from land
    (runoff) and air (dust) possibly input from
    upwelling of deep water

78
Major Sources of Nutrients for Coral Reefs
Aerial Deposition / Terrestrial Run-off
N2
Air
N- (and P- ?) compounds
Ocean
N-Fixation
N2
Ammonia Nitrate
Bacteria Algae Plants
N-Fixing Bacteria
On and in sediments on animals and plants
Primary Producers
Nitrate (and Phosphate?)
Upwelling of Nutrients From Deep Ocean
79
High Primary Productivity on Coral Reefs due to
  • Abundant sunlight
  • Clear, shallow water with stable temperature
  • N2 fixation by bacteria on surfaces and in
    sediments
  • Nitrogen (and Phosphorus?) input from land
    (runoff) and air (dust) possibly input from
    upwelling of deep water
  • Retention and recycling of C and nutrients (esp.
    N and P) within reef ecosystem

80
Retention and recycling of C and nutrients (esp.
N and P) within reef ecosystem
  • Coral zooxanthellae endosymbiosis
  • Endosymbiosis Two organisms living together, one
    inside the cells of the other.

81
Coral zooxanthellae endosymbiosis
Coral Polyp Gastrodermal Cell
CO2
NH3
CH2O?

?
Zooxanthella
PO4-3
82
Retention and recycling of C and nutrients (esp.
N and P) within reef ecosystem
  • Coral zooxanthellae endosymbiosis
  • Coral-cyanobacteria endosymbiosis

83
Coral Cyanobacteria Endosymbiosis
Coral Polyp Gastrodermal Cell
CO2
NH3
CH2O?
N2

N-ase
NH3
N-Fixing Cyanobacterium
Zooxanthella
?
PO4-3
Reported for boulder coral, Montastrea
cavernosa Lesser, M.P., et al. (2007) Marine
Ecology-progress Series, 346 143-152
84
Retention and recycling of C and nutrients (esp.
N and P) within reef ecosystem
  • Coral zooxanthellae endosymbiosis
  • Coral cyanobacteria endosymbiosis
  • Detritus pathway

85
Detritus Pathway on Coral Reefs
  • carnivores/grazers corals/algae

Energy and nutrients move from corals and algae
into animals that prey or graze upon them.
86
Detritus Pathway on Coral Reefs
  • carnivores/grazers corals/algae
  • decomposers

When these organisms die, their tissues and cell
contents form detritus containing energy and
nutrients. This detritus Is consumed by
decomposers - bacteria, fungi, et al.
87
Detritus Pathway on Coral Reefs
  • carnivores/grazers corals/algae
  • decomposers

Plankton
Some decomposers may be consumed by zooplankton,
which in turn are consumed by coral polyps.
88
Detritus Pathway on Coral Reefs
  • carnivores/grazers corals/algae
  • decomposers seawater

Zooplankton
Some decomposers are eaten by zooplankton, which
are eaten by corals Others die, releasing their
nutrients into the seawater taken up by
algae.
89
Detritus Pathway on Coral Reefs
  • seagrass/mangroves
  • decomposers

Seagrasses and mangroves living adjacent to the
reef (e.g., in the lagoon) also contribute
energy and nutrients to a detrital pathway.
90
Detritus Pathway on Coral Reefs
  • seagrass/mangroves
  • decomposers sediments

Nutrients released into the sediments can be
taken up by the roots of the grasses and
mangroves.
91
Detrital Pathway on Coral Reefs
  • seagrass/mangroves carnivores/grazers
    corals/algae
  • decomposers sediments decomposers seawater

Plankton
Energy and nutrients can be transported between
the reef and lagoon. How?
92
Retention and recycling of C and nutrients (esp.
N and P) within reef ecosystem
  • Coral zooxanthellae endosymbiosis
  • Coral cyanobacteria endosymbiosis
  • Detritus pathway
  • Recirculation of water over reef and lagoon

93
Recirculation of water over reef and lagoon
  • Flood tide Ocean water flows across the reef,
    carrying dissolved nutrients and organic matter
    into the lagoon.
  • Ebb tide Some lagoon water flows back across the
    reef, carrying dissolved nutrients and organic
    matter and plankton to reef organisms.

94
Retention and recycling of C and nutrients (esp.
N and P) within reef ecosystem
  • Coral - zooxanthellae symbiosis
  • Coral -cyanobacteria symbiosis
  • Detrital pathway
  • Recirculation of water over reef and lagoon
  • Migration of fish (and invertebrates?) between
    the reef and lagoon

95
Major Sources of Nutrients for Coral Reefs
Aerial Deposition / Terrestrial Run-off
N2
Air
N- and P- compounds
Ocean
N-Fixation
N2
Ammonia Nitrate
Bacteria Algae Plants
N-Fixing Bacteria
On and in sediments on animals and plants
Primary Producers
Recycled N- and P- compounds
Detritus
Nitrate (and Phosphate?)
Upwelling of Nutrients From Deep Ocean
96
High Primary Productivity on Coral Reefs due to
  • Abundant sunlight
  • Clear, shallow water with stable temperature
  • N2 fixation by bacteria and cyanobacteria on
    surfaces, in sediments, and in tissues of some
    corals
  • Nutrient input from land (runoff) and air (dust)
    possibly input from upwelling of deep water
  • Retention and recycling of C and nutrients (esp.
    N and P) within reef ecosystem
  • Other factors?

97
High Species Diversity on Coral Reefs
  • Species diversity a measure of
  • the number of species present (species richness)
    and
  • the number of individuals of each species
    (evenness of species abundance)

98
Species Richness on Coral Reefs
  • Coral reefs represent 0.2 of the oceans
    surface area, but are home to an estimated 1
    million species ( 25 of all marine species),
    including
  • 4,000 5,000 species of fish
  • gt 700 species of corals
  • gt 6,000 species of molluscs

99
Studies on Indo-Pacific coral reefs have shown
that a single coral head (2-3 meters in diameter)
may be inhabited by as many as
  • Species of polychaete worms
  • 75 species of fish
  • 2,000 individual organisms from 220 species

100
  • Why is species diversity so high on coral reefs?
  • Why is species diversity on coral reefs higher in
    the Indo-Pacific than in the Caribbean?

101
Threats to Coral Reefs
  • Coastal development (on mainland and islands)
  • Terrestrial runoff carrying pollution and/or
    sediments
  • Marine sources of pollution
  • Unregulated tourism activities
  • Unregulated fishing
  • Overfishing
  • Unregulated collecting for marine aquarium trade
  • Global climate change
  • Coral diseases
  • And other threats.

102
Reefs are no longer used to test nuclear weapons,
but...
103
The potential for human impact on coral reefs is
great
(millions)
50
100
150
200
250
104
Standing on coral can damage it.
http//coralreefnetwork.com/research/kbay/introduc
tion.htm
105
Wrecked freighter on the fore-reef of central
Belize barrier reef.
Photo Credit Jörne Geister, www.reefbase.org
106
Treated Sewage Outflow, Pompano Beach, FL
Source South Florida Sun Sentinel, Nov. 1, 2010
http//www.sun-sentinel.com/videobeta/0396149c-9a3
d-4677-94a2-7dd4591db657/News/Pompano-Beach-outfal
l-pipe
107
Dynamite Fishing Kills Fish and Damages the Reef
Source http//oceanworld.tamu.edu/students/coral
/coral5.htm
108
AN UNDERWATER WAR IS RAGING IN THE CORAL REEFS OF
INDONESIA
  • Dynamite- or blast-fishing is doing an estimated
    half million dollars worth of damage every day in
    Indonesia, threatening the "Amazon of the oceanic
    world".
  • May/June (2001) issue of World Watch

109
Caribbean Coral Suffers Record Bleaching, Death
  • "WASHINGTON (AP) -- A one-two punch of bleaching
    from record hot water followed by disease has
    killed ancient and delicate coral in the biggest
    loss of reefs scientists have ever seen in
    Caribbean waters.
  • Researchers from around the globe are scrambling
    to figure out the extent of the loss. Early
    conservative estimates from Puerto Rico and the
    U.S. Virgin Islands find that about one-third of
    the coral in official monitoring sites has
    recently died
  • Source http//www.cnn.com March 31, 2006

110
Tourism, Water Quality and Coral Reef
HealthFilmed and edited by Dr. Tom GoreauGlobal
Coral Reef Alliance 2006
http//www.youtube.com/watch?vxDT_q1LwGmA
http//www.globalcoral.org/
111
Why Worry About Coral Reefs?
  • Coral reefs provide
  • Habitat More than 1 million marine species
    (25 of all marine spp) inhabit coral reefs
  • Income 375 billion each year in goods and
    services (e.g., tourism fishing) in more than
    100 countries around the world
  • Food Coral reef fish and shellfish are a major
    source of protein for people living near reefs,
    especially on small islands
  • Protection Reefs form a natural barrier
    protecting shorelines from erosion and storm
    damage
  • Medicine Extracts from reef organisms offer
    potential treatments for many of the world's
    most prevalent and dangerous illnesses and
    diseases (e.g., AIDS, cancer, asthma, arthritis,
    inflammatory disorders) and other medicinal
    products (e.g., painkillers).

http//www.coral.org/resources/about_coral_reefs/w
hy_care http//coralreef.noaa.gov/aboutcorals/valu
es/medicine/
112
End of Slide Show April 4, 2011Next Week
Island Biogeography
Supplemental Slides Photos of San Salvador
113
Caribbean Sea
Source http//search.msn.com/images/details.aspx?
qCaribbeanbeachessize1pht449wd728tht98t
wd160suhttp3a2f2fwww.caribbean-direct.com2f
Antilles.htmliuhttp3a2f2fwww.caribbean-direct
.com2fhome2520page2520images2fCaribbeanMapCart
e.jpgtuhttp3a2f2ft1.images.live.com2fimages
2fthumbnail.aspx3fq3d115191196928026id3d0daebe
76e832a519a956df42d793d51dtiCaribbeanMapCarte.jp
gru2fimages2fresults.aspx3fFORM3dMOCAXA262
6q3dCaribbean2520beaches26mkt3den-US26setlang
3den-US26setflight3d0sz208
114
(No Transcript)
115
Previous Slide NASA LandSat False Color
Infrared Photograph of San Salvador
IslandOriginal Source (without labels)
Gottfried, P. K., C. A. Clark, P. J. Godfrey, and
G. W. Smith, 1992, 4th Symposium on the Natural
History of the Bahamas
116
Photos of San Salvador
Dr. R. Hays Cummins, Miami University Tropical
Marine Ecology Course Website http//jrscience.wcp
.muohio.edu/html/tropecoimages.htmlanchor941622
San Salvador Coral Reefs Assorted
Photos http//www.flickr.com/photos/rhizomatist/se
ts/72157600706020488/
San Salvadors Living Jewels Foundation http//www
.flickr.com/photos/rhizomatist/sets/72157600706020
488
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