L3 Marine Microbes Flashcards
What has recorded microbial composition for dacades?
Continuos plankton recorder, Plymouth.
Filters dragged behind boats, with different mesh sizes. Good resource to find out changes over time.
What is the most common biological agent in the ocean?
Viruses
eg marine virus
CroV - most complex and largest.
Attacks heteroflagellates
What is the largest PK?
Thiomargarita 0.75mm
Why are PK important in ocean?
Major role as decomposers, recycle DOM
degrade oil spills
Labile sea foam broken down by PK
draw the microbial loop
.
define:
Endophytes
Epipyhtes
Endolithic
Endophytes- live inside plants
Epipyhtes - Live on plants
Endolithic - Burrrow into rocks
What pigment do cyanobacteria use?
Where does ph occur?
Phycocyanin, over Chl a
folded membranes, not chloroplasts
What is Trichodesmium?
Most abundant group of cyanobacteria
Trichodesmium hotspots..
can be seen from space
N low regions
A special cell type in Trichodesmium
Diazocyte - N fixing
inhibited in presence of O2.
What is the most abundant photosynthesiser?
Prochloroccus
type of cyanobacteria
very small, <1/2 micrometer
What is an issue with N fixing bacteria?
When they die, N sinks with them to lower levels so N at surface must be replenished.
What other nutrients does Trichodesmium utilise?
Phosphonates
Phosphates
What are Crenarcheota?
Extremophile archaea capable of transforming ammonia
What is marine snow?
stream of particles sinking to depth
Bacteria and archaea embedded in marine snow
What is another pigment some bacteria use to capture light energy?
Proteorhodopsin
3 EK phytoplanktom
Diatoms
Dinoflagellates
Coccolithiphores
Which EK phytoplankton migrate to depth daily?
Dinoflagellates, when nutrients depleted in upper layers go down.
How do diatoms stay afloat?
Huge extensions of cell aid flotation
3 heterotrophic protists
Foraminifera - planktonic and benthic
Radiolaria - siliceous sediment formed from shells when dead
Ciliates - can inhabit guts of sea urchins, fish skin or are planktonic.
What is a Tintinnid?
Heterotrophic protist, ciliate
What is the claw hypothesis?
There is a homeostatic feedback which balances oceanic phytoplankton and climatic production of DMS
What is DMS?
Dimethyl sulphide
Flux from sea to air is important in the biogeochamical sulphur cycle
How do algae produce DMS?
algal metabolite DMSP is considered a major precursor to DMS
How may symbiosis have evolved?
coevolution of bacteria and hosts.
maybe began association by living alongside host and increasing host chances of survival. Over time became so intimate that host couldn’t survive without it.
example of symbiosis` 3
- Bacteria in Shipworms digest wood as shipworms lack cellulase.
- Bioluminescent bacteria are enclosed in photophores . eg Flashlight fish have bioluminescence beneath each eye with shutter mechanism to control emmission of light.
- Chemosynthetic bacteria are symbiotic with mussels and clams from hydrothermal vents.
Why might protozoans be more impressive than animals?
As they are single celled organisms, each cell carries out every function that all the cells in a multicellular animal would carry out.
What is a protozoan?
AKA protist
Single celled, eukaryotic
Not true animals or plants, different kingdom
What are 3 protists?
Radiolarians
Ciliates
Foraminiferans
Describe Radiolarians
Elaborate silica skeletons which form radiolarian ooze due to pressure in deep water.
Spherical with radiating spines
Describe Ciliates
Use cilia for feeding and movement
some live on gills of clams, fish skin, sea urchin intestines, or attached to substrate
eg Tintinnids, Paramecium.
Describe foraminiferans
CaCO3 test with several chambers
Retractable pseudopodia (extensions of cytoplasm) protrude through pores in test and trap diatoms.
Many benthic, attached to substrate (<5cm)
Tests form foraminiferan ooze after death.
How can foraminiferans be used to detect changes in temperature?
identify species in glaciers to determine temperatures back in time.
How many species of marine fungi are there?
1500, mostly microscopic
What ecosystem roles do fungi have?
Important decomposers of cellulose eg mangrove leaves, driftwood, detritus that accumulates in blooms.
Nutrient recycling in estuaries.
Parasites of seagrass
How do fungi affect economy and human life?
Possible source of antibiotics
Cause economically damaging diseases.
