Mod8-C Introduction to Lake Surveys - Basic

Introduction to Lake Surveys

Basic Water Quality Assessment

Unit 3 Module 8

Part C Lake Sampling

Objectives

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Students will be able to:

 explain methods used for collecting water, sediment and aquatic organisms.

identify reasons for collecting water and sediment samples.

compare and contrast the characteristics and use of discrete water samplers, integrated water samplers, grab samples and pumps. explain methods used for collecting contaminants and microbes.

utilize guidelines to determine the size of the water sample needed to conduct specific analyses.

demonstrate specified labeling techniques.

describe the different methods of sediment sampling.

categorize aquatic organisms by size.

describe procedures used in sampling phytoplankton/algae, periphyton, zooplankton, and benthic invertebrates.

 compare and contrast direct and indirect quantitative analysis with qualitative analysis used to study phytoplankton.

classify periphyton by the substrates they grow on.

compare and contrast quantitative and qualitative analysis used to study periphyton, zooplankton, and benthic invertebrates.

describe procedures used in sampling aquatic vegetation.

explain the importance of diatoms in determining water quality.

Developed by: E. Ruzycki and R. Axler Updated: 12-14-03 U3-m8c-s2

Basic water quality assessment

These slides focus on learning basic field techniques used by limnologists:

 Morphometry - estimating critical lake basin measurements

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Field Profiles - physical and chemical parameters measured from top to bottom of the water column

Sampling – collecting water, sediments, and aquatic organisms


Lake sampling

 This module contains information about the basic techniques needed to perform a baseline characterization of a lake.

 Learn how to collect water, sediment and aquatic organisms from different habitats.


Lake sampling

Water samples collected for:

 major ions

 nutrients

 chlorophyll-a, phytoplankton

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 total suspended solids, turbidity color, organic carbon, biochemical oxygen demand

Iron (Fe) and other metals (special case mercury-

Hg)

 organic contaminants (PCBs, PAHs, pesticides, hydrocarbons)

 bacteria (fecal coliforms, E. coli and other pathogens)


Lake sampling

Sediment samples collected for:

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 bulk properties nutrients

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 contaminants (heavy metals, organics) organisms

 paleolimnological studies of lake history (fossil algae, zooplankton, insects, pollen)


Lake sampling

Aquatic Organisms:

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Phytoplankton

Zooplankton

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Benthos and sediment

Aquatic vegetation

 Fish and fish habitat assessment


Water sampling

 Conventional

 Automated water sampling

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Contaminants

Microbes

How much to collect ?

 Sample preservation and storage

 Where to sample ?


Water sampling – conventional

Conventional:

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Discrete water samplers

 Van Dorn, Kemmerer, Go-flow, Niskin and other closing bottles that collect water samples at discrete depths

Integrated water samplers

 Tubes that composite water from the surface to a set depth

Grab samples

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Dipping a bottle at the water surface

Pumps

 Can provide discrete or integrated samples


Water sampling – discrete samplers

 Uses bottles that have external trip mechanisms that close the bottle at depth.

 Requires a carefully metered or measured, nonstretching rope or cable

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 nylon is notorious for stretching over 10% tightly braided cotton or synthetic “non-stretch” sail rigging lines (<5% stretch) work well

 research vessels with winches use steel cable


Water sampling – devices

 Which one to use?

CTD with Rosette

Niskin

Developed by: E. Ruzycki and R. Axler

Van Dorn

Updated: 12-14-03

Kemmerer

U3-m8c-s11

Water sampling - conventional

 The closing mechanism on the sampler is triggered by dropping a weight called a messenger down the line

 Make sure the line is vertical; attach appropriate weights if it is angled due to currents or boat drift www.wildco.com

Updated: 12-14-03 Developed by: E. Ruzycki and R. Axler U3-m8c-s12

Water sampling – integrated samplers

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 Integrated water samplers:

 Used to collect water representing an entire column of depths (e.g., 0 to

2 m) and mix it into one composite sample.

 Simple to use and inexpensive to make

 Can be made with rigid PVC or flexible tubing

Many state long-term monitoring programs use a 2 meter sampler since this stratum is where most of the algal activity is during the stratified period.


Water sampling – integrated samplers

 Method

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Tube is lowered to desired depth

Surface end is capped to allow air pressure to hold the water in the tube

 Bottom end of tube is raised, cap removed and sample is allowed to flow out into a bottle or carboy


Water sampling – grab samples

 Sometimes it is OK just to dip a bottle into the water to sample.

 Usually, this is the method of choice for collecting contaminants and bacteria (while wearing clean and sterile gloves).

 This is a good method to use to sample a surface algal scum.


Water sampling – pumps

Pump types

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Peristaltic pumps

Bilge pumps and submersible pumps are also sometimes used

Developed by: E. Ruzycki and R. Axler http://www.forestry-suppliers.com

Updated: 12-14-03 U3-m8c-s16

Water sampling – pumps

Advantages

 Greater volumes at discrete depths

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Shallow lake sampling without disturbing sediments

Samples from depth can be collected with little or no exposure to the atmosphere (i.e., anoxic sample)

 Good for trace elements and organics because sample only comes in contact with the tubing (silicone or teflon)

Disadvantages

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Requires power

Head pressure – pump must be able to overcome hydraulic head to pull up water from depth over the side of the boat.


Water sampling – automatic samplers

 Primarily for stream, estuary and storm water collection

 Usually triggered remotely:

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Phone call via modem

Precipitation or high flow

 Water quality parameter measured with an automated sensor exceeds a preset level


Water sampling – contaminants - metals

Mercury (Hg) in water

 Equipment cannot have metal or rubber components

 Containers require special preparation to ensure no

Hg contamination

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Clean hands/dirty hands technique

Usually, but not always, tissue and sediment sampling do not require “ultra-clean” techniques

Other priority pollutant metals

 Usually, but not always, less stringent protocols than for Hg because problem levels only occur when concentrations in water are much higher than for Hg (see notes)


Water sampling – contaminants - organic

Organic contaminants

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PCB’s, PAH’s, pesticides, etc.

Containers specially cleaned with solvents (hexane, acetone, methanol…)

 Glass or teflon bottles in most cases

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Aluminum foil, solvent cleaned, for fish tissue

Sediments stored in glass jars using plastic or teflon utensils

 Sometimes bake (> 550 o C) glassware to vaporize trace organic chemicals


Water sampling - contaminants

 Clean hands/dirty hands (CH/DH) method should be used for collecting and processing samples vulnerable to trace contamination by metals or trace organic compounds.

 CH/DH are required when collecting samples to be analyzed for metals (e.g.,

Hg) and other trace organic contaminants and inorganic elements.


Water sampling - microbes

 Sterile technique:

 Containers must be sterilized by autoclaving or with gas used to kill microbes

 Take care not to contaminate the container

 Water samplers should be swabbed with 70 % alcohol


Water sampling – microbes

 Grab samples taken with sterile containers


Sampling – how much water do you need?

 Depends on the parameters to be analyzed

 Chlorophyll and TSS often require the greatest volume (>

1L)

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 Often depends on how productive the system is

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Better to be safe and have too much water rather than too little

Also depends on how practical it is to carry out large volumes of water


Suggested sample volumes chlorophyll

Analyte

Analyte/ volume table

Volume needed

>500 mLs

TSS total phosphorus total nitrogen anions

Dissolved nutrients

Total and dissolved carbon

Metals

Often > 1 L

200 to 500 mLs

~ 100mLs

~60 mLs

~60 mLs color, DOC ~60 mLs

Updated: 12-14-03 Developed by: E. Ruzycki and R. Axler U3-m8c-s25

Lake sampling – filling the bottles

 Rinse containers with a small amount of sample, discard, then fill with fresh sample

 Fill bottles completely to eliminate head space

(unless the bottles are going to be frozen immediately)

 If using cubitainers put the cap on loosely, squeeze out all of the air, then tighten the cap

 Leave space in bottles that are to be frozen


Lake sampling – sample bottles

 Cubitainers work well for bulk samples that are to be split and processed later in the laboratory.

 High density polyethylene wide mouth bottles (60 to 1 L volume) work well for most analytes.

They freeze well, don’t crack and the wide mouth is easy to fill.


Lake sampling – sample labeling

 An unlabeled sample may as well just be dumped down the drain.

 Use good labels not masking tape, etc.

Poor labels often fall off when frozen samples are thawed.

 Use permanent markers NOT ball point pens, pencils in a pinch


Lake sampling – sample labeling

 A simple sample label with the minimum amount of information needed…

WOW project

Shagawa Lake 7/26/02 1m

Site, date, depth

RAW, frozen

Sample processing and preservation info

Often, much more information may be needed by the laboratory performing your analyses. You will also need to supply a chain of custody form.


Sediment sampling http://www.fdlrez.org/nr/environmental/water.htm


Sediment sampling

 Dredges

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Commonly used to grab a bottom sediment sample in lakes, estuaries and slower moving rivers

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 Collect soft sediments (mud and muck) for sieving out benthic organisms and also obtaining bulk sediment characteristics

Common types

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Ekman

Peterson

Ponar

Quantitative corers

Box corers


Sediment sampling – Ekman dredge

Photos of sediment samplers www.wildco.com



 small, light, easy to trigger by messenger (usually)

 stainless steel – usually OK for contaminants

 best for muck, soft mud and silt where a relatively undisturbed sample down to 15 cm or more may be collected

 most common size = 6 inch cube (15 cm)

 not as good for sand; if sediment is compacted, or if much gravel, rocks, or large debris is present, the heavier Peterson or Ponar dredge is preferred



 This animation of the

Ekman dredge, illustrates the chain of events during use.

Developed by: E. Ruzycki and R. Axler http://www.cee.vt.edu/program_areas/environmental/teach/smpr imer/dredges/dredges.html

Updated: 12-14-03 U3-m8c-s34


Sample collection photos

Extruding (sub-coring)

Into the baggie…


Sediment sampling – Ekman safety


Sediment sampling – Peterson and Ponar

 usually require winches

 can sample coarser material than the

Ekman (small woody debris and gravel) photos

Peterson

Developed by: E. Ruzycki and R. Axler Updated: 12-14-03

Ponar www.wildco.com

U3-m8c-s37

Sediment – “quantitative” corer

 variety of devices to collect undisturbed cores www.wildco.com


Sediment sampling – box corers

 Used for large lake and oceanographic research


Sampling aquatic organisms

 Learn how to collect water, sediment and aquatic organisms from different habitats.


Sampling aquatic organisms – algae

 Phytoplankton (float freely in the water)

 Periphyton (attached to aquatic vegetation, rocks, wood and other substrates)

 Benthic algae (grow on the lake bottom/sediments); also sometimes called periphyton www.duluthstreams.org/understanding/algae.html

Developed by: E. Ruzycki and R. Axler www.cawthron.org.nz/periphyton_image.htm

Updated: 12-14-03 U3-m8c-s41

Sampling aquatic organisms – zooplankton

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Zooplankton:

 Crustaceans (Cladocerans, copepods)

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Rotifers

Protozoans, ciliates

 Aquatic insects (e.g., Chaoborus) www.aims.gov.au/pages/research

/hatchery-feeds/hfa-01.html

http://cgee.hamline.edu/see/questions/dp_biosp here/bios_place/dp_bios_place_ocean.htm

Developed by: E. Ruzycki and R. Axler http://lsda.jsc.nasa.gov/scripts/cf/res ult2.cfm?mis_index=110 photo source: North American Benthological Society

Updated: 12-14-03 U3-m8c-s42

Sampling aquatic organisms - benthos

 Benthic macroinvertebrates

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Aquatic insects (adults and larvae)

Leeches

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Crayfish

Mussels, snails http://www.usask.ca/biology/skabugs/ http://www.usask.ca/biology/skabugs/ http://www.usask.ca/biology/skabugs/ http://www.usask.ca/biology/skabugs/

Developed by: E. Ruzycki and R. Axler http://www.usask.ca/biology/skabugs/

Updated: 12-14-03 U3-m8c-s43


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 Aquatic macrophytes

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Submergent

Emergent

Floating

Bacterioplankton

Fish

Paleolimnology- reconstructing historical biological communities

 Algae (usually diatoms)

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Zooplankton

Benthic invertebrates



 An alternate way of grouping aquatic organisms:

 Plankton (open water communities) = phytoplankton and zooplankton

 Benthos (bottom communities) = periphyton, benthic macroinvertebrates, aquatic macrophytes

 Fish (organisms that go where they choose)

 Dead stuff = detritus


Sampling aquatic organisms – by size

 Most plankton sampling techniques are size selective (based on mesh size).

 Phytoplankton range in size from 0.2um to > 200 um (from bacteria sized to colonies and filaments easily seen by the human eye).

 Zooplankton range from single-celled protozoans,

< 80 um rotifers, to crustaceans and insects (up to millimeters in length).

www.aims.gov.au/pages/re search/hatchery-feeds/hfa-

01.html



 Terminology is often confusing

 Nannoplankton: < 60

 m

 Net plankton: > 80

 m

 From Wetzel 2001:

 picoplankton: 0.2 to 2.0

 m

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 ultraplankton : 2 to 20

 m microplankton: 20 to 200

 m; usually refers to phytoplankton

 Macroplankton: > 2mm (2000 um) and up to cm in length

 Densities are expressed as:

 individuals per unit volume (#/L)

 biomass or weight (mg/L)



Micron Size Plankton Classification

Reference table of sizes ranges

1000 Largest zooplankton and icthyoplankton (larval fish)

118

80

63

10

750

600

500

363

243

153

Larger zooplankton and icthyoplankton

Large zooplankton and icthyoplankton

Small zooplankton and icthyoplankton

Large microcrustacea

Microcrustacea

Microcrustacea and most rotifers

Small rotifers

Net phytoplankton and net zooplankton

Large nannoplankton and large diatoms

Small nannoplankton


Sampling - algae/phytoplankton

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Phytoplankton (float freely in the water)

Periphyton (attached to aquatic vegetation, rocks, wood and other substrates)

Benthic algae (grow on the lake bottom/sediments); also sometimes called periphyton



I. Goals of analysis

1.

2.

Quantitative, direct; biomass, cell density

Quantitative, but indirect; measuring chlorophyll concentration

3.

Qualitative; presence/absence, dominance

II. Sampling

1.

2.

Methods

Frequency



III. Ancillary information

IV. Preservation methods:

IV. Counting methods:

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 taxonomic guides counting chambers, slides

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 microscopes

Archiving

V. Monitoring for toxic algae


Phytoplankton – I. Goals of analysis

1.

Quantitative analysis (direct):

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For monitoring and research purposes

Requires a high level of expertise

 The cost (~$250/sample) and time involved are usually too high for a typical water quality assessment

 Typically surface water (0 m) or a 0-2 m composite is collected for long-term monitoring

(because noxious scums of blue-greens collect in surface water; site of water contact recreation)



2.

Quantitative analysis (indirect):

 such as chlorophyll concentration, provide an excellent index of the total amount of phytoplankton, but not what species are actually present.

 A cost-effective strategy for many long-term monitoring efforts is to combine chlorophyll data with periodic qualitative community structure estimates.



3.

Qualitative analysis

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Yields presence/absence information

Costs less to analyze

 Still requires taxonomic expertise but goals of analysis are often different than quantitative

(i.e., ID to genus level is often enough) or even to Class (blue-greens, diatoms, greens etc.)

 Collected as a whole water sample or by plankton net


Phytoplankton – II. Sampling

1.

Methods

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Whole water; integrated or grab sample

Nets: mesh size appropriate to analysis goals

 10 um mesh will capture most phytoplankton; clogs easily however

 Blue-green algal scum can often be sampled by dipping a sample bottle – but is effected by:

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 time of day wind conditions



Images of phytoplankton samplers www.wildco.com

Integrated (whole water) sampler http://www.fdlrez.org/nr/environmental/water.htm

Van Dorn (whole water) sampler

Developed by: E. Ruzycki and R. Axler Updated: 12-14-03

Plankton net

U3-m8c-s56


2.

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Frequency

Weekly to bi-weekly sampling is necessary to capture the seasonal dynamics of phytoplankton and to quantify abundance and biomass.

 Monthly may be adequate to provide an overall picture of the changes occurring in the ice-free growing season when water quality criteria are usually most critical.


Phytoplankton – III. Ancillary information

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 Chlorophyll

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The most common estimator of algal biomass

Ideally best to have both chlorophyll and algal community identification

 More sophisticated techniques are becoming more available for major algal groups via detailed pigment analysis

Other important data

 Note any unusual odors when sampling

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Secchi depth and nutrients, silica

Temperature, DO, and light profiles


Phytoplankton – IV. Sample preservation

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Lugol’s Iodine

 Store in airtight glass container

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Store in darkness (light sensitive)

Stains starch a dark color which is useful for identifying green alga

 Add enough to make 1% solution (~ 0.5 mL to 50 mL sample yields the color of a fine brandy)


Phytoplankton – IV. Sample preservation

 Other preservatives:

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 acid formalin solution (FAA)

Gluteraldehyde

 These are known or suspected carcinogens and

OSHA and state regulations for the workplace should be checked before use

 Long-term archiving may prove useful to identify trends in species composition or even changes in morphology


Sampling - periphyton

 Periphyton (attached to aquatic vegetation, rocks, wood and other substrates)

 Benthic algae (grow on the lake bottom/sediments); also sometimes called periphyton

Photo source: Tahoe Research Group, U California-Davis


Sampling - periphyton

 Periphyton are algae attached to solid substrates; bottom sediment, rocks, twigs, beer cans, VW Beetles

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These benthic algae are classified by the substrates that they grow on:

 Epilithic- on rock or other non-living substrate

Epiphytic- on plants

Epizoic- on the surface of an animal

Epipelic- on soft organic or silty sediments

Episammonic- on sand

Epirefusic- on garbage in the lake


Periphyton - sampling

I.

Goals of analysis

1.

Quantitative:

 biomass, chlorophyll (standing crop) per unit area, species ID, AFDW, organic matter

2.

Qualitative

 presence/absence, relative abundance, dominance

II.

Sampling methods

III.

Preservation


Periphyton – I. Goals of analysis

Do you want to estimate the actual in situ (i.e., in place) amount of periphyton or do you want a index of how well periphyton might grow at one site relative to another?

 In-situ sampling:

 remove all the material in a prescribed area

 Artificial substrates:

 provides easily calculated areal estimates, are cheap, and easy to deploy / retrieve


Periphyton – II. Sampling methods

 Artificial substrates (these are slide holders)

Before…


….. and after

Updated: 12-14-03 U3-m8c-s65


 One way to scrape a known area is to lay a plastic 35 mm slide (film removed) over the rock and scrape off the material within the slide area scrub area =

2.3cmX3.5cm=8cm2



Visual of matter taken from a rock

Rocks don’t always look like they have much on them

Nearly all the stuff scrubbed off this rock was organic matter –most of it living algae

S.Loeb and J.Reuter images



 Resulting material from a rock scrub (to the right) containing:

 Macroinvertebrates

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Detritus

Fungi

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Bacteria as well as algae



Photos of sampling methods http://www.nmu.edu/wwwedgar/biology/web/Strand/wave%20zone.htm


Periphyton – III. Preservation methods

 Lugols’s iodine can be used if the algae of interest are soft bodied forms (i.e., blue-greens and green algae).

 If interested only in diatoms, it may be best to preserve in 70% ethanol.

 Freeze sediment samples if they are to be analyzed for surficial chlorophyll.

Developed by: E. Ruzycki and R. Axler Updated: 12-14-03 www.urbanrivers.org/web_images/diatoms.gif

U3-m8c-s70

Zooplankton - sampling methods


Zooplankton

I.

Goals of analysis

1.

Quantitative:

 biomass, absolute abundance

2.

Qualitative

 presence/absence, relative abundance, dominance

II. Sampling

1.

Methods

2.

Frequency iii.

Ancillary information

IV. Preservation methods


Zooplankton – I. Goals of analysis

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Biodiversity

Abundance

Biomass

Community/ecosystem interactions (food webs)


Zooplankton – I. Goals of analysis, cont.

1.



Qualitative-presence/absence of different species

Relatively simple qualitative techniques; less expensive

2.

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Quantitative

Determining absolute and relative abundance of different species; more expensive and time intensive

 Again, as for the algal community, you must assess whether increased effort to obtain more detailed information is worth the time and expense


Zooplankton – II. sampling methods

 Plankton bottles, traps, tubes, pumps and nets

 Mesh size: balance between catching smaller organisms such as rotifers without reducing net efficiency too much due to algal clogging because of small mesh size

 Vertical net tows are the simplest approach

 Collect vertically-integrated samples from the entire water column or use a closing net that can sample a discrete depth stratum (e.g., 5 to 10 m)

 Discrete depth samplers (e.g. 10m)


Zooplankton – II. sampling methods, cont.

 Zooplankton distribution varies seasonally, temporally, and spatially in a lake

 Widely variable across the lake, inshore vs. offshore and from day to night (diel “dye-eel” variations)

 Zooplankton can sometimes avoid nets and traps

 Sampling effectiveness may vary for

Crustacea, macrozooplankton, and Rotifera


Zooplankton – sampling methods

Zooplankton samplers Birge closing net and Wisconsin Net

Simple zoop nets wildco.com

Schindler traps for sampling discrete depths

Aquatic Research Instruments


Zooplankton – using a net

 Nets should be hauled from just above the lake bottom to the lake surface at a constant speed

(about 1 sec per meter or as a rule of thumb, count 1000, 2000 etc., as you pull the net in hand-over-hand).

 Information required for quantitative analysis includes:

 depth of tow,



 mesh size, diameter of net opening



 Wash plankton concentrate into a jar/bottle with filtered lake water

 Rinse net at least with filtered lake water or by raising and lowering the net

(without introducing new lake water through the mouth)



 Nets can sample a large volume of water

Example

Using a Wisconsin net with a small, 13 cm diameter opening for a 0 to 5 m vertical tow: volume ( m

3

)



 d

2

4

 z

Where d = 0.13 m and z = 5.0 m

 volume ( m

3

)





4



0 .

13

2





 

= 0.66 m 3

= 66 liters


Zooplankton – III. Sample preservation

• Zooplankton samples can be preserved in 95% ethanol or 5% formaldehyde (formalin).

• Animals preserved in formalin sometimes become distorted, which complicates size measurements.

One solution involves the addition of 40 g/L sucrose to the 5% formaldehyde.


Benthic invertebrates

New Section Photo


Benthic invertebrates

I. Goals of analysis

1.

Qualitative: presence/absence, relative abundance, dominance, biodiversity

2.

Quantitative: biomass, absolute abundance, biodiversity

II. Sampling

1.

Methods

2.

Frequency

III.

Preservation

IV.

Equipment


Benthic invertebrates – Qualitative

 Simple, cost-effective



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Easily standardized and repeatable

Number of sampling sites should reflect the habitat diversity:

 Substrates; bedrock, cobbles, sand, mud, organic debris, rooted macrophytes

 Groundwater upwellings, lake inflows and outflows





Different wave exposures

Different types of shoreline vegetation


Benthic invertebrates – Qualitative

 Near shore sampling

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Rock pick

Kick and sweep

Activity trap

 Off shore sampling

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

Grab (Ekman sampler)

Nighttime vertical net tow

St Louis Riverwatch http://lakes.chebucto.org/contract.html

Updated: 12-14-03 U3-m8c-s85 Developed by: E. Ruzycki and R. Axler

Benthic invertebrates - Quantitative

 Quantitative sampling

 Density expressed as individuals per unit area; biomass per unit area

 Sampling methods dependent upon substrate and habitat type

 Use cores of known cross-sectional area (usually

5 to10 cm diameter) for soft sediments

 Emergence traps


Benthic invertebrates – II. Sampling cores activity traps dip nets sediment dredges

Wildco.com


Benthic invertebrates – Sampling

 Adult emergence traps

 http://www.usask.ca/biology/skabugs/CandleL.html


Benthic invertebrates – III. Preservation

 10 % formalin

 Good for general use but remember that formalin is a carcinogen







Fixes (preserves tissues well)

 70 % ethanol

 Good preservative but does not fix tissue

Low toxicity to humans

Major disadvantage is that large volumes are required, which can be difficult to carry in the field.


Aquatic vegetation



 Visual assessment





Grabs

Census transects (point and quadrant)

 Aerial surveys


AW Research

Updated: 12-14-03 U3-m8c-s91


 Aquatic plant survey methods vary, depending on the objectives of the study.

Including:

 Surveying for a particular species (e.g., an exotic species)

 Creating a plant community map

 Conducted as part of a general fish and wildlife habitat survey



 Survey techniques must account for the three growth types:

 Emergent





Submergent

Floating



 Plant survey:



Surface survey – uses a boat and trained observer to survey the littoral zone





Divers can produce similar but more thorough results

Aerial survey – works well for looking for wetland species like purple loosestrife or floating species but doesn’t work well for submerged species.

 Satellite imagery is potentially well-suited for aquatic plant surveys in lakes and wetlands and current research shows promise



 Satellite image of

Swan Lake, MN

 UM researchers are determining the effectiveness of this technique



Developing a map of the aquatic plant community

 Surface survey

 Quick but not very accurate if the water is turbid

 Sample regularly at different depths

 A weighted plant rake (rake on a rope) can used as a sampling tool

 Plants are marked on a map as they are identified http://www.state.ma.us/dem/programs/lakepond/

Updated: 12-14-03 U3-m8c-s96 Developed by: E. Ruzycki and R. Axler


 Here is a graph showing the % cover of several aquatic plant species in Lake

Independence (MN).



 Here is a presence/ absence map from

Lake Okeechobee.

 This type of map is useful in tracking the spread of exotic species from year to year.



 Quantifying aquatic plants


Fish

New section - fish image


Fish

Image of large fyke net


Fish

Netting fish - photo


Fish

Lab investigation photo


Paleolimnology

Photos of microscopic images


Paleolimnology

 Paleolimnology is the study of past freshwater, saline, and brackish environments

 In some cases, the history of the water body itself is important, but typically information is used in a wider geographical and ecological context

 These clues can often result in quantitative and qualitative reconstructions of important lake chemistry and biology


Paleolimnology – diatoms

 Diatoms are powerful indicators of water quality

 There are hundreds of species in all aquatic habitats



They respond quickly and integratively to environmental gradients

 Diatoms are the most used group of algae used in bioassessment



 A sediment core is collected

 The fossils, geological, and chemical signals that are preserved in the core are the clues to revealing the ecological history of the lake and the surrounding landscape.



 The core is essentially sliced into slabs (1 to 4 cm) that represent different historic time periods.

 The sub-samples are dated using 210 Pb and other isotope methods to determine the age and sediment accumulation rates over the past hundreds of years.



Graphical representation


Profiling techniques

New section – image of profiling techniques


Physical and chemical profiles – Ex. 1

Grindstone Lake

 Temp gradient sharpest from

5-6m

 No really sharp gradients in

DO where it drops to critical levels

 Conclusion: You might sample every meter to ~ 8 –

10 m to characterize the thermocline. Then sample at

2 or even 5 m intervals to save time without losing much information.


DO

Updated: 12-14-03

T

U3-m8c-s111


 West Upper Lake

Minnetonka

 Temp gradient sharpest from

10-11m

 DO also sharp from 10 -

11m,dropping to zero.

 Conclusion: sample every meter to ~12m to characterize the thermocline and “oxycline.”

Then sample at 2 m intervals to save time without losing information.

* DO is already zero at 13m and temp is decreasing near linearly

DO

T



 Sampling interval decisions become more important when you’re on a deep lake (>50 m) where time at a site is important.





Lake Mead is 150 m deep

Lake Washington is > 65 m



Profile of lake Washington



Mod8-C Introduction to Lake Surveys - Basic

Introduction to Lake Surveys

Basic Water Quality Assessment

Unit 3 Module 8

Part C Lake Sampling

Sampling aquatic organisms – zooplankton

Lugol’s Iodine

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Mod8-C Introduction to Lake Surveys - Basic

Introduction to Lake Surveys

Basic Water Quality Assessment

Unit 3 Module 8

Part C Lake Sampling

Sampling aquatic organisms – zooplankton

Lugol’s Iodine

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