Transcript Plankton - BIOL265MarineBiology

Ch. 5 The Microbial World
pp.85-100
Size classification




ultraplankton - bacteria and other very small plankton, <5 µm
(0.005 mm)
nannoplankton - mostly phytoplankton, 5 - 70 µm (0.005-0.07
mm)
microplankton - mostly zooplankton, 70 - 100 µm (0.07 0.1mm). 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
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
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.
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
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).
2. Major Phytoplankton Groups
2.1 Diatoms
 2.2 Dinoflagellates
 2.3 Coccolithophores

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
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.
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).
Dinoflagellates

Habitat
Ubiquitous, favor warmer & more
nutrient-depleted water than diatoms.
 In temperate regions, often "bloom" in
late summer or early fall.

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.
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
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
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.
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
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
Zooplankton

Heterotrophs-
consume organic matter
– Zooplankton can be: Herbivores, carnivores, detritus
feeders, omnivores
– Zooplankton includes




Crustaceans
Protozoan
Gelatinous zooplankton
Meroplankton
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 lowproductivity 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.
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.
4. Gelatinous Zooplankton: includes a variety of fragile, jellylike 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".
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 "ciliarymucous" filter feeder.
Overall: Gelatinous zooplankton are very important, but littlestudied because of sampling problems; they often disintegrate
in nets or other sampling devices.
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.


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.
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 nutrientdepleted areas of the open ocean.
Copepod

http://www.bigelow.org/amt/copepod.j
pg
Naupilus Larva

http://www.onlineenzyklopaedie.de/Ima
ges/1/180px-naupilus.jpg
Oyster Trocophore Larva

http://www3.csc.noaa.gov/scoysters/im
ages/bio/lifecycl.gif
Polychaete Larva

http://www.amonline.net.au/exhibitions
/beyond/images/400/d020.jpg
Horseshoe crab larva