Chapter 19.2

AQUATIC ECOSYSTEMS

Vocabulary Salinity – the amount of salt dissolved in water Wetland – aquatic ecosystems that have a thin layer

of water covering soil that is wet most of the time Estuary – regions along coastlines where streams or

rivers flow into a body of salt water Intertidal Zone – the ocean shore between the

lowest low tide and the highest high tide Coral Reef– an underwater structure made from

outside skeletons of tiny, soft-bodied animals called coral

Introduction to Aquatic Ecosystems There are four major types of water, or

aquatic, ecosystems Freshwater

Rivers and Streams Lakes and Ponds

Wetland Estuary Ocean

Open ocean Coastal ocean Coral Reefs

Introduction to Aquatic Ecosystems Abiotic factors include

Temperature Sunlight Dissolved oxygen Salinity

Each has a unique variety of organisms in and out of the water

Aquatic species have adaptations that enable them to use oxygen underwater Fish use gills Mangrove plants take in oxygen through small pores in

their leaves and roots

Mangroves

Introduction to Aquatic Ecosystems Salinity is another important abiotic factor

Salinity is the amount of salt dissolved in water Water in saltwater ecosystems has high

salinity compared to water in freshwater ecosystems, which contain little salt (…obviously)

Freshwater: Streams and Rivers Streams are usually narrow, shallow, and

fast-flowing Rivers are larger, deeper, and flow more

slowly

Streams... form from underground sources of water,

such as springs or from runoff from rain and melting snow

have water that is often clear. Soil particles are quickly washed downstream

have high oxygen levels because air mixes into the water as it splashes over rocks

Rivers... form when streams flow together have muddy water from the soil that washes

into it from streams or nearby land Soil adds nutrients, such as nitrogen, into rivers

that are slow-moving have higher levels or nutrients and lower levels of dissolved oxygen compared to fast-moving water (obviously!)

Biodiversity Willows and cottonwood trees are water-

loving and grow along streams and on river banks

Trout, salmon, crayfish, and many insects are adapted to fast-moving water

Snails and catfish are adapted to slow-moving water.

Human Impact Streams and rivers are over-used

for drinking, laundry, bathing, crop irrigation, and industrial purposes

Hydroelectric plants use the energy of flowing water to create electricity.

Dams stop the water’s flow and impede anadromous and catadromous fish species

Runoff from cities, industries, and farms is a source of pollution

Freshwater: Ponds and Lakes Ponds and lakes contain freshwater that is not

flowing downhill

Ponds Shallow and warm Sunlight can reach the bottom

Lakes Larger and deeper Sunlight penetrates into the top few feet. Deeper water is dark and cold

Biodiversity Plants surround ponds and lake shores Surface water contains plants, algae, and

microscopic organisms that rely on photosynthesis

Cattails, reeds, insects, crayfish, frogs, fish and turtles live in shallow water near shorelines

Fewer organisms live in deeper, colder water of lakes where there is little sunlight

Lake fish include perch, trout, bass, and walleye

Human Impact Humans fill in ponds and lakes with

sediment to create land for houses and other structures

Runoff from farms, gardens, and roads washes pollutants into ponds and lakes, disrupting food webs

Wetlands Wetlands are aquatic ecosystems that have

a thin layer of water covering soil that is wet most of the time (not necessarily all the time)

Wetlands can be freshwater, saltwater, or both

They are among Earth’s most fertile ecosystems

Wetlands Freshwater wetlands form at the edges of

lakes and ponds and in low areas on land Saltwater wetlands form along ocean coasts High nutrient levels High biodiversity Wetlands trap sediment and purify water Plants and microscope organisms filter out

pollution and waste materials

Biodiversity Water-tolerate plants include grasses and cattails Few trees live in saltwater wetlands Willows, cottonwoods, and swamp oaks are trees found

in freshwater wetlands Insects are abundant

Dragonflies, and butterflies More than one-third of North American bird species,

including ducks, geese, herons, loons, warblers, and egrets, use wetlands for nesting and feeding

Alligators, frogs, turtles, and beavers depends on wetlands for food and breaking grounds.

Cattails and Reeds

Human Impact In the past, many people considered

wetlands as unimportant environments. Water was drained away to build homes and roads and to raise crops.

Today, many wetlands are being preserved and drained wetlands are being restored

Estuaries Estuaries are regions along coastlines where

streams or rivers flow into a body of salt water

Most estuaries form along coastlines, where freshwater in rivers meets salt water in oceans.

They have varying degrees of salinity

Estuaries Salinity depends on rainfall, the amount of freshwater

flowing from land, and the amount of saltwater pushed in by tides

Estuaries help protect coastal land from flooding and erosion.

Like wetlands, estuaries purify water and filter out pollution

Nutrient levels and biodiversity are high

Biodiversity Plants that grow in salt water include mangroves,

pickleweeds, and seagrasses Animals include worms and snails They also have oysters, shrimp, crabs, and clams

(yummmm) Striped bass, salmon, flounder, and many other ocean fish

lay their eggs in estuaries Many species of birds depend on estuaries for breeding,

nesting, and feeding

Human Impact Large portions of estuaries have been filled

with soil to make land for roads and buildings

Destruction of estuaries reduces habitat for estuary species and exposes the coastline to flooding and storm damage

Ocean: Open Oceans Most of Earth’s surface is covered by ocean

water with high salinity Oceans have many different types of

ecosystems The open ocean extends from the steep

edges of continental shelves to the deepest parts of the ocean

The amount of light depends on the depth

Ocean: Open Oceans Photosynthesis can take place only in the

uppermost, or sunlit, zone. Very little sunlight reaches the twilight zone. None reaches the deepest water, known as

the dark zone. (no way!) Decaying matter and nutrients float down

from the sunlit zone, through the twilight and dark zones, to the seafloor

Biodiversity The sunlit zone is home to microscopic algae and

other producers. They form the base of the food chain

Jellies, tuna, mackerel, and dolphins also live here. Many species of fish stay in the twilight zone

during the day and swim to the sunlit zone at night to feed.

Biodiversity Sea cucumbers, brittle stars, and other

bottom-dwelling organisms feed on decaying matter that drifts down from above

Many organisms in the dark zone live near cracks in the seafloor where lava erupts and new seafloor forms

Human Impact Over fishing Trash discarded from ocean vessels or

washed into oceans from land is a source of pollution.

Ocean: Coastal Oceans Coastal oceans include several types of

ecosystems, including continental shelves and intertidal zones

The intertidal zone is the ocean shore between the lowest low tide and the highest high tide

Sunlight reaches the bottom of shallow coastal oceans

Nutrients washed in from rivers and streams contribute to high biodiversity

Biodiversity It is home to mussels, fish, crabs, sea stars,

dolphins, and whales Intertidal species have adaptations for

surviving exposure to air during low tides and to heavy waves during high tides

Human Impact Oil spills and other pollution harm coastal

organisms

Ocean: Coral Reefs A coral reef is an underwater structure made

from outside skeletons of tiny, soft-bodied animals called coral

High biodiversity Form in shallow tropical oceans Protect coastlines from storm damage and

erosion

Biodiversity Coral reefs provide food and shelter for

many animals, including parrotfish, groupers, angelfish, eels, shrimp, crabs, scallops, clams, worms, and snails

Human Impact Pollution, overfishing, and harvesting of

coral threaten coral reefs