ECOLOGICAL SAMPLING Sampling Program l l Diagnostics of

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ECOLOGICAL SAMPLING

ECOLOGICAL SAMPLING

Sampling Program l l Diagnostics of an ecological study Entails Planning: – – –

Sampling Program l l Diagnostics of an ecological study Entails Planning: – – – l Design (research question) Logistics (field work) Analysis (statistical) Involves taking sets of samples

What is a sample? l “A portion, piece, or segment that is representative of

What is a sample? l “A portion, piece, or segment that is representative of a whole”

Why do we sample? l Because it is usually impossible to know all the

Why do we sample? l Because it is usually impossible to know all the plants or animals present in a given area – – – e. g. # insect larvae in a pond e. g. # coral colonies on a reef e. g. # trees on a river terrace

Why do we sample? l or measure every value of a parameter – –

Why do we sample? l or measure every value of a parameter – – e. g. dissolved nutrients in tide pools e. g. sorting of sand grains on beaches e. g. species along an exposure gradient e. g. plant cover on backshore beaches

NON-INVASIVE SAMPLING l l Avoid any degradation of the habitat when sampling Removal of

NON-INVASIVE SAMPLING l l Avoid any degradation of the habitat when sampling Removal of whole or parts of organisms should be limited to species that can quickly recover

REPRESENTATIVE SAMPLING l Take a number of samples from around the sampling site so

REPRESENTATIVE SAMPLING l Take a number of samples from around the sampling site so as to be reasonably sure that the samples represent the site in general

Necessities… l For the samples to represent the whole it is necessary to: –

Necessities… l For the samples to represent the whole it is necessary to: – – – take appropriate samples take enough samples avoid bias when sampling

SAMPLING UNITS l The type of sample unit is determined by the organisms and

SAMPLING UNITS l The type of sample unit is determined by the organisms and the physical nature of the habitat being sampled – – Volume of water, air, or soil Area of ground surface

Regular Units l Standard units enable comparison of results – – Spatial Temporal

Regular Units l Standard units enable comparison of results – – Spatial Temporal

Bottles l Provide a standard, volume sampling unit

Bottles l Provide a standard, volume sampling unit

Nets l Also provide a standard, volume sampling unit

Nets l Also provide a standard, volume sampling unit

Cores l Provide a standard, volume sampling unit

Cores l Provide a standard, volume sampling unit

QUADRATS l Provide a standard, area sampling unit – l eg. square frame Consistent

QUADRATS l Provide a standard, area sampling unit – l eg. square frame Consistent size and shape is essential for comparing samples from different places and/or times

Quadrat Size l l l Chosen to suit sampling goals A balance between what

Quadrat Size l l l Chosen to suit sampling goals A balance between what is best and what is practical is always necessary Should suit: – – – habitat organism practical constraints

Habitat size l Appropriate sample unit size and numbers depend on size scale of

Habitat size l Appropriate sample unit size and numbers depend on size scale of the habitat – Small scale habitats require smaller sized samples l – Ex. Boulders Large scale habitats require larger sized samples l Ex. Forests

Organism size and density l Small, dense organisms require smaller samples – l Ex.

Organism size and density l Small, dense organisms require smaller samples – l Ex. grass Large, scattered organisms require larger samples – Ex. trees

Practical Constraints l Small quadrats – – – l quicker to survey yield a

Practical Constraints l Small quadrats – – – l quicker to survey yield a smaller individual sample of habitat larger # of samples required to represent the habitat Large quadrats – – – more time and effort to survey provide a larger individual sample of habitat smaller # of samples required to represent the habitat

Number of Quadrats l l More quadrats are more representative but there are time

Number of Quadrats l l More quadrats are more representative but there are time and effort limitations How many is enough? – Determine by plotting a graph of a given feature vs. number of quadrats

TYPES OF SAMPLING l l l Systematic Stratified Random

TYPES OF SAMPLING l l l Systematic Stratified Random

SYSTEMATIC SAMPLING l l Often used when the area being studied is varied, not

SYSTEMATIC SAMPLING l l Often used when the area being studied is varied, not very large, or when time is available Samples are taken at fixed intervals

How to sample systematically l l Systematic samples are usually taken along a transect

How to sample systematically l l Systematic samples are usually taken along a transect line marked by a tape measure Transect- a line laid across an area

Types of transect sampling l l Line transect Belt transect

Types of transect sampling l l Line transect Belt transect

Line Transect Method l A measured line is laid across the area and species

Line Transect Method l A measured line is laid across the area and species touching the line are recorded – – along the whole length of the line (continuous) or at specific points along the line (discontinuous)

Line Intercept Percent cover can be determined from a transect

Line Intercept Percent cover can be determined from a transect

Percent Cover

Percent Cover

Locate a Quadrat along a Transect

Locate a Quadrat along a Transect

Abundance

Abundance

Point Counts Good when distinguishing individuals is difficult

Point Counts Good when distinguishing individuals is difficult

Timed Search Used for Rarer or hard to find organisms Catch per Unit Effort

Timed Search Used for Rarer or hard to find organisms Catch per Unit Effort

Belt transect method l Similar to a line transect but widens the sampling area

Belt transect method l Similar to a line transect but widens the sampling area – – Samples are taken in an area that is a defined distance from a line Samples can be taken all the way along the line, at specific intervals, or even randomly 6 min

Sampling Along Gradients l Transects are often set up along environmental gradients – –

Sampling Along Gradients l Transects are often set up along environmental gradients – – – down a hillside across a streambed out from a source of pollution

Specific Considerations of Habitat 7 min

Specific Considerations of Habitat 7 min

Coral Reef Surveys l l l Surveying the GBR Monitoring impacts Long Term Ecological

Coral Reef Surveys l l l Surveying the GBR Monitoring impacts Long Term Ecological Research Sampling the same sites annually http: //reefcheck. org/ 1. 5 min

Targeting Research Questions • Site Descriptions • Types of Surveys o. Substrate ID o.

Targeting Research Questions • Site Descriptions • Types of Surveys o. Substrate ID o. Impact ID o. Fish ID

Two 100 m Transects at 2 Depths 100 m Transect Line Slate Underwater Transects

Two 100 m Transects at 2 Depths 100 m Transect Line Slate Underwater Transects

Substrate ID Line Intercept Point Sampling

Substrate ID Line Intercept Point Sampling

Substrate Surveys-Algal Overgrowth Line Intercept Point Sampling 1 min

Substrate Surveys-Algal Overgrowth Line Intercept Point Sampling 1 min

Impact Surveys-Coral Bleaching Belt Transects Area Searches 3 min

Impact Surveys-Coral Bleaching Belt Transects Area Searches 3 min

Invert Surveys-Coral Predators Belt Transects- Area Searches 1. 5 min

Invert Surveys-Coral Predators Belt Transects- Area Searches 1. 5 min

Fish Surveys-Keystone Species Belt Transects Swim & Pause 1. 5 min

Fish Surveys-Keystone Species Belt Transects Swim & Pause 1. 5 min

4 min

4 min

Freedom from Transect Lines Navigating along compass headings using Kick-Cycles and a watch to

Freedom from Transect Lines Navigating along compass headings using Kick-Cycles and a watch to determine distance

Relative Abundance

Relative Abundance

STRATIFIED SAMPLING l l Often used when there are small areas within a larger

STRATIFIED SAMPLING l l Often used when there are small areas within a larger habitat that are clearly different Strata- major differences within communities recognized before sampling begins

Strata in a Riverside Site l l l bank terrace channel ponds streams

Strata in a Riverside Site l l l bank terrace channel ponds streams

Intertidal Microhabitats Beachrock Seashore

Intertidal Microhabitats Beachrock Seashore

Multiple Sampling Techniques Timed Searches on Reef Edge Quadrates in the boulder fields

Multiple Sampling Techniques Timed Searches on Reef Edge Quadrates in the boulder fields

RANDOM SAMPLING l l Often used when the area being studied is fairly uniform,

RANDOM SAMPLING l l Often used when the area being studied is fairly uniform, very large, or when there is a limited amount of time available Random = chosen by chance rather than according to a plan; all outcomes are equally likely

Haphazard Sampling l Choose individuals or place “sampling units” arbitrarily – This is rarely

Haphazard Sampling l Choose individuals or place “sampling units” arbitrarily – This is rarely completely random OR…

How to sample randomly l Samples are taken from different positions within a habitat

How to sample randomly l Samples are taken from different positions within a habitat and those positions are chosen randomly l Assign numbers to the areas or individuals to be sampled – Use a random number table to select which areas or individuals will be sampled

How to sample randomly

How to sample randomly