Climate and Biomes
IV. Aquatic Systems
Climate and Biomes
IV. Aquatic Systems
A. Overview
Characterized by physical characteristics and general biological
parameters like productivity, not plant growth form (algae)
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
Where precip > evaporation, excess soil water runs to water table. Where
water table is expressed above land = stream.
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
- High gradient
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
- High gradient
- low primary productivity; no
upstream source of
nutrients, organics from
riparian zone (allochthonous)
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
- High gradient
- low primary productivity; no
upstream source of
nutrients, organics from
riparian zone (allochthonous)
- usually with a complete
canopy that reduces
photosynthesis
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
- High gradient
- low primary productivity; no
upstream source of
nutrients, organics from
riparian zone (allochthonous)
- usually with a complete
canopy that reduces
photosynthesis
- sequence of riffle
(production) and pool
(decomposition)
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
- High gradient
- low primary productivity; no
upstream source of
nutrients, organics from
riparian zone (allochthonous)
- usually with a complete
canopy that reduces
photosynthesis
- sequence of riffle
(production) and pool
(decomposition)
- Communities driven by detritivores consuming allochthonous inputs, not
aquatic primary productivity
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
Rivers = order 6-12
Ohio = 8
Mississippi = 10
Amazon = 12
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
- lower gradient; more volume and force
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
- lower gradient
- Higher productivity, fed by nutrients from
upstream
- wider waterway allows sunlight to feed
local productivity and
decomposition (autochthonous)
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
- lower gradient
- Higher productivity, fed by nutrients from
upstream
- wider waterway allows sunlight to feed
local productivity and
decomposition (autochthonous)
- meanders dominate, creating lateral
habitats from cut bank and pool to sand
bar and riffle across the course of the river.
Oxbow Lake
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
- lower gradient
- Higher productivity, fed by nutrients from
upstream
- wider waterway allows sunlight to feed
local productivity and
decomposition (autochthonous)
- meanders dominate, creating lateral
habitats from cut bank and pool to sand
bar and riffle across the course of the river.
- in large, deep rivers, the amount of
sediment carried in the river, coupled with
water depth, may reduce algal
photosynthesis at depth and decrease
productivity.
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
a. Headwater Streams
b. Rivers
River Continuum Concept
Moving downstream:
- NPP increases, changes from
periphyton (attached algae) to
phytoplankton (floating).
- Proportional E input by CPOM
declines, shredders decline.
- FPOM and UFPOM increase, and
collectors (filterers) increase
- “downstream succession” of
increasing productivity
- Upstream, P/R < 1
- Downstream, P/R > 1
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
c. Marshes and Swamps
- these are habitats that are flooded periodically, either by rainfall, rivers, or
tidal inundation (though these would be saline salt marshes).
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
a. Headwater Streams
b. Rivers
c. Marshes and Swamps
- They are highly productive habitats, receiving nutrients from both aquatic
and terrestrial sources. They are often shallow, also, so there are high
autochthonous productivity. This high biological productivity can reduce
oxygen levels in the water and sediment, however. Also, the high
biological activity serves to detoxify and filter surface and ground water.
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
2. Lentic Systems
a. Lakes
- temporary habitats, as they will eventually fill
with sediment carried by stream inputs or surface
runoff.
- formed by natural dams (beaver, mudslide),
glacial retreat, limestone erosion, changes in river
channels (oxbows), continental drift (rift lakes),
and man-made dams
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
2. Lentic Systems
a. Lakes
- Littoral Zone: edge with rooted plants
- Limnetic/Pelagic Zone: no rooted plants; in
deep lakes this may be further subdivided
- subdivided by temperature stratification:
epilimnion
thermocline
hypolimnion
- subdivided by light penetration:
euphotic zone
compensation depth
aphotic zone
- Benthic zone: sediments where decomposition
occurs and nutrients accumulate
Lentic Systems: Ponds and Lakes
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems (moving waters)
2. Lentic Systems
a. Lakes
- In deep lakes, the spatial separation of nutrients beneath
the photic zone means that algae are nutrient limited until
turnover occurs in fall and spring.
- Deep lakes often have low productivity = oligotrophic.
Shallow lakes have more productivity = eutrophic.
The release of nutrient limitation – eutrophication.
IV. Aquatic Systems
B. Freshwater Habitats
1. Lotic Systems
2. Lentic Systems
b. Ponds and bogs
- A smaller water body, often later
in lake succession:
Lake
Pond
Bog
Marsh
Meadow
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
- Place where rivers meet
the ocean; often made
discrete by barrier islands
offshore.
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
- Place where rivers meet
the ocean; often made
discrete by barrier islands
offshore.
- direction of water flow,
depth, and salinity changes
with the tides
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
- highest productivity aquatic habitat;
nutrients accumulate and feed
surrounding salt marshes or
mangroves, which add nutrients to
the estuary. Truly a highly connected
mix of terrestrial, marine, and aquatic
habitats.
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
2. Intertidal (littoral)
- habitat between high and low tide
- zonation of organisms based on
desiccation tolerance and frequency and
length of exposure.
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
2. Intertidal (littoral)
3. Neritic Zone (Cont. Shelf)
- usually to a depth of 200m
- productive because benthic nutrients
are close to the photic zone
and the habitat is well mixed.
Marine Systems
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
2. Intertidal (littoral)
3. Neritic Zone (Cont. Shelf)
4. Oceanic (Pelagic)
- open ocean to depth of 5 miles in trenches.
- photic and aphotic zones
- very low productivity except in upwelling areas
where nutrients are brought up into the photic zone, or
hydrothermal vent communities where chemosynthetic
bacteria are the primary producers.
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
2. Intertidal (littoral)
3. Neritic Zone (Cont. Shelf)
4. Oceanic (Pelagic)
5. Coral Reefs
- typically shallow, tropical habitats
with high productivity of algal symbiots in
coral polyps.
- also, structural complexity of the reef
increases habitat variation and diversity.
- most diverse marine systems.
IV. Aquatic Systems
C. Marine Habitats
1. Estuaries
2. Intertidal (littoral)
3. Neritic Zone (Cont. Shelf)
4. Oceanic (Pelagic)
5. Coral Reefs
6. Hydrothermal Vent Communities
- primary producers are chemosynthetic sulphur bacteria; some
of which have become endosymbionts of giant polychaete worms (Riftia
sp.).