Practicals

Question 1

Practical 1: What are Meiofauna?

Answer 1

A large and diverse group of organisms that are defined by their size
- They are exclusively benthic (i.e. not planktonic)

Question 2

Practical 1: What is the size of meiofauna defined as?

Answer 2

Can pass through a 1mm sieve but are retained on a 45um mesh (i.e. they are between 1mm and 45um in size)

Question 3

Practical 1: Where can meiofauna be found?

Answer 3

In both marine and freshwater habitats

Question 4

Practical 1: Where are meiofauna found in the ocean?

Answer 4

At all depths

Question 5

Practical 1: What are some of the most important meiofauna taxa?

Answer 5

• Nematoda
• Ostracoda
• Copepoda
• Halacaroidea
• Gastropoda
  etc.

Question 6

Practical 1: What copepods are the dominant meiofaunal taxa?

Answer 6

Nematodes & Harpacticoid

Question 7

Practical 1: What percentage of all animal phyla have at least some meiofaunal taxa?

Answer 7

66%

Question 8

Practical 1: For meiofauna, how many animals are there per m^2?

Answer 8

As many as 1 million

Question 9

Practical 1: What is the role of meiofauna in benthic ecology?

Answer 9

• 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)

Question 10

Practical 1: What is the role of meiofauna in phytal (algal) habitats?

Answer 10

• Meiofauna live on rocky shores as well, but almost exclusively within macroalgal substrates
• The diversity and abundance of meiofauna increases with increasing algal complexity

Question 11

Practical 1: What is the relationship between algae and meiofauna in phytal (algal) habitats?

Answer 11

• 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

Question 12

Practical 1: What is the distribution and abundance of meiofauna?

Answer 12

• On average ~1 million meiofaunal organisms per square meter of sediment surface

Question 13

Practical 1: What factors cause distribution and abundance of meiofauna to vary?

Answer 13

• Numbers vary according to:
• > Season
• > Latitude
• > Depth
• > Tidal exposure
• > Grain size
• > Habitat type (e.g. phytal substrate, sand, mud)

Question 14

Practical 1: What was the aim?

Answer 14

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)

Question 15

Practical 1: Where were the two samples sites?

Answer 15

1. Swanage (natural rocky shore

2. Highcliffe (“artificial” rocky shore)

Question 16

Practical 1: What were the observations made about Swanage?

Answer 16

• Natural rocky shore
• Algae/invertebrates are not regularly disturbed by people
• High diversity & abundance of macrofauna

Question 17

Practical 1: What were the observations made about Highcliffe?

Answer 17

• The coastal defenses at Highcliffe undergo maintenance and replacement of rocks
• Algae/invertebrates are regularly disturbed
• Low diversity & abundance of macrofauna

Question 18

Practical 1: What was the alternate hypothesis?

Answer 18

The abundance & taxonomic richness of meiofauna should be higher in Swanage, compared to Highcliffe

Question 19

Practical 1: What is the method?

Answer 19

1. 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)
2. In the lab, wash each sample of algae through a 1mm mesh sieve (on top) and then a 250μm mesh sieve (on bottom)
3. 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)
4. Use a microscope to identify and count the number of meiofauna in each jar (done in practical session)
5. Statistically compare the number of meiofauna in
   Swanage versus Highcliffe (done in lecture)

Question 20

Practical 1: What was found?

Answer 20

Swanage has greater diversity and abundance of meiofauna (biodiversity) - what was expected as it is more natural than Highcliffe