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A simple system for recovering zooplanktonic faecal pellets in quantity
Deep-SeaResearch,1976,Vol.23, pp. 995 to 997. PergamonPress. Printedin Great Britain.
INSTRUMENTS
AND METHODS
A simple system for recovering zooplanktonic faecal pellets in quantity JACQUES LA
ROSA*
(Received 18 February 1976; in revised form 1 March 1976; accepted 1 March 1976) Al~tmet--A simple, inexpensive and effective system for collecting faecal pellet material from marine zooplankton is described. With euphausiids, about 750mg wet weight of faecal material of excellent consistency can be recovered from about 1000 euphausiids within 12h of shipboard collection of the animals.
SIMPLE and effective experimental techniques are 1969; STEELEand BAIRD, 1972). Laboratory coldeveloped regularly in many laboratories but lection avoids this difficulty but creates others. nonetheless fail to be recorded in the scientific The animals concerned have to be transported literature. As a result, subsequent workers fre- to the laboratory in such a way that their conquently waste time and energy. This brief com- dition is maintained; moreover, relatively large munication describes a simple system which is amounts of natural faecal pellets are required if used routinely in this laboratory for collecting low-level constituent concentrations are to be detrital material which is of increasing interest determined. The system used must ensure that the to marine biologists, chemists and geologists, viz. faecal pellets produced between the time of capthe faecal pellets excreted by marine zooplankton. ture and the arrival of the organisms at the The role played by these pellets in the transport laboratory remain intact and in good condition. of oceanic constituents has been shown to be Placing animals in individual bottles and colimportant, and sometimes crucial, in several lecting the pellets subsequently (e.g. with an eye'cases: thus, faecal pellets have been implicated dropper) is far too tedious and provides inin the accelerated sinking of phytoplankton re- adequate quantities of material for many analyses; mains to depth (SMAYDA, 1971) and in a geo- placing many animals in a large container withlogically significant mechanism for depositing out additional refinement results in many of the fine suspended matter (MANHEIM, HATHAWAY pellets being lost or destroyed as a result of reand UCHUPI, 1972); they have, moreover, been ingestion or mechanical action on the part of the shown to contain significant levels of the natural animals themselves. alpharadioactive nuclide 21°Po (CHERRY, The system now used in this laboratory avoids FOWLER, BEASLEYand HEYRAUD,1975), of heavy these difficulties. It has been used mainly for colmetals (SMALL, FOWLER and KECKES, 1973; lecting euphausiid faecal pellets for radioactive BENAYOUN, FOWLER and OREGIONI, 1974), of element and heavy metal analysis, but can be hydrocarbons (CoNOVER,1971) and of chlorinated adapted easily for use with other species and/or hydrocarbons (Fowler and Elder, unpublished for other types of analysis. It consists basically results). of a large 80-1itre plastic container of the type Collection of faecal pellet material is in used frequently as a domestic rubbish bin. In this principle a simple matter, bt~t several problems is placed an approximately cylindrical bag made arise in practice. In situ traps result in a sample which contains not only non-specific faecal * International Laboratory of Marine Radioactivity, Musre material but also inorganic particles (SMAYDA, Ocranographique, Principality of Monaco. 995
996
JACQUES LA ROSA
from a nylon type material (tergal) but whose bottom is replaced by a rigid plastic netting with a mesh size of 1.5 by 1.5 mm. The container is filled to about 60 litres with filtered seawater of the appropriate temperature, and the animals are placed therein immediately after shipboard collection. The faecal pellets which are produced fall through the netting to the bottom of the container, while the animals themselves, as well as large particulate matter such as moults, remain in the bag. More than a thousand euphausiids can be placed in the container; with large numbers of animals, the system should be provided with an aerator. In order to avoid gross resuspension of faecal pellets upwards through the netting by mechanical agitation, it is necessary to leave about 10cm between the netting and the bottom of the container. The container is covered and allowed to stand for several hours while the organisms defecate. Provided that the correct conditions are maintained (filtered seawater, gentle aeration, darkness, temperature equivalent to the organisms' ambient seawater), animals such as the euphausiids we have collected will generally void themselves completely before death and subsequent fouling occur. In our experience 10 to 12 h will suffice to produce a mass of faecal material which is approximately quantitative and of excellent consistency; about 750 mg wet (or about 170 mg dry) faecal pellets are recovered per 1000 euphausiids of a size averaging about 180mg wet weight per animal. The faecal pellets should be recovered from the bottom of the container as soon as possible after the animals have voided in order to minimize possible loss of the constituent of interest by dissolution in the surrounding seawater. The recovery procedure is again very simple; the bag containing the animals and moults is removed carefully and placed immediately in a second plastic container filled with seawater so that the animals can be used for other purposes. The water remaining in the original container is allowed to settle for a few minutes, and is then siphoned off until about 5 cm remains at the bottom. Smooth but vigorous circular agitation of this remaining water results
in the faecal pellets being deposited on a small area of the centre of the bottom of the container, after which they can be recovered with the aid of a pipette or an eye-dropper. The recovered material is concentrated and rinsed with distilled water on very fine mesh nylon plankton netting and the surface moisture is removed either with absorbent paper or by gentle vacuum. The clumps of faecal material can then be prepared in the manner required by the subsequent analysis. The above system has been tested thoroughly in practice. It is simple, inexpensive and consistent, and should prove to be flexible; thus, use of a finer mesh netting should allow the faecal pellets from smaller zooplanktonic organisms such as copepods to be collected, while replacing nylon and plastic with organically inert materials should suffice if the subsequent analyses are to be for organic rather than inorganic constituents. We recommend the system to research workers who need to collect zooplankton faecal pellets in a quantity and a condition which will permit the detection of constituents which are normally present at the low levels applicable to natural samples. Acknowledgements--The International Laboratory of Marine Radioactivity operates under a tripartite agreement between the International Atomic Energy Agency, the Government of the Principality of Monaco and the Oceanographic Institute at Monaco. Support for the present work is gratefully acknowledged.
REFERENCES BENAYOUN G., S. W. FOWLER and B. OREGIONI (1974) Flux of cadmium through euphausiids. Marine Biology, 27, 205-212. CHERRY R. D., S. W. FOWLER, T. M. BEASLEY and M. HEYRAUD (1975) Polonium-210: its vertical oceanic transport by zooplankton metabolic activity. Marine Chemistry, 3, 105-110. CONOVER R. J. (1971) Some relations between zooplankton and Bunker C Oil in Chedabucto Bay following the wreck of the tanker Arrow. Journal of the Fisheries Research Board of Canada, 28, 1327-1330. MANHEIM F. T., J. C. HATHAWAY and E. UCHUPl (1972) Suspended matter in surface waters of the Northern Gulf of Mexico. Limnology and Oceanography, 17, 17-27. SMALL L. F., S. W. FOWLER and S. KECKES (1973) Flux of zinc through a macroplanktonic crustacean, In : Radioactive contamination of the marine environment, IAEA, Vienna, pp. 437-552.
A simple system for recovering zooplanktonic faecal pellets in quantity
SMAYDA T. J. (1969) Some measurements of the sinking rate of fecal pellets. Liranology and Oceanography, 14, 621-625. SMAYDA T. J. (1971) Normal and accelerated sinking of phytoplankton in the sea. Marine Geology, ll, 105-122.
997
STEELE J. H. and I. E. BAIRD (1972) Sedimentation of organic matter in a Scottish sea loch. Meraorie dell'lstituto italiano di idrobiologia Dott. Marco de Marchi, 29, Supplement, 73-88.
INSTRUMENTS
AND METHODS
A simple system for recovering zooplanktonic faecal pellets in quantity JACQUES LA
ROSA*
(Received 18 February 1976; in revised form 1 March 1976; accepted 1 March 1976) Al~tmet--A simple, inexpensive and effective system for collecting faecal pellet material from marine zooplankton is described. With euphausiids, about 750mg wet weight of faecal material of excellent consistency can be recovered from about 1000 euphausiids within 12h of shipboard collection of the animals.
SIMPLE and effective experimental techniques are 1969; STEELEand BAIRD, 1972). Laboratory coldeveloped regularly in many laboratories but lection avoids this difficulty but creates others. nonetheless fail to be recorded in the scientific The animals concerned have to be transported literature. As a result, subsequent workers fre- to the laboratory in such a way that their conquently waste time and energy. This brief com- dition is maintained; moreover, relatively large munication describes a simple system which is amounts of natural faecal pellets are required if used routinely in this laboratory for collecting low-level constituent concentrations are to be detrital material which is of increasing interest determined. The system used must ensure that the to marine biologists, chemists and geologists, viz. faecal pellets produced between the time of capthe faecal pellets excreted by marine zooplankton. ture and the arrival of the organisms at the The role played by these pellets in the transport laboratory remain intact and in good condition. of oceanic constituents has been shown to be Placing animals in individual bottles and colimportant, and sometimes crucial, in several lecting the pellets subsequently (e.g. with an eye'cases: thus, faecal pellets have been implicated dropper) is far too tedious and provides inin the accelerated sinking of phytoplankton re- adequate quantities of material for many analyses; mains to depth (SMAYDA, 1971) and in a geo- placing many animals in a large container withlogically significant mechanism for depositing out additional refinement results in many of the fine suspended matter (MANHEIM, HATHAWAY pellets being lost or destroyed as a result of reand UCHUPI, 1972); they have, moreover, been ingestion or mechanical action on the part of the shown to contain significant levels of the natural animals themselves. alpharadioactive nuclide 21°Po (CHERRY, The system now used in this laboratory avoids FOWLER, BEASLEYand HEYRAUD,1975), of heavy these difficulties. It has been used mainly for colmetals (SMALL, FOWLER and KECKES, 1973; lecting euphausiid faecal pellets for radioactive BENAYOUN, FOWLER and OREGIONI, 1974), of element and heavy metal analysis, but can be hydrocarbons (CoNOVER,1971) and of chlorinated adapted easily for use with other species and/or hydrocarbons (Fowler and Elder, unpublished for other types of analysis. It consists basically results). of a large 80-1itre plastic container of the type Collection of faecal pellet material is in used frequently as a domestic rubbish bin. In this principle a simple matter, bt~t several problems is placed an approximately cylindrical bag made arise in practice. In situ traps result in a sample which contains not only non-specific faecal * International Laboratory of Marine Radioactivity, Musre material but also inorganic particles (SMAYDA, Ocranographique, Principality of Monaco. 995
996
JACQUES LA ROSA
from a nylon type material (tergal) but whose bottom is replaced by a rigid plastic netting with a mesh size of 1.5 by 1.5 mm. The container is filled to about 60 litres with filtered seawater of the appropriate temperature, and the animals are placed therein immediately after shipboard collection. The faecal pellets which are produced fall through the netting to the bottom of the container, while the animals themselves, as well as large particulate matter such as moults, remain in the bag. More than a thousand euphausiids can be placed in the container; with large numbers of animals, the system should be provided with an aerator. In order to avoid gross resuspension of faecal pellets upwards through the netting by mechanical agitation, it is necessary to leave about 10cm between the netting and the bottom of the container. The container is covered and allowed to stand for several hours while the organisms defecate. Provided that the correct conditions are maintained (filtered seawater, gentle aeration, darkness, temperature equivalent to the organisms' ambient seawater), animals such as the euphausiids we have collected will generally void themselves completely before death and subsequent fouling occur. In our experience 10 to 12 h will suffice to produce a mass of faecal material which is approximately quantitative and of excellent consistency; about 750 mg wet (or about 170 mg dry) faecal pellets are recovered per 1000 euphausiids of a size averaging about 180mg wet weight per animal. The faecal pellets should be recovered from the bottom of the container as soon as possible after the animals have voided in order to minimize possible loss of the constituent of interest by dissolution in the surrounding seawater. The recovery procedure is again very simple; the bag containing the animals and moults is removed carefully and placed immediately in a second plastic container filled with seawater so that the animals can be used for other purposes. The water remaining in the original container is allowed to settle for a few minutes, and is then siphoned off until about 5 cm remains at the bottom. Smooth but vigorous circular agitation of this remaining water results
in the faecal pellets being deposited on a small area of the centre of the bottom of the container, after which they can be recovered with the aid of a pipette or an eye-dropper. The recovered material is concentrated and rinsed with distilled water on very fine mesh nylon plankton netting and the surface moisture is removed either with absorbent paper or by gentle vacuum. The clumps of faecal material can then be prepared in the manner required by the subsequent analysis. The above system has been tested thoroughly in practice. It is simple, inexpensive and consistent, and should prove to be flexible; thus, use of a finer mesh netting should allow the faecal pellets from smaller zooplanktonic organisms such as copepods to be collected, while replacing nylon and plastic with organically inert materials should suffice if the subsequent analyses are to be for organic rather than inorganic constituents. We recommend the system to research workers who need to collect zooplankton faecal pellets in a quantity and a condition which will permit the detection of constituents which are normally present at the low levels applicable to natural samples. Acknowledgements--The International Laboratory of Marine Radioactivity operates under a tripartite agreement between the International Atomic Energy Agency, the Government of the Principality of Monaco and the Oceanographic Institute at Monaco. Support for the present work is gratefully acknowledged.
REFERENCES BENAYOUN G., S. W. FOWLER and B. OREGIONI (1974) Flux of cadmium through euphausiids. Marine Biology, 27, 205-212. CHERRY R. D., S. W. FOWLER, T. M. BEASLEY and M. HEYRAUD (1975) Polonium-210: its vertical oceanic transport by zooplankton metabolic activity. Marine Chemistry, 3, 105-110. CONOVER R. J. (1971) Some relations between zooplankton and Bunker C Oil in Chedabucto Bay following the wreck of the tanker Arrow. Journal of the Fisheries Research Board of Canada, 28, 1327-1330. MANHEIM F. T., J. C. HATHAWAY and E. UCHUPl (1972) Suspended matter in surface waters of the Northern Gulf of Mexico. Limnology and Oceanography, 17, 17-27. SMALL L. F., S. W. FOWLER and S. KECKES (1973) Flux of zinc through a macroplanktonic crustacean, In : Radioactive contamination of the marine environment, IAEA, Vienna, pp. 437-552.
A simple system for recovering zooplanktonic faecal pellets in quantity
SMAYDA T. J. (1969) Some measurements of the sinking rate of fecal pellets. Liranology and Oceanography, 14, 621-625. SMAYDA T. J. (1971) Normal and accelerated sinking of phytoplankton in the sea. Marine Geology, ll, 105-122.
997
STEELE J. H. and I. E. BAIRD (1972) Sedimentation of organic matter in a Scottish sea loch. Meraorie dell'lstituto italiano di idrobiologia Dott. Marco de Marchi, 29, Supplement, 73-88.