Chapter 7 Freshwater

life zones Marine

Life zones

Chapter 24 Importance of

Aquatic Biodiversity Human impacts Laws of Protection Sustainability

Freshwater -defined as having a low salt concentration—usually less than 1% Lakes Ponds Rivers Streams wetlands

Saltwater or Marine Estuaries coastlines, Coral refs Marshes mangrove swamps oceans

Phytoplankton –free floating cyanobacteria

Zooplankton – primary consumers eat phytoplankton, secondary consumers eat other zooplankton

Nekton – strong swimmers Benthos – bottom dwellers Decomposers - bacteria

Temperature Access to sunlight

Highest in the upper layer (euphotic zone) Dissolved oxygen

Produced by photosynthesis Atmospheric interaction (waves)

Nutrient availability

range in size from just a few square meters to thousands of square kilometersponds may be seasonal, lasting just a couple of months (such as sessile pools)lakes may exist for hundreds of years or more may have limited species diversity since they are often isolated from one another and from other water sources like rivers and oceans

divided into three different “zones” determined by depth and distance from the shoreline

littoral zonelimnetic zoneprofundal zone

warmest since it is shallow and can absorb more of the Sun’s heat sustains a fairly diverse community, which can include several species of algae (like diatoms), rooted and floating aquatic plants, grazing snails, clams, insects, crustaceans, fishes, and amphibiansthe egg and larvae stages of some insects are found in this zonevegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks

near-surface open water surrounded by the littoral zone well-lighted (like the littoral zone) and is dominated by plankton, both phytoplankton and zooplanktonplankton are small organisms that play a crucial role in the food chain – most life would not be possible without them variety of freshwater fish also occupy this zone

Plankton have short life spans—when they die, they fall into the deep-water part of the lake/pondmuch colder and denser than the other twolittle light penetrates all the way through the limnetic zone into the profundal zoneanimals are decomposers

Temperaturevaries seasonally. Summer

from 4° C near the bottom to 22° C at the top

Winterfrom 4° C while the top is 0° C (ice)

between the two layers is a narrow zone called the thermocline where the temperature of the water changes rapidly with depth

during the spring and fall seasons is a mixing of the top and bottom layers resulting in a uniform water temperature of around 4° Cmixing also circulates oxygen throughout the lakemany lakes and ponds do not freeze during the winter resulting in the top layer being a little warmer

ice can develop on the top of lakes during winter

blocks out sunlight and can prevent photosynthesisoxygen levels drop and some plants and animals may die called "winterkill."

bodies of flowing water moving in one direction

found everywhere—they get their start at headwaters, which may be springs, snowmelt or even lakes

travel all the way to their mouths, usually another water channel or the ocean

describes an area of land that contains a common set of streams and rivers

drains into a single larger body of water, such as a larger river, a lake or an ocean

characteristics change during the journey from the source to the mouth

Source temperature is cooler at the than it is at the

mouth water is also clearer, has higher oxygen levels,

and freshwater fish such as trout and heterotrophs can be found there

Transition Zone the middle part of the stream/river the width/depth increases Temperature increases species diversity increases — numerous aquatic

green plants and algae can be found

Mouth Wider/deeper/slower water becomes murky from all the sediments

that it has picked up upstream decreasing the amount of light that can

penetrate through the water less light

less diversity of flora lower oxygen levels fish that require less oxygen, such as catfish and carp,

can be found

A wetland is any area that is inundated (flooded) or saturated for a certain number of days in a row that add up to 7.5% of the growing season in an area.

Contains: Water Hydrophyllic (water loving) plants Hydric (saturated) soils with low oxygen

content

Wildlife Habitat Flood control Sediment filters and erosion control Water quality Water supply Recreation

Bogs Pocosin

Fen Swamps

Forested Marshes

Tidal Salt Water Marsh

Non-tidal Vernal Pools Fresh Water Marsh

Extremely flat with poor natural drainage

Thick layers of peat – decomposed organic material

Shrub vegetation is common, pond pines, loblolly and longleaf pines are also present.

Fire adapted

Fed primarily by rainwater

Acidic Vegetation varies

from mosses and grasses to trees depending on elevation

Fed by surface and/or groundwater

Water is alkaline (basic)

Usually inhabited by mosses and grasses

Can be a stage in succession from lake to woodland

seasonal (yearly) marshes that occur in depressions of land

covered with ice and water from winter to spring

dry during the summer and fall. all.

bottom of the pools are made of bedrock or hard clay which keeps the water from leaking out.

Creatures may include the spring peeper, eastern spotted newt, green frog, spotted salamanders

A shallow wetland with few trees and standing water for most of the year

Not Tidal Flocks of wading

birds, fish, exotic plants, alligators, and numerous invertabrates

Dominated by trees with few shrubs

water inflow through streams, rivers, and run-off.

Trees have shallow root systems to gain exposure to oxygen.

Common trees include red maple, bald cypress, sweet gum and American elm.

Wood ducks, gray treefrog, wood frogs, barred owls and pileated woodpeckers live in the forested swamp