VIII - Aquatic Ecology Flashcards
Factors Affecting Life in Aquatic Ecosystems
Temperature
Solar radiation
Dissolved oxygen
Nutrient Availability
Temperature
decreases with depth because of decreasing energy
input from sun; affects dissolved gases, rates of chemical reactions, & where organisms can live
Solar radiation
decreases with depth because of absorption by water,
suspended materials, & phytoplankton; essential for
photosynthesis
Dissolved oxygen
varies with temperature, producers, & consumers;
essential for respiration of organisms
Nutrient Availability
most limiting macronutrients are phosphorus (P) &
nitrogen (N); limiting micronutrients include iron (Fe);
essential for growth of phytoplankton
Characteristics of Oceans
• cover 71% of the earth’s surface • ocean currents distribute solar heat • reservoir for carbon dioxide (CO2) • regulates temperature of the troposphere • habitat for plants & animals, including critical food sources for humans • communal dumping ground
Life zones of ocean
Euphotic zone
Bathyl zone
Abyssal zone
zones defined
by amount of
solar radiation
penetrating
the water
Coastal Zone of the Ocean
High tide mark to edge of continental shelf Within euphotic zone Nutrient rich Site of most commercial fisheries High primary productivity
The coastal zone includes
estuaries
wetlands
barrier islands
coral reefs
Estuary
where seawater mixes with freshwater from land, generally at the mouth of a river
Coastal wetland
where seawater mixes with freshwater from land, generally at the mouth of a river
Importance of estuaries & coastal wetlands
• nutrient rich • high primary productivity • nurseries for fish & other aquatic animals • waterfowl & shorebird breeding areas • filter water pollutants
Human Impacts of estuaries & coastal wetlands
• world has lost over half of its estuaries & coastal wetlands • percentage lost in the U.S. even higher most lost to coastal development
Causes of degradation of estuaries & coastal wetlands
urban runoff, sewage
treatment plant effluent, sediment & chemical
runoff from agricultural
lands
Barrier Islands
long, thin, low offshore islands of sand that run
parallel to the shore.
Barrier Islands Importance
• protect mainland from offshore storms • shelter inland bays, estuaries, & wetlands • popular recreational & residential areas
Human Impacts of Barrier Islands
Development of barrier islands
Destroys dunes & vegetation
Causes beach erosion
destroys & disturbs wildlife habitat
Primary Dune
No direct passage or building
Back Dune
Most suitable for development
Beach
Intensive recreation
No building
Trough
Limited recreation & walkways
Secondary dune
No direct passage & building
Bay/ Lagoon
Intensive recreation
Sea walls
Protect the cities from beach retreat during natural disaster
Beach replenishment
Twice a year the Army Corps of Engineers survey our beach to determine the need for any additional sand.
Replanting Dune Vegetation
Controlling development
Coral reefs
Mutualism between polyps & algae
Colonies of polyps secrete limestone hard deposits remain when polyps die
Located in coastal zones of tropical oceans
Importance of coral reefs
High biodiversity
Protect coastlines from storms & high waves
Nurseries for many fish species
Disappearing
Vulnerability of coral reefs
Slow growing
Easily disturbed
Thrive only in clear water
Human impacts on coral reefs
• sediment runoff & effluent • increased UV radiation • fishing with cyanide & dynamite
Lakes
standing (lentic) body of freshwater formed when rain,
runoff, or groundwater fills depressions in the landscape
Lake zones
Littoral zone
Limnetic zone
Profundal zone
Benthic zone
Littoral zone
shallow area near the shore, to the depth at which rooted
plants stop growing
Limnetic zone
open, sunlit, surface layer away from the shore. Depth is
the limit of light penetration.
Profundal zone
deep, open water where there is no light penetration
Benthic zone
the bottom of a lake; inhabited by insect larvae, decomposers, & clams
Types of Lakes
Oligotrophic
Eutrophic
Oligotrophic
– low nutrient supply – low primary productivity – clear water, few plants & fish
Eutrophic
– excess supply of nutrients – high primary productivity – murky water, large phytoplankton population
Thermal stratification occurs during
Summer in temperate lakes
Epilimnion
warm, upper layer
of water
Thermocline
zone of lake where
temperature
changes rapidly
with depth
Hypolimnion
colder, denser lower layer of water can be depleted of oxygen in eutrophic lakes
Going from surface to bottom, the temperature of a lake
Gradually decreases
Going from surface to bottom, the dissolved oxygen concentration of a lake
Epilimnion -> high
Thermocline -> medium
Hypolimnion -> low
Lake overturn occurs during
Spring & fall
What happens during overturn?
•upper layer of water sinks & winds mix layers •redistributes oxygen & temperature evenly •redistributes nutrients from the lower layers
Watershed
the land area that delivers water, sediment, & dissolved substances to a water body.
Stream zones
Source zone
Transition zone
Flood plain zone
Source zone
cold,
clear, fast–running
streams in upper
watershed
Transition zone
middle part of watershed, where streams widens & join, flow slows, water temperature increases
flood plain zone
many streams join to form a broad, slow–moving, meandering river in lower watershed
In source zone common features includes
Rain & snow Lake Glacier Rapids Waterfall
In transition zone common features includes
Tributary
Flood plain
In flood plain zone common features includes
Oxbow lake Salt marsh Delta Deposited sediment Ocean
Human impacts on streams & rivers
• pollution • sediments • channelization • dams • introduction of exotic species, • removal of vegetation from banks • change of flow (more floods, lower base flow)
