Monitoring Flashcards
(18 cards)
What is the challenge with monitoring?
Obtaining accurate information about population size and genetic diversity
What is monitoring?
use of indicators to understand what is happening about population size and genetic diversity. The reward is accurate information about biodiversity trends and success of management
What does a project need to be counted as monitoring?
Systematic in time and space.
long-term (minimum 10 years).
Should be targeted at specific purpose/hypothesis
What is occupancy?
Proportion of sites where a species occurs.
Hard to prove species doesn’t occur here but opposite is real data.
With systematic sampling, lack of record can be meaningful but needs care in interpretation and statistical interpretation in uncertainty
Only many repeated visits to a site can separate detectability from occupancy
If species is really rare, the number of visits to a site needed to be sure of absence increases and isn’t always linear relationship
What is occupancy in monitoring?
Combination of true occupancy and detectability.
Good when species isn’t too rare/elusive nor too common.
Must visit large number of sites repeatedly over time and carry on for a predetermined set time for survey if individuals/group are not seen, else stop when one is observed.
Rare species are hard, especially if they don’t shed eDNA
Random sampling
Unformly or randomly distributed species
Stratified sampling
Species that are clumped (split area into different sub-areas, each of which is sampled at random; denser sub-areas should be sampled more, objective is efficient use of sampling effort)
Adaptive sampling
Sparse but highly clustered spp - sampling effort depends on what you find, more sampling where you’re successful
Systematic sampling
Where the objective is to produce a map of population density
When do you use density estimation?
plants/fixed organisms - usually absolute density required (not cover)
Quadrats/belt transects
5 or more per site, slow but accurate, choice of quadrat size is critical (<20% of quadrats should be empty)
Permanent quadrats
at least 10 permanently marked out, total at least 100, initial quadrat placement requires care, record survival or plants already marked and count new recruits into population at an appropriate time each year
Remote sensing
suitable in sparsely vegetated lands for large shrubs and trees visible from satellites - buy image at same time every year, count number and cover of each species - expensive but getting cheaper
Point counts
Traditionally for birds. Very inaccurate without distances. detects more than camera traps but these tend to be more common species than elusive ones
Marking methods
Elsuive organisms.
Capture sample –> mark –> release –> recapture sample and count proportion of marked individuals and hence estimate density
Recapture rates usually vanishingly small so difficult to analyse
What does mark recapture assume?
Equal catchability
Population is closed
Marks don’t come off
Marking doesn’t affect survival e.g. clipping toes off frogs does impact their survival
Process of eDNA sampling and analysis
Water through syringe and filter
extract DNA
NGS metabarcoding (can also do qPCR)
Process of biodiversity survey
Design survey plan.
Construct eDNA sampling kits.
Conduct field work.
Extract eDNA.
Quality control eDNA.
Sequence metazoan COI and bacterial 16S barcoding region from samples collected.
Compare to reference DNA database.
Generate list of species.
Conduct biodiversity analysis.
Write report
