Planktonic

Biogenic Ma.teria.ls, Deep ocean calcareous or siUceous oo2es are sediments containing >30% of biogenic material. Foraminifera, the skeletal remains of calcareous plankton, are found extensively in deep equatorial waters above the calcium carbonate compensation depth of 4000 to 5000 m. 

BloFIms. Microbiologists recognize two different populations of microorganisms. Free-floating (planktonic) populations are found in the bulk water. Attached (sessile) populations colonize surfaces. The same kinds of microorganisms can be found in either population, but the sessile population is responsible for biofouling. 

Planktonic counts (in water samples) are usually unreliable as an indicator of active corrosion. The presence of any sulfate reducers in the water, however, indicates much higher concentrations of these organisms on surfaces somewhere in the system. 

Oceanic biology is a sink for atmospheric CO2 because of the involvement of the aqueous form of this gas in planktonic photosynthesis. This complex process can be summarized by... 

Other limitations on phytoplankton growth are chemical in nature. Nitrogen, in the form of nitrate, nitrite and ammonium ions, forms a basic building material of a plankton s cells. In some species silicon, as silicate, takes on this role. Phosphorus, in the form of phosphate, is in both cell walls and DNA. Iron, in the form of Fe(III) hydroxyl species, is an important trace element. Extensive areas of the mixed layer of the upper ocean have low nitrate and phosphate levels during... 

Figure 7 Diagram of the feedback loop involving climate and planktonic production of DMS. The ( + ) under biological production of DMS in the ocean indicates the uncertainty in the direction of the net feedback loop (Taken from Bigg," with permission of Cambridge University Press)...

A number of current coupled ocean-atmosphere climate models predict that the overturning of the North Atlantic may decrease somewhat under a future warmer climate.While this is not a feature that coupled models deal with well, its direct impact on the ocean s sequestration of carbon would be to cause a significant decline in the carbon that is stored in the deep water. This is a positive feedback, as oceanic carbon uptake would decline. Flowever, the expansion of area populated by the productive cool water plankton, and the associated decline... 

There is a further complication in shallow lakes containing macrophytes (aquatic flowering plants, pteridophytes, and macroalgae). These take up and accumulate nutrients from the water and from the aquatic soil in which they are rooted (sediment). Although these plants are sometimes classed as nuisance weeds, they nevertheless act as an important alternative sink for nutrients which are denied to the plankton. In recent times, a key role of macrophytes in the successful and sustained management of water quality has been identified and explained. ... 

Seine net A net designed to collect aquatic organisms inhabiting natural waters from the shoreline to 3 depths is called a seine net. Most often a plankton seine. Selvage A loom finished edge that prevents cloth unravelling. 

A certain compound of molecular formula Ci9H3g was isolated from fish oil and from plankton. On hydrogenation it gave 2,6,10,14-tetramethylpentadecane. Ozonolysis gave (CH3)2C=0 and a 16-carbon aldehyde. What is the structure of the natural product What is the structure of the aldehyde ... 

Auftriebt m, buoyancy upward thrust lift plankton, -mittel, n. buoying agent swelling agent. 

The subclass Copepoda contains at least 10 bioluminescent genera, such as Metridia, Pleuromamma, Oncaea and Gaussia (Harvey, 1952 Herring, 1978a,b). They are all very small planktonic... 

Guillard, R. R. L., and Ryther, J. H. (1962). Studies of marine planktonic diatoms 1. Cyclotella nana Hustedt and Detonula confervacea (cleve). Canadian J. Microbiol. 8 229-239. 

NOTE Compare this with similar problems in CW systems—those of easily and accurately (and at low-cost) determining levels of microbiological contamination. In most CW systems, apart from a general maintenance quality indicator, the levels of bulk water planktonic organisms tend to have little relevance to sessile organism-biofilm reactions occurring at the metal-water interface. 

Table I summarizes some typical distribution coefficients. Sediments become enriched in plutonium with respect to water, usually with a factor of vlO5. Also living organisms enrich plutonium from natural waters, but usually less than sediments a factor of 103 - 101 is common. This indicates that the Kd-value for sediment (and soil) is probably governed by surface sorption phenomena. From the simplest organisms (plankton and plants) to man there is clear evidence of metabolic discrimination against transfer of plutonium. In general, the higher the species is on the trophic level, the smaller is the Kd-value. One may deduce from the Table that the concentration of plutonium accumulated in man in equilibrium with the environment, will not exceed the concentration of plutonium in the ground water, independent of the mode of ingestion.

Losses of crustaceans, crayfish, mayflies, and some algal and zooplankton species occur as the pH approaches 6, but most fish are largely unaffected. In the range from pH 6 to 5, major population losses are experienced. Major changes of plankton species happen while progressive loss of fish species is hkely. Fish decline is often reflected in a failure of the species to reproduce... 

Consequences of Ozone Depletion. Ozone depletion over Antarctica is causing renewed concern about the consequences of increased levels of UV reaching the earth s biosphere. One area of concern involves the free-floating microscopic plants, known collectively as phytoplankton (the grass of the sea), which through the process of photosynthesis, fix carbon dioxide into living organic matter. Phytoplankton forms the basis of the marine food chain on which zooplankton (animal plankton) and all other components of the ecosystem depend for their sustenance. 

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