Characteristics, dynamics and significance of marine snow
TL;DR: Diatom flocculation is a poorly understood source of marine snow of potential global significance and rates of snow production and breakdown are critical to predicting flux and to understanding biological community structure and transformations of matter and energy in the water column.
About: This article is published in Progress in Oceanography.The article was published on 1988-01-01. It has received 1319 citations till now. The article focuses on the topics: Marine snow & Snow.
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29 May 2006TL;DR: Reynolds as discussed by the authors provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity.
Abstract: Communities of microscopic plant life, or phytoplankton, dominate the Earth's aquatic ecosystems. This important new book by Colin Reynolds covers the adaptations, physiology and population dynamics of phytoplankton communities in lakes and rivers and oceans. It provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and in addition reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity. Although focussed on one group of organisms, the book develops many concepts relevant to ecology in the broadest sense, and as such will appeal to graduate students and researchers in ecology, limnology and oceanography.
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TL;DR: It is shown for the first time ever, that microplastics have indeed reached the most remote of marine environments: the deep sea, and microplastic pollution has spread throughout the world's seas and oceans.
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...This marine snow is produced as a biologically enhanced aggregation of small particles (Alldredge and Silver, 1988)....
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...Sinking rates of marine snow are estimated to range from 1 to 368 m d 1 (Alldredge and Silver, 1988)....
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...Sinking rates of marine snow are estimated to range from 1 to 368 m d!1 (Alldredge and Silver, 1988)....
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TL;DR: The data indicate that specific bacterial populations, different from those which predominate in free-living bacterioplankton, develop on marine phytodetrital aggregates.
Abstract: The phylogenetic diversity of macroaggregate-attached vs. free-living marine bacteria, co-occurring in the same water mass, was compared. Bacterial diversity and phylogcnetic identity were inferred by analyzing polymerase chain reaction (PCR) amplified, cloned ribosomal RNA (rRNA) genes. Ribosomal RNA genes from macroaggregatc-associated bacteria were fundamentally different from those of free-living bacterioplankton. Most rRNA types recovered from the free-living bacterioplankton were closely related to a phenotypically undcscribcd (Y Proteobacteria group, previously detected in surface waters of North Pacific and Atlantic central ocean gyres. The results suggest that members of this phylogenetically distinct, (Y proteobacterial group are abundant free-living bactcrioplankters in coastal, as well as open-ocean habitats. In contrast, most macroaggregate-associated rRNA clones were closely related to Cytophuga, Planctomyce.s, or y Proteobacteria, within the domain Bacteria. These data indicate that specific bacterial populations, different from those which predominate in free-living bacterioplankton, develop on marine phytodetrital aggregates. The inferred properties of attached bacterial assemblages have significant implications for models of microbially mediated transformation of particulate organic material.
992 citations
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...Aggregates may also serve as localized microhabitats, highly enriched in a variety of micronutrients and microbial assemblages (Alldredge and Silver 1988)....
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TL;DR: The significance of aggregate-associated micro- bial processes as key processes and also for the overall decomposition and flux of organic matter- varies greatly among the various systems, and is greatly affected by the total amount of suspended particulate matter.
Abstract: Macroscopic organic aggregates, which are >500 µm and known as marine and lake snow, are important components in the turnover, decomposition and sinking flux of both organic and inorganic matter and elements in aquatic ecosystems. They are composed of various organic and inorganic materials depending largely on the given system and environmental conditions. The sys- tems include the pelagic limnetic, the neritic and oceanic marine region, as well as shallow turbid environments, e.g. rivers, the littoral zone of lakes, estuaries and tidally affected coastal areas with intense turbulence and a high load of suspended matter. Aggregate abundance and size vary greatly among these systems. Macroaggregates are heavily colonized by bacteria and other heterotrophic microbes and greatly enriched in organic and inorganic nutrients as compared to the surrounding water. During the last 15 yr, many studies have been carried out to examine various aspects of the formation of aggregates, their microbial colonization and decomposition, nutrient recycling and their significance for the sinking flux. They have been identified as hot-spots of the microbial decomposi- tion of organic matter. Further, microaggregates, which are <5 to 500 µm in size and stained by different dyes, such as transparent exopolymer particles (TEP) and Coomassie blue-stained particles, have been discovered and shown also to be important in the formation and decomposition of macroaggregates. In this review we give an overview of the present state of the microbial ecology of macro- and microaggregates, including the mentioned points but highlighting in particular the recent findings on the bacterial colonization of aggregates using molecular tools, their microbial decomposition and mineralization, and the significance of protozoans and metazoans for the colo- nization and decomposition of macroaggregates. Today it is evident that not only the aggregates but also their surroundings are sites and hot-spots of microbial processes, with the plume of solutes leak- ing out of the aggregates and greatly extending the volume of the intense decomposition processes. This microheterogeneity has important implications for the spatial and temporal dynamics of the organic-matter field in aquatic ecosystems and for our understanding of how heterotrophic organisms are involved in the decomposition of organic matter. The significance of aggregate-associated micro- bial processes as key processes and also for the overall decomposition and flux of organic matter- varies greatly among the various systems, and is greatly affected by the total amount of suspended particulate matter. A conclusion from the presented studies and results is that the significance of bac- teria for the formation and decomposition of aggregates appears to be much greater than previously estimated. For a better understanding of the functioning of aquatic ecosystems it is of great impor- tance to include aggregate-associated processes in ecosystem modeling approaches.
940 citations
Cites background from "Characteristics, dynamics and signi..."
...…studied extensively in marine systems since then and more recently, to a lesser extent, also in lakes, rivers and estuaries (Fowler & Knauer 1986, Alldredge & Silver 1988, Alldredge & Gotschalk 1990, 180 Simon et al.: Microbial ecology of organic aggregates Alldredge 1992, 1998, Herndl 1992,…...
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...…Ecol 28: 175–211, 2002184 Simon et al.: Microbial ecology of organic aggregates tive function of the aggregate size except for larvacean houses, which are not formed by aggregation (Alldredge & Silver 1988, Grossart & Simon 1993, MüllerNiklas et al. 1994, Alldredge 1998, Grossart & Ploug 2000)....
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...It may be important under certain conditions for passively capturing particles that do not actively form aggregates such as discarded larvacean houses, pteropod webs and non-sticky dinoflagellates (Alldredge & Silver 1988, Alldredge et al. 1998, Silver et al. 1998)....
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...Sinking rates of macroaggregates range from <5 to 200 m d–1 and are a positive function of their size (Alldredge et al. 1987, Asper 1987, Alldredge & Gotschalk 1988, 1989, Alldredge & Silver 1988, Grossart & Simon 1993, Kiørboe et al. 1994, Hansen et al. 1996, Pilskaln et al. 1998)....
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...Thus, macroaggregates dominate the sinking POM in marine as well as in lacustrine systems (Fowler & Knauer 1986, Asper 1987, Alldredge & Silver 1988, Riebesell 1991a, Walsh et al. 1997, Grossart & Simon 1998a, Pilskaln et al. 1998)....
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References
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TL;DR: In this paper, the vertical derivative of particulate fluxes may indicate solute regeneration rates, and accordingly regeneration rates for C, H and N were estimated under the assumption that 1.5, 1.0 and 0.25 moles of O 2 were used for each mole of N, C and H regenerated.
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TL;DR: In this paper, an empirical relationship was established that predicts organic carbon flux at any depth in the oceans below the base of the euphotic zone as a function of the mean net primary production rate at the surface and depth-dependent consumption.
Abstract: Organic detritus passing from the sea surface through the water column to the sea floor controls nutrient regeneration, fuels benthic life and affects burial of organic carbon in the sediment record1–3. Particle trap systems have enabled the first quantification of this important process. The results suggest that the dominant mechanism of vertical transport is by rapid settling of rare large particles, most likely of faecal pellets or marine snow of the order of >200 μm in diameter, whereas the more frequent small particles have an insignificant role in vertical mass flux4–6. The ultimate source of organic detritus is biological production in surface waters of the oceans. I determine here an empirical relationship that predicts organic carbon flux at any depth in the oceans below the base of the euphotic zone as a function of the mean net primary production rate at the surface and depth-dependent consumption. Such a relationship aids in estimating rates of decay of organic matter in the water column, benthic and water column respiration of oxygen in the deep sea and burial of organic carbon in the sediment record.
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TL;DR: In this paper, the frequency distributions of particIe size between sizes of about I and 100 p are given for both surface and deep water of the Atlantic and Pacific Oceans.
Abstract: Frequency distributions of particIe size between sizes of about I and 100 p are given for both surface and deep water of the Atlantic and Pacific Oceans. The form of the size spectra varies predictably both geographically and with depth. A hypothesis is presented to show that, to a first approximation, roughly equal concentrations of material occur at all particle sizes within the range from 1 p to about 10” p, i.e. from bacteria to whales.
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TL;DR: In this paper, a new approach to estuarine studies is presented which establishes 1) the extent and salinity dependence of non-conservative behaviour; 2) composition and chemical form of removal products; and 3) abiological removal mechanisms.
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TL;DR: Rapid mass sinking of cells following diatom blooms is argued here to represent the transition from a growing to a resting stage in the life histories of these algae.
Abstract: Rapid mass sinking of cells following diatom blooms, observed in lakes and the sea, is argued here to represent the transition from a growing to a resting stage in the life histories of these algae. Mass sinking is of survival value in those bloom diatoms that retain viability over long periods in cold, dark water but not in warm, nutrient-depleted surface water. Mechanisms for accelerating sinking speed of populations entering a resting or “seeding” mode are proposed. Previously unexplained features of diatom form and behaviour take on a new meaning in this context of diatom seeding strategies. Diatoms have physiological control over buoyancy as declining growth is accompanied by increasing sinking rates, where the frustule acts as ballast. Increased mucous secretion in conjunction with the cell protuberances characteristic of bloom diatoms leads to entanglement and aggregate formation during sinking; the “sticky” aggregates scavenge mineral and other particles during descent which further accelerates the sinking rate. Such diatom flocs will have sinking rates of ∼ 100 m d-1 or more. This is corroborated by recent observations of mass phytoplankton sedimentation to the deep sea. This mechanism would explain the origin of marine snow flocs containing diatoms in high productivity areas and also the well-known presence of a viable deep sea flora. That mortality is high in such a seeding strategy is not surprising. A number of species-specific variables pertaining to size, morphology, physiology, spore formation and frustule dissolution rate will determine the sinking behaviour and thus control positioning of resting stages in the water column or on the bottom. It is argued that sinking behaviour patterns will be environmentally selected and that some baffling aspects of diatom form and distribution can be explained in this light. Rapid diatom sedimentation is currently believed to be mediated by zooplankton faecal pellets, particularly those of copepods. This view is not supported by recently published observations. I speculate that copepod grazing actually retards rather than accelerates vertical flux, because faecal pellets tend to be recycled within the surface layer by the common herbivorous copepods. Egestion of undigested food by copepods during blooms acts as a storage mechanism, as ungrazed cells are likely to initiate mass precipitation and depletion of the surface layer in essential elements. Unique features of diatoms are discussed in the light of their possible evolution from resting spores of other algae. An evolutionary ecology of pelagic bloom diatoms is deduced from behavioural and morphological characteristics of meroplanktonic and tychopelagic forms. Other shell-bearing protistan plankters share common features with diatoms. Similar life-history patterns are likely to be present in species from all these groups. The geological significance of mass diatom sinking in rapidly affecting transfer of biogenic and mineral particles to the sea floor is pointed out.
951 citations