7. Sampling Equipment

John W. Fleeger, David Thistle, and Hjalmar Thiel

Practical meiofauna work usually begins withsampling. Almost all investigators have considered theproblems associated with sampling, and many havearrived at individualized solutions to their problems.However, certain concepts apply to all samplingmethods. In this chapter we shall discuss theseprinciples and describe the more common samplingmethods and equipment for use in different habitats.We hope that a discussion of the principles behindgood sampling technique will direct the choice ofequipment in future investigations, and that acomparison of methods will facilitate the exchangeof data.

Ideally, samples should always accurately reflectthe populations from which the sample was taken.Such samples would be unbiased and quantitative, andshould serve as the basis of studies of meiofaunalabundance, biomass, production and communitystructure. Unbiased samples are not always required,however. Qualitative collections are those in whicha device or method captures fauna in anunpredictable or variable fashion. They are useful toformulate a partial and biased faunistic list or tocollect specimens of specific taxa for culturing,physiological, or systematic studies. Qualitative andquantitative sampling methods vary with habitat andsediment type, and whether sampling is done withvisual contact, i.e., with close inspection of thesampling site, or by remote means in whichequipment is deployed without visual contact.

Qualitative Sampling

Qualitative collection methods differ betweenair-exposed and water-covered sediments, and maybe visual or remote. In the supralittoral, any methodof digging or scraping sediments may be sufficientto collect meiofauna. The washings of coarsersubstrates, including stranded materials and algae mayalso be used.

A method frequently used in beaches is theconcentration of meiofauna from the water thatseeps from the sides of a pit. This water may bescooped up and filtered through a net or sieved withmesh of the appropriate size (see meiofaunadefinition, Chapter 1), or the animals may be stirred

115

into the water and filtered with a small hand netSimilarly, the Bou-Rouch pump has been used toconcentrate meiofauna from coarse river sands. Ithas a perforated lower hollow column that allowswater and associated fauna to seep into it. Thecollected water is then pumped up and sieved (Bou,1974). Meiofauna may be isolated and concentratedfrom large-volume sand samples by decantation afteranesthetization with 6% MgClz (i.e., 73.2 g/I) or aweak solution of formaldehyde. In muds, meiofaunacan be concentrated by sieving hand-scoopedsuperficial sediments through a coarse screen toremove large detritus particles and a smaller screen,of appropriate size, to retain fauna. Livingmeiofauna can be extracted from this retainedmaterial by sucrose flotation or by the use ofphototactic responses. For example, some harpacticoidspecies will swim from such material into theoverlying water of a bucket toward a beam of light(cool light from a fiber-optics illuminator is bestbecause it does not cause a temperature change inthe water), and can be captured by aspiration.Subtidal qualitative collection may be achieved withany of several types of grabs or corers (see below),from which surface scrapings or sediment subsamplesmay be extracted to obtain meiofauna. Much of theequipment described by Eleftheriou and Holme(1984) for macrofauna sampling is appropriate formeiofauna qualitative sampling.

Several researchers (e.g., Higgins, 1964;Ockelmann, 1964; Bieri and Tokioka, 1968) have usedsmall dredges (Figure 7.1) for remote collection ofmeiofauna. Such a dredge should be constructedfrom light-weight materials and the bottom or skidsshould be relatively large so that the gear remainson the sediment surface. The cutting edge of thedredge mouth suspends sediment, and the bagcaptures and sieves the material. The upper sedimentsare skimmed off, but do not always flow freely intothe dredge bag because sediment accumulates infront of the dredge. With the resulting increase inwire tension, the dredge is frequently lifted from thesediment surface, and it jumps from bite to bite.Dredge samples cannot be related to sediment area,and are therefore not quantitative. Nevertheless,dredges may be useful for the collection of larger

116 INTRODUCTION TO THE STUDY OF MEIOFAUNA

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When used with care, corers are excellent samplersbecause they collect a known area or volume ofsediment with all depths equally represented, and allanimals present before sampling are captured. Threegeneral problems arise with core sampling: abow-wave-induced reduction in abundance, effectson population parameters due to the underlyingdistribution of the fauna, and sample distortion dueto core compaction. Care should be taken tominimize these problems, and we discuss below someways to accomplish this.

The bow wave arises because water can flow moreeasily around a corer than through it due to thefriction water exerts against the walls of the corer.As the corer approaches the sediment, surfacematerial and attendant meiofauna may be caught inthis flow around the corer and washed out of theregion to be sampled, thereby biasing the sample.However, if the surface of the sediment lacks aresuspendable layer, the bow wave may be irrelevant.The investigator can minimize it by taking cores

Figure 7.2.-Proper technique for using a piston-style corerfor visual sampling and subsampling. The plunger of thecorer should be located near the sediment surface (a) andthe wall of the corer pushed downward while holding theplunger in place (b). Suction from the plunger retains thesediment while the corer is removed (c).

corer tube should then be pushed slOWly into thesediment to the desired depth while holding theplunger in place. The plunger provides the suctionnecessary to retain the core while the corer iscarefully removed from the sediment. These modifiedsyringes can be re-used, but if so, syringe plungerheads made of rubber, rather than plastic, are bestbecause they retain their flexibility and suction.

Figure 7.1.-Meiobenthic sled. Note: cod-end untied (open)in illustration (see Higgins, 1964).

Quantitative Sampling

Meiobenthologists take quantitative samplesprimarily for two reasons. They wish to describe thetemporal or spatial distribution of meiofaunal taxa,or they wish to test hypotheses. In both cases,sampling is critical to the quality of the answerobtained. For most ecological work, unbiased,quantitative samples are required. Unfortunately, theefficiency and sources of bias of most samplingtechniques are poorly studied. Nevertheless, effortsare continually made to understand sampler bias andto design gear that takes the best samples possible.

We summarize below quantitative samplingtechniques according to major habitat types.

Sediments. - - In sediments, coring is the bestquantitative sampling or subsampling technique.Corers are devices with a known surface area. Mostare cylindrical, and can be made from tubing orpiping of any available rigid material (e.g., Cubit,1970). The diameter chosen depends on the volumeand depth of sample required. Corers should havea smooth internal surface to facilitate sedimentpenetration and core removal. Corer inner diametersof 2-4 cm have been used in many habitats, andprovide a meiofaunal sample that can be sorted inits entirety. Smaller corers (1 cm diameter or less)are desirable in sediments where densities areunusually high, or to determine small-scaledistributions. Tubes of clear plastic allow the coreto be viewed through the walls, The lower end ofthe tube should be beveled to facilitate sedimentpenetration. Hand-held corers may also be made bycutting the needle end from a plastic, disposablesyringe (e.g., Chandler and Fleeger, 1983) for use insampling low-tide intertidal sediments or forsUbsampling (discussed later). For best results theplunger of this piston-style corer initially should benear the level of the tube opening (Figure 7.2). The

and temporary meiofauna, which often occur indensities too low to be sampled in large enoughnumbers with corers.

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CHAPTER 7: SAMPLING EQUIPMENT 117

slowly and by using flow-through corer designs.Meiofauna are well known for their spatial

patchiness, and the size of the corer can interactwith the underlying spatial distribution, or dispersion,of the fauna. Estimates of interspecific associationand population parameters such as density and patchsize may be affected by this interaction. Many smallcores (samples or subsamples) provide better densityestimates (and tighter confidence limits) than a smallnumber of large cores (Elliot, 1977), and thisapproach is recommended for general use inmeiofaunal studies. However, there is a limit on howsmall a corer should be, and Green (1979) cautionsthat the corer should be sufficiently large so thatthe ratio of the area of the organism to the areaof the sample unit be 0.05 or less. Too little is nowknown of the small-scale distribution of meiofaunato suggest an optimal corer size for all situations (butsee Findlay, 1982, for an approach to the problem).Preliminary or theoretical studies should be done toselect an appropriate core size before a study ofdispersion or species associations is begun. Corersizes that coincide with any scale of patch size shouldbe avoided (Green, 1979).

Compaction may occur as the corer is forced intothe sediment (Williams and Pashley, 1979). Frictionbetween the sediment and the walls of the corer cancompress the contained sediment, so the volume ofthe core does not represent the volume of sedimentsampled. This effect can bias the reconstruction ofvertical profiles from cores divided into layers (seebelow). A related problem is the drawing down ofindividuals from upper layers into lower layers alongthe wall as the corer is inserted into the sediment.Some sediments resist compaction, in particular, sandsand muds of low-water content. Compaction anddraw-down of material can be minimized byincreasing the diameter of the corer, which alsominimizes the fraction of the volume of the coreaffected by the walls. For subsampling, a secondsolution is to use a corer with a piston (the syringecorer discussed above or the corer of Cubit, 1970).

Intertidal.--Intertidal sampling has typically beendone at low tide to allow easy access to the studysite. This advantage is tempered by the need to avoiddisturbing the location to be sampled. Intertidalhabitats vary from fine muds to gravels. In mostsediment types, tubes with the characteristicsdescribed above may serve as a sampler for the upper« 10 em) portion of the sediment. A tight-fittingstopper secured in the upper end of the coring tubeor the piston of the syringe will provide suction tohold the sediment in place while the corer isremoved. Another stopper may secure the lower endof the tube for transport.

These techniques will not work well if the fauna

extends deep into the sediment. In the supralittoralof beaches, which can be inhabited to depths ofgreater than 2 m (Fenchel, 1978), specialdemountable corers have been developed, e.g.,Renaud-Debyser (1957). Alternatively, a pit can bedug to the required depth and core samples takenfrom the vertical face (Pollock, 1970).

Subtidal.--If at all possible, subtidal samplesshould be taken by SCUBA divers. Divers usuallyobtain superior samples because they are able toposition the samplers with care and insert the corerslowly (see McIntyre, 1971). Also, the presence ofthe investigator will often yield important insightsabout the ecology of the site or practical aspects ofsampling. Similarly, cores from submersibles andremotely controlled vehicles (Thiel and Hessler, 1974;Thistle, 1978) may be taken carefully, and with visualobservation. As an aid in diver coring, Jensen (1983)devised a three-tube-corer with a circular handlingplate to allow careful positioning with the diver somedistance from the actual sampling site. McIntyre(1971) and Holopainen and Sarvala (1975) usedsubsampled diver cores to suggest that larger corers(> 8 cm2) are more efficient than smaller corers inestimating meiofaunal abundance. The higherestimates in larger, but subsampled, diver-collectedcores could partly be due to a concentration ofmeiofauna in the center of the core, rather than atruly higher sampling efficiency (Rutledge andFleeger, 1988).

A variety of remote samplers have been developedfor use in shallow water. Pole samplers (Figure 7.3)with closing mechanisms that minimally block theflow of water through the corer are likely to takeunbiased samples because entrance velocities will below and the bow wave should be small. The deviceof Frithsen et al. (1983) consists of a tube mountedon a long, light pole, and can be used in depths upto 4 m. The top lid is held open during descent andsediment penetration. A plate triggers the lid releasemechanism on full penetration, and the tube is wellsealed to secure the core in the tube. In theHamburg pole corer (Figure 7.3), the closingmechanism is triggered by a line running up the pole.This system has the advantage that closure isindependent from penetration depth. In contrast,free-fall corers (e.g., traditional geological gravitycorers) enter the sediment at a relatively highvelocity and have a severe bow wave (McIntyre,1971). Therefore, they are unlikely to sample thesurface of the sediment or a flocculent layer well,and their use should be avoided.

Several new, relatively inexpensive corers are lightenough to be used on smaller research vessels thatcannot accommodate a box corer (see below), andyet take samples yielding densities similar to those

118 INTRODUCTION TO THE STUDY OF MEIOFAUNA

of diver-collected cores. Ankar and Elmgren (1976)described a simple one-tube corer which free fallsonly the last 2 m. The devices of Plocki andRadziejewska (1980) and Raisanen et a!. (1981) weredesigned for coarse subtidal sands, and may serveas alternatives to grab samplers in such conditions.The Kajak corer (Hakala, 1971)works well in muddysediments and takes multiple cores (Holopainen andSarvala, 1975; Jensen, 1983; Chandler et a!., 1988).Good design features include slow sedimentpenetration. large, flow-through tubes and a tripmechanism that does not interfere with water flowthrough the tube core or disturb the sediment beforepenetration.

o

Figure 7.3.-The Hamburg pole corer. A pin holds the springloaded lid open during descent. The pin is pulled away torelease the lid after sediment penetration.

Environments with a well-developed flocculentlayer or an easily resuspended sediment surface are

the most difficult to sample. Deliberate corer samplesare the least disturbed in these circumstances(McIntyre and Warwick, 1984),and are therefore themost highly recommended for remote sampling.These wire-lowered corers consist of a supportingframe and a movable sampling unit. The framearrives on the bottom first. When it stops, thesampling unit is positioned some 30 cm above thesediment surface. It is released and slowly descendsto penetrate the sediment with one or severalcollecting tubes. Their penetration is slow, retardedby the action of a piston. Flocculent material isretained, and the water above the sample is truly anear-bottom water sample. Craib (1%5) describes asingle-corer device for use from a small boat inshallow water; Barnett et a!. (1984) have devised aversion that takes 12 cores simultaneously (Figure7.4), but requires the gear-handling facilities of alarge vessel.

Figure 7.4.-The Scottish Marine Biological Laboratory corer,a 12-place deliberate corer after Barnett et al. (1984). Theframework is 3.5 m high and 2.4 m across at its widest point.Some details, e.g., bottom core catchers, are not shown.

Cores, especially from sandy sediments. willsometimes be lost during retrieval if the tube is notclosed at its lower end; upper lid suction may notbe strong enough to hold the core in place. Variousstyles of core "catchers" are available to aid in coreretention. Many are internal to the corer (e.g., theorange-peel type), and typically disturb the surfaceand furrow the sides of the core. External core

catchers are therefore recommended. Mills (1961)describes a catcher consisting of two half lidsscrewed to phosphor bronze spring strips (Figure7.5a). The lids are held open by the tube. At corerpenetration, the lids are triggered, move down thetube on retrieval, and the springs pull the lids intothe closing position. Fenchel (1967) used a ball ona rubber band design (Figure 7.5b). Core penetration

-RUBBER BAND-BRASS TUBE

b

Figure 7.5.-External core catchers. The design of Mills (1961)with a two-sided closing lid (a), and the design of Fenchel(1967) using a baIl and rubber band (b). (Courtesy OpheliaPublications.)

CHAPTER 7: SAMPLING EQUIPMENT 119

releases the ball, it moves to the tube opening, coversit and stays in position by the force of the partiallyreleased rubber band. The multiple-corer design ofBarnett et aI. (1984) has two· lids; the lower ismounted on a long lever that falls onto the sedimentafter triggering and swings in Closing position whenthe tubes are raised above the sediment surface.

Box (spade) corers frequently have been usedsuccessfully in the sampling of large areas ofsediment (Thiel, 1971; Dinet, 1973; Coull et al., 1977;Fleeger et aI., 1983). First described by Reineck(1958) as the "Kastengreifer," the box corer has beenenlarged as the USNEL corer, Hessler and Jumars,(1974) and modified by Thiel (1983). Subsequentunpublished modifications have been made (Hessler,personal communication) (Figure 7.6).

E

Figure 7.6.--A box corer. The corer is shown in the closedposition. A, is the detachable spade, which allows the coreto be removed without inserting a bottom plate. n, showsthe positions of the flaps. open for descent. C, shows theflaps closed for ascent. D, is the safety pin. E, is the cableto the ship. The details of the firing mechanism and thepre-trip device have been omitted. This design is afterunpublished modifications of the Hessler and Jumars (1974)USNEL corer. (Courtesy Ocean Instruments, Inc.)

Box corers weigh from 150 to 750 kg empty, andcollect a block of sediment from 0.02 to 0.25 m2 insurface area, and from 20 to 50 cm in depth. In

120 INTRODUCTION TO THE STUDY OF MEIOF AUNA

a

\\\

effect, the corer is an open box which penetrates thesediment under its own weight after reaching the seafloor (after the frame of the box corer comes torest on the bottom, the open box is released and isslowly pushed into the sediment). As the corer ispulled from the sediments, a lever is turned thatcauses a spade to cut through the sediment belowthe box. Upper lids close off the top of the corer,and the sediment and overlying water are firmly heldin place while the box corer is retrieved.

Because the box enters the sediment at a moderatespeed, and because in recent designs, water flowthrough the corer is relatively unobstructed (theupper opening totals 50% of the corer surface area),the bow wave is modest Thistle (1983) and Thistleand Sherman (1985) detected no evidence ofbow-wave-induced bias in samples of harpacticoidcopepods and nematodes respectively at a site withlittle or no flocculent layer. However, the box corerprobably does not routinely take samples with aquality equal to the deliberate corer. Thiel et aI.(personal communication) simUltaneously employeda box corer and the corer of Barnett et aI. (1984).The deliberate corer regularly collected a layer ofphytodetritus on the sediment surface which wasmissing in box corer samples. This suggests that veryflocculent materials are inadequately sampled by thebox corer.

Sometimes a relatively large volume of water maybe retained in the box corer, e.g., when samplingsandy sediments that limit penetration. This wateroverlying the sediment can percolate through thesample and disturb the faunal distribution and mayeven erode the sediment surface. Currents may causethe box to penetrate at an angle, or may not allowthe corer to be pulled from the sediment in anupright manner; either effect will cause the surfaceof the sample to be disturbed. Box-corer samplesbiased by any of these means should be rejected.

Although grabs have been used for quantitativemeiofaunal sampling, many workers have severereservations about the quality of such samples (e.g.,Elmgren, 1973; Heip et aI., 1977). Grabs are usuallyconstructed from two compact claws which can createstrong bow waves and cause the loss of surfacematerial (Ankar, 1977). Additionally, claw pen­etration and closure disturb and compress thesediment. This is especially true for grabs closed byinternal chains or other structural parts (Petersen,Okean-50 grabs). Even with open space inside thegrab (Van Veen grab, Figure 7.7), disturbance isstrong. Grabs often do not close properly (due toconstruction defects or to shell or debris becomingwedged between the claws), and overlying water withfauna will drain from the grab during recovery.Therefore, grab samples are usually too disturbed forquantitative meiofaunal subsampling, and they should

be avoided if possible.

I

/1'/ ,/ ,/ ,/ ,/ ,/ '/ '/ /, "/ /, ,

/ / \ '/ •.••••••• --0<':'.-;';-;';';';'="""""""":':',-,"-'-",'.'._,'_.,._._",_._. __ . ..... / .. '.""" .._,_._, ,__, :_,.:_;_;.;.:.::::::~_:::_:_:,:.;,:;::;;:::::::::::::::8::;:::::::::::nr::::;:{n::~~ •••••

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Figure 7.7.-The Van Veen grab sampler in open (a) andclosed (b) position.

To sample larger, temporary meiofauna, Muus(1964) designed the "mousetrap" (Figure 7.8). Oncontact with the bottom, a stationary plate and aframe with a plankton net are positioned oppositeto each other. The frame penetrates the sediment afew centimeters, and moves to the sealing plate,scraping the surface sediment (200 cm2) into the net.

Vertical Profiles. --The vertical distribution ofmeiofauna is frequently of interest. The appropriatemethod to determine vertical profiles varies with thesediment type. When the deposit is such thatcompaction is not a concern (e.g., coarse sand), thecore can be extruded from below and sliced off in

appropriate layers (e.g., Thiel, 1971; Thistle, 1978).If the surface layer is poorly consolidated and cannotbe extruded without loss, as with soft muds, then thecore can be allowed to slip down the core tube byloosening the top stopper. Careful manipulation will

Figure 7.8.-The Muus (1964) "mousetrap," a samplerdesigned to collect a large area of superficial sediments.(Courtesy Ophelia Publications.)

allow the core to be cut into appropriate depthintervals, avoiding additional compaction that mayoccur in extrusion. Markings at appropriate intervalson the corer or the extruder help identify thethickness to be sliced. Cores should be processedimmediately because meiofauna are known to migratein standing sediments. When the vertical profile isvery deep, specialized corers (Renaud-Debyser, 1957)may be necessary. An approach to this problem fora beach has been discussed above. Very small-scaleprofiles can be measured by the technique of Jointet al. (1982) in which a micrometer is attached toa core tube, allowing 1-mm layers to be extruded.The "meiostecher" (Figure 7.9a) of Thiel (1966) allowsfor good profiling at em-intervals from subsamplesby using a plate support (Figure 7.9b). Although coreshave been fast frozen in liquid nitrogen in the fieldto preserve the vertical profile (Bell and Sherman,1980; Chandler and Fleeger, 1983), convective flows

CHAPTER 7: SAMPLING EQUIPMENT 121

within the core during freezing disrupt the profilegreatly (Rutledge and Fleeger, 1988), destroying theutility of this technique. Slow freezing causes lessdisturbance but also permits meiofauna the chanceto migrate before freezing takes place.

2

b

Figure 7.9.--The meiostecher after Thiel (1966). The deviceitself takes subsamples (a), and includes (1) a plastic tongueto cut the subsample, (2) a slot for the tongue, and (3)grooves to guide the tongue horizontally. A Plexiglas supportallows sectioning of the subsample (b). A plunger pushes thecore up and a sliding bar pulls away single sediment layers.

For larger samples in soft sediments, Hagge(personal communication) used a corer in which halfthe tube from the upper 1-cm had been cut off.The remaining half supported the core when pushedup, and a rounded plate fit to the inside of the tubewas used to separate the layers of the core (Figure7.10).

Plants. - - Macroalgae (Hicks, 1977) and seagrasses

122 INTRODUCTION TO THE STUDY OF MEIOFAUNA

(Novak, 1982; Bell et al., 1984) have meiofauna livingon them. Quantitative sampling usually involvesremoving the entire above-ground portion of theplant or some piece of it (e.g., an algal blade) andthen extracting the fauna. Samples taken while theplant is exposed by the receding tide need no specialtreatment They are usually fixed in the field inindividual containers so animals are not lost (Gunnill,1982). When samples are taken underwater, it isnecessary to contain the fauna present on thestructure. For example, the plant can be placed ina bag underwater (Hicks, 1977). Care must be takenso that disturbances resulting from placing thestructure in a sample container and then detachingit do not result in a loss of animals, andsimultaneously that contaminants do not enter thesample container from the water column. In dataanalysis, abundances should be normalized, forexample, to plant weight or surface area.

{)

has been done on the meiofauna of aufwuchs, hardsubstrates, or hyperbenthos (near-bottom water).Suction devices are described (e.g., Tanner et al.,1977) that might be useful to collect aufwuchs ormeiofauna from hard substrates, although mostsamples are taken by scraping a known area.Meiofauna that reside in near-bottom waters orthose which leave the sediment have been sampledby pumps (Sibert, 1981; Palmer and Gust, 1985), andby emergence traps (Alldredge and King, 1980;Fleeger et al., 1983; Walters and Bell, 1986) (Figure7.11). No clear consensus is available on the

~-M"h"P

- Catch - tube

°C/ P\I \~FunnelI \;-----\1

-Trap base

Figure 7.10.-The Hagge corer for vertical sectioning. Onehalf of the circumference of the upper part of the corer isremoved and a plate fit to the dimensions of the corer isused to section and remove layers of sediment.

Other Habitats. - - Relatively little quantitative work

Figure 7.11.-The emergence trap of Walters and Bell (1986).This Plexiglas trap captures meiofauna that emerge from thesediment and enter the catch tube through the funnel. Amesh cover allows movement of water but retains themeiofauna.

efficiency of such sampling devices (but seeYoungbluth, 1982. for comparisons of emergencetraps).

Subsampling

CHAPTER 7: SAMPLING EQUIPMENT 123

3.17em

By sUbsampling. we refer to procedures in which asample is removed from a larger sample. forexample, a small core taken from a box core. Thenecessity for subsampling arises when more than onetype of analysis is to be done on each sample orwhen the sample is too large to be processed in itsentirety (e.g.• box cores or cores from deliberatecorers). Deep-sea investigations are frequentlylimited in sample number. and many subsamples (forgrain size and chemical and faunal analyses) fromone box core must be taken. When surface ornear-surface values are of interest. subsamplingshould be done before the sample is removed fromthe sediment. because during recovery. water motionin the sampler may resuspend the superficialsediment layers. The flocculent-Iayer and superficialsediment meiofauna can be redistributed in the core.and the natural variability present when the corewas taken will be replaced by a variability createdby the mixing during recovery (Rutledge and Fleeger.1988). "In situ" subsampling techniques that avoid thisproblem have been developed. For example. a smallcorer may be inserted on the site to be sampledbefore a larger diameter corer is used to collect itand the surrounding sediment. In subtidal work.subcorers of an appropriate size should be mountedwithin larger samplers. so both sample andsubsample are taken simultaneously (Bacescu, 1957;Jumars. 1975; Burnett. 1979). If coring and recoveryresult in a truly undisturbed core (the deliberatecorers approach this goal). careful subsamplingshould result in an unbiased sample.

Data Standardization

10 em2

4.0 em

IOem2

3.17em

l3.57

J

2.5em

Faunal densities and biomass values from sedimentsare frequently reported in terms of a standard surfacearea to facilitate comparisons between studies usingdifferent sampling techniques. Although thisprocedure will ease comparisons among reports.statistical tests must be run on raw, non-standardizeddata to assure correct variance estimates (Elliot.1977). By convention. the number of individuals (orbiomass) per 10 cm2 (i.e.• 10 square centimeters not10 centimeters squared) are reported. Figure 7.12clarifies this issue by illustrating the exact area of10 square centimeters. A 10 centimeter squared areais equivalent to a square 10 cm on a side. or 100cm2.

Figure 7.12.-Areas of 10 cm2 (Le .. 10 square centimeters)drawn to original size in a square, circle and rectangle. Incontrast, 10 centimeters squared (10 cm x 10 cm) is 100 cm2in surface area.

References

Alldredge. A~., and J .M. King1980. Effects of Moonlight on the Vertical Migration

Patterns of Demersal Zooplankton. Journal ofExperimental Marine Biology and Ecology. 44: 133-156.

Ankar, S.1977. Digging Profile and Penetration of the Van Veen

Grab in Different Sediment Types. Contributions ofthe Ask6 Laboratory, University of Stockholm, 16:1-22.

Ankar. 5., and R. Elmgren1976. The Benthic Macro- and Meiofauna of the

Asko-Landsort Area (Northern Baltic Proper). AStratified Random Sampling Survey. Contributions ofthe Ask6Laboratory, University of Stockholm, 11:1-115.

124 INTRODUCTION TO THE STUDY OF MEIOFAUNA

Bicescu, M.1957. Apucatorul-sonda pentru studiul cantitativ al

organ ismelor de fundun aparat mixt pentrucolectarea simultana a macro-si microbentosulia.Buletinul Institutului de Cercetari Piscicole, 16:69-82.

Barnett, P.R.O., J. Watson, and D. Connelly1984. A Multiple Corer for Taking Virtually Undisturbed

Samples from Shelf, Bathyal and AbyssalSediments. Oceanologica Acta, 7:399-408.

Bell, S.S., and K.M. Sherman1980. A Field Investigation of Meiofaunal Dispersal: Tidal

Resuspension and Implications. Marine EcologyProgress Series, 3:245-249.

Bell, S.S., K. Walters, and J.C. Kern1984. Meiofauna from Seagrass Habitats: A Review and

Prospectus for Future Research. Estuaries, 7:331-339.Bieri, R., and T. Tokioka

1968. Dragonet II, An Opening-closing QuantitativeTrawl for the Study of Micro-vertical Distributionof Zooplankton and Meio-epibenthos. Publications ofthe Seto Marine Biology Laboratory, 15:373-390.

Bou, C.1974. Les methodes de recolte dans les eaux souterraines

interstitielle. Annales of Speleology, 29:611-619.Burnett, B.R.

1979. Quantitative Sampling of Microbiota of the Deep-seaBenthos. II. Evaluation of Technique andIntroduction to the Biota of the San Diego Trough.Transactions of the American Microscopical Society,98:233-242.

Chandler, G.T., and J.'''. Fleeger1983. Meiofaunal Colonization of Azoic Estuarine

Sediment in Louisiana: Mechanisms of Dispersal.Journal of Experimental Marine Biology and Ecology,69:175-188.

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