Plankton zooplankton

Great Lakes, Lake Ontario Plankton Zooplankton Fish... 

One of the most useful findings that oceanographers have made in support of a chemical perspective on ocean processes has been that the C N P ratios of mixed marine plankton (zooplankton and ph5doplankton) collected by towing nets (>64 rmmesh) through the surface ocean occur at relatively constant values, near 106 16 1. This observation was published by Redfleld (1958) and then later elaborated by Redfleld, Ketchum, and Richards (RKR, 1963), who fleshed out the ratios in the form of an equation for photosynthesis ... 

Heavy metals can cause inhibition of plankton, even in concentrations at ppb level. Among plankton, zooplankton, especially larvae zooplankton, are very sensitive to heavy metal pollution. In an enclosure ecosystem, concentrations of dissolved heavy metals decreased exponentially with deposition of particulates, with the removal efficiency Pb>Hg>Zn>Cu>Cd then the dissolved heavy metals were transformed to particulate forms by biological activities. After 27 d, Cd and Cu existed mostly in the dissolved form, most of Pb and Hg were transported to the bottom, and about half of Zn was transported to the bottom. The release of heavy metals from the sediments was determined by both the nature of the metals themselves and the environmental conditions. An anoxic environment is beneficial to the release of heavy metals. In an oxidizing environment, release fluxes of Cu and Zn were 1 2 order(s) of magnitude higher than those of Cd and Pb. 

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. 

This equation was originally proposed for "average" plankton, a category that included both zooplankton and phytoplankton. This mean elemental ratio of C/N/P = 106/16/1 by atoms is highly conserved (Falkowski et al., 1998) and reflects the average biochemical composition of marine phytoplankton and their early degradation products. 

Basu BK, Pick FR (1997) Phytoplankton and zooplankton in a lowland, temperate river. J Plankton Res 19 237-253... 

Greig, R.A., A. Adams, and D.R. Wenzloff. 1977. Trace metal content of plankton and zooplankton collected from the New York Bight and Long Island Sound. Bull. Environ. Contam. Toxicol. 18 3-8. 

Day, K.E., N.K. Kaushik, and K.R. Solomon. 1987. Impact of fenvalerate on enclosed freshwater planktonic communities and on in situ rates of filtration of zooplankton. Canad. Jour. Fish. Aquat. Sci. 44 1714-1728. 

Fulton III RS, Paerl HW (1987) Toxic and inhibitory effects of the blue-green alga Microcystis aeruginosa on herbivorous zooplankton. J. Plankton Res 9 837-855 Gilbert JJ (1990) Differential effects of Anabaena afflnis on cladocerans and rotifers mechanisms and implications. Ecology 71 1727-1740... 

A one-page essay in which it is suggested that evolution in plankton is driven by a watery arms race has attracted much attention (Smetacek 2001). Smetacek discusses the concept that defence of phytoplankton by mechanical protection, increased cell size, formation of spines, or production of noxious chemicals leads to the adaptation of zooplankton to these measures. This process resulted in the shape and properties of phyto- and zooplankton that we observe today. In the years following that essay several candidate molecules were discovered and intensely studied. The concept that chemical signals and defence metabolites are important factors in plankton ecology has now become widely accepted. 

Caldwell GS, Watson SB, Bentley MG (2004) How to assess toxin ingestion and postingestion partitioning in zooplankton J Plankton Res 26 1369-1377 Cembella AD (2003) Chemical ecology of eukaryotic microalgae in marine ecosystems. Phycologia 42 420 147... 

Redfield (1934), who analyzed the major elemental content of many samples of mixed plankton (phytoplankton and zooplankton) caught in nets towed through the surface ocean. They compared the carbon, nitrogen, and phosphorus composition of these collections to concentration profiles of dissolved inorganic carbon (DIC), NOs, and P04 throughout the water column. This pioneering research demonstrated that these three elements are continually redistributed in the ocean by selective removal into plankton cells and their remains (i.e., fecal pellets), which are then efficiently respired as they sink through the marine water column. 

In some cases, exudates enable the plankton to control their environment. For example, diatoms release compounds, called oxyUpins, that induce natural abortions and growth reduction in the zooplankton that are their primary predators. Other exudates complex with trace metals, serving to reduce the bioavailability of toxics, such as copper, and enhance the bioavailability of micronutrients, such as iron. Examples of iron-binding extracellular DOM are the siderophores (Figure 5.11). 

Ocean. The former is estimated to have a surface area the size of Texas. The focusing effect of the Kuroshio Current on the density of plastics collected in plankton net tows is shown in Figure 28.35. In some locations, particle densities are greater than that of the local zooplankton. High concentrations have also been reported on the seabed near industrialized areas such as the Mediterranean and the North Seas. In 2000, the volume of litter estimated to be residing on the seabed of the North Sea was 600,000 m. ... 

Plankton Organisms that drift passively or are weak swimmers. Includes mostly microscopic plants (phytoplankton) and protozoans, as well as larval animals and small filter feeders (zooplankton). 

It is likely that cyanobactria synthesize poisons to ward off attack by other planktonic species. Carmichael etal. have found that cyanobacterial neurotoxins and hepatotoxins can be extremely harmful to the zooplankton living in the marine environment. This is a good example of the natural task of the toxins in protecting the organism that produces them. ... 

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