December 9th class

NOTICE: Please attend next week; we assign the reports on this day!

Today`s class: Outline
• 1. A new species of whale!
• 2. Atlantic and Pacific corals.
• 3. Four species of COTS.
• 4. Review of Symbiodinium and coral bleaching.



Part 1 - A new species of whale!
Dalebout et al. 2002. A new species of beaked whale Mesoplodon perrini sp. n. (Cetacea: Ziphiidae) discovered through mitochondrial DNA sequences. Marine Mammal Science 18: 577-608.
Introduction
• Beaked whales are rare, with cryptic lifestyles. Most never observed alive.
• 12 species described in last 100 years!
• Mesoplodon hectori common in southeast Pacific.
Materials & Methods
• 5 specimens of beaked whale stranded in California, 1977-1995.
• Thought to be M. hectori based on morphology.
• Researchers then examined 2 mt DNA markers…
Results
• Results surprisingly show five specimens not M. hectori.
• New species!
• Re-examination shows morphological differences as well.
Discussion
• Authors suggest genetic voucher material for all taxa.
• Also state there are likely 40 marine mammal species still unknown!
• Cookiecutter sharks feed on M. perrini.

• Who knows what species await description?
Part 2 Atlantic & Pacific corals
Fukami et al. 2008. Mitochondrial and nuclear genes suggest that stony corals are monophyletic but most families of stony corals are not (Order Scleractinia, Class Anthozoa, Phylum Cnidaria). PLoS One 3:9: e3222

• Coral phylogeny has been in flux for 10+ years.
• Perhaps corallimorphs within hard corals.
• Here examine 127 species, 75 genera, 17 families.
• Four markers; 2 nuclear, 2 mitochondrial.

• Corals monophyletic.
• 11/16 families not monophyletic.
• Corresponding morphological characters found.
• Corallimorphs not part of stony corals.

• Many Atlantic corals are very unique, and should be conserved.
• Some clades vulnerable to extinction (II, V, VI, XV, XVIII+XX).
• Ability to conserve depends on knowing what to conserve.

• Re-organize based on DNA, re-examine morphology.
• Atlantic corals must be protected more strongly.
• Basic ideas need to be re-examined (e.g. favids).
Part 3 - Crown-of-thorns
Vogler et al. 2008. A threat to coral reefs multiplied? Four species of crown-of-thorns starfish. Biology Letters doi:1-.1098/rsbl.2008.0454

• Acanthaster planci outbreaks threaten coral reefs.
• Causes of outbreaks not clear.
• Species has long-lived larvae, but apparent population structure.
• Here used COI sequences from 237 samples.

• Four clades found, 8.8-10.6% divergent.
• Diverged 1.95-3.65 mya.
• Species show geographical partitioning. Due to sea level changes.
• All populations expanding.

• Four species, SIO, NIO, Red Sea, and Pacific.
• Outbreaks mainly seen in Pacific - could this be a species difference?
• Clearly more research needed, critical for coral reef management.

Overall conclusions:
1. Genetics already impacting our understanding of diversity.
2. Expect more surprises in the future.
3. Massive revision of all coral reef organisms!

Part 4 Review of Symbiodinium and bleaching.
• Dangers facing coral reefs:
• Global warming is raising the temperature of the ocean; this kills corals - “coral bleaching”.
• Also, as the oceans become more acidic, it is more difficult for corals to make their skeletons.
• Perhaps 90% of coral reefs will be dead by 2050.
• Diagram of iving tissue
• Numbers of zooxanthellate genera over time, increase in ZX genera of corals.
• More diverse than ever, showing benefits of symbioses.
• Believed to have started approximately 60 million years ago.
• Symbiodinium spp. in invertebrates holobiont=host+symbiont(s)
• Corals and symbionts
• Many shallow water corals get their energy from symbiotic zooxanthellae.
• These small animals make it possible for corals to live in the warm oceans.
• But, these symbionts are sensitive to hot ocean temperatures.
• What turns the coral white?
• As a stress response, corals expel the symbiotic zooxanthellae from their tissues
• The coral tissue is clear, so you see the white limestone skeleton underneath
• What can stress a coral?
• High light or UV levels
• Cold temperatures
• Low salinity and high turbidity from coastal runoff events or heavy rain
• Exposure to air during very low tides
• Major: high water temperatures
• Thermal stress
• Corals live close to their thermal maximum limit
• If water temperature gets 1 or 2°C higher than the summer average in many parts of the world, corals may get stressed and bleach
• NOAA satellites measure global ocean temperature and thermal stress
• How warm is warm?
• How hot do you think the ocean has to get before corals start to bleach?
• GLOBAL WARMING
• Glaciers and Sea Ice are melting
• World map showing levels of coral bleaching. Source: ReefBase
• Can corals recover?
• Yes, if the stress doesn’t last too long
• Some corals can eat more zooplankton to help survive the lack of zooxanthellae
• Some species are more resistant to bleaching, and more able to recover
• Can corals recover?
• Corals may eventually regain color by repopulating their zooxanthellae
• Algae may come from the water column
• Or they may come from reproduction of the few cells that remain in the coral
• Can corals recover?
• Corals can begin to recover after a few weeks
• Does bleaching kill corals?
• Yes, if the stress is severe
• Some of the polyps in a colony might die
• If the bleaching is really severe, whole colonies might die
• Bleaching in Puerto Rico killed an 800-year-old star coral colony in 2005
• What else can stress do to corals?
• Question: what is something that happens to people when they are highly stressed?
• What else can stress do to corals?
• Question: what is something that happens to people when they are highly stressed?
• Bleaching and coral disease
• Coral diseases are found around the world
• High temperatures and bleaching can leave corals more vulnerable to disease
• Can quickly kill part or all of the coral colony
• Bleaching and bioerosion
• We have seen that bleaching can kill part or all of a coral colony
• Areas of dead coral are more vulnerable to bioerosion (when animals wear away the coral reef’s limestone structure)
• Storms & coral bleaching
• The same warm water that causes corals to bleach can also lead to strong storms.
• Storms: a mixed blessing
• Storms: a mixed blessing
• Each passing hurricane in 2005 cooled the water in the Florida Keys.


References:
1. Dalebout et al. 2002. A new species of beaked whale Mesoplodon perrini sp. n. (Cetacea: Ziphiidae) discovered through phylogenetic analyses of mitochondrial DNA sequences. Marine Mammal Science 18: 577-608.
2. Fukami et al. 2008. Mitochondrial and nuclear genes suggest that stony corals are monophyletic but most families of stony corals are not (Order Scleractinia, Class Anthozoa, Phylum Cnidaria). PLoS One 3:9: e3222.
3. Vogler et al. 2008. A threat to coral reefs multiplied? Four species of crown-of-thorns starfish. Biology Letters doi:1-.1098/rsbl.2008.0454