Climate Change and Corals. Are they plants? Are they animals? Are they rocks? What are Corals?
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Transcript of Climate Change and Corals. Are they plants? Are they animals? Are they rocks? What are Corals?
Climate Change
and Corals
Are they plants?
Are they animals?
Are they rocks?
What are Corals?
Invertebrates Phylum Cnidaria Class Anthozoa
(relatives of jellyfish and anemones)
Predators
Corals are Animals
Individual coral polyps sit inside a hard, calcium carbonate cup called the calyx
But kind of like a Rock…
The polyp is the soft part of the coral’s body resting inside of the calyx cup (a jellyfish with its head stuck)
Tentacles and mouth face upwards
Mostly come out at night to feed on plankton
What is a polyp?
Photo: NOAA Office of National Marine Sanctuaries
Symbiotic Relationship
ShelterProvides CO2
Fertilizer from waste
Provides O2
Sugar (up to 90% to coral)
Coloration Symbiotic Algae
ZooxanthellaeCorals
Not a plant – more like a farmer Symbiotic relationship with photosynthetic
Zooxanthellae (pronounced zoo-zan-tell-e)
Shallow Water Corals
Deep Water
Sometimes called cold-water corals, live
in deep waters on continental shelves,
slopes, canyons
Lack zooxanthellae, consume detritus and
plankton
Only a few species build reefs, mostly
these corals mound or create patches
Provide habitat for important fisheries
species like sea bass and snapper
Destroyed by bottom fishing and oil/gas
exploration
Shallow Water
Require warm, clear water, restricted to
tropics
Have zooxanthellae
Reef builders
Provide habitat for numerous species like sponges, fish,
lobsters, clams, etc.
Threatened by pollution, climate change, damaging fishing practices
Deep Water Corals
Two Types of Corals: Differences and Similarities
Polyp Close-up
Photo credit: Maricopa Community College.
Algae
In some corals, the males and females are separate
Some species are hermaphroditic Male and female colonies can be
far apart so they release sperm and egg cells simultaneously
Can be initiated by change in temperature, lunar cycle, day length
Broadcast spawning species only release gametes on a few nights a year, different species may spawn at different times
Some corals reproduce asexually by budding
Something to Think About…
Symmetrical brain coral releasing eggs during a spawning event in the Flower Garden Banks National Marine Sanctuary.
Photo credit: Emma Hickerson, Flower Garden Banks National Marine Sanctuary;
Corals are stuck in one place, so how do they reproduce? Are they male, female, or
both?
Marine Fisheries = 1 million marine species
depend on corals 25% of all species in the
ocean (rainforests of the ocean)
60 nations and ½ billion people depend on reefs for food, income, and protection
Net benefit thought to be $29.8 billion/year
Why are Corals Important?
Tour
ism
Coast
al P
rote
ctio
n
Fishe
ries
Biodi
vers
ity0
4
8 9.6 95.7 5.5
Economic Value Per Year of the World's
Coral Reefs
Billions o
f D
ollars
http://www.coastalvalues.org/work/coralvalues.pdf
Status of Coral Reef Ecosystems of the World - 2008 Report
http://coralreef.noaa.gov/conservation/status/
19%15%
20%
46%
2008 Status of Coral Reef Ecosystems of the World
Report 19% original worldwide area lost 15% seriously threatened in 10-20 yrs
20% threat of loss in 20-40 yrs 46% not under threat
business as usual estimates
Where are the U.S. Protected Reefs?
3 Major Threats: Climate Change Pollution Unsustainable
Fishing EDUCATION IS THE KEY TO REEF SURVIVAL!
Why Teach About Corals?
Tourism: SCUBA diving, snorkeling, glass-bottom-boat viewing
Fisheries: Coral reefs and their surrounding ecosystems (mangroves and seagrass beds) provide fish habitat, spawning grounds
Coastal protection: Coral reefs = natural barriers to storm surges
Biodiversity: UN’s Atlas of the Oceans describes coral reefs as among the most biologically rich ecosystems on earth, with about 4,000 species of fish and 800 species of reef-building corals
Carbon sequestration: Coral reefs remove CO2 from atmosphere - important for the mitigation of global warming
http://www.coastalvalues.org/work/coralvalues.pdf
What’s the Big Deal?
Organisms found in coral ecosystems sources of medicine:
cancer, arthritis, asthma, ulcers, human bacterial infections, heart disease, viruses, etc.
Anti-viral drugs like AZT and the anti-cancer agent Ara-C developed from extracts of sponges found on a Caribbean reef
Limestone skeleton of corals tested in bone grafts
There’s a Medical Element too…
Climate Change is a GLOBAL problem!
The majority of ocean pollution comes from activities on LAND (fertilizers, sediment, toxins, trash, etc…)
Do you know where the fish that you eat comes from?
But I don’t live near an ocean…
Coral Bleaching
Photo credit: Erinn Muller, Florida Institute of Technology
Bleached Elkhorn Coral U.S. Virgin Islands, 2005
Photo credit: NOAA
Elkhorn Coral normal coloration - prior to 2005, no reported cases of Elkhorn Coral bleaching in region.
When corals are stressed by changes in light, temperature, and/or nutrients, they
expel their symbiotic algae and turn white.
Tropical weather systems can cool high temperatures that might cause bleaching 2005 - the worst bleaching on
record in the Caribbean 80% of corals bleached 40% + died at many sites
across Caribbean No tropical storms passed close
enough to cool the Virgin Islands 90% of area corals bleached 60% died
Most intense thermal stress recorded in Caribbean during 25-year NOAA satellite record
Weather Matters!
Bleached fire coral and Christmas tree worm on top - Flower Gardens Bank bleaching 2010, Credit:
NOAA, FGBNMS
Bleached corals can regain their zooxanthellae, but it depends on the intensity and duration of stress.
Once corals are bleached, they begin to starve.
NOAA Environmental Visualization Laboratory
Satellite-based data from NOAA Coral Reef Watch uses sea surface temperature measurements to determine # of weeks of the year
the coral were exposed to water temperatures that exceed traditional conditions
NOAA Environmental Visualization Laboratory
http://www.nnvl.noaa.gov/MediaDetail2.php?MediaID=545&MediaTypeID=1
pH Time Series
What’s happening over time?
CO2+ H2O
HCO3-
Bicarbonate ion
H2CO3 Carbonic
acid
CO32-
Carbonate ion
H+ Hydrogen
ion
+
Ca2+
pH
CO2
+ = CaCO3
Calcium Carbonate
X X
pHOcean pH
Ocean pH
Ocean pH
(pH not to scale)
?
Ocean water will never be acidic, acidification simply means “lowering pH”
Reefs naturally grow and shrink (accretion and dissolution)
Ocean acidification won’t dissolve the reefs, but it will slow accretion – less available carbonate to bind to Ca
pH is lowered and then raises a bit when bicarbonate is formed, but the net pH is still lower than the original
Corals aren’t the only organisms that need CaCO3
Key Points on Ocean Acidification
Pteropods, a pea-sized food source for organisms ranging from whales to salmon. This specimen was placed in seawater with a pH and carbonate level that is projected for the year 2100. After 45 days, the shell is dissolved.