APES 8-4 Aquatic Biodiversity: Why are freshwater Ecosystems Important?

Lentic (standing) Bodies of water

lakes, ponds, inland wetlands

Lotic (flowing) bodies of water

Streams, river

Formation of lakes

Lakes form when water collects in natural depressions

Four zones based on depth and distance from shore

littoral zone, limnetic zone, profundal zone, benthic zone

littoral zone

a shallow zone in a freshwater habitat where light reaches the bottom and nurtures plants (most photosyntehtic and high in NPP)

Limnetic zone

a zone of open water in lakes and ponds

Profundal zone

a region of water where sunlight does not reach, below the limnetic zone in very deep lakes

benthic zone

the muddy bottom of a lake, pond, or ocean

Ecological services of freshwater systems

climate moderation, nutrient cycling, waste treatment, flood control, groundwater recharge, habitats for many species, genetic resources and biodiversity, scientific information

Economical services of freshwater systems

food

drinking water

irrigarion water

hydroelectricity

transportation corridors

recreation

employment

oligotrophic lakes

Low levels of nutrients and low NPP

Eutrophic lakes

High levels of nutrients and high NPP

mesotrophic lakes

lakes with a moderate level of productivity

hypereutrophic lake

Result of excessive inputs (cultural eutrophication) of nutrients in a lake.

surface water

Water above the surface of the land, including lakes, rivers, streams, ponds, floodwater, and runoff.

runoff

water that flows over the ground surface rather than soaking into the ground

watershed, drainage basin

land area that delivers runoff, sediment, and dissolved substances to a stream

three aquatic life zones

source zone, transition zone, floodplain zone

source zone

narrow, mountain stream section at high elevation (Youth Stage), low nutrients

transition zone

an area in which the properties of the land undergo a radical change

floodplain zone

streams join into wider and deeper rivers that flow across broad, flat valleys

How do dams and levees affect sediment flow to deltas? Why is this significant?

Dams trap sediment upstream

Levees prevent flooding and sediment deposition

Results: delta erosion, wetland loss, reduced nutrients, higher flood risk

Why are New Orleans and Hurricane Katrina important examples in environmental science?

Dams & levees reduced sediment → wetlands lost → weaker delta → catastrophic flooding during Katrina

Types of freshwater inland wetlands

marshes

swamps

prarie potholes

floodplains

arctic tundra in summer

ecological services of freshwater inland wetlands

filter and degrade toxic wastes

reduce flooding and erosion

help replenish streams

biodiversity

economical services of freshwater inland wetlands

recharges groundwater aquifers

food and timper

recreation areas