Ecological Sampling

Why Do We Sample?

• Determine presence and/or abundance

• Monitor population fluctuations

• Assess ‘ecological damage’

• Assess quality of habitat

• Assess population responses

What Do We Sample?

• Physical Environment– Temperature, DO, pH, salinity, clarity, flow,

sediment

• Biotic Environment– All living things

Physical Habitat• Temperature

– Mercury thermometer– Electronic thermometer– Long-term thermometers

• Dissolved Oxygen– Winkler method (titration)– DO meter (electrode)

• pH– Litmus paper– pH meter (electrode)

• Salinity– Salinity Meter

YSI 550A DO Meter w/12' cable

Water Clarity• Secchi Disk– Disk is attached to a calibrated rope. The disk

is lowered into the water until the white parts can no longer be seen. Secchi disk depth is then recorded and serves as the waters transparency index. The clearer the water, the greater the secchi disk depth.

Secchi Disk

Current Velocity (flow)

• Floating-orange method.– Put an orange (or something else that floats

just below the water surface) and measure the time it takes it to float across a known distance.

• Odometer-type flow meter– Number of revolutions the propeller makes for

a given time is calibrated to flow velocity.

Sediment

• Sediment size is important to many aquatic organisms.

• Sieve’s are used to separate and grade sediment samples.– Percent of each size grade can be determined

Water Sample

• Water and plankton from various depths can be collected.

• A trigger mechanism is used to close the sampler.– Sample is then brought back to the surface

Small Mammals

• Mouse/rat Traps– Fatal

• Pit Falls– Bucket is placed in the ground– Sometimes have ‘leads’ to the buckets

• Live traps– Havahart– Sherman

• Spot-light

Sherman trapHavahart trap

Birds• Stick-under-the-box method• Bird-trap– Works like a minnow trap

• Mist net– Captures birds in flight

• Rocket net– Uses a propellant to throw a net

over birds

Terrestrial Insects

• Sticky paper– flies

• Baited Traps– Fire ants

• Nets– butterflies

• Foggers– Collect insects from tree canopies

Aquatic Insects• Drift Net

– Place net in flowing water

• Kick Net– ‘Kick’ sediment upstream

from block net and the flow will wash them into the net

– Wash bucket

• Serber or Hess Sampler– Stir up known area of

sediment – Animals are collected by a

catch net

• Multi-plate Sampler– Become colonized

Crawfish and Crab Traps

Fish Larvae• Light Traps– Larvae are attracted to the light

• Ichthyoplankton nets– Can be towed at various depths– Fish collect at the ‘cod’end

Fish• Lift net– Net is placed down, and after

a set amount of time it is quickly lifted

• Pop-net– Similar to a lift net, but floats

are attached to a framed net.– Operated by a trigger

mechanism

• Throw net– A net attached to a heavy

frame is thrown and every thing inside is netted out

Throw net

Pop-net

Lift net

Minnow trap

• Usually use bait to attract small fish– Light is used sometimes as an attractant

Fish

• Electrofishing– Electricity is put into the water– Fish are temporarily stunned and usually swim

towards the electricity source– Usually non-fatal but may cause some damage

Fish

• Gill Net– Gill nets resemble tennis nets– Fish can not swim completely through the net

and get caught– Gill nets are size selective (based on mesh size)

Square Mesh

Bar mesh

Stretch mesh

Fish• Trammel Net– Three panels: two large

mesh on the outside and a small mesh on the inside

– Fish swim through the outer mesh, pushes the small mesh through the other side and becomes entangeled

Hoop nets (and other similar nets) can have bait or not.

Fyke nets have leads to help guide fish to the net.

Seine• Seines are nets that are pulled through

shallow water to catch fish.

Purse Seine• Used to encircle entire schools of fish– Usually involves a spotter plane and a second

boat

Trotline (longline)• A series of baited drop lines connected to

a main line.

Can be deployed by tying one end to the bank and tying the other end with a heavy weight.

Shrimp (or fish) Trawl

• Net pulled behind a boat along the bottom– Either a beam or otter

boards keep the net open

Tagging Individuals

• Coded Wire Tags– Microwire that has a unique

label– Magnetic wand detects the tag– Tag retention should be

determined

• T-Bar tags– Can be individually numbered– External tag

• PIT tags (Passive Integrated Transponders)– Wand induces the tag to

transmit, individual number is displayed

Other Tagging Methods

• Toe clip– Amphibian and reptile– Clip of one or more toes to

identify individuals

• Bird Band– Place a metal band on a

bird leg– Generally has

identification information