Download I. Marine Viruses

Chapter 6
Chapter Outline
I.
Marine Viruses

Viruses are more abundant than other microbes in the sea. Marine planktonic viruses are icosahedral
and lytic and are responsible for the death of many bacteria and phytoplankton in the epipelagic
zone. Viruses in marine sediments are mostly helical and lysogenic.
A. Viral Characteristics
1. Viral Structure
2. Viral Life Cycle
B. Biodiversity and Distribution of Marine Viruses
C. Ecology of Marine Viruses
II. Marine Bacteria

Bacteria have cells with a simple, prokaryotic organization. Chemosynthetic and photosynthetic
bacteria extract inorganic nutrients, such as nitrogen, phosphorus, and carbon dioxide, from the
environment and incorporate them into organic molecules. Chemosynthetic bacteria use energy
derived from chemical reactions (often involving compounds of sulfur) to produce their food
molecules, whereas photosynthetic ones use the radiant energy from the sun. Some producers, such
as blue-green bacteria, release oxygen during photosynthesis. Such primary producers as well as
heterotrophic bacteria form the base of marine food webs. In addition, marine bacteria play a critical
role in nitrogen fixation and nitrification. As decomposers, bacteria return dead organic matter to
biogeochemical cycles as inorganic matter that primary producers can incorporate into living
biomass. The chemosynthetic bacteria of hydrothermal vent communities and the bioluminescent
bacteria found in association with deep-sea organisms are some examples of symbiotic relationships.
A. General Characteristics
B. Nutritional Types
1. Cyanobacteria
2. Other Photosynthetic Bacteria
3. Chemosynthetic Bacteria
4. Heterotrophic Bacteria
C. Nitrogen-Fixation and Nitrification
D. Symbiotic Bacteria
 Marine Adaptation – Halobacteria
72
Chapter 6
III. Archaea

Like bacteria, archaeons are prokaryotes. Most archaeons are methanogens, anaerobic organisms that
live in environments that are rich in organic matter, and they make significant contributions to
methane production. Archaeons have an unsurpassed ability in the natural world to tolerate extreme
environmental conditions.
A. General Characteristics
B. Nutritional Types
C. Hyperthermophiles
IV. Eukarya
A. Fungi

Marine fungi are microscopic decomposers and pathogens. Most are sac fungi that can degrade the
cell walls of terrestrial, maritime, and marine plants. Some fungi digest chitin and other
decayresistant molecules that otherwise would accumulate in seafloor sediments. Marine fungi take
advantage of water currents and sea foam for the transport of spores. They form lichen associations
with green algae and blue-green bacteria in maritime communities.
1.
2.
3.
4.
5.

History of Marine Mycology
General Features of Fungi
Ecology and Physiology of Marine Fungi
Reproduction of Marine Fungi
Maritime Lichens
In marine environments, nonfungal eukaryotes make up a large portion of the plankton and benthos.
Dinoflagellates, diatoms, coccolithophores, and silicoflagellates are photosynthetic producers and
members of the phytoplankton. Dinoflagellates form symbiotic relationships as the zooxanthellae of
some eukaryotic microbes and of many invertebrates. Labyrinthomorphs are decomposers and
pathogens. Heterotrophic consumers include ciliates (especially the tintinnids), choanoflagellates,
foraminiferans, radiolarians, and some dinoflagellates. Among the consumers, a few groups are
grazers of bacteria, allowing for the transfer of prokaryotic biomass to higher levels of marine food
webs. Some of these producers and consumers incorporate calcium carbonate and silicon dioxide into
their cell walls or skeletons, adding to seafloor oozes upon their death and sedimentation.
B. Stramenopiles
1. Diatoms
a. Diatom Structure
b. Locomotion in Diatoms
c. Reproduction in Diatoms
d. Diatomaceous Sediments
2. Other Ochrophytes
3. Labrinthomorphs
a. Labyrinthulids
b. Thraustochytrids
C. Haptophytes
73
Chapter 6
D. Alveolates
1. Dinoflagellates
a. Dinoflagellate Structure
b. Dinoflagellate Nutrition
c. Reproduction in Dinoflagellates
d. Ecological Roles of Dinoflagellates
e. Harmful Algal Blooms
 Marine Biology and the Human Connection – Harmful Algal Blooms
2. Ciliates
a. Types of Marine Ciliates
b. Ecological Roles of Marine Ciliates

The eukaryotic groups are distinguished by their cell coverings, the structure of their cell membranes,
their possession of cilia, flagella, and pseudopods of various shapes for locomotion and prey capture,
the chemistry of pigments and food-storage compounds, life-history characteristics, and many other
features.
E. Choanoflagellates
F. Amoeboid Protozoans
1. Foraminiferans
a. Foraminiferan Test
b. Foraminiferans and Zooxanthellae
2. Radiolarians
74