the microbial loop the microbial food web Mikrobiel løkke det mikrobielle næringsnett
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BIO4400 Akvatisk økologi/Marin biologi the microbial loop the microbial food web Mikrobiel løkke det mikrobielle næringsnett POM and DOM The microbial foodweb Microbial loop POM micro-, nano- and picoplankton, and debris POM = Particulate Organic Matter DOM Molecules DOM = Dissolved Organic Matter Sources of DOM • From land – plantmaterial • Marint – phytoplankton - zooplankton (feces, ”sloppy feeding) - Death and viral infections (Passing through a 0.7 µm filter) DOM - dissolved molecules originating from dead organisms (detritus) or molecules that are excreted from living organisms (eg from microalgae, heterotrphic flagellates, virus) Detritus - dead particular material, dead organisms or parts of dead organisms Detrivors - feeds on detritus, makes it available for bacteria (and fungus, the decomposers) • POM algae, heterotrophic microorganisms, bakteria and debris (debris; parts of organisms <50 µm). Marine snow - aggregates • • • • • Who produce DOM? Who concume DOM? Who produce POM? Who consume POM? How are nutrients produced (e.g remineralization)? • Which are the consumers of micro nutrients? Sources of energy used by the aktors in the microbial foodweb • • • • Algae and cyanobacteria – sun light Bakteria - DOM Heterotrotrophic flagellats and ciliats – POM Virus - POM Actors in the microbial food web heterotrophic • Bacteria; Archaea og Eubacteria • Eukaryote; micro-, nano- and pico zoo plankton autotrophic • Bacteria; Cyanobacteria (incl Prochlorophyta) • Eukaryote; mikro-, nano- and pico plankton algae Virus Definition of size fractions Primary producers Autotrophic cyanobakteria and eukaryote algae • produce POM • produce DOM Secondary producers Heterotrophic bacteria • Take up DOM Eukaryotic predators • Take up POM • Archea • Ca 1970 • Archea cell membrane different from bacteria (eubacteria) and from Eukarya • The form and function of some DNA structures are more similar to Eukarya • Three large ecological groups - thermophile - halophile - methanogene Bacteria (Eubacteria) • Cellwall – murein (peptidoglucan) • Dominates the less extreme habitats (but chemotrophs and termophils are present) Pelagic free living bacteria – coccoide – the majority - rod shaped – ofte with flagellum - some have bacterial photosynthesis classification according to metabolic activity, morphologiy and DNA strutures Cellwall components (phospholipids) Eubacteria and Eukaryota Fosforylert gruppe Glycerol backbone linked by ester bonds to two long fatty acid groups and a phosphatidyl group Cellwall components (membran-lipids) Archaea hydrophil hydrophob Hydorphobe polyisoprenes are linked to the glycerol by ether bonds Ribosomal DNA Phylogeny Aarchea Bacteria Eukarya Miller 2004 Phylogeny Eubacteria - Archea 16 rRNA Miller 2004 Virus 10 mill -1000 mill viruses/ ml sea water - low biomass Lyses 2-25% of the bacteria/day in the open ocean Measures 20-100 nm >90% of particles containing DNA Ca 5% of biomass Virus • liberates DOM Lytic, lysogenic cycles 0.1 µm Virus and eukaryote organic scales Virus Scales from Prasinophytes Miller 2004 Heterotrofe bakterier 0.4-2µm 100 thousend-10mill/ml Bacteria dominates Fra Miller 2004 DNA stained heterotrophic bacteria with fluorescens microscopy 50-80% of C in the ocean are bacteria Consums ca 50% of C fixed in the primary production Predators in the mikrobial foodweb Feeds on phytoplankton Feeds on bacteria 100-1000 cells/ml 3µm -50 (200)µm Vørs Different kinds of heterotrophic flagellates Pteridomonas Pseudobodo? Bodo Nanoplankton Bicosoeca 2-20 µm Paraphysomonas Ciliophrys Cafeteria Bodo Codosiga Thecamonas Goniomonas Bordnamonas Metromonas Telonema Massisteria Salpingoeca Ancyromonas Rhynchomonas nasuta Diplonema Ebria Ploeotia ¾20 µm microplankton Leucocryptos Diaphanoeca Heterotrophic Dinoflagellets microplankton Protoperidinium species = Minuscula bipes Food uptake fra Hausmann & al. 2003 Cafeteria roenbergensis Food uptake Bodo saltans Spumella sp. fra Hausmann & al. 2003 Feeding in Polykrikos kofoidii Pallium feeding in Protoperidinium spinulosum Peduncle in Phiesteria (arrow head) Oedogonium ”Peduncle-like” feeding in Stylodinium Appendicularian Oikopleura From Hardy 1956 ”house length” 10-20 mm Retension in Oikopleura vanhoeffeni : 58% retention of 1 µm particles, 88% for 3 µm particles. Deibel & Lee 1992 Mucus net feeder Bakterioplankton og predators in Limfjorden Primary producers • Algae (pico, nano and microplankton) • Cyanobakterier (picoplankton) Picoplankton with fluorescens microscopy, blue light Synechococcus - orange Eukaryote - red Miller 2004 Synechococcus Cyanobacteria are picoplankton mmmmmmmmmm mmmmmmmmmm mmmmmmmmmm mmmmmmmmmm x mmmmmmmmmm Prochlorococcus Cyanobium Rippka et Cohen-Bazire 1983 Picoplankton Cyanobium species species authors size µm colour (Butcher) Komárek, Kopecký & Cepák 1.7-4.5 blue-green C. gaarderii (Ålvik) Komárek, Kopecký & Cepák Yellow1.5-2.8 green blue-green C. oceanicum (Hall & Claus) Komárek, Kopecký & Cepák C. waterburyi Komárek C. bacillare 1-2.8 2? green red Based on Komárek 2002 Micromonas pusilla (Butcher) Manton & Parke 1960 1.5-2.5 µm Pico sized prasinophyte Scanning electron microscope Micromonas pusilla Bolidomonas mastigoneme Chloroplast anterior flagellum A pico sized heterokont alga posterior flagellum Cell size ca 2µm Chlorophyta, Chlorophyceae; nanoplankton flagella Cell wall Chlamydomonas Euglenophyta - microplankton øyeflekk eyespot nucleus kjerne flagella flagell rproximal proxima del l part pellicular pellicula stripes striper paramylon korn Cryptophyta nanoplankton Cryptomonas sp ejectosomer TEM-snitt SEM Haptophyta pico and nanoplankton Cl. Coccolithophyceae Class Pavlovophyceae mixotroph phototroph Interferens contrast Pavlova lutheri phase kontrast Phase contrast Prymnesium parvum Dinoflagellates heterotrof Prorocentrum micans Protoperidinium sp. mixotroph Dinophysis acuta Karenia mikimotoi Heterokontophyta pico, nano and microplankton Cl. Bacillariophyceae Cl. Dictyocophyceae Pseudochattonella farcimen Thalassionema nitzschioides Chaetoceros decipiens Dictyocha speculum Foodwebs in the ocean Skjoldal 2004 The microbial food web includes more than the microbial loop (all communities less than 100 µm pathways relating bacteria to bactivorous protists and DOM microbial food webs in the ocean Microbial food web = microbial loop ? organic O2, CO2, other gases material hν GRAZING CH4 DMS Phytoplankton POM Zooplankton C, N, P, S, Fe,... aggregates 0-200 m Protozoa DOM MICROBIAL LOOP SEDIMENTATION Viruses 200-11000 m bentos Fish Bacteria solubilization
