Ecology and Epidemiology of Coral Diseases

How have disease reports changed over time?

they have increased

How have the number of coral diseases changed over time?

they have increased

What we can do to figure out if coral diseases are actually increasing in prevalence versus increases in the number of people looking for coral diseases?

have the same people monitor the same exact spot on many reefs over many years

What happened after the same people monitored the same exact spot on many reefs over many years?

Proportion of sites with diseases detected increased over time

What is the leading cause of coral decline in many regions?

disease

What do coral diseases outbreaks have consequences for?

the entire ecosystem

Why do coral disease outbreaks have consequences for the entire ecosystem?

corals are ecosystem engineers

what are ecosystem engineers?

Any organism that creates, significantly modifies, maintains, or destroys a physical habitat.

why are coral reefs considered ecosystem engineers?

They shape local biodiversity and landscape structure

What is a disease?

any impairment of vital body function, systems, or organs

what is prevalence?

proportion of population impacted by disease (%)

What is etiology?

cause of disease (biotic or abiotic)

What kind of processes are disease in healthy ecosystems?

normal processes

Why can diseases become problematic?

they can lead to local host extinctions

What causes problematic increases in disease?

stressor like global climate change, land-based pollution, sedimentation, overfishing, invasive species, and human interaction

Why do these stressors increase disease?

because they lead to novel pathogens, increased virulence, changes in transmission dynamics, and decreased host defense

What word describes the ability to detect and describe coral disease?

difficult

What do white plague, white band, white syndrome, white pox, and stony coral tissue loss disease all have in common?

they all refer to tissue loss diseases

What causes disease in coral reefs?

Bacteria, fungi, viruses, protozoans, and abiotic factors

What is the cause of some coral diseases?

Environmental stress

Why does environmental stress cause some coral diseases?

because it leads to bacterial ‘dysbiosis’ and opportunistic infection

What is dysbiosis?

A microbial imbalance or disruption in the hosts normal community of microorganisms (the microbiome)

Can some coral diseases be seasonal?

yes some are some are not

Can some coral diseases be enhanced by nutrient enrichment?

yes

what are the reasons behind why nutrient enrichment may enhance disease?

influences directly transmitted parasites

i. by changing the density of host

ii. altering the duration of infectivity by hosts

iii. providing additional resources to the pathogen

What coral diseases is host specific

Trematodiasis

Name a disease that is not host specific

black band disease

Can coral diseases be transmissable by direct contact?

yes some are

What type of transmission has been suggested as an important mechanism of coral disease transmission but is difficult to prove in the field?

Water-borne transmission

Are any coral diseases shown to spread by vector-borne transmission

yes only 1 coral disease have been proven

What is vector-borne transmission?

Vector borne transmission is the process by which living organisms known as vectors transmit infectious pathogens

What varies among corals?

pathogenesis

What is pathogenesis?

The biological origin and chronological development of a disease

What is the pathogenesis of chronic montipora white syndrome?

33% mortality in 5-6 month

What is the pathogenesis of acute montipora white syndrome?

90% mortality in 2-5 days

What defenses do corals have against diseases?

Mucus, microbiota, cellular responses (phagocytosis), reactive oxygen species response, and chemical response (melanin)

what is phagocytosis?

Cell eating, a specific type of endocytosis where a cell uses its plasma membrane to engulf a large particle

What do corals harbor that is abundance and diverse?

microbiota

What is physical barrier to entry, antimicrobial production, and the occupation of metabolic niches an example of?

bacterial contributions to coral disease defenses

what do corals secrete to control bacterial load?

mucus

what do corals use to control bacterial load

cilia

What are cilia?

Microscopic hair-like structures that project from the surface of many eukaryotic cells

How do cilia protect the coral?

they move particle and bacterial cells of the colony

how does mucus help to control the bacterial load?

they can trap microbes and slough off layers

What are progressive tissue loss, discoloration, inflammation, and skeletal deformities?

visual signs of coral disease

What is acute, subacute, chronic, banded, and multi-focal?

different patterns of progressive tissue loss

What are fish predation, invertebrate predation, algal interaction, and coral competition

biotic interaction that can be easily confused with coral diases

How can we tell when spots on a coral are from fish predation?

there will be numerous distinct bites, large deep scrapes, fresh bites over old ones, and areas of tissues loss will be about the same size

What causes discoloration due to algal abrasion and irritation that is usually pink?

coral-algal interactions

What is coral competition?

corals use stinging cells, which result in white dead areas

What are examples of well-described coral diseases?

black band disease, white plague, white pox, white syndromes, trematodiasis, dark spot disease, aspergillosis, and stony coral tissue loss disease

which disease was described in 1973 on Brazilian coral reefs, has a global distribution, banded tissue loss, is a host-generalist disease, increases in prevalence and severity in summer and has a multi-pathogen etiology?

black band disease

What causes black band disease?

a microbial consortium including cyanobacteria, sulfur-reducing bacteria, sulfur-oxidizing bacteria, and heterotrophic bacteria

Which disease is global but mostly caribbean distribution, is a host generalist disease, causes progressive tissue loss, has multiple names based on the speed of progression and a putative or unknown etiology?

White Plague

What does it mean to have a putative etiolody?

Having a supposed or strongly suspected cause that hasn’t been definitely proven by direct evidence

What is thought to cause white plague in red sea?

Thallosomonas loyana

What causes white pox diease?

reverse zoonosis

what is zoonosis?

disease transmitted from animals to humans

what is reverse zoonosis?

disease transmitted from humans to animals

which disease has a caribbean distribution, causes multi-focal progressive tissue loss, is reposible for large declines in coral cover in flordia keys, is host-specialist (infects acropora palmata) and is caused by the pathogen serratia marcescens from human sewage?

White pox disease

Which disease has been thought to have appeared without the etiological agent and without sewage effleunt?

White pox disease

What are the implications of having coral colonies have signs of white pox without serratia being detected or no sewage influence?

Potential of there being a new pathogen that causes the disease creates challenges in coral disease research

Which design is many diseases with one name, is a catch-all for progressive tissue loss, is named after teh hist impacted, and has the same signs but different (unknown) etiology like vibrio coralliilyticus, Vibrio owensii, Pseudoalteromonas piratii

White syndromes

Which pathogen is a global coral pathogen that is temperature-dependent and infects at a higher temperature?

Vibrio coralliilyticus

Which disease has a pacific distribution, is a host-specialist (porites), is generally not harmful to host, and has a trematode infection which causes cysts and swollen polyps?

Porites trematodiasis?

What is porites trematodiasis an example of?

parasitism

Who is the final host for the trematode?

corallivorous butterfly fish

Why are the swollen polyps beneficial for the trematode?

because the corallivorous butterfly fish can easily eat the swollen infected polyps

How do the fish shed the trematode eggs?

in feces

Who is the putative intermediate host that transmits the trematode to the coral?

snail

Which disease is in the Caribbean, primarily impacts Siderastrea, in the Pacific, primarily impacts Pavona, is called endolithic hypermycosis, causes multifocal discoloration that may develop into tissue loss and the putative etiology is an unknown fungus?

Dark Spots Disease

Which disease has a Caribbean distribution, primarily impacts the octocoral Gorgonia ventalina, the etiology is aspergillus sydowii fungus, and is potentially sources from terrestrial runoff and african dust?

Aspergillosis

What is one way to remove black band disease?

to suck it off the infected coral

What is Koch’s postulate?

scientific criteria to prove a specific microorganims causes a particular infectious disease

What is the first step of Koch’s postulate?

the suspected causative agent must be absent from all healthy organisms and present in all diseased organisms

What is the second step for Koch’s postulate?

The causative agent must be isolated from the disease and grown in pure culture

What is the third step of Koch’s postulate?

The cultured agent must cause the same disease when inoculated into a healthy susceptible organism

What is the fourth step of Koch’s postulate?

The same causative agent must then be reisolated from the inoculated diseased organism

Is it easy to satisfy Koch’s postulate for coral diseases?

no it is very challenging due to several key limiting factors?

What limiting factors keep us from satisfying Koch’s postulate for coral diseases?

the reef and aquarium are very different, it is tough to isolate microbes, we don’t know how exactly infection occurs or if lab transmission mimics transmission on the reef, and there are potentially lots of other microbes involved

What disease has been devastating the Florida reef tract since 2014 and has seen potential signs of the disease in the Caribbean including the USVI?

stony coral tissue loss disease

Where did stony coral tissue loss disease first appear?

Part of Miami

How many species does stony coral tissue loss disease affect?

22+ species

What is the cause of stony coral tissue loss disease?

unknown etiology or pathogens

Which disease is the longest deadliest coral disease outbreak on record (30-60% mortality on affected reefs)

stony coral tissue loss disease

How does stony coral tissue loss disease appear to be dispersed?

on ocean currents

What scales are SIR disease epidemic models used for?

both local scale and global

What are a set of simple differential equations that can predict or explain how an epidemic moves through a population?

SIR disease epidemic models

What does SIR stand for?

susceptible infected recovered