Photosynthetically-Competent Phytoplankton from the Aphotic Zone of the Deep Ocean

Piatt, T.; Rao, DV Subba; Smith, J. C.; Li, WK; Irwin, B.; Home, Epw; Sameoto, D. D.

doi:10.3354/meps010105

Cited by 43 publications

(16 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These were suggested to be waste products from either partial degradation of algae ingested by herbivores, cells that had undergone autolysis, egested vacuolar residues of protozoans or fecal pellets of microzooplankton, which had been eaten by consumers, evacuated in fecal pellets and then after subsequent fecal pellet sinking and degradation were released back into the water column at depth. The finding of photosynthetically competent phytoplankton cells from 1000 m prompted Platt et al (1983) to suggest that the cells had reached depth after surviving grazer gut passage and fecal pellet sinking and decomposition.…”

Section: Fecal Pellet Contentsmentioning

confidence: 99%

Zooplankton fecal pellets, marine snow and sinking phytoplankton blooms

Turner¹

2002

Aquat. Microb. Ecol.

646

464

View full text Add to dashboard Cite

Zooplankton fecal pellets have long been thought to be a dominant component of the sedimentary flux in marine and freshwater ecosystems, but that view is changing. The last 2 decades have seen publication of > 500 studies using sediment traps, which reveal that zooplankton fecal pellets often constitute only a minor or variable proportion of the sedimentary flux. Substantial proportions of this flux are from organic aggregates ('marine snow') of various origins, including phytoplankton blooms, which sediment directly to the benthos. It now appears that mainly large fecal pellets of macrozooplankton and fish are involved in the sedimentary flux. Smaller fecal pellets of microzooplankton and small mesozooplankton are mostly recycled or repackaged in the water column by microbial decomposition and coprophagy, contributing more to processes in the water column than flux to the benthos. The relative contributions of fecal pellets, marine snow and sinking phytoplankton to the vertical flux and recycling of materials in the water column are highly variable, dependent upon multiple interacting factors. These include variations in productivity, biomass, size spectra and composition of communities in the overlying water columns, and trophic interactions between various components of the plankton and nekton communities at various times, locations and depths. Other factors include differences in sinking rates, sizes, composition and pollutant contents of fecal pellets produced by various sizes of zooplankters, and zooplankton feeding-fecal pellet production interactions in relation to upwelling and El Niño periods, seasonal life-history-related zooplankton vertical migrations and long-term oceanographic regime shifts. There are also suggestions from the geological record that zooplankton fecal pellets may have been important in ancient oceans. The ecological roles of marine snow and phytoplankton aggregates in sedimentary flux also depend on a variety of interacting factors, including sources of origin, degrees of microbial colonization, depth distributions, sinking rates and ingestibility by consumers. Perhaps the major reversal of the previous paradigm on the role of fecal pellets in the sedimentary flux over the last 2 decades has been the realization that much, if not most, of the organic rain from the epipelagic to the abyss is due to direct sedimentation of aggregated phytoplankton, which does not appear to undergo consumption in the water column, and which may be related to seasonality of surface production cycles. Further, there is emerging evidence for benthic responses to sedimented phytodetritus, including apparent synchrony of reproductive cycles of some deep-sea benthic animals with seasonality of sinking of surface blooms. Such episodic input of surface phytodetritus may help resolve apparent discrepancies between average supply and demand of organic matter required to maintain benthic community metabolism. The sedimentary flux of fecal pellets, marine snow and sinking phytoplankton is an important c...

show abstract

Section: Fecal Pellet Contentsmentioning

confidence: 99%

Zooplankton fecal pellets, marine snow and sinking phytoplankton blooms

Turner¹

2002

Aquat. Microb. Ecol.

646

464

View full text Add to dashboard Cite

show abstract

“…Also, Winn and Karl (1984a) worked both within and below the photic zone and asserted that below the photic zone nucleic acid metabolism is predominantly due to heterotrophic bacteria. However protozoa and other eucaryotes, such as sinking viable phytoplankton (Smayda 197 1;Platt et al 1983), may be important there and need to be considered in studies of this type. As a final note, we suggest that automatic interpretation of adenine incorporation in terms of growth may be premature for organisms such as chemolithotrophs (Karl et al 1984 …”

Section: Discussionmentioning

confidence: 99%

Does adenine incorporation into nucleic acids measure total microbial production?1

Fuhrman

Ducklow

Kirchman

et al. 1986

Limnology & Oceanography

View full text Add to dashboard Cite

Incorporation of radioactive adenine into DNA has recently been used as a measure of total microbial production in marine environments, sometimes with unexpected results. We have examined two of the assumptions on which the method is based, particularly regarding the distribution of adenine uptake and nucleic acid content in mixed natural microbial assemblages. Size fractionation, autoradiography, and metabolic inhibition data indicate that the requirement that bacteria, algae, and protozoa have a uniform uptake and metabolism of added dissolved adenine dots not appear to hold. In systems where the biomass and productivity were greatly dominated by large phytoplankton, bacteria took up almost all of the adenine added at nanomolar concentrations. A separate experiment with marine ciliates also showed adenine uptake by eucaryotes to be negligible compared to that by bacteria, The method requires a measurement of microbial adenosine triphosphate (ATP) specific activity. In our experiments this quantity would be dominated by ATP in the eucaryotes that took up negligible adenine. In this situation, mostly eucaryotic biomass and not production would influence the "total microbial production" measurement. Second, the C: DNA ratio of 50 used in reports to date is too high for natural bacteria, which have a ratio closer to 5. We conclude that the method is likely to have produced large overestimates of production and that variations (e.g. with depth) may not reflect growth rates, but rather a complicated combination of activities and ratios of eucaryotic : procaryotic biomasses.

show abstract

“…Typical s i n h g rates of marine phytoplankton, mostly diatoms, cover a wide range from a few meters up to several hundred meters per day (Smayda 1970, von Bodungen et al 1981, Billett et al 1983, Platt et al 1983, Passotv 1991. Cells might sink during a winter season to depths of thousands of meters in the deep ocean and consequently would not be available for the next spring bloom.…”

Section: Introductionmentioning

confidence: 99%

Phyto-convection:the role of oceanic convection in primary production

Backhaus¹,

Wehde²,

Hegseth³

et al. 1999

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

Typical sinking rates of marine phytoplankton cover a range extending from a few meters up to several hundred meters.per day. If it were not for a process which maintains plankton near the sea surface, in the euphotic layer, it would sink to depths of thousands of meters in the deep ocean during the winter season. Consequently, plankton would not be available for the next spring bloom. In shelf seas and coastal areas, as well as in fjords, deep sinking is prohibited by the proximity of the sea bed. The mechanism which reliably initiates a spring bloom is generally not considered in models of marine primary production. Such models generally rely on the assumption that a very small background concentration of plankton is available to initiate a bloom. Penetrative oceanic convection in the open ocean forms the perennial thermocline in winter in mid and high latitudes. The thermocline is situated at depths of several hundred meters. On a shelf, or in a fjord, convection may penetrate to the seabed, thereby affecting the entire water column. We argue that oceanic convection in winter accounts for the availability of plankton in the euphotic layer in spring. In support of this hypothesis a coupled phytoplankton convection model was developed. In this model plankton, i.e. resting spores and vegetative cells, is simulated by Lagrangian tracers moving within the flow predicted by the convection model. For each tracer a simple phytoplankton model predicts growth dependent on light conditions. Plankton spores sink with a prescribed velocity of 120 m d-'. Growing vegetative cells have a sinking rate of only 1 m d-' The model operates in a vertical ocean slice covering the water column. The width of the slice is typically 1 to 3 km, and it is resolved by an isotropic grid size of 5 m. The phyto-convection model was applied to a region in the Barents Sea shelf and to a coastal fjord in the north of Norway. It was run over winter/spring periods under realistic meteorological forcing. Tracers representing resting spores were initially introduced into a thin bottom layer of the model domain, which constitutes the worst case in terms of maximum sinking. The water column, apart from the bottom layer, was assumed to be void of plankton. In both cases convection eroded the initial stratification and dispersed plankton over the entire water column. The onset of a phytoplankton bloom coinciding with the establishment of a (weak) seasonal thermocline in spring was predicted, which agrees with observations from both regions considered. The simulations support the hypothesised role of oceanic convection in primary production.

show abstract

Photosynthetically-Competent Phytoplankton from the Aphotic Zone of the Deep Ocean

Cited by 43 publications

References 29 publications

Zooplankton fecal pellets, marine snow and sinking phytoplankton blooms

Zooplankton fecal pellets, marine snow and sinking phytoplankton blooms

Does adenine incorporation into nucleic acids measure total microbial production?1

Phyto-convection:the role of oceanic convection in primary production

Contact Info

Product

Resources

About