Marine Biology Chapter 6 Marine Microbes

Microbes Any living thing that is microscopic Can be one of the following: Viruses Prokaryotes (Bacteria) Unicellular Protists Unicellular Fungi Even very tiny animals

Marine Viruses Virology—the study of viruses Viruses are diverse and are more abundant than any other organism in the sea Have significance for marine food webs, population biology and diseases of marine organisms

Viral Characteristics Are they “alive”? Most say no Remember you have to be made of at least one cell to be alive, viruses are not cells Viruses consist of bits of DNA or RNA surrounded by protein Have no metabolism, and rely entirely on host organism for energy, material and organelles to reproduce themselves Viral replication must occur within a host cell Viruses infect all groups of living organisms, but may be specialized Infect specific species Infect specific tissues of that species Influenza infects respiratory cells Hepatitis infects liver cells

Viral Characteristics Viral structure virus particle is called a virion when outside the host cell Can’t do anything until it enters into a host cell virion composed of a nucleic acid core surrounded by a coat of protein called a capsid may have a protective envelope, a membrane derived from the host’s nuclear or cell membrane

Figure 6-2 STRUCTURE OF MARINE VIRUSES.

Biodiversity and Distribution of Marine Viruses 10 times more abundant than marine prokaryotes (bacteria) may reach 1010 virons per liter of seawater, 1013 per kilogram of sediment Bacteriophages – viruses that infect bacteria

Ecology of Marine Viruses Viruses kill host cells, and thus control populations of bacteria and other microbes in plankton communities in the marine environment Viruses also responsible for chronic infection and mass mortality of populations of marine animals Examples: Problems with shrimp aquaculture Papillomivirus and morbillivirus in marine mammal populations

Now we will talk about bacteria

Marine Bacteria General characteristics simple, prokaryotic organization: no nuclei or membrane-bound organelles, few genes, nonliving cell wall reproduce asexually by binary fission many shapes and sizes bacillus—rod shape coccus—spherical shape

Marine bacteria play many different roles based on species Some photosynthesize Some are important in the nitrogen cycle Some cause disease Some decompose Some have symbiotic relationships with other organisms

Nutritional Types of bacteria Cyanobacteria (blue-green bacteria) photosynthetic bacteria which are found in environments high in dissolved oxygen, and produce free oxygen

Figure 6-8 (a) BACTERIAL PHOTOSYNTHESIS.

Cyanobacteria may exist as single cells or form dense mats held together by mucilage form associates called stromatolites—a coral-like mound of microbes that trap sediment and precipitate minerals in shallow tropical seas

Nutritional Types of Bacteria Heterotrophic bacteria decomposers that obtain energy and materials from organic matter in their surroundings return many chemicals to the marine environment through respiration and fermentation

Nutritional Types (Heterotrophic Bacteria) marine snow: large, cobweb-like drifting structures formed by mucus secreted by many kinds of plankton and bacteria, where particles may accumulate Feces, dead material accumulate as marine snow Drops through the water column feeding other species that are deeper

Nitrogen Fixation and Nitrification Nitrogen cycle – nitrogen fixation and nitrification Why do we need nitrogen? Nitrogen is needed to make DNA and amino acids to make proteins There is lots of nitrogen gas in the atmosphere, but most species are not able to use it in that form Therefore, there are some bacteria that can convert the atomospheric nitrogen into nitrogen they can use to make their DNA and proteins That nitrogen then makes it’s way up the food chain There are bacteria that during the decomposition process can convert the nitrogen back into nitrogen gas, therefore continuing the nitrogen cycle

Symbiotic Bacteria Many bacteria have evolved symbiotic relationships with a variety of marine organisms Endosymbiotic theory mitochondria, plastids & hydrogenosomes evolved as symbionts within other cells Chemosynthetic bacteria live within tube worms and clams Some deep-sea or nocturnal animals host helpful bioluminescent bacteria photophores embedded in the ink sacs of squid

Archaea Bacteria Archaeans are bacteria that include the “extremophile” bacteria Example: Hyperthermophiles organisms that can survive at temperatures exceeding 100o C, such as near deep-sea vents Potential for biomedical and industrial application

Nutritional Types of Bacteria Chemosynthetic bacteria Chemosynthesize instead of photosynthesize Use sulfides and elemental sulfur, nitrites, hydrogen, and ferrous ion that are coming up from hydrothermal vents chemosynthesis is less efficient than photosynthesis, so rates of cell growth and division are slower found around hydrothermal vents and some shallower habitats where needed materials are available in abundance

Figure 6-10 CHEMOSYNTHESIS.

Figure 6-8 (b) BACTERIAL PHOTOSYNTHESIS.

Now we will talk about Eukaryotes

Eukarya Eukarya includes all organisms with eukaryotic cells Examples: plants animals fungi algae single-celled animal-like protozoa

For this chapter, we are only going to talk about Eukaryotes that are microscopic Within Eukarya, we will now talk about the Fungi

Fungi General features of fungi eukaryotes with cell walls of chitin many are unicellular yeasts filamentous fungi grow into long, multi-cellular filaments called hyphae that can branch to produce a tangled mass called a mycelium heterotrohic decomposers that recycle organic material can digest lignin (major component of wood)

Fungi Kingdom Fungi is divided into 4 phyla: Chytridiomycota (motile cells) Zygomycota (e.g. black bread mold) Basidiomycota (club fungi, e.g. mushrooms) Ascomycota (sac fungi) in the sea, ascomycotes are the most diverse and abundant fungi

Fungi Ecology and physiology of marine fungi can be either obligately marine, requiring ocean or brakish water or facultatively marine (primarily of terrestrial or fresh water origin) salinity is toxic to fungi, so they must devote energy to removing sodium most marine fungi live on wood from land some live on grass in salt marshes others live on algae, mangroves or sand fungi decompose the chitinous remains of dead crustaceans in open sea plankton communities

Now we will talk about the protists Here we will talk mainly about the unicellular protists Unicellular algae – Phytoplankton Unicellular heterotrophs - protozoans Later, we will talk about multicellular protists Algae - “seaweed”

Diatoms Extremely diverse and distinct members of marine phytoplankton Diatom structure frustule—a two-part, box-shaped organic cell wall impregnated with silica

Pls note: I do not see this figure in text Pls note: I do not see this figure in text. Has it been preplaced by Figure 6-18 DIATOMS ?

Diatoms Diatomaceous sediments frustules of dead diatoms sink and collect on the seafloor to form siliceous oozes accumulations form sedimentary rock these deposits, called diatomaceous earth, are mined for use as filtering material, a mild abrasive, and for soundproofing and insulation products nutrient reserves, stored as lipids, accumulate in siliceous oozes accounting for most of the worlds petroleum reserves Ancient diatoms sank to the bottom of the ocean, were covered by sediment before they decomposed, were subjected to pressure and heat and turned into petroleum

Diatoms

Coccolithophores Photosynthetic organisms with 2 simple flagella both used for locomotion Most are coccolithophores with a surface coating of disc-shaped scales (coliths) of calcium carbonate remains form calcereous oozes

Alveolates Examples: dinoflagellates ciliates apicomplexans (strictly parasitic)

Dinoflagellates globular, unicellular (sometimes colonial) with 2 flagella Most are planktonic, some are benthic and others parasitic, also can be bioluminescent – Bioluminescent Bay, Puerto Rico

Dinoflagellates Ecological roles of dinoflagellates major component of phytoplankton some are parasites of copepods (crustaceans) zooxanthellae: species lacking flagella which are symbionts of jellyfish, corals and molluscs photosynthetic zooxanthellae provide food for hosts hosts provide carbon dioxide, other nutrients, and shelter Harmful Algal Blooms (HABs) occur when photosynthetic dinoflagellates undergo a population explosion colors the water red, orange or brown dinoflagellates that cause HABs produce toxins paralytic shellfish poisoning (PSP) occurs in humans who consume shellfish contaminated with these toxins toxins cannot be destroyed by cooking oxygen content of the water may be reduced to deadly levels as bacteria decompose animals killed by dinoflagellate toxins

Red Tides

Figure 6-25 DINOFLAGELLATES.

Ciliates protozoans that bear cilia for locomotion and for gathering food membranelles—tufts or long rows of fused adjacent cilia cytostome—an organelle serving as a permanent site for phagocytosis of food planktonic and benthic major links in marine food chains form symbiotic and parasitic relationships

Paramecium – a ciliate

Choanoflagellates Phylum of marine and freshwater flagellated cells that are more closely related to animals than any other group of one-celled microbes Unicellular or colonial colonies may be stalked or embedded in a gelatinous mass Highly efficient consumers of bacteria Ancestors to the animals?

Choanoflagellate Figure 6-27 (a) CHOANOFLAGELLATES. Sponge

Amoeboid Protozoans All have an organelle called a pseudopod—an extension of the cell surface that can change shape and is used for locomotion (benthic species) and food capture (benthic and pelagic) Are hererotrophs consuming bacteria and other small organisms

Amoeboid Protozoans foraminiferans radiolarians

Amoeboid Protozoans Foraminiferans (forams) have branched pseudopods that form reticulopods (elaborate, net-like structures) used to: snare prey crawl (benthic) reduce sinking rate (pelagic) consume bacteria and diatoms some harbor symbiotic green and red algae and zooxanthellae

Amoeboid Protozoans Radiolarians named for long, needle-like pseudopods pseudopods capture food and slow sinking radiolarian oozes form from the internal siliceous skeleton of dead radiolarians live in the photic zone and capture phyto- and zooplankton, sometimes copepods larger radiolarians prey on copepods and other planktonic crustaceans

So far, we have talked about: Viruses Infect bacteria, protists, plants and animals in the marine environment Domain Archaea – prokaryotes, extremophiles Domain Bacteria Cyanobacteria – photosynthetic bacteria Heterotrophic bacteria – can be nitrogen fixers, can have symbiotic relationship with other organisms, can infect other organisms, can help with decay Domain Eukarya Fungi Protists Unicellular algae – diatoms, dinoflagellates, coccolithophores (Phytoplankton) Protozoans – ciliates, choanoflagellates, amoeboids (foraminiferans, radiolarians)