Producers and Processes Involved in Primary Production
There are many kinds of marine organisms that fix inorganic carbon into organic compounds using external sources of energy. There are many thousands of producer species with widely different phyletic origins (Taylor 1978), including single-celled phytoplankton and bottom-dwelling benthic algae, large many-celled macroalgae or seaweeds, symbiotic producers such as corals, and higher plants such as seagrasses.
KeywordsCoral Reef Salt Marsh Particulate Organic Carbon Standing Crop Kelp Forest
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- *.The rocky coasts of Antarctica are uniquely devoid of kelp (Laminariales); they are replaced there by kelp-like macroalgae of the Desmarestiales, which form thickets rather than forests (Moe and Silva 1977).Google Scholar
- *.Respiration of course occurs in all organisms. In animals or many microbes, ingested or absorbed carbon compounds serve as the principal substrate for respiration (cf. Sections 7.3 and 10.1232). Organisms whose metabolism is based on organic compounds fixed by autotrophs are called heterotrophs. This is in contrast to autotrophs, defined as organisms able to use CO2 by reductive assimilation to supply carbon requirements.Google Scholar
- *.Gross production minus respiration is referred to as net production.Google Scholar
- *.These observations include (a) measurements of changes in O2, CO2, and dissolved organic carbon that suggest that CO2 consumed or O2 released exceeds primary production as measured by 14C [Shulenberger and Reid (1981) and studies summarized in Johnson et al. (1981)]; (b) measurements of formation of particulate carbon exceeding rates of 14C primary production (Postma and Rommets 1979); (c) estimates of rates of O2 formation in water masses whose age has been established by tritium and 3He dating (Jenkins 1977), where estimates of O2 formed exceed rates obtained by 14C; (d) measurement of high primary production (11–56% of total water column production) associated with fragile aggregates that are seldom sampled by usual water sampling methods (G. A. Knauer, personal communication). All of these observations need confirmation and evaluation.Google Scholar
- †.The bottle size effect has been claimed to be due to enhanced mortality of algal cells through contact with bottle walls, nutrient depletion within the container, toxic effects of trace contaminants in the chemicals used in the 14C method (Fitzwater et al. 1982), changes in the species composition within the container, enhanced bacterial activity, and inhibition of photosynthesis due to constant exposure to high light intensity (Venrick et al. 1977; Gieskes et al. 1979; J. Goldman personal communication). All these factors are more serious in small containers, and all these postulated mechanisms need further study.Google Scholar
- *.Advection and turbulent (or eddy) diffusion can both be agents of transport of substances. Advection refers to the mass movement of a parcel of water. Diffusion in seawater tends to occur primarily due to small turbulent eddies rather than to molecular diffusion. In sediments molecular diffusion is more important.Google Scholar