2.4. (9/4) Oceans, lakes, streams, & wetlands Flashcards
What is turnover time?
the time required for the entire volume of a reservoir to be renewed
what is the turnover time for the atmosphere?
9 days
What is the turnover time for rivers?
12 days
What is the turnover time for the ocean?
8,000 years
How much of the Earth’s surface is covered by water?
71%
How is the water divided amongst oceans, polar ice caps and glaciers, and freshwater?
97% in ocean
2% in polar ice caps and glaciers
1% in lakes, streams, and ground water
How do we classify aquatic systems?
with physical and chemical factors like flow, depth, and salinity
What are the reservoirs in the hydrologic cycle?
- ocean is the largest
- smallest in atmosphere (quickly regenerated)
- large amount in ice
What is ocean diversity based on?
Depth, distance from continent, latitude
Where are most species found?
continental shelf, shallow water, near land, 8% of total ocean area
What is the intertidal zone?
inundation by tides, different species are found along tidal gradient
- defined by highest and lowest tide
What is the neritic zone?
beyond intertidal zone to continental zone
-productive
What is the oceanic zone?
everything else
- photic and aphotic zone
what is the photic zone?
where light penetrates
- depth of light penetration
What is the aphotic zone?
light does not reach this area
How do oceanic conditions vary?
temperature, depth, current, substrate, tides
What is another factor that decides how light travels?
particle concentrations
Why are there chemical differences at certain depths
temperature -> solubility of gasses
* decreased solubility as temperature rises
What are the abyssal and hadal zones?
- deeper than 3000 m
- bioluminescent creatures
- scarce prey
- high diversity
Why can we find the highest salinity in subtropics?
when evaporation exceeds precipitation
- melting of freshwater ice at higher latitudes
- landlocked dry areas like the Mediterranean
How does salinity vary in the open ocean?
34 ppt to 36.5 ppt
What are the most important organisms?
photosynthetic phytoplankton (1/4)
What occurs near undersea hot springs?
chemosynthesis
What are two prominent shallow-water ecosystems?
(coral) reefs and kelp beds
*productive and diverse
Describe coral reefs
- thousands of species (only some build reefs)
- reef building is important: provide habitat
- eat zooplankton
- gain their color from algae living in symbiosis with them
describe kelp forests
- similar to terrestrial forest
- canopy reaches ocean surface
- diverse
Where can we find coral reefs and kelp beds?
corals: everywhere
coral reefs: warm, clear water (nutrient-poor)
kelp: mid-latitudes, cooler water (<20*C), rocky shores
Describe the intertidal zone
- adapted to handle various water exposures
- distribution and abundance affected by waves and tides
- air and salinity tolerances
What is zonation?
different organisms found along tidal gradient
What are estuaries?
where saltwater meets freshwater
- brackish water
- tidal salt marshes
- an influx of nutrients
- highly productive
Why is there vertical variability in estuaries?
in salinity
- salt water is more dense
How much of the world’s freshwater in located in the Great Lakes?
20%
How are lakes structured?
littoral, limnetic, profundal, benthic
What is the littoral zone?
- edge
- shallow zone with rooted vegetation
- defined by where the plants stop
What is the limnetic zone?
- open water in middle
What is the profundal zone?
no light
What is the benthic zone?
- along the bottom
- habitat for burrowing animals and microorganisms
- interface between water and sediment
In what ways are lakes classified?
- nutrients in water (N, P)
- number of times lake mixing/ turnover takes place
- stratification
What is an oligotrophic lake?
- nutrient-poor (N, P)
- cooler, higher oxygen levels
What is a eutrophic lake?
- productive
- algae and other vegetation
- more nutrients fueling photosynthesis
- high decomposition rate
- low oxygen
What is lake turnover?
- mixing
- deep lake
- once in a while
- surface waters can go to the bottom
- only during certain times of the year
Why is lake turnover important?
- nutrients released from sediments
- changing chemistry (oxygen releases things/stimulates decomposition)
What is a monomictic lake?
mix once a year (cold/warm)
What is a dimictic lake?
twice per year
What is a polymictic lake?
multiple times per year
What is a meromictic lake?
does not mix
Why do annual laminations occur?
- diatoms bloom in the spring (light in color, silica)
- Summer productivity organics
Why don’t meromictic lakes mix?
- saline at depth, fresh on top (density -> permanent)
- not enough wind energy (small, deep lakes)
What defines a wetland?
- hydrology: presence of water at or near the surface for some time, standing water
- vegetation: hydrophytic, saturation
- soil: organic-rich, redoximorphic features, hydric
What does hydrophytic mean?
adapted to wet conditions (chemical, physical)
What are redoximorphic features?
characteristics that emerge because of a change in reduction (wet)/oxidation (dry) reaction states
Describe a marsh
- not forested (woody vegetation minor)
- floating aquatics
- mineral-enriched soils (some inorganic)
- herbs
- shallow
- tide/no tide
- along ocean
- salt marshes
Describe a swamp
- trees and shrubs
- minerals in soil (organics and inorganics)
- strong seasonal water fluctuations
- non-peaty
- along ocean
Describe salt marshes/swamps
- mid-latitudes
- behind barrier islands
- eastern north America is dominated by salt-tolerant grass
- highly productive
- zonation (inundation) caused by tides (in mangroves too)
where can you find mangrove swamps?
lower latitudes/ tropics
Describe peatlands (mires)
- very deep organic soils
- freshwater
- plant production exceeds decomposition (accumulation of peat)
- fens or bogs (where nutrients come from)
- best preservative
Describe a fen
- groundwater
- surface flows
- precipitation
- abundance of nutrients
- neutral to basic
- sedges, brown mosses, vascular plants
Describe a bog
- big dome of peat
- the only way to get nutrients into roots is through precipitation (rain does not have a lot so nutrient-poor)
- sphagnum moss dominated
- low pH
Where do wetlands occur?
- everywhere
- maybe Antarctica (coastal)
- ~6 million km^2 (5-8% of land surface)
- interaction between climate and topography/geomorphology that allow water to remain near the surface for periods
- require water (precipitation, aquifer, large body of water)
*precipitation exceeds evaporation (positive water balance) - higher latitudes
What are some characteristics of wetland plants?
- lack of oxygen in the soil and its consequences
- limited nutrients
- water-level fluctuations
- aerenchyma (in leaves too)
- adventitious roots
- shallow roots
- pneumatophores
- carnivory (in nutrient-lacking environments)
what is aerenchyma?
- pore space in tissue
- hollow areas
- gas diffusion: gas to roots
- expand and contract
what are adventitious roots?
- response to flooding
- gets roots close to the atmosphere for gas diffusion
What pneumatophores for?
- special roots that grow pointing up
- knees
- exchange gas
- found in mangroves, bald cypress
Describe the Utricularia
- carnivory in roots
- roots covered with bladders that have hairs
- trapdoor with vacuum
