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Chapter 33 : Primary Productivity and Producers
Analyses of long-term data sets have demonstrated the utility of primary productivity measurements as indicators of either natural or anthropogenic ecosystem alterations. A suite of microscopic identification and enumeration techniques including various cytological stains, immuno-and autofluorescence, and microautoradiography coupled to fluorescence in situ hybridization are available. These techniques add to the sensitivity, specificity, relevance, and utility of productivity measurements as indicators of ecosystem structure, function, and change. The general use and application of these ancillary techniques are discussed in this chapter. The chapter discusses methods for measuring primary pathways in aquatic habitats. Studies on diverse marine and freshwater systems have shown that the highest rates of primary productivity occur during mid to late morning, prior to the period of maximum irradiance. Oxygen can be measured electrochemically by using several types of electrodes. The construction and general application of cathode-style microelectrodes in microbial O2 production and consumption studies are discussed in detail by Revsbech and Jørgensen. Standard measurements of primary productivity can be complemented by modifications, ancillary techniques, and procedures that enhance physiological, ecological, and taxonomic interpretations of productivity measurements. Microautoradiography and radiolabeling of diagnostic microalgal pigments can enhance the specificity and dimensionality of primary productivity measurements. Both natural perturbations and human activities can strongly impact aquatic primary production by modifying nutrient, sediment, toxin, and other xenobiotic inputs. Evolving remote-sensing techniques will help clarify and evaluate the nutrient-production interactions on scales appropriate for a broad range of aquatic ecosystems.
Key Concept Ranking
- High-Performance Liquid Chromatography
Diagram illustrating the combined use of HPLC and a matrix factorization program (ChemTax) for separating and identifying photopigments diagnostic of microalgal taxonomic groups mediating aquatic primary production.
Major functional groups of aquatic microbial autotrophs, categorized according to environmental requirements and oxic/anoxic characteristics a
Commonly used methods for determining primary production in planktonic and benthic aquatic environments