Lakes and wetlands Flashcards
(28 cards)
Lake
lentic (non-flowing) body of water which is not directly connected to the sea
Deep enough to stratify
Ponds
shallow body of water
can be part of a river or in floodplains
not deep enough to stratify
Succession
lakes and ponds are temporary
filling with sediments spill out of their basin
Origins of lakes
Glacial and ice-scour lakes
Tectonic lakes
Solution lakes
Volcanic lakes
landslide lakes
Lake zones
Littoral zone
Limnetic zone
Profundal zone
Benthic zone
Pelagic zone (open water)
Littoral zone
until aquatic plants disappear
warm but fluctuating temperature
much light
waves are relevant
divers community
Limnetic zone
open water near the surface
well lighted
dominated by plankton
main photosynthetic body of the lake
Profundal zone
Cold and dense regions of the lake
below the range of effective light penetration
benthis organisms dominate
temperature nearly uniform
Benthic zone
bottom area of the lake
low levels of dissolved oxygen
decomposition occurs here
Pelagic zone
the water column of the lake
pelagic fish (not near the bottom and plankton
Lake communities - In the pelagic zone
Plankton (suspended in water, Zooplankton: Protozoans, Phytoplankton: Cyanobacteria) and Nekton (ac-
tive swimmers like fish) are two components of an integrated community in the pelagic zone.
Lake communities . in the benthic zone
Primary producers: cyanobacteria, higher taxa of algae, flowering plants
The littoral region of the benthic zone is very diverse, while the profundal zone is inhabited only by con-
sumers and chemoautotrophic bacteria.
Lake stratification
change in the temperature at different depth in the lake and is dues to the change in water’s density with temperaure
Three layers
Epilimnion
Warmer, higher pH, higher DO concentration, mixed as a result of wind/wave most light
Metalimnion
of thermocline, which changes depth throught the year
thinn, temperature changes wuickly with depth, can be semipermanent or temporarily
Hypolimnion
dense, coldest layer in the summer, warmes in the winter, insuffisient light for photosynthesis, close to 4 °C thoughout the year
Lake factors
Light (Photosynthesis, temperature control)
Temperature (solubility of gases, biological activiy)
Morphology (Surface to volume ratio, higher depth –> higher water quality)
Quality of lakes
linked to the trophic status and parameters describing it
Olgiotrophic (low productiviy, low nutrients –> clear water with high drinking water quality)
Mesotrophic (intermediate)
Eutrophic (exessive nutrients can be caused naturally and through humans)
Qualiy criteria (COT-PH)
Clarity
Oxygen
Temperature
pH
Phosphorus
Chlorophyll A
Phytoplankton
Calrity
measured with a Secci disk, measure how deep the sund can reach into the water
Oxygen
determines types and abundance of fish, depens on photosynthestic ans respiration activity
Temperature
presence and absence of thermal stratification, controls rate of chemical reactions
pH
reduced rates of photosynthesis lead to higher pH
Phosphorous
major nutrient for plant growth (limiting factor)
