Practicals Flashcards
Practical 1: What are Meiofauna?
A large and diverse group of organisms that are defined by their size
- They are exclusively benthic (i.e. not planktonic)
Practical 1: What is the size of meiofauna defined as?
Can pass through a 1mm sieve but are retained on a 45um mesh (i.e. they are between 1mm and 45um in size)
Practical 1: Where can meiofauna be found?
In both marine and freshwater habitats
Practical 1: Where are meiofauna found in the ocean?
At all depths
Practical 1: What are some of the most important meiofauna taxa?
- Nematoda
- Ostracoda
- Copepoda
- Halacaroidea
- Gastropoda
etc.
Practical 1: What copepods are the dominant meiofaunal taxa?
Nematodes & Harpacticoid
Practical 1: What percentage of all animal phyla have at least some meiofaunal taxa?
66%
Practical 1: For meiofauna, how many animals are there per m^2?
As many as 1 million
Practical 1: What is the role of meiofauna in benthic ecology?
- Meiofauna are primarily detritus, bacteria and diatom feeders
- Some meiofauna are predators (e.g. turbellarians - flatworms), preying on other meiofauna
- Meiofauna are food for higher trophic levels, such as juvenile fish, shrimp, crabs, worms, and some filter feeders (if the meiofauna become suspended in the water column)
Practical 1: What is the role of meiofauna in phytal (algal) habitats?
- Meiofauna live on rocky shores as well, but almost exclusively within macroalgal substrates
- The diversity and abundance of meiofauna increases with increasing algal complexity
Practical 1: What is the relationship between algae and meiofauna in phytal (algal) habitats?
- Structurally complex macroalgae creates multiple microhabitats in a complex hydrodynamic environment - offering protection and foraging opportunities (e.g. fronds harbour detritus, bacteria, diatoms and protozoans)
- Holdfasts of larger algae, such as kelps, also offer habitat
Practical 1: What is the distribution and abundance of meiofauna?
- On average ~1 million meiofaunal organisms per square meter of sediment surface
Practical 1: What factors cause distribution and abundance of meiofauna to vary?
- Numbers vary according to:
- > Season
- > Latitude
- > Depth
- > Tidal exposure
- > Grain size
- > Habitat type (e.g. phytal substrate, sand, mud)
Practical 1: What was the aim?
To determine if the abundance and diversity of meiofauna are different between two different habitats:
- Within algae attached to natural rocky shore
vs
- Within algae attached to coastal defenses (artificial habitat)
Practical 1: Where were the two samples sites?
- Swanage (natural rocky shore
2. Highcliffe (“artificial” rocky shore)
Practical 1: What were the observations made about Swanage?
- Natural rocky shore
- Algae/invertebrates are not regularly disturbed by people
- High diversity & abundance of macrofauna
Practical 1: What were the observations made about Highcliffe?
- The coastal defenses at Highcliffe undergo maintenance and replacement of rocks
- Algae/invertebrates are regularly disturbed
- Low diversity & abundance of macrofauna
Practical 1: What was the alternate hypothesis?
The abundance & taxonomic richness of meiofauna should be higher in Swanage, compared to Highcliffe
Practical 1: What is the method?
- Remove 40 random samples of algae from the mid-intertidal zone of equal size (~ the volume of a petri dish) from both field sites (i.e. 80 samples of algae)
- In the lab, wash each sample of algae through a 1mm mesh sieve (on top) and then a 250μm mesh sieve (on bottom)
- Once all contents are sieved, use EtOH (ethanol) to transfer the meiofauna (on the bottom sieve) into a
collection jar for later analysis (1-3 done in 2018) - Use a microscope to identify and count the number of meiofauna in each jar (done in practical session)
- Statistically compare the number of meiofauna in
Swanage versus Highcliffe (done in lecture)
Practical 1: What was found?
Swanage has greater diversity and abundance of meiofauna (biodiversity) - what was expected as it is more natural than Highcliffe
