aquatic ecosystems

lotic ecosystems

running water, streams and rivers

properties change across river networks, needs to be considered at scales

lentic ecosystems

standing water ecosystems, ponds and lakes
wetlands ponds and lakes can have fuzzy boundaries

ab has lots of shallow lakes, catchment area important for aquatic systems

hyporheic zone

the region of sediment under or near river channel where there is mixing of groundwater (upwelling) and surface water (downwelling)

water moves slow, moderates stream temp, improves water quality (filters and denitrification)

unique habitat for biota

tectonic lake

very deep

caused by the deformation of earth’s crust

volcanic lake

formed in volcanic craters, by damming by lava, etc

small, unqiue chemistry with lots of sulfur

glacial lake

prairie potholes, kettle lakes, canadian shield

dropping ice as glaciers retreat cause depression and then melts into it

or scraping of glaciers over bedrock

fluvial lakes

formed in the course of a meandering river which is cut off

solution lakes

underground deposits are dissolved by water running through the area causing a lake to form

landslide lakes

can cause damming of a river which can be temporary or permanent

aeolian lakes

wind blown sediments act like a dam and cause a lake

shoreline lake

found near coastlines but occur due to buildup of sediment, ocean blocking an estuary, or a lake being divided

organic lake

peatlands or tropical swamps

can be up to 10 m of organics, dark water

can also be causes by beavers damming

anthropogenic lakes

reservoirs

for power generation, water supply, etc

meteortie lakes

impact crater fills with water

lake density and area

canada has 880 000 lakes > 10ha , 62% of lakes that size in the world

canadian shield, prairie potholes, etc

macrophytes

producers in aquatic ecosystems

flowering plants, mosses, and liverworts

no gymnosperms

slow flowing, shallow ecosystems mainly for light

includes emergent, rooted, free floaters and submerged

algae

attached in rivers to rocks/sediments/wood

or freefloating in lakes

can be green, yellow-brown or red

diatoms have high diversity and specific requirements

allochtonous

energy from adjacent terrestrial food webs making its way into aquatic ecosystems

autochtonous

energy from within the aquatic ecosystem

primary productivity limitations

limited by nutrients, light and temperature

water with high turbidity or DOC absorbs light and causes low productivity

consumers in aquatic ecosystems

herbivores like zooplankton, macroinvertebrates, fish

carnivores like fish, amphibians, invertebrate larvae

detrivores (allochtonous material), and parasites w high diversity

macroinvertebrates

filter feeders, collectors - FPOM, detritus and algae

grazers/scrapers, predators, shredders, parasites

meiofauna

invertebrates <0.25 mm

can be substantial component but often overlooked

aquatic food webs

interconnectedness, role of parasites, allochtonous inputs

basal, intermediate and top levels

biomass decreases with trophic levels - turns into energy

secondary production

river continuum concept

entire river system as a continuously integrating series of physical gradients and associated biotic adjustments as the river flows from headwater to mouth

aquatic invasive species

cascading effects on foodwebs

direct top down (fish) and bottom up (algal) effects

indirect affects and competitive effects, can be positive for some instances but over all poor

can also impact water quality - turbidity, light conditions and oxygen