Coral Microbiology

Question 1

Corals are within what Phylum

Answer 1

Phylum Cnidaria
* related to jellyfish
* Bottom of the metazoan tree

Question 2

Class and order of corals

Answer 2

Class: Hexacorallia
Order: Scleractinia

Question 3

Where are stony corals (Scleractinia) found

Answer 3

tropical coral reefs
* oligotrophic waters (nutrient poor)

Question 4

Tissue layers of a coral

Answer 4

Endoderm and ectoderm separated by mesoglea
* thickness ranges between species

Question 5

Most well studied part of the moral microbiome

Answer 5

obligate symbiont Symbiodiniceae (dinoflagellates)

Question 6

Where are Symbiodiniceae housed

Answer 6

gastrodermal cells

Question 7

Why are Symbiodiniceae important for the coral

Answer 7

photosynthetic and provide photosynthates to the coral host

Question 8

What causes coral bleaching

Answer 8

Heat stess causes breakdown of the obligate symbioses
- they are literally expelled out
- Corals go bright white

Question 9

is bleached coral dead

Answer 9

no it just lacks symbiodiniceae

Question 10

If heat maintains during bleaching, what happens to corals? what if heating stops?

Answer 10

• heat maintains = corals eventually die
• heating stops = corals can recover the dinoflagellates (Symbiodiniceae) and survive

Question 11

Currently, what is undergoing a mass bleaching event

Answer 11

Great Barrier reef
* due to anthropogenic climate change

Question 12

Second most well studied part of the coral microbiome

Answer 12

Prokaryotes (bacteria and archae)

Question 13

Whats the role of prokaryotes in the coral microbiome

Answer 13

important roles in the coral host
* N cycling
* shelter, protection, source of nutrients

Question 14

Components of relative abundance plots

Answer 14

• 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

Question 15

do all coral species show stable microbiomes over time and space

Answer 15

NO!
* some species show stable microbiomes over time and space
* some show differences between genotypes
* some show differences in geographic location

Question 16

Functions of surface mucus layer of corals

Answer 16

• Coral health: reduce pathogen colonization, undergo cycling functions (new mucus)

Question 17

What are viruses proposed to be important in with the coral microbiome

Answer 17

• microbiome maintenance - Bacteriophages
• Horizontal gene transfer

much more research needed

Question 18

What might fungus be important with in coral microbiome

Answer 18

• nutrient cycling - carbon and nitrogen
• implicated in antimicrobial activity

Question 19

Do corals have a complex microbiome

Answer 19

Yes: despite being basal metazoans, coral have complex microbiome

Question 20

coral microbiome vs. surrounding marine environment

Answer 20

microbiome is different to the surrounding marine environment

Question 21

Diseases in corals causes

Answer 21

dysbiosis

Question 22

What is a diseased coral microbiome dubbed

Answer 22

pathobiome

Question 23

coral microbiome and coral disease study

Answer 23

• 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

Question 24

Exact mechanisms of microbiome maintainence are unknown, but it probably involves

Answer 24

• Microbe to microbe
• Microbe to host
• Host to microbe

Question 25

Environmental perturbations can disrupt the microbiome and shift it to a pathobiome state. What are 2 examples of this?

Answer 25

• heat stress and dinoflagellates
• disease and prokaryotes