Chapter 5 Microbes

Viruses Viruses in the Marine Community: They are common in marine waters They can infect bacteria, plankton, fish, sea turtles and marine mammals Lysis (bursting) of viral infected cells spills contents and releases large amounts of organic matter that can be utilized by other organisms (dissolved organic matter or DOM)

Prokaryotes Archea and Bacteria Prokaryotic- no nucleus Single chromosome (normally circular)- some also with plasmids Most with cell wall Great metabolic diversity

Prokaryotes Archea – Widely distributed in the marine community They can tolerate wide ranges in temperature, salinity and even desiccation (drying out) Can be found in many areas including near hydrothermal vents and salt flats (two very extreme environments)

Special Features of Bacteria: One of the most important jobs of bacteria in the marine community is to break down dead organic matter – this forms detritus, which are minute particles of organic matter now available as nutrition for other organisms

Diatoms Diatoms: Photosynthetic Yellow-brown color in life is a result of photosynthetic pigments, chlorophyll A and C and carotenoids Shell of silica called a frustule Most important primary producer on Earth Mostly solitary and unicellular Some can form colonies

Most are planktonic Some produce a toxin, known as domoic acid, that can accumulate in the tissues or organisms that eat diatoms such as shellfish and small fish Larger organisms that eat these shellfish or small fish can become ill or die from this accumulated toxin

Mainly reproduce by cellular division Due to this, diatoms get smaller each time they reproduce To restore normal size, they must sexual reproduce

Dinoflagellates Dinoflagellates Most species live in marine environment Mostly photosynthetic, some can ingest particles Two flagella Also reproduce by cellular division Some are bioluminescent

Dinoflagellates Dinoflagellates Zooxanthellae are important dinoflagellates that live in a symbiotic relationship with corals, sea anemones and other organisms

Algal Blooms Dinoflagellates can go through periods of rapid growth known as “blooms” Result of high levels of nutrients in the water Can be harmful to marine organisms and even people at times Called “Red Tides”

Pfiesteria is a dinoflagellate that produces very serious toxins that can cause massive fish kills, harm shellfish and impair the nervous system in humans. Pfiesteria was discovered near the Outer Banks in North Carolina

Protozoa Foraminiferans (forams) Found on sandy or rocky bottoms Shells of calcium carbonate Can be important contributors of calcareous material on coral reefs or sandy beaches Pseudopods (false feet) extend through pores in the shell where they are used to capture minute food particles such as phytoplankton

Protozoa Radiolarians Planktonic, mostly microscopic, although a few can reach large sizes Shell of silica Like forams, they use pseudopods.

Protozoa Ciliates Cilia present for locomotion Most live as solitary cells Some build shells made of organic debris May live on hard substrate Some are planktonic

Fungi Eukaryotic and mostly multicellular Heterotrophic Most of the 1500 species of marine fungi are microscopic

Fungi Like bacteria, many fungus break down dead organic matter into detritus Some fungus live in symbiosis with cyanobacteria, these are known as lichens Marine lichens often live in wave-splashed areas of rocky shorelines and other hard substrate