Week 6 The Coral Holobiont Flashcards
What is the definition of a coral holobiont?
An assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit
When do symbiodinia live? Where do green algal, fungi and prokaryotes live? Where do most prokaryotes live?
- Gastrodermal tissue
- Skeleton
- Coral tissue and mucus
What two things allow corals to survive in oligotrophic water?
Access to two independent sources of nutrients
Recycling of nutrients within the holobiont
What are the two methods of coral feeding?
Heterotrophs by the animal and the algal partner transfers nutritious photosynthetic products to the animal host
What does the coral give to the symbionts?
Inorganic N/P waste
What are Clades?
Genera, distinguished by LSU rRNA
What is different inside the coral compared to ocean seawater?
Different environmental conditions
What is ostreobium?
A symbiont that lives in coral tissue, it forms bands in slow growing corals and diffuse location in fast growing corals
What did combined analysis of tufA and ribosomal RNA gene markers reveal about ostreobium clade?
- Contains more than 80 taxonomic units at near species level
- Ostreobidineae form a complex that has evolved over the last 500 million years
Light environment inside the coral tends to be <1% of PAR, so how do ostreobium adapt?
Use light not use by zooxanthellae, near the infrared spectrum
It is likely that ostreobium has low productivity, so what could their relationship with the coral be?
Comensalistic
How can ostreobium be detrimental?
- May play a role in bleaching
- Boring activity creates micro pores
- Can weaken the reef by dissolving 0.9kg of CaCO3 per m2 of reef.year
How can endolithic fungi such as Ascomycota and Basidiomycota interact with Ostreobium?
Can convert green to black bands
What do corals do in response in endolithic fungi?
Deposit skeletal material around the hyphae when they come close
Are endolithic fungi considered good or bad?
They can be considered a potential pathogen but can be commensalistic in healthy corals
Filamentous marine Cyanobacteria are examples of endolithic prokaryotes, where are they found?
Green bands in corals
What helped discover filamentous marine Cyanobacteria?
16S rRNA gene sample on sequencing
What is this?
Prosthecochloris, a anaerobic green sulphur bacteria
What does high concentrations of inorganic nitrogen within the pore water of coral skeletons suggest?
That endolithic microbes actively accumulate and efficiently recycle the nitrogen within this environment
What are the three forms of prokaryotes associated with coral tissue?
Commensalism, mutualistic or pathogenic
How many cells are there per 1cm2?
100-1,000,000
Communities are often host-specific, and bacteria are often found in CAMAs, what are they?
Cell associated microbial aggregates
What does this image show, these are densities of CAMAs in acrophobia hyacynthus?
That the density of CAMAs were negatively correlated with the distance from the coastline
Do coral associated bacteria differ more with location or species?
Location
