Aquatic Eco Wetlands, Lakes and Pondsand

Net Ecosystem Production NEP

Net Energy/ organic carbon fixed by entires ecosystem or community after accounting for al respiration( inlcuding heterotrophs

Heterotropic Ecosystem

NEP <0

GPP< Rtotal

NPP>R Hetero

Autotrophic Ecosystem

NEP >0

GPP> Rtotal

NPP>R Hetero

Oligotrophic

Not very productive

• low nutrient availability

crater lake is clear- good for recreation

Eutrophic

Very productive

• High nutrient availability

• Associated with high human activity

  • Input of nutrient through fertilizers

• Ex Lake that is associated with cyanobacterial blooms

Limnology

Study of inland waters

• Rivers

• lakes

• Wetlands

Mesotrophic

in between Eutrophic and oligotrophic

Formation of lake basins

• Spread of technonic plates

• Glacier carving of the land

• volcanic eruptions formed basins

• Water and lava created steam, creating an open-mouthed cave

• Oxbows: extreme erosion from meanders

• Human made lakes

  • Hydropower

  • water source

  • Flood control

  • Recreation

Basin in Bedrock

basins in bedrock tend to be more oligotrophic

Ex: glacial lakes

Basins in sediment

basins tend to be more eutrophic

Ex: Oxbow

Lakes vs Rivers

Lakes:

• Fueled by water draining from a catchment

• Flow is slow

• Longer residence time( lower turn over of water)

Rivers

• Flow of water is faster and more consistent direction

• Shorter residence time

Hydrology of Lake Myvatn in Iceland

Water input: Glacier

• Large catchment

• Little precipitation

• extensive contact with rock—> More nutrients in water

• Limited vegetation to consume nutrients-

  • Limited vegetation due to little precipitation

Lake Askja

• Large and DEEP crater

• Extremely oligotrophic— low nutrient inputs

• Sustains little life

Holomictic Lakes

• Complete mixing of entire volume at some point during yearly cycle

• Most lakes are holomictic

Meromictic

• Multiple thermoclines

• Seasonal Stratification and mixing within upper layer

• Permanent lower layers this is not mixed with upper layer ( similar to open ocean)

• Only in deepest lakes

Ex: Crater lates

Amictic Lakes

• Never mix completely

  • No wind to help with mixing of water

• Permanently frozen on the surface

• Mainly found at the poles (rare)

Mixing Regimes in Lakes

Monomictic

dimictic

Polymictic

Monomictic

1 seasonal mixing

Dimictic

2 seasonal mixings

Polymictic

many mixing within a season * typically daily in summer

Turnover Rate vs Turnover

Turnover rate: inverse of residence time

• Rate at which all the water is replaced in a lake

• Determined mu inflows and outflows

Turnover ; Context of mixing and stratification

• Breakdown of stratification and subsequent mixing

• Typically refers to seasonal change that occurs with cooling surface waters

Thermal stratification

Density of liquid water increase as it cools over most of the temperature range

• Conditions are anoxic below stratification layer

Photosynthesis Equation

CO2 + H2O —> CH20 + O2

Respiration Equation

CH20 + O2 —> CO2 + h

Rivers Oxygen Source

• Exchange with atmosphere

  • Direction of Exchange is determined by solubility of oxygen in water

  • >100% = over saturated

  • <100% = Undersaturated

Factors affecting interaction between air and water

• Wind speed

• Turbulence of water

  • Increase turbulence —> increase interaction with air

• Temperatures

  • Warmer water—> faster o2 exchange

Oxygen Production in lakes are affected by

Photosynthetic organisms

Floating:

• Neuston

• Phytoplankton

Attached

• Macrophytes

  • Submerged

  • Emergent

Benthic

• Algae/ periphyton

  • Often dominated by diatoms

Organisms consuming oxygen in lakes

• fish and other animals

• Microbes

  • Eukaryotes

  • Protozoa

  • Prokaryotes

  • Bacteria: especially in sediment

How does oxygen concentration change with depth in lakes?

Primary production is low;

• Atmosphere is O2 source

• Sediment is O2 sink

• O2 is highest at the surface

Primary Production is high

• Depends on distribution of photosynthetic organism

• Dominante by floating plants/phytoplankton- high O2 levels on the surface

• Dominance by Periphyton create increase in oxygen

Periphyton

• Strong competitors for nutrients

• Weak competitors for light

• Best when attached to the substrate

Phytoplankton

• Weak competitors for nutrients

• Strong competitors for light

Macrophytes

• strong competitors fro nutrients

• Intermediate — strong competitors for light

Aquatic Marginal Wetlands

Fringe

• immediate proximity to parent water body

• Frequently watered

Flood

• Exist far from parent water

• watered on occasion during high flood/tide conditions

Mire Wetland

• Independent of parent water body

• Fed by groundwater, precipitation and run off.

Swamp

Forested wetland

Marsh

non-woody vegetation wetland

Wetland: Minerotrophic

saturated below water table

Hydrological inputs from groundwater and runoff

Wetland: Ombrotrophic

• Situated above the water table

• Hydrological inputs primarily from precipitation

• “bog”