Marine snow studies in the Northeast Atlantic Ocean: distribution, composition and role as a food source for migrating plankton

During a 25 d Lagrangian study in May and June 1990 in the Northeast Atlantic Ocean, marine snow aggregates were collected using a novel water bottle, and the composition was determined microscopically. The aggregates contained a characteristic signature of a matrix of bacteria, cyanobacteria and autotrophic picoplankton with inter alia inclusions of the tintiniid Dictyocysta elegans and large pennate diatoms. The concentration of bacteria and cyanobacteria was much greater on the aggregates than when free-living by factors of 100 to 6000 and 3000 to 2 500 000, respectively, depending on depth. Various species of crustacean plankton and micronekton were collected, and the faecal pellets produced after capture were examined. These often contained the marine snow signature, indicating that these organisms had been consuming marine snow. In some cases, marine snow material appeared to dominate the diet. This implies a food-chain short cut wherby material, normally too small to be consumed by the mesozooplankton, and considered to constitute the diet of the microplankton can become part of the diet of organisms higher in the food-chain. The micronekton was dominated by the amphipod Themisto compressa, whose pellets also contained the marine snow signature. Shipboard incubation experiments with this species indicated that (1) it does consume marine snow, and (2) its gut-passage time is sufficiently long for material it has eaten in the upper water to be defecated at its day-time depth of several hundred meters. Plankton and micronekton were collected with nets to examine their vertical distribution and diel migration and to put into context the significance of the flux of material in the guts of migrants. “Gut flux” for the T. compressa population was calculated to be up to 2% of the flux measured simultaneously by drifting sediment traps and <5% when all migrants are considered. The in situ abundance and distribution of marine snow aggregates (>0.6 mm) was examined photographically. A sharp concentration peak was usually encountered in the depth range 40 to 80 m which was not associated with peaks of in situ fluorescence or attenuation but was just below or at the base of the upper mixed layer. The feeding behaviour of zooplankton and nekton may influence these concentration gradients to a considerable extent, and hence affect the flux due to passive settling of marine snow aggregates.

[1]  G. Riley,et al.  ORGANIC AGGREGATES IN SURFACE AND DEEP WATERS OF THE SARGASSO SEA1 , 1965 .

[2]  I. Bellan,et al.  A controlled-temperature plankton wheel , 1986 .

[3]  K. Banse.  New views on the degradation and disposition of organic particles as collected by sediment traps in the open sea , 1990 .

[4]  A. Alldredge,et al.  In situ settling behavior of marine snow1 , 1988 .

[5]  A. Longhurst,et al.  Vertical flux of respiratory carbon by oceanic diel migrant biota , 1990 .

[6]  O. Pfannkuche,et al.  Open ocean pelago-benthic coupling: cyanobacteria as tracers of sedimenting salp faeces , 1993 .

[7]  H. Roe,et al.  The diel migrations and distributions within a Mesopelagic community in the North East Atlantic. 1. Introduction and sampling procedures , 1984 .

[8]  C. Hemleben,et al.  Phytodetritus on the deep-sea floor in a central oceanic region of the Northeast Atlantic , 1989 .

[9]  A. Alldredge.  Abandoned Larvacean Houses: A Unique Food Source in the Pelagic Environment , 1972, Science.

[10]  Paul W. Johnson,et al.  Chroococcoid cyanobacteria in the sea: A ubiquitous and diverse phototrophic biomass1 , 1979 .

[11]  Martin V. Angel,et al.  Detrital Organic Fluxes Through Pelagic Ecosystems , 1984 .

[12]  R. Lampitt.  Evidence for the seasonal deposition of detritus to the deep-sea floor and its subsequent resuspension , 1985 .

[13]  W. Gardner.  Incomplete extraction of rapidly settling particles from water samplers1 , 1977 .

[14]  Yogesh C. Agrawal,et al.  Direct optical assessment of large amorphous aggregates (marine snow) in the deep ocean , 1984 .

[15]  R. W. Gilmer,et al.  Underwater observations of gelatinous zooplankton : Sampling problems, feeding biology, and behavior1 , 1975 .

[16]  B. Irwin,et al.  NFLUX: a test of vertical nitrogen flux by diel migrant biota , 1989 .

[17]  Alice L. Alldredge,et al.  Characteristics, dynamics and significance of marine snow , 1988 .

[18]  A. Alldredge,et al.  The physical strength of marine snow and its implications for particle disaggregation in the ocean , 1990 .

[19]  N. Inoue,et al.  PHOTOGRAPHIC STUDY OF SUSPENDED MATTER AND PLANKTON IN THE SEA , 1954 .

[20]  B. Frost.  EFFECTS OF SIZE AND CONCENTRATION OF FOOD PARTICLES ON THE FEEDING BEHAVIOR OF THE MARINE PLANKTONIC COPEPOD CALANUS PACIFICUS1 , 1972 .

[21]  J. Hobbie,et al.  Use of nuclepore filters for counting bacteria by fluorescence microscopy , 1977, Applied and environmental microbiology.

[22]  C. Turley,et al.  Bacteria and cyanobacteria associated with phytodetritus in the deep sea , 1988, Nature.

[23]  P. Johson.  The utilization of chroococcoid cyanobacteria by marine protozooplankters but not by calanoid copepods. , 1982 .

[24]  J. Trent,et al.  Marine snow: sinking rates and potential role in vertical flux , 1980 .

[25]  K. Porter,et al.  The use of DAPI for identifying and counting aquatic microflora1 , 1980 .

[26]  W. Gardner,et al.  Distribution of macroaggregates and fine-grained particles across a continental margin and their potential role in fluxes , 1990 .

[27]  R. Lampitt.  The contribution of deep-sea macroplankton to organic remineralization: results from sediment trap and zooplankton studies over the Madeira Abyssal Plain , 1992 .

[28]  J. Hobbie,et al.  Direct counts of aquatic bacteria by a modified epifluorescence technique1 , 1975 .

[29]  D. Patterson,et al.  A barophilic flagellate isolated from 4500 m in the mid-North Atlantic , 1988 .

[30]  K. Wishner,et al.  Feeding ecology of benthopelagic zooplankton on an eastern tropical Pacific seamount , 1992 .

[31]  A. Gooday,et al.  Maintenance of abyssal benthic foraminifera under high pressure and low temperature: some preliminary results , 1993 .

[32]  A. Longhurst,et al.  Vertical nitrogen flux from the oceanic photic zone by diel migrant zooplankton and nekton , 1988 .

[33]  C. Turley.  Protozoa Associated with Marine ‘Snow’ and ‘Fluff’ — Session Summary , 1991 .

[34]  M. C. Macaulay,et al.  Copepod patches and right whales in the great south channel off new England , 1988 .

[35]  T. Noji,et al.  What happens to zooplankton faecal pellets? Implications for material flux , 1990 .

[36]  B. Frost,et al.  Copepod diel migration, feeding, and the: vertical flux of pheopigments , 1989 .

[37]  R. Williams,et al.  Seasonal Variability in Abundance and Vertical Distribution of Parathemisto gaudichaudi (Amphipoda: Hyperiidea) in the North East Atlantic Ocean , 1981 .

[38]  David C. Smith,et al.  Intense hydrolytic enzyme activity on marine aggregates and implications for rapid particle dissolution , 1992, Nature.

[39]  M. Sheader,et al.  Feeding and gut structure of Parathemisto gaudichaudi (Guerin) (Amphipoda, Hyperiidea) , 1975, Journal of the Marine Biological Association of the United Kingdom.

[40]  A. Alldredge,et al.  The relative contribution of marine snow of different origins to biological processes in coastal waters , 1990 .

[41]  S. Fowler,et al.  Role of large particles in the transport of elements and organic compounds through the oceanic water column , 1986 .

[42]  J. Kane.  Observations On the Moulting and Feeding of a Hyperiid Amphipod , 1963 .

[43]  M. Angel.  Vertical profiles of pelagic communities in the vicinity of the Azores Front and their implications to deep ocean ecology , 1989 .

[44]  M. Silver,et al.  Differential feeding and fecal pellet composition of salps and pteropods, and the possible origin of the deep-water flora and olive-green “Cells” , 1981 .

[45]  V. Asper.  Accelerated settling of particulate matter by ’marine snow’ aggregates , 1985 .

[46]  P. Burkill,et al.  Microzooplankton grazing and selectivity of phytoplankton in coastal waters , 1987 .

[47]  M. Silver,et al.  Primary production, sinking fluxes and the microbial food web , 1988 .

[48]  T. Tsujita.  A Preliminary Study on Naturally Occurring Suspended Organic Matter in Waters Adjacent to Japan , 1953 .

[49]  P. Wangersky,et al.  A recording backward scattering meter and camera system for examination of the distribution and morphology of macroaggregates , 1985 .

[50]  S. Knowles,et al.  Ecological implications of fecal pellet size, production and consumption by copepods , 1979 .

[51]  F. Riemann.  Gelatinous phytoplankton detritus aggregates on the Atlantic deep-sea bed , 1989 .

[52]  C. Turley.  Direct estimates of bacterial numbers in seawater samples without incurring cell loss due to sample storage , 1993 .

[53]  D. Caron,et al.  Enrichment of microbial populations in macroaggregates (marine snow) from surface waters of the North Atlantic , 1986 .

[54]  A. Gooday.  A response by benthic Foraminifera to the deposition of phytodetritus in the deep sea , 1988, Nature.

[55]  M. Sheader.  Development and growth in laboratory-maintained and field populations of Parathemisto gaudichaudi (Hyperiidea: Amphipoda) , 1981, Journal of the Marine Biological Association of the United Kingdom.

[56]  J. Strickland,et al.  A note on the feeding of Calanus helgolandicus on detritus , 1970 .

[57]  R. Forward.  Diel vertical migration: zooplankton photobiology and behaviour , 1988 .

[58]  L. Madin,et al.  Pelagic Tunicates: Unique Herbivores in the Marine Plankton , 1982 .

[59]  S. Fowler,et al.  An analysis of sinking rates of natural copepod and euphausiid fecal pellets1 , 1981 .

[60]  H. Roe,et al.  A new multiple rectangular midwater trawl (RMT 1+8M) and some modifications to the institute of oceanographic sciences' RMT 1+8 , 1979 .

[61]  M. Fasham,et al.  Natural tracers in dietary studies: data for 210Po and 210Pb in decapod shrimp and other pelagic organisms in the Northeast Atlantic Ocean , 1988 .

[62]  P. G. Challenor,et al.  Seasonal and diel variation in the open ocean concentration of marine snow aggregates , 1993, Nature.

[63]  Alice L. Alldredge,et al.  Discarded appendicularian houses as sources of food, surface habitats, and particulate organic matter in planktonic environments , 1976 .

[64]  D. C. Gordon.  Some studies on the distribution and composition of particulate organic carbon in the North Atlantic Ocean , 1970 .