Habitat
A habitat is the place where organisms live. It provides the resources needed for survival.
Lesson 2:
Ecological
Sampling
Techniques
Learn how ecologists sample habitats using quadrats, transects, collection apparatus, and mark-release-recapture population estimates.
Section
A
Objective
2.1
Quiz
18 marks
Ecologist's Toolkit
Watch first, then use the summary and flashcards before attempting the full quiz.
Study Guide Summary
Key ideas for CSEC Biology sampling technique questions.
Species Lists
A species list tells which organisms are present, but not their numbers or exact distribution within the habitat.
Quadrats
Quadrats enclose a known area, commonly 0.25 m2 or 1 m2, so species density can be estimated.
Transects
Transects are used when organisms change gradually across a habitat, such as vegetation from the sea inland.
Sampling Tools
Know when to use pooters, sweep nets, pond nets, beating trays, and pitfall traps.
Population Estimates
Mark-release-recapture estimates mobile animal populations using capture, marking, release, and recapture data.
Lesson Flashcards
Use each card as a quick oral test before the quiz.
Definitions and Ethics
A habitat is a place where organisms live and where they obtain the resources needed to survive.
It shows which organisms are present, but not where they live within the habitat or how many there are.
Cause minimum disruption. If you move stones or objects, return them exactly as you found them.
Quadrats and Density
A quadrat is a wire or wooden frame that encloses a known area for sampling organisms.
Species density is the number of organisms of each species within 1 m2.
Place quadrats randomly, count individuals in each sample, add the counts, then divide by the number of quadrats.
Transects
Use a transect when species are not randomly distributed and change across a habitat gradient.
A tape is laid across a habitat and the organisms found at intervals along the line are recorded.
Quadrats are placed at intervals along a line, giving abundance or density data at each point.
Mark-Release-Recapture
Estimated population = (number captured and marked x number recaptured) / number recaptured that were marked.
Marks must be non-toxic, must not make animals more visible to predators, and should not rub off before recapture.
Estimated population = (36 x 45) / 6 = 1620 / 6 = 270 crabs.
Sampling Apparatus
Use a pond net for ponds, a beating tray for tree branches, and a pitfall trap for ground-dwelling insects.
A pooter draws tiny or small animals into a container by suction through a tube.
Self-Assessment Quiz
Answer all sections. Numeric answers can be typed as whole numbers.