Week 6 The Coral Holobiont

Question 1

What is the definition of a coral holobiont?

Answer 1

An assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit

Question 2

When do symbiodinia live? Where do green algal, fungi and prokaryotes live? Where do most prokaryotes live?

Answer 2

1. Gastrodermal tissue
2. Skeleton
3. Coral tissue and mucus

Question 3

What two things allow corals to survive in oligotrophic water?

Answer 3

Access to two independent sources of nutrients

Recycling of nutrients within the holobiont

Question 4

What are the two methods of coral feeding?

Answer 4

Heterotrophs by the animal and the algal partner transfers nutritious photosynthetic products to the animal host

Question 5

What does the coral give to the symbionts?

Answer 5

Inorganic N/P waste

Question 6

What are Clades?

Answer 6

Genera, distinguished by LSU rRNA

Question 7

What is different inside the coral compared to ocean seawater?

Answer 7

Different environmental conditions

Question 8

What is ostreobium?

Answer 8

A symbiont that lives in coral tissue, it forms bands in slow growing corals and diffuse location in fast growing corals

Question 9

What did combined analysis of tufA and ribosomal RNA gene markers reveal about ostreobium clade?

Answer 9

1. Contains more than 80 taxonomic units at near species level
2. Ostreobidineae form a complex that has evolved over the last 500 million years

Question 10

Light environment inside the coral tends to be <1% of PAR, so how do ostreobium adapt?

Answer 10

Use light not use by zooxanthellae, near the infrared spectrum

Question 11

It is likely that ostreobium has low productivity, so what could their relationship with the coral be?

Answer 11

Comensalistic

Question 12

How can ostreobium be detrimental?

Answer 12

1. May play a role in bleaching
2. Boring activity creates micro pores
3. Can weaken the reef by dissolving 0.9kg of CaCO3 per m2 of reef.year

Question 13

How can endolithic fungi such as Ascomycota and Basidiomycota interact with Ostreobium?

Answer 13

Can convert green to black bands

Question 14

What do corals do in response in endolithic fungi?

Answer 14

Deposit skeletal material around the hyphae when they come close

Question 15

Are endolithic fungi considered good or bad?

Answer 15

They can be considered a potential pathogen but can be commensalistic in healthy corals

Question 16

Filamentous marine Cyanobacteria are examples of endolithic prokaryotes, where are they found?

Answer 16

Green bands in corals

Question 17

What helped discover filamentous marine Cyanobacteria?

Answer 17

16S rRNA gene sample on sequencing

Question 18

What is this?

Answer 18

Prosthecochloris, a anaerobic green sulphur bacteria

Question 19

What does high concentrations of inorganic nitrogen within the pore water of coral skeletons suggest?

Answer 19

That endolithic microbes actively accumulate and efficiently recycle the nitrogen within this environment

Question 20

What are the three forms of prokaryotes associated with coral tissue?

Answer 20

Commensalism, mutualistic or pathogenic

Question 21

How many cells are there per 1cm2?

Answer 21

100-1,000,000

Question 22

Communities are often host-specific, and bacteria are often found in CAMAs, what are they?

Answer 22

Cell associated microbial aggregates

Question 23

What does this image show, these are densities of CAMAs in acrophobia hyacynthus?

Answer 23

That the density of CAMAs were negatively correlated with the distance from the coastline

Question 24

Do coral associated bacteria differ more with location or species?

Answer 24

Location

Question 25

What has a strong influence on the coral microbiome?

Answer 25

Environment

Question 26

What are Koch postures?

Answer 26

1. The pathogen is present in all diseased individuals and absent in healthy ones
2. The presumed pathogen is isolated in pure culture
3. The pathogen infects healthy individuals and causes the appropriate disease signs
4. The pathogen and be re-isolated and shown to be the same as the original

Question 27

Why is it not always possible to demonstrate Kochs postures in corals?

Answer 27

1. Some pathogens cannot be grown as pure cultures

2. The method of infection may not be understood

Question 28

What is this and what can it cause?

Answer 28

A vibrio species and it can cause bleaching

Question 29

What is this?

Answer 29

Aspergillosis a fungal disease in seafans

Question 30

This causative agent of white pox disease is non-pigmented serratia marcescens, how does it spread?

Answer 30

It is an opportunistic pathogen associated with waterborne infections

Question 31

What is this?

Answer 31

A roadmap for future research