Functional Ecology of Fishes on Coral Reefs Flashcards
What is species richness a measure of?
Biodiversity
What are three types of diversity that can be measured to understand biodiversity within a region? What do they mean?
- ⍺ diversity - within a given area (species richness/number of species at each site)
- β diversity – comparison of areas (a measure of variability between sampling areas calculated using Ɣ/⍺ - the above and below diversity indices)
- Ɣ diversity – within the entire region (total number of species across all sampling)
Where is the highest species richness globally?
The Indo-Australian Archipelago (IAA) (also known as the Coral Triangle – however this is a less good name as the shape of highest biodiversity is not exactly a triangle).
Roughly how many fish species are found in the IAA?
~1,600
This is 1,600 out of ~6,000 marine fish species that live on coral reefs.
In total there are approximately 15,000 marine fish species.
The number of fish species in the IAA is a measure of what type of diversity?
Gamma diversity (the total sampling area of the IAA)
What is the definition of functional diversity?
The variety of ecological roles performed by species
What is a simple definition of a biological function?
The movement or storage of energy or material
Will species richness be the same as functional diversity?
No - for example, there could be a high number of different species, but only a very low functional diversity if many carry out the same function
Which regions are most vulnerable to species loss in terms of the ratio of functional diversity to species richness?
Regions where the functional diversity is higher in comparison to the species richness are likely to be more vulnerable to species loss as there are fewer redundant species.
What is it called when a species carries out the same functional role as another?
Functional Redundancy
What does BEF stand for and what is the big debate in the field?
Biodiversity and Ecosystem Function -> there is a big debate about whether the number of species (biodiversity) or function is more important
What kind of fishes consume macroalgae in reef crevices and why is this important?
Rabbitfishes -> Juvenile corals were far more likely to be successful and healthy when there is limited macroalgae in the regions of settlement (normally little holes in the reefs). Rabbitfishes consume this macroalgae and therefore increase juvenile coral success.
How do rabbitfishes feed and what is the name for this method?
Coordinated vigilance.
They are normally found in pairs so one fish can feed whilst the other watches out for predators (sticks out fin spines as a warning if a predator is spotted - both for the predator and for the partner)
What technique can be used to ensure accurate abundance measurements are taken for crypto-benthic reef fishes? Why for these fishes is this required?
An anesthetic collection technique (causes temporary immobility so easier to study).
They are often very small and so are therefore often missed in fish censuses when using visual techniques
Why are crypto-benthic fishes crucial to the movement of energy in reef systems?
- Fast growth rates
- Quick death rates (normally in large numbers, with 7-8% of the population dying daily)
- Replace populations with larvae quickly
Therefore, despite only accounting for 1% of the biomass, the potentially account for 2/3 of the biomass of eaten fish on the coral reef!
How do crypto-benthic fishes maintain their populations despite such a high death rate? How much faster do they do this than the average reef fishes?
The larvae somehow maintain proximity to the reef - would normally be dispersed. This means there are high numbers of larvae ready in the region to replace the dying adults.
This allows crypto-benthic species to replace themselves 26 times faster than the average large reef fish
How they maintain proximity is still not properly understood - could relate to parent care.
How can broad patterns in functional ecology be analysed? How does this work?
Functional Niche Analyses
Carries out an MDS on the behavioural attributes of all species in a region. If there is great spread, there are many different functional traits present in a region, if close they are then very similar.
Do Functional Niche Analyses show the number of functions or the type of functions? Do they show redundancy?
Can be used to measure the “number” of functions (rather than identifying the actual function, looking at diversity of functions).
They can identify crossovers across species, therefore highlighting redundancy.
What is it called when there is limited functional redundancy?
Functional vulnerability
Is biodiversity important to maintain on coral reefs?
It depends -> depends on functions present and the requirements of the reef.
Some species may be more important to maintain than others (e.g., where there is limited redundancy, to prevent phase shifts, such as rabbitfishes etc.).
