하구및 연안생태Coastal management 2014 년 가을학기

Microbial Ecology nutrient recycling by microorganisms is important Estuary have high level of organic materials High primary productions Production exceeds consumption accumulation Input of O2 is less  can not convert CO2 Oxic surface less than a few mm Oxygen demand of 1 ml of sediment is same as O2 in 900 ml of water Oxygen limitation result in a large anaerobic subsystem In land: OM oxidized rapidly Deep sea: little OM

Ecology of estuarine microorganisms viruses, bacteria, fungi, protozoans, algae Blue-green algae : cyano bacteria : procatyotic; monera Virus: obscure position Small metazoans : nematods and harpacticoid: meiofauna Direct identification is almost impossible Very diverse Small size Easy to contaminate Morphology changes continuously often classfied by functional groups rather than individual species

Identification and enumeration morphology, cultural, staining, physiological, biochemical and genetic characteristics Isolation  pure culture  tests Unique morphology is rare Often “function” is more important Enumeration: viable count : dilution and colony count ; depends on medium Microscopic: stain and count: acridine orange : epifluorescence microscope Total : viable=10:1~10000:1 Sediment has more bacteria

Identification and enumeration of fungi Morphology, physiological characteristics Difficult to identify and enumeration: Contamination Differential growth Difficult separate in filamentous mycelia Over 100 species filamentous fungi occur in spartina Fungi can occur large densities in various estuarine habitats Much of the microbial biomass in decaying material may be fungi hyphae 9 x 104 yeasts/cm3 sediments Candida spp: 104 cells/g dry weight of macroalgae

Biochemical technique ATP : gives an index of the microbial biomass Sediment: 640~6400 ng/g Decreased with depth Larger in estuary Estuarine water: 100~1200 ng/L Conversion : 250g C: 1g ATP ATP + total adenylate nucleotide pool concentration: living biomass Muramic acid(ceel wall): biomass index Lipid posphate: biomass Poly(beta-hydroxybutyrate): nutritional history Lipid composition: community structure Relative importance of bacteria, protozoan algal biomass

Habitate composition water column sediments sea grasses “everything is everywhere !!”: difficult ot assign species lists to the habitate Bacterial specialist can only deal with small portions : “ aerobic, heterotrophic “ It’s difficult to identify species level

Processes What do they do? Almost everything!!; depends on the methods that may be used. Much of the processing of energy and matter in many, if not most estuaries is done by microbes. Half of aerobic respiration + almost all anaerobic transformation

Energy flow and carbon cycling Estuarine food chain : staring grasses and ending with large carnivores ? Microbes represents major portion Producers : Nanoplankton is responsible for primary production Macrophyte; lost by respiration of the microbes, leached as DOM, incorporated into bacterial biomass, transformed to other OM decomposers : dead plant tissue: Structural lignocellulose: need gastrointestinal enzyme ; if this is transformed into bacterial biomass, it will be available to animal consumers DOM consumer; amino acid can be consumed only by bacteria Bacteria as a grazers and pathogens

Bacterial metabolism: photoautotrophy Photoheterotrophy Chemoautotrophy chemoheterotrophy

Catabolic processes fermentation Dissimilatory nitrogenous oxide recuction Dissimilatory sulfate reduction Methanogenesis Complex OM : Nox reducers and fermenters Simple OM: sulfate reducers and methanogens Limiting factors : electron acceptors

Microbial secondary production uptake of radioactive nucleic acid precursors Density uincrease measurments in the absence of predators Measurements of the frequency of dividing cells 0.01~ 10 mg C /3/h

Nitrogen cycling major limiting nutrient N transformation by microorganisms To get the N for their body To get energy: Nitrification; Nitrosomonas nitrobacter Dissimilatory nitrogenous oxide reduction (4 final products) NO2- N2O; DNF N2;DNF NH3 Nitrogen fixation; nitrogenase: anaerobic environments: micro-environments in the cell Assimilatory nitrogenous oxide reduction Ammonification Ammonium immobilation