1. Ch. 5 The Microbial World pp

4. Size classification
ultraplankton - bacteria and other very small plankton, <5 µm (0.005 mm)
nannoplankton - mostly phytoplankton, µm ( mm)
microplankton - mostly zooplankton, µm ( mm). Also called "net plankton"
macroplankton - not microscopic, for example:
jellyfish
Sargassum (a type of seaweed that floats at the sea surface)
———————>Size——————>
ultra—>nanno—>micro—>macro

7. Another classification of marine organisms is:
(4) Nekton - Not plankton. Swimming organisms, mostly high trophic level carnivores, but a few are herbivores (e.g.,anchovy). All are heterotrophs.
Examples: fish, squid, marine mammals

8. Another classification of marine organisms is:
(5) Benthos - Not plankton. Bottom-dwelling plants and animals. These can be any size and have any degree of mobility.

9. Another classification of marine organisms is:
(6) Intertidal and coastal organisms - Not plankton.
Plants and animals often closely related to benthos living in deeper water; some are land organisms adapted to tolerate salt.
Primary producers include seaweeds of coastal areas, sea grasses, mangroves, and other coastal plants

10. Another classification of marine organisms is:
(1) Phytoplankton - plants, primary producers or autotrophs.
The most important primary producers of the sea.
can grow only in photic zone, but can be found in deeper water.
Most are microscopic algae, and the vast majority are single-celled (unicellular) or colonial (made up of many, identical cells).

13. 2. Major Phytoplankton Groups
2.1 Diatoms
2.2 Dinoflagellates
2.3 Coccolithophores

14. 2.1 Diatoms Characteristics
Golden-brown color due to a pigment fucoxanthin in addition to chlorophyll.
frustule (shell-like covering) made of an organic matrix or framework impregnated with silica (SiO2)
2 basic shapes: centric and pennate

15. Diatoms
Habitat
Ubiquitous, but most abundant in cold, nutrient-rich water.
Often make up >45% of phytoplankton biomass in such waters.
Often responsible for spring phytoplankton blooms in temperate and polar oceans. Also abundant in upwelling regions at low latitudes.
Siliceous sediments are often found under regions of high diatom productivity.

18. 2.2 Dinoflagellates
Characteristics
red or red-brown in color, due to carotene and xanthophyll pigments.
Have flagella, and are motile. (Move vertically in response to light).
Some can absorb organic substances from solution (heterotrophy).
Most have "armor" made of cellulose.
Many are bioluminescent (glow, especially when agitated).

19. Dinoflagellates Habitat
Ubiquitous, favor warmer & more nutrient-depleted water than diatoms.
In temperate regions, often "bloom" in late summer or early fall.

21. Dinoflagellates Cont. Dinoflagellates and "Red Tides"
Blooms of certain species of dinoflagellates give reddish or brownish color to the water.
PSP (paralytic shellfish poisoning) or NSP (neurotoxic shellfish poisoning).For example: Gonyaulax and Ptychodiscus are major toxic species in U.S. waters.
Shellfish accumulate toxin as they filter-feed on algae. They are not affected by the toxin. Crabs, shrimp, fish, marine mammals, and humans are affected.
human lethal dose is ~1mg.

22. Dinoflagellates Cont. Occurrence and Causes of Harmful Algal Blooms
Worldwide, harmful algal blooms (HABs) appear to be increasing in frequency or duration. Possible causes of increased HABs are:
Excessive nutrient input to coastal due to agricultural fertilizers, sewage
Transport of new species from their habitat to new locations, mostly in ships ballast water
Climatic warming

24. 2.3 Coccolithophores Characteristics single cells.
Covered by plates made of calcite (calcium carbonate) called coccoliths which make up some calcareous sediments on the sea floor.
2 flagella.
Are smaller in size than most diatoms or dinoflagellates.
Habitat
Dominate in warm, low nutrient, low productivity waters of the oceans.
However, blooms occur in colder waters as well, e.g., Bering Sea since 1997, North Atlantic

26. Another classification of marine organisms is:
(2) Bacterioplankton - Bacteria
Some are primary producers or autotrophs:
Blue-green "algae" or cyanobacteria may be responsible for most primary production in some areas of the open sea
Some other bacterioplankton, such as sulfur oxidizing bacteria, are important primary producers in specific locations
Some are heterotrophs and decompose the remains of dead organisms, excreta, etc.

28. 3. Bacterioplankton
The most abundant organisms in the ocean (1,000,000 per ml). Have the greatest "standing stock" of biomass in low-productivity regions of the ocean

29. Another classification of marine organisms is:
(3) Zooplankton - Animals, may be either herbivores (eat plants) or carnivores (eat other animals) or bacteriovores (eat bacteria) or omnivores (eat plants or animals). All are heterotrophs.
Examples: copepods, euphausiids, jellyfish

31. Zooplankton Crustaceans Protozoan Gelatinous zooplankton Meroplankton
Heterotrophs- consume organic matter
Zooplankton can be: Herbivores, carnivores, detritus feeders, omnivores
Zooplankton includes
Crustaceans
Protozoan
Gelatinous zooplankton
Meroplankton

32. 1. Crustaceans- include shrimp, copepods, euphausiids ("krill")
Characteristics: Copepods, euphausiids and shrimp superficially resemble one another.
Habitats: Ubiquitous.
Euphausiids predominate in the Antarctic Ocean, but are common in most temperate and polar oceans.
Copepods are found everywhere, but are less important in low-productivity areas of the ocean - the "central ocean gyres". They are found at all depths but are more abundant near the surface.
Role in food webs:
Euphausiids and copepods are filter-feeders. Copepods are usually herbivores, while the larger euphausiids consume both phytoplankton and other zooplankton.
Shrimp are usually carnivores or scavengers.

33. 3. Protozoan - Include foraminifera, radiolarians, tintinnids and "microflagellates" ca. 0.002 mm
Characteristics:
Single-celled animals.
Forams have calcareous shell
Radiolarians have siliceous shell.
Both Forams and Radiolarians have spines.
Habitat: Ubiquitous
Radiolarians are especially abundant in the Pacific equatorial upwelling region.
Protozoa are especially important components of the food web in low-productivity ocean areas.
Both are found in sediments as well as in the water column.
Role in food web: Feed on small phytoplankton, bacterioplankton, and other protozoans. They can be bacteriovores, herbivores, or carnivores.

34. Cnidarians: jellyfish
4. Gelatinous Zooplankton: includes a variety of fragile, jelly-like organisms which are not closely related taxonomically.
Cnidarians: jellyfish
Habitat: Found everywhere and at all depths. More abundant in surface waters.
Role in food web: Carnivores, trap prey in tentacles.
Ctenophores: "comb jellies".

35. Gelatinous Zooplankton:
Salps: A type of tunicate.
Characteristics:
Members of the phylum Chordata.
Have a complex body structure including internal organs and a nervous system as larvae but are "degenerate" as adults.
May be solitary or colonial.
Habitat: Warm surface waters. Rare at high latitudes.
Role in food web: Largely feeds on phytoplankton. A "ciliary-mucous" filter feeder.
Overall: Gelatinous zooplankton are very important, but little-studied because of sampling problems; they often disintegrate in nets or other sampling devices.

36. 6. Meroplankton
Meroplankton are organisms which are part of the plankton for only part of their life cycle, usually an early, larval stage.
As adults the meroplankton are benthos (including intertidal organisms) or nekton.
The meroplankton often do not resemble the adult forms, to the extent that some were once thought to be separate species.
Meroplanktonic larvae promote survival of the species:
Currents carry the offspring to new areas, especially important for sessile (immobile) benthic animals. Thus, the offspring do not compete with the parents for scarce resources such as food or space. Also, local "disasters" will not wipe out all close relatives.
Meroplankton live in surface waters where food is abundant. Sometimes, the habitat of the adult would not have enough food, especially for a very small organism that could not effectively use the feeding strategy (for example, predation, filter feeding) of the adult.

37. Meroplanktonic larvae also have disadvantages:
Often, reproduction occurs to coincide with the spring bloom and abundant food. If the spring bloom is not "on time", meroplankton may starve.
Meroplankton are food for the many predators on plankton.
The currents may not carry the meroplankton to an area that provides suitable conditions for adults.
Therefore, organisms which have meroplanktonic larvae usually produce hundreds or thousands of eggs, so that a few will survive.

39. 4. Summary
(1) Plankton are drifting organisms at the mercy of the currents.
(2) There are 3major groups of plankton, phytoplankton, the main primary producers of the ocean; bacterioplankton, which can be either primary producers or decomposers; and zooplankton, which are animals.
(3) The four major groups of primary producers (autotrophs) in the ocean are:
diatoms, golden-brown algae with siliceous frustules that are commonest in cold, nutrient-rich water
coccolithophores, algae that are covered with small, calcareous plates (coccoliths) and are commonest in warm, tropical waters.
dinoflagellates, red or brown algae that usually have hard coverings of cellulose and are motile by means of a flagellum. They are commonest in summer and fall in the temperate zone of the oceans, and can cause PSP.
cyanobacteria (blue-green algae) are really bacteria that are photosynthetic primary producers, commonest in nutrient-depleted areas of the open ocean.

40. Copepod

41. Naupilus Larva

42. Oyster Trocophore Larva

43. Polychaete Larva

44. Horseshoe crab larva