January 9, 2013 class notes

Outline

1. Quick introduction to diseases.
2. Common coral reef diseases.
3. Why are diseases becoming common?
4. How do diseases affect conservation?
5. Terpios: a new threat
6. Conclusions

Part 1: DiseaseExample 1: Plague in humans

• Plagues have struck humans many times.
• Often kill 10-50% of population.
• Caused by an influenza virus.
• Two most infamous cases are 13th century Black Plague, and 1919-1920 Spanish Influenza.
• No one knows where plagues came from.
• Spread through common routes of trade.
• Spread faster in modern cases.
• Often affects young adults worse due to “cytokine storms”.
Spanish Influenza
• In some countries fatalities were as high as 50%.
• Killed more people than WWI.

How does this happen?
• New mutation in influenza virus that most humans do not have capability to respond to.
• Genetic variation provides resistance.
• SARS is a more recent case.


Example 2:
Introduction of a new disease into an isolated area
Elm trees common in North America and Eurasia.
Preyed upon by two species of bark beetles.
Beginning in the 1910s, some elms began to die.
Die-offs became rapid in 1960s.
Bark beetles somehow involved in the disease.

Survival of elms close to 0%.
• The causative agents of DED are ascomycete microfungi.
• Carried by the elm bark beetles.

• Three species are now recognized: Ophiostoma ulmi, which afflicted Europe in 1910, reaching North America on imported timber in 1928, Ophiostoma himal-ulmi, a species endemic to the western Himalaya, and the extremely virulent species, Ophiostoma novo-ulmi, which was first described in Europe and North America in the 1940s and has devastated elms in both areas since the late 1960s.
• The origin of O. novo-ulmi remains unknown but may have arisen as a hybrid between O. ulmi andO. himal-ulmi.

Part 2: Common coral reef diseasesIntroduction to
coral reef diseases
• Bacteria observed in corals in early 1900s.
• Diseases noticed in 1970s, seemingly increasing over last 30 years.
• 34 mass events, affecting sponges, seagrasses, cetaceans, urchins, fish, molluscs, corals.
• Have changed composition of reefs.

Diseases affecting Scleractinia
• Many diseases named, but very little known.
• Most pathogens still unknown.
• Most common in Atlantic (Green & Bruckner).
• Not to be confused with coral bleaching.
Green & Bruckner 2000
Black Band Disease (BBD) Caused by numerous cyanobacteria (500 spp.) as a microbial mat.
Mat makes the colored band.
First observed in 1973.
Moves 3mm to 1cm/day.
Found in 42 spp. of coral.

Kuta & Richardson 2002
• BBD correlates strongly with depth, temperature, nitrites.
• Also correlates with diversity and orthophosphate.
White band disease: Pathogen unknown, may be bacteria. Noticed in 1981.
Tissue loss from base to tip.
Affects two species, Acropora cervicornis and A. palmata.
Moves 3mm to 1cm/day.
• WBD has drastically altered Caribbean reefs.
• Shifts in coral species.
• Loss of overall coral cover; algae increasing.

• Both species now “threatened”.
• Losses of over 98% of A. cervicornis. Locally extinct.
White plague: Affects many species, but no acroporoids.
Caused by Aurantimonas bacteria.
First observed in 1977.

Aspergillosis: Caused by terrestrial fungi.
Affect mainly Atlantic gorgonians.
Also affects waterfowl.
Noted in 1997.

Tumors: Similar to cancer.
Affects mainly A. palmata.
Irregular growth, no zooxanthellae.
Noted in 1960s and 1970s.

Other diseases: Many other diseases.
Mostly known from Atlantic.
Yellow band disease, yellow spot disease, white pox disease, brown band disease.
Most noted for first time in last 20 years.
Pathogens usually unknown.

Part 3: Why are diseases becoming common?1. Global warming?
• Many people blame global warming.
• But likely much more complex.
2. Nutrient enrichment - Bruno et al. 2003
• Experiments done with YBD and Aspergillosis.
• Controls were disease only, experimental with added nitrogen and phosphorus.
Results - Aspergillosis
• Nutrients increased severity of disease in sea fans.
Results - YBD
• Presence of nutrients increased rate at which YBD developed in two species of coral.
3. Dust? -
Garrison et al. 2003
• Airborne dust from Africa and Asia carries many contaminants to reefs.
• Global warming and desertification increasing dust, therefore increasing contaminants.

Part 4: How do diseases affect conservation?Effects are widespread
Many studies have documented widespread coral decline in almost ALL coral species.
Porter et al. 2001 showed many declines 1996-1998 NOT due to coral bleaching but disease.

• Porter et al. 2001 cont
• Green & Bruckner 2000

• Green & Bruckner 2000
Many examples of diseases spreading, many examples of reef degradation (show many photos).

Overview of disease
• All diseases have negative effects.
• Only WBD has changed communities drastically.
• Pacific 15 years behind Atlantic.
• Compounded negative influences more severe for coral reefs.

Part 5: Preliminary results of field surveys of Terpios outbreaks in the Nansei Islands, Japan
Terpios hoshinota Rützler and Muzik 1993
Terpios in the Nansei Islands - history
Outbreak noticed in Mariana Is. 1973. (Bryan 1973 )
Terpios-Nansei project
Assess the current distribution of Terpios in the Nansei Islands.
Establish monitoring sites.
If present, characterize sexual reproduction & ecology.
Methods
Survey all major islands by snorkel/scuba (Reimer).
Monthly/bi-monthly sampling at designated locations – histology (Hirose), genetics (Chen).
Permanent transects at massive outbreak (Reimer), analyses (Reimer, Nozawa).
Preliminary results
Three situations observed: none, small amounts, massive outbreak
Disappearance?
Yonama, Tokunoshima had massive outbreak (87.9% cover) in 1986 (Marine Park Center Foundation 1986).
Discussion
Terpios absent or present in small numbers in most reefs in Nansei Islands (38/39 examined locations).
Coverage does not appear to fluctuate much in most locations.
Discussion & Questions
Massive outbreaks still occur in Nansei Islands.
How long do outbreaks last?
“Recovery” observed at Yonama, but is this true recovery? At least, not a dead-end.
Results suggest outbreaks are linked to reef degradation, but factors not clear.
Future work
Permanent transect results & analyses.
Try to quantify speed at which massive outbreaks can occur.
Combine analyses with genetic, histological results.
Examine Yakomo (current outbreak location) to understand causes of outbreaks. Why this location?

Part 6: Conclusions.Conclusion 1
• Disease more widespread on reefs in Caribbean.
• More research? Partially.
• Monitoring in Pacific very critical.
Conclusion 2
• Only one disease has permanently changed community structure (WBD).
• Other diseases locally important.
Conclusion 3
• Very few studies have investigated in detail mortality rates.
• Monitoring of individual colonies needed.
Conclusion 4
• Diseases increasing.
• Bleaching appears to be more critical, but two problems appear related.
Conclusion 5
• Diseases not well understood.
• Many diseases affect many species; possibly more or less diseases.
• Pathogens need to be investigated.
Conclusion 6
• While bleaching currently more serious, foolish to ignore diseases.
• May be “indicator” of serious problems, similar to amphibians.
What needs to be done
• <3% of reefs in danger have low human impact.
• More research needed on human influences and pathogens.
• Management and conservation then follow.
References:
1. Green & Bruckner. 2000. The significance of coral disease epizootiology for coral reef conservation. Biological Conservation 96: 347-361.
2. Aronson & Precht. 2001. White-band disease and the changing face of Caribbean coral reefs. Hydrobiologia 460: 25-38.
3. Garrison et al. 2003. African and Asian dust: from desert soils to coral reefs. BioScience 53: 469-481.
4. Bruno et al. 2003. Nutrient enrichment can increase the severity of coral diseases. Ecology Letters 6: 1056-1061.
5. Kuta & Richardson. 2002. Ecological aspects of black band disease of corals: relationships between disease incidence and environmental factors. Coral Reefs 21: 393-398.
6. Porter et al. 2001. Patterns of spread of disease in the Florida Keys. Hydrobiologia 460: 1-24.
7. Reimer, Hirose, et al. new Terpios papers.