Lecture 1 Flashcards
What is a CTD?
Oceanography instrument used to measure conductivity, temperature and pressure (D for depth)
Why is conductivity measured by a CTD?
It can be used to determine salinity
Why must huge amounts of water be sampled to examine organisms distribution?
Organisms are often distributed heterogeneously
In the study by Vargas et al. (2015), where was the greatest diversity found?
In the heterotrophic protist groups, especially those known to be parasites or symbiotic hosts
What are some key planktonic players in the ocean?
- Viruses e.g. CroV
- Bacteria e.g. Trichodesmium and Prochlorococcus
- Archaea
- Photosynthetic protists e.g. diatoms, dinoflagellates and coccolithophores
- Heterotrophic protists e.g. Foraminifera, Radiolaria and Ciliates
How do viruses impact oceans?
- Parasitic, control many autotrophs
- Impact nitrogen cycling, particle size distributions, sinking rates of plankton
- Most abundant biological agent in the ocean
Why are bacteria so important in oceans?
They play a major role as decomposers, recycling nutrients and releasing dissolved organic matter (DOM)
Play a role in carbon flux
What is the process by which bacteria release nutrients back into water?
- Organic particles sink
- Bacterial decay regenerates nutrients
- Occurs below the photic zone
- Nutrients carried into deep water
What is a diazocyte?
A special nitrogen-fixing cell of the marine cyanobacteria Trichodesmium
What is the most abundant photosynthetic organism in the sea?
Prochlorococcus
Hotspots of Trichodesmium
Found in areas of warmer currents, where nutrients are low so not many other species could survive
What is Trichodesmium limited by? How do they get past it?
Phosphorus
They can use unusual sources of phosphorus - monophosphate esters and phosphonates
Example of symbiosis; puffer fish
Contain symbiotic bacteria that produce a deadly toxin called tetrodotoxin - puffer fish and detoxify the toxin
Archaea in oceans
- Can make up 20% of prokaryotes in particular regions of the oceans
- Many are extremophiles
- Common in water and sediments, important in coastal waters
Distribution of bacteria and archaea
Mainly in photic layer but still present in small amounts in deep oceans
Can be embedded in marine snow deep in oceans
How much of oceans biomass do microbes make up
More than 90%
Features and name of coccolithophores
Haptophyta Photosynthetic protist Calcium carbonate exoskeleton Important photosynthesisers Highly reflective so can cause changes in sea surface temperature
Diatom name and features
Eukaryotic plankton
Photosynthetic protist
Bacillariophyta
Cell extensions to aid flotation
Features and name of dinoflagellate
Photosynthetic protist
Dinophyta
Can bioluminesce
Up to 2 flagella for motility if waters are nutrient depleted
Features of Foraminifera
Single called heterotroph
Planktonic and benthic
Occur in animal guts, plankton, sediments and seaweed
Feature of Radiolaria
Shells form siliceous sediment on sea floor when they die
Ocean virus example
CroV attacks flagellate heterotroph Cafeteria roenbergensis
Features of ciliates
Many benthic but may inhabit guts or sea urchins
Some are planktonic
Important in the microbial loop
What work by Rumbo et al. (2000) sparks debate about symbiosis
The sea slug eats green algae and breaks down most of the algae but retains the chloroplasts to use for photosynthesis - is this symbiosis or just use of organelles?
