Coral Microbiology Flashcards
Corals are within what Phylum
Phylum Cnidaria
* related to jellyfish
* Bottom of the metazoan tree
Class and order of corals
Class: Hexacorallia
Order: Scleractinia
Where are stony corals (Scleractinia) found
tropical coral reefs
* oligotrophic waters (nutrient poor)
Tissue layers of a coral
Endoderm and ectoderm separated by mesoglea
* thickness ranges between species
Most well studied part of the moral microbiome
obligate symbiont Symbiodiniceae (dinoflagellates)
Where are Symbiodiniceae housed
gastrodermal cells
Why are Symbiodiniceae important for the coral
photosynthetic and provide photosynthates to the coral host
What causes coral bleaching
Heat stess causes breakdown of the obligate symbioses
- they are literally expelled out
- Corals go bright white
is bleached coral dead
no it just lacks symbiodiniceae
If heat maintains during bleaching, what happens to corals? what if heating stops?
- heat maintains = corals eventually die
- heating stops = corals can recover the dinoflagellates (Symbiodiniceae) and survive
Currently, what is undergoing a mass bleaching event
Great Barrier reef
* due to anthropogenic climate change
Second most well studied part of the coral microbiome
Prokaryotes (bacteria and archae)
Whats the role of prokaryotes in the coral microbiome
important roles in the coral host
* N cycling
* shelter, protection, source of nutrients
Components of relative abundance plots
- Y-axis: relative abundance of a microbe
- X-axis: factor variable (treatment, species, genotype, etc.)
- Fill of the bars is normally taxonomic rank
- Size of the bar is the proportion identified in a sample
do all coral species show stable microbiomes over time and space
NO!
* some species show stable microbiomes over time and space
* some show differences between genotypes
* some show differences in geographic location
Functions of surface mucus layer of corals
- Coral health: reduce pathogen colonization, undergo cycling functions (new mucus)
What are viruses proposed to be important in with the coral microbiome
- microbiome maintenance - Bacteriophages
- Horizontal gene transfer
much more research needed
What might fungus be important with in coral microbiome
- nutrient cycling - carbon and nitrogen
- implicated in antimicrobial activity
Do corals have a complex microbiome
Yes: despite being basal metazoans, coral have complex microbiome
coral microbiome vs. surrounding marine environment
microbiome is different to the surrounding marine environment
Diseases in corals causes
dysbiosis
What is a diseased coral microbiome dubbed
pathobiome
coral microbiome and coral disease study
- disease research in Acropora palmata
- exposed fragments of A. palmata to disease
- disease causes a shift from healthy microbiome to a pathobiome
- pathobiome is much more diverse than the healthy microbiome
Exact mechanisms of microbiome maintainence are unknown, but it probably involves
- Microbe to microbe
- Microbe to host
- Host to microbe
Environmental perturbations can disrupt the microbiome and shift it to a pathobiome state. What are 2 examples of this?
- heat stress and dinoflagellates
- disease and prokaryotes
