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Structure of Aquatic Ecosystems. Relative importance of allochthonous versus autochthonous sources of nutrients sediments o rganic matter (dissolved and particulate). Productivity within a Watershed. Wetland very productive Terrestrial systems moderately productive
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Relative importance of allochthonous versus autochthonous sources of • nutrients • sediments • organic matter (dissolved and particulate)
Productivity within a Watershed • Wetland very productive • Terrestrial systems moderately productive • Aquatic systems least productive
Categories of Aufwuchs • Epiphytic • Epipelic • Episammic • Epilithic
Trophic Structure Primary Producers Primary Consumers Secondary Consumers (carnivores) Decomposers
Productivity Rate at which energy enters one trophic level from a lower trophic level.
Efficiency Energy transfers not very efficient because of dissipation through metabolism, etc. Also, mechanisms of energy transfer not inherently efficient. For example photosynthesis is less than 1% efficient in water.
Diversity Complexity of a community
Biomass Ways to determine: • Volume and number • Weight –fresh and dry • Oxidize living matter to CO2 • Total ATP • For primary producers, extract chlorophylls
Production • New organic mass per unit of time • Σ [new organic biomass - respiration -excretion - secretion – injury – death – grazing]