Chapter 6
Biomes and Aquatic Ecosystems
Aquatic
Ecosystems
Aquatic Ecosystems
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Differ from terrestrial ecosystems
Temperature variations usually less pronounced
Salinity a major factor (Fresh water vs. salt water)
Three major groups of aquatic organisms1. Plankton (Microscopic, carried by current)
a. Zooplankton = Protozoans (animals)
b. Phytoplankton = Photosynthetic
2. Nekton- Large, swimming organisms (fish, turtles, etc.)
3. Benthos- Bottom dwelling organisms/Sessile and mobile
Plankton, nekton or benthic?
Freshwater Ecosystems
• Flowing-water ecosystems
change greatly between the
source (start) and the mouth
(end).
• Source  headwater tributaries 
 flood plain  meanders 
Estuary (Salt marsh) mouth  delta
The Hudson River
• ADK’s to NYC:
Lake Tear of the Clouds
…Albany…Newburg… NYC
(delta) …Atlantic ocean
mouth
Mount Marcy- Elevation 5344 ft.
Headwater Streams: are usually
shallow, cold, swiftly flowing, &
highly oxygenated.
Rivers & Steams:
Flowing-water Ecosystems.
Streams with fast currents have organisms with
adaptations such as sucker-mouth catfish, fish
with streamlined bodies, and black fly larvae
(suction disc).
Estuaries
• Where “rivers meet the sea”
• Very productive ecosystems!
Standing-Water Ecosystems
Lakes & pondsStanding-Water ecosystems are
characterized by zonation.
1)Littoral zone
2) Limnetic Zone
3) Profundal Zone
“Lit”toral Zone: shallow-water area along the
shore. Plants include; Cattails, bur reeds,
aquatic plants (Elodea), & Algae. This is the
most productive section of a lake.
Animals include; Frogs,
tadpoles,worms, crayfish, insect
larvae, fishes like Perch, carp, &
Bass. Water striders, whirligig
beetles are often on the surface.
Limnetic Zone: the open water beyond the littoral
zone(away from the shore). This area extends as
far as light can penetrate (photosynthesis).
Main organisms are phytoplankton &
zooplankton.
Large fish are found here most of the
time.
3) Profundal Zone: this is the
deepest zone.
Small bodies of water typically lack
a profundal zone.
Thermal Stratification: the layering
of large temperate lakes.
Temperature changes drastically
with depth.
Summer: Cool water remain at the
bottom.
A thermocline separates the warm
(less dense) water from the cool
deep section.
More oxygen dissolves (D.O.) in
water at cooler temperatures.
Fall Turnover: falling temperature
causes a mixing of the the layers.
Mixing ceases when the lake
reaches a uniform temp.
throughout.
Mangrove Forests are habitat for
most larval shellfish, game fishes
(Mullet, migratory birds, Manatee,
mudskippers, snakes, crabs, &
monkeys.
Mangrove Swamps of the World
The
Open
Ocean
The open
ocean is or
is not a
highly
productive
ecosystem?
Coral Reefs
Coral Reefs of the world
Changes of the Florida Everglades