Marine Microbes Marine Bacteria Autotrophic Photosynthetic Cyanobacteria

Marine Microbes • Marine Bacteria • Autotrophic • Photosynthetic • Cyanobacteria • Nitrogen fixation - IMPORTANT • Contain chlorophyll + phycocyanin & phycoerythrin • Occur in a variety of habitats - Polar bear hair - Endolithic (inside calcareous rocks, coral skeletons) - Epiphytic (on algae or plants) - Endophytic (inside algal or plant cells) • Some form filaments or mats (aids N fixation) • Some similarities to eukaryotic algae: - Contain chlorophyll a - Produce gaseous O2 • May have been first photosynthetic organisms on earth • Fossil stromatolites from 3 billion years ago - Calcareous mounds: sediment + cyanobacteria

Stromatolites Fig. 6-10

http://www.fossilmall.com/Science/About_Stromatolite.htm

Marine Microbes • Marine Bacteria • Autotrophic • Chemosynthetic • Obtain energy from chemical compounds • Ex: Hydrogen, hydrogen sulfide, ammonium ion • Often anaerobic, may be symbiotic • Carry out primary production without sunlight

Fig. 6-11

Marine Microbes • Marine Bacteria • Heterotrophic • Most are decomposers (break down organic material) • Important in nutrient cycling (microbial loop) • May be symbiotic Fig. 6-14

Marine Microbes • Archaea • Resemble bacteria superficially but may be more closely related to eukaryotes than bacteria • Includes extremophiles and mesophiles; may comprise up to 40% of microbial biomass in open ocean • Biochemically distinct from Eubacteria and Eukarya • Structure of membranes, cell walls, etc. • Bacteriorhodopsins to capture light • Pigments similar to eukaryotic rhodopsins

San Francisco Bay salt ponds environmentalgraffiti.com wikimedia.com

Marine Microbes • Eukarya • Stramenopiles (Heterokonts) • Diatoms • Unicellular; some may form chains, which then may form mats • Important open-water primary producers, especially in temperate and polar regions • Prefer well-mixed, nutrient-rich conditions (Why?) • Explosive population growth --> Bloom - May deplete nutrients locally • Important food source for planktonic grazers • Sediments beneath areas where diatoms are abundant may contain many tests - Diatomaceous oozes (>30% diatom tests) • Life cycle includes sexual & asexual reproduction

Fig. 6-20

Marine Microbes • Eukarya • Haptophytes • Coccolithophores • Very small (typically less than 20 μm) • Usually in warm water at relatively low light intensities - Most abundant at depths of ca. 100 m in clear, tropical, oceanic water • Blooms may cover extensive areas Ex – Bloom covering 1000 x 500 km of sea surface in North Atlantic (area ~Great Britain) • Coccoliths may be important components of sediments

Marine Microbes • Eukarya • Alveolates • Membranous sacs (alveoli) beneath cell membranes • Dinoflagellates • Ciliates Fig. 6-25

Marine Microbes • Eukarya • Alveolates • Dinoflagellates • Important open-water primary producers, especially in tropical regions • More tolerant of low nutrients and low light than diatoms - Advantage under post-diatom-bloom conditions - Often abundant in summer/autumn following spring and summer diatom blooms - Motility allows individuals to maintain position in water column under low-turbulence conditions • Motility also allows individuals to spend daylight hours in surface waters and night hours in deeper waters (Why?) • Most abundant phytoplankton in stratified, nutrient-poor tropical and subtropical waters • Blooms can produce harmful algal blooms (HABs), aka red tides or brown tides Ceratium furca blogs.scotland.gov.uk

http://www.whoi.edu/redtide/

1.bp.blogspot.com Blue Surf - YouTube

Marine Microbes • Eukarya • Alveolates • Dinoflagellates • Red tides typically visible @ densities >2-8 x 106 cells l-1 - Cell densities may exceed 108 cells l-1 • Nutrient depletion + viral effects (if any)  bloom breakdown - Bacteria decompose senescing cells  O2 depletion • Red tides may not be toxic; HABs are • Toxin (Saxitoxin) may be 1) Released into water 2) Transmitted directly to higher organisms, esp. suspension feeders (e.g. clams, mussels, scallops, oysters), which may be eaten by larger animals • Consuming tainted fish or bivalves can  Paralytic Shellfish Poisoning (PSP)

Marine Microbes • Eukarya • Alveolates • Ciliates • Present in all parts of ocean • May be extremely abundant in some areas • Cilia may be used for both locomotion and feeding • Typically prey on small phytoplankton, zooplankton, bacteria • Tintinnids - Vase-shaped, proteinaceous external shells - Relatively small (20-640 μm); may be important because of wide distribution - May consume up to 60% of primary production in some coastal waters

Marine Microbes • Eukarya • Amoeboid Protozoans • Foraminiferans • Test (shell) made of calcium carbonate (CaCO3) or agglutinated sediment particles - Fossil tests used to age geological deposits • May have multiple chambers - Tests increase in size as organism grows • Feed by extending pseudopodia through pores in test - Trap bacteria and other small organisms/detritus - Some have bacterial symbionts • Pelagic forms (calcareous) - Often have spines - Especially abundant in surface waters b/w 40oN and 40oS - Tests may form foraminiferan oozes, esp. in shallow waters beneath tropics • Benthic forms (calcareous or agglutinated) - Calcareous tests can be important sources of beach sand

Homotrema rubrum www.bios.edu www.travelimg.org

Fig. 6-29 http://www.ucl.ac.uk/GeolSci/micropal/foram.html

Globigerinoides ruber

Marine Microbes • Eukarya • Amoeboid Protozoans • Radiolarians • Common in all oceanic regions, especially in cold waters, including deep sea • Test made of silica (SiO2) • Tests may form radiolarian oozes, esp. in deep water in temperate and polar regions • Feed by extending branched pseudopodia (axopodia) through pores in test • Trap bacteria, protists, detritus, other small organisms including diatoms (Why diatoms?) • May form gelatinous colonies up to 1 m across Fig. 6-30

Marine Microbes Marine Bacteria Autotrophic Photosynthetic Cyanobacteria