The document discusses the impact of climate change on coral reefs, highlighting changing ocean temperatures, sea levels, and ocean pH by the year 2100. It explains the ideal conditions for coral growth, the types of reefs, and the symbiotic relationships corals have with zooxanthellae. Additionally, it presents research on coral metabolism and calcification, illustrating how light affects photosynthesis and calcification rates in different water depths.

1. Tali Mass & Jeana Drake
January 30, 2013

2. Focus on climate change
1. Changing ocean temperatures
2 - 4oC (3.6 - 7.2oF) global average increase by year
2100
2. Changing sea level
1.5 – 10 mm/year (0.06 – 0.4 inches/year) global
average increase to year 2100
3. Changing ocean pH
Average surface ocean pH decrease from 8.2 to 7.8
by year 2100

3. Conditions preferred by corals
• Temperature: 23-25°C;
• Light: for photosynthesis;
• Salinity required;
• Clean, clear water, sediment free;
• Well oxygenated water produced by
strong wave action

4. Coral’s ideal environment
Coral reefs are concentrated in a band around
the equator between 30°N and 30°S latitude.

5. Types of Reefs
• Fringing reef – reef that is directly attached to a
shore or borders it with an intervening shallow
channel or lagoon.
• Barrier reef – reef separated from a mainland or
island shore by a deep lagoon.
• Atoll reef – a more or less circular or continuous
barrier reef extending all the way around a lagoon
without a central island.

6. Darwin’s Theory of Reefs

7. Class: Scyphozoa Class: Hydrozoa
Class: Anthozoa
Ahermatypic Sea anemone Hermatypic

8. Types of Corals
Hard corals (hermatypic): secrete a
limestone (CaCO3) exoskeleton around
itself as protection. This exoskeleton
remains even after the organism dies.
Soft corals (ahermatypic): tree-like and
flexible with a skeleton within their bodies
giving them shape but allowing movement
with the waves

9. Growth forms

10. Basic structure
z • Polyps = basis of life on reef.
• Produce calcium carbonate
skeleton as they grow.
• Polyp growth = symbiotic
relationship between the
coral animal and
zooxanthellae (algae).
• Zooxanthellae
photosynthesize and give
sugars and fats to polyp.
Veron (1986)

11. Communication, allocation and
Colonial coral polyps
translocation between polyps

12. • Corals feed on zooplankton
• Tentacles help capture food
• Tentacles contain stinging cells

13. Symbiotic relationship with
zooxanthellae
 Algae in the coral polyp
produce oxygen and
organic products for the
polyp
 Coral polyps produce
carbon dioxide for the
algae and give protection

14. Reproduction
Corals reproduce either asexually by budding or by
sexually releasing gametes (sperm and eggs).
Sexual reproduction Asexual reproduction
Fertilization can occur within Budding occurs when a new
a coral known as “brooding” zygote grows onto another one
or outside of a coral known and remains attached,
as “broadcasting” separating only when mature.
.

15. SEX ON THE REEF: Broadcast spawning

16. Morphology and physiology:
adaptation to local environment
1. Water depth 2. Water movement
5m
50m
Photo by Shai Einbinder
Mass et al. MEPS, 2007 Veron & Pichon, 1976

17. Seawater Carbonate System
pH , total
CO2 + H2O CH2O + O2 photosynthesis alkalinity-
unchanged
pH , total
CH2O + O2 CO2 + H2O respiration
alkalinity-
unchanged
Ca2+ +2HCO-3 CaCO3 + CO2 + H2O calcification
pH , total
alkalinity-
changed
Bjerrum plot (Zeebe, 1999)

18. A Study of a Mesophotic Coral
Ecosystem
5m 5m
60 m Photo by Shai Einbinder 50 m Photo by Shai Einbinder
Stylophora pistillata

19. Study Objectives
• Coral metabolism and calcification due to:
 Light acclimation
• What response variables to measure (3 things):
 1. Oxygen
 2. pH
 3. Alkalinity
• Things to vary (i.e.; when/where would these be different?):
 1. Day/Night
 2. Depth
• Hypotheses:
 1. Calcification rates higher during the day than at night.
 2. Shallower coral have higher maximum photosynthesis
but lower pigment concentration than deeper corals.

21. The Inter-University Institute for Marine Sciences in Eilat
21

22. Methods

23. Methods
• The deep water colonies were carried inside
black bags to the experiment site (~5 m depth)
• We placed the colonies at a light level of the
origin growth place.
PAR (%) ~ noon
0 20 40 60 80 100
0
10
20
30
Depth (m)
40
July
50
60 Feb
70
80
90
100

24. Methods
• Tissue analysis:
 Pigment (chlorophyll a & c)
concentration
• Diel cycles of photosynthesis
and calcification were studied
using a submersible
Stylophora pistillata
respirometer (AIMS, Australia).

26. Results & Discussion
Photoacclimation - Pigments
Stylophora pistillata

27. Results & Discussion
Photoacclimation - Max. Photosynthetic
Rate
Maximum Photosynthetic Rate
P max
µmole o2 cm-2 h-1
0.00 .02 .04 .06 .08 .10 .12 .14 .16
5
10
50
Depth (m)
July
Feb
65
n=3, Kruskal Wallis ANOVA p<0.05

28. Results & Discussion
Photoacclimation - Dark Respiration
Dark Respiration
µmole o2 cm-2 h-1
0.0 -.2 -.4 -.6
5
10
50
Depth (m)
July
Feb
65

29. Results & Discussion
Calcification
Day & night calcification (µmol CaCO3 cm-2 h-1)
-4 -2 0 2 4 6 8 10 12
5
10
50
Depth (m)
July day
July night
65 Feb day
Feb night
24h experiment, n=3

30. Summary
• Photosynthesis and calcification are light
dependent
• Photo-acclimation of endosymbiotic algae with
depth
– Pigment Concentration
– Maximum Photosynthetic Rate
– Respiration
• Light enhances calcification, calcification rates:
– Diel Cycle - Night vs. Day
– Depth - Deep vs. Shallow

31. Corals in the Future
Given what we learned in this study, how do
you think coral calcification might be
affected by:
1. increasing temperature?
2. sea level rise?
3. decreasing surface ocean pH?