Kinds of Ecosystems

Chapter 4

“In all things of nature there is something of the marvelous.”Aristotle, Greek Philosopher

Biomes of the World

• Earth is covered by hundreds of types of ecosystems which are grouped into a few biomes

• Biomes have distinctive climates, plants and organisms; they are named for their plant life but the main determinant is the climate (temperature, precipitation, humidity, winds)

• Most organisms are adapted to live within a particular range of temperatures and will not survive at temperatures too far above or below their range.

• There are nine terrestrial biomes in the world: tropical rain forest, temperate forest, taiga, savanna, grasslands, chaparral, desert, tundra, mountains

Latitude and Altitude

• Biomes, climate and vegetation vary with latitude and altitude.

• Latitude is the distance north or south of the equator and is measured in degrees.

• Altitude is the height of an object above sea level.• Climate gets colder as latitude and altitude

increase. Therefore, climate also gets colder as you move farther up a mountain.

Biomes and Vegetation

• Biomes are described by their vegetation because plants that grow in an area determine the other organisms that can live there.

• Plants in a particular biome have characteristics, specialized structures, or adaptations that allow the plants to survive in that biome (size, shape, color) ex: plants in tunda tend to be short, cactus in deserts have no leaves

Forests:Tropical Rainforests

• Occur in a belt around the Earth near the equator• Always humid and warm; get about 250 cm (100 in) of rain per year• Get strong sunlight year-round; maintains a climate with little

seasonal variation in temperature.• Ideal climate for growing plants; nourishes more plant species than

any other biome (1 hectare temperate forest contains 10 species of trees/ same area of tropical rainforest contain over 100 species)

• Soil is not rich, usually thin and poor; rapid decay of plants and animals return nutrients to soil---used up by plants or washed away by rainfall

• Trees form aboveground roots—growing sideways from the trees, providing extra support

Rainforest: Plant Adaptations

• Plants grow in layers; trees more than 30 m (100 ft) tall form a dense canopy-absorbs at least 95% of the sunlight

• Little light reaches below the canopy (understory); only trees and shrubs adapted to shade can grow (ex: herbs with large flat leaves)

• When trees fall, tree seedlings adapted to grow quickly outcompete other seedlings

• Orchids and monkey ladder vines use the tall tree trunks for support high in the canopy

Layers of the Rain Forest

• There are four main layers above the forest floor: the emergent layer, the upper canopy, the lower canopy, and the understory

• The top layer, the emergent layer, consists of the tallest trees (60-70 m); trunks can measure up to 5 m around; they grow and emerge into direct sunlight; animals such as eagles, bats, monkeys, and snakes live in the emergent layer

Layers of the Rain Forest…con’t

• The next layer, the canopy, is the primary layer of the rain forest; trees grow more than 30 m tall; they form a dense layer that absorbs up to 95% of the sunlight; divided into two (upper and lower canopy); the lower canopy receives less light than the upper canopy; epiphytes grow in upper canopy and use the entire surface of a tree as a place to live; capture lots of sunlight, water and nutrients from the rain; most animals live in the canopy to feed on the flowers and fruits that grow there

Layers of the Rain Forest…con’t

• The bottom layer, the understory, receives very little light; trees and shrubs are adapted grow in low light conditions; they grow to about 3.5 m tall; herbs with large, flat leaves grow on the forest floor must be able to grow in darker spots and get only the small amount of sunlight that reaches there; when trees fall, seedlings from trees must grow quickly to compete with other seedlings

Rainforest: Animal Adaptations

• Incredible diversity of vegetation may have led to the evolution of the greatest diversity of animals anywhere on Earth

• Little competition; most animals are specialists and are adapted for a specific purpose

ex: antwrens – variety of species that eat insects at different layers; flowering plants that can be pollinated by only one species of insect, bat or bird

• Some animals have developed elaborate methods for escaping predators; others have equally evolved methods of capturing their prey

ex: insects (butterfly) that looks like a leaf or twig; frogs that blend perfectly with plants; poisons on their skin with bright colors to warn predators

Threats to Rainforests• Used to cover 20% of Earth’s surface; today, only about 7%

• Every year tropical rainforests are stripped by logging operations or cleared for farming or cattle grazing (the size of North and South Carolina combined)

• As they disappear, so do the habitats, plants and animals become extinct

• Traditions and cultures are lost as native people are displaced

• Help save the rainforests by looking for rain-forest friendly products and support organizations that preserve tropical forests

Temperate Rain Forest

• Found in North and South America, Australia and New Zealand

• Pacific Northwest is home of the only North American temperate rainforest

• 300 ft tall evergreen trees (Sitka spruce, Douglas fir) dominate the forest; mosses, lichens and ferns are abundant

• Moisture pervades everything; cool, humid forest• Located at 48° north latitude; rarely freezes (Pacific Ocean

moderates the temperature)

4.3: Temperate Deciduous Forests

• Occur between 30° and 50° north latitude; seasonal variations can be extreme and growing season is from 4 to 6 months

• Trees drop their leaves in the fall; summer temperatures can soar to 35° C ( 95° F); winter temperatures plummet below freezing

• Deciduous forests are moist receiving 75-250 cm (30-100 in) of precipitation

• Rain and snow help decompose dead organic matter (leaves) contributing to the deep, rich soil

Deciduous Forests: Plant Adaptations

• Plants grow in layers; forest canopy is dominated by tall trees (maple, oak, birch)

• Small trees, shrubs, bushes grow in the understory• Forest floor gets more light than the rain forest floor, thus

more ferns, herbs and mosses grow there• Plants are adapted to survive seasonal changes; seeds,

bulbs and rhizomes become dormant in the ground, trees lose their leaves

• In spring, as sunlight increases and temperatures increase, leaves re-emerge on trees, seeds germinate and rhizomes and roots put forth new shoots

Deciduous Forests: Animal Adaptations

• Animals are adapted to forage the forest plants for food and shelter

• Squirrels eat nuts, seeds and fruits; bears eat leaves and berries, deer eat leaves from trees and shrubs; birds nest in the tops of trees

• Birds are migratory—fly south in the winter to avoid the harsh weather; return in spring

• Animals that stay use various strategies for survival—bears and squirrels become inactive; insects enter a state of very low metabolic activity

Taiga

• Aka: boreal forest; has rough terrain and the forest floor is sparsely vegetated

• Trees seem barren until you look up to see the green tops• Located across the northern hemisphere just below the

Arctic Circle; winters are 6 to 10 months and extremely cold with subfreezing temperatures that plummet to -20°C (-4°F).

• The frost-free growing season may be as short as 50 days depending on the latitude; enhanced only by constant daylight during the summer months

Taiga: Plant Adaptations

• Trees whose seeds develop cones (conifers, such as, pine, hemlock, fir, spruce) do not shed their needle-shaped leaves; narrow shape leaves and waxy coating retain water when moisture in the ground in frozen

• The shape (pointed) of the tree helps it shed snow; otherwise the snow would crush the tree

• Conifer needles (contain acidic substances), acidify the soil when they fall, preventing other plants from growing; blueberries, a few ferns and mosses can survive the acidic soil

• Climate and acidity hinder decomposition which results in slow soil formation

Taiga: Animal Adaptations

• This biome is dotted with lakes and swamps in the summer, attracting birds that feed on insects, fish or other wetland organisms

• Birds migrate south in the winter; shrews and voles burrow underground; moose and arctic hare eat whatever vegetation they can find; lynx, wolves and foxes eat the hare and shed their brown summer fur and re-grow a thick white fur in the winter

4.4: Grasslands, Chaparral, Deserts and Tundra

• Climates with less rainfall: forests savannas, grasslands, chaparrals deserts

• As precipitation decreases, so does the diversity of species present

• Number of different species is smaller, individuals of each species is even smaller

• Another type of “desert” is present far to the north. It is called the tundra. Very little precipitation occurs here and temperatures stay very cold year round

Savannas

• Parts of Africa, western India, northern Australia and some parts of South America are covered by grasslands called savanna; located in tropical and subtropical areas, between tropical rain forests and deserts

• West African plains contain the greatest collection of grazing animals on Earth and the predators that hunt them

• Not many trees, too little rainfall • Savannas have a wet season and a dry season; grass

fires may sweep across savannas in the dry season

Savannas: Animal Adaptations

• Migratory lifestyle of the large, grazing herbivores, such as the elephant

• Animals follow the rains to newly sprouted grasses• Predatory animals follow their mobile food source• Give birth during rainy season when food is more

abundant and survival is greatest• Avoid competition by eating vegetation at different

heights; ex: small gazelle grass on grasses, black rhinos browse on shrubs and giraffes feed on tree leaves

Savannas: Plant Adaptations

• Most rain falls during the wet season, therefore, plants must be able to survive long periods without water

• Savanna trees and grasses have horizontal underground root systems to obtain water and enable them that survive long dry seasons and regrow quickly after fires

• Course savanna grasses have vertical leaves• Trees and shrubs have thorns or razor sharp leaves

– deter herbivores

Temperate Grasslands: Prairies, Steppes and Pampas

• This biome is dominated by grasses and has very few trees; hot summers and cold winters; temperate grassland can receive 50 to 88 cm of precipitation per year

• Grasslands have the most fertile soil of any biome• Many natural temperate grasslands have been

replaced with crops of corn, soybean and wheat• Grasslands at one time covered 42% of the total

land surface on Earth; today, they cover only about 12%

Temperate Grasslands: Prairies, Steppes and Pampas

• Found on interiors of continents where there is too little rainfall for trees to grow; prairies of North America, steppes of Russia and Ukraine, pampas of South America

• Mountains play a crucial role in maintaining grasslands by blocking rain clouds thus maintaining low rainfalls; rainfall increases as you move eastward, thus larger grasses/shrubs can grow

• Sizzling summer temperatures make grasslands a tinderbox; fire is common in grasslands

Temperate Grasslands: Plant Adaptations

• Prairie grasses are perennials, surviving from year to year

• Root systems form dense mats the survive drought and fire and hold the soil in place

• Rainfall determines what type of grasses will grow in an area

• Few trees will survive on the grasslands because of drought, fire and constant battering of winds

Temperate Grasslands: Animal Adaptations

• Grazing animals (pronghorn antelope and American Buffalo) have large, flat back teeth for chewing coarse prairie grasses

• Grazers cope with severe winters by growing thick coats of fur which they shed in spring

• Badgers, prairie dogs, owls live in protected underground burrows; these burrows shield them from fire, the elements and predators

Threats to Temperate Grasslands

• Cultivation and overgrazing have changed the grasslands

• Grain crops have replaced native grasses and cannot hold the soil in place as well because their roots are shallow, resulting in soil erosion

• Overgrazed animals are constantly chewing down the grasses hindering them from regenerating or holding the soil, thus furthering soil erosion; constant use is changing the fruitful grasslands into less productive, desert like biomes

Chaparral

• A type of temperate woodland biome; have fairly dry climates but get enough rainfall to support more plants than a desert; have scattered trees communities (coniferous trees such as pinon pines, junipers)

• Occurs in the mid-latitudes (30 degrees north and south of the equator)

• Lies primarily in coastal areas that have Mediterranean climates, ex: Hollywood, Calif

• Known for their hot, dry summers; mild, wet winters; and slight variations in seasonal temperatures

Chaparral: Plant Adaptations

• Mostly low-lying evergreen shrubs and small trees

ex: chamise, manzanita, shrub oak, olive trees and cooking herbs like sage and bay

• Plants have small, leathery leaves that resist water loss; they contain oils that promote burning

• Natural fires destroy trees that compete with chaparral plants, thus allowing light and space for the smaller plants

• Plants are well adapted and can regrow from small bits of surviving tissue

Chaparral: Animal Adaptations

• Common adaptation is camouflage – shape or coloring that allows them to blend with their environment

• Quail, lizards, chipmunks and mule deer have brownish gray coats that allows them to move through the brush

• Animals have adapted to seasonal differences for food

ex: scrub jay (bird) has a beak adapted for a

varied diet (insects, seeds, other birds’ eggs

and baby birds)

Threats to the Chaparral

• Biggest threat worldwide is human development

• This biome has lots of sun, access to oceans and mild year-round climates which is inviting to humans

4.5 Deserts

• They are the driest places on Earth, receiving less than 25 cm (10 in) of precipitation a year

• Hot deserts occur closer to the equator than cold deserts

• Often occur in the rain shadow of mountains (leeward side of the mountain)

Deserts: Plant Adaptations• Plants in the desert have adaptations for obtaining and

conserving water• Succulents and cacti have thick, fleshy stems and leaves

that store water; have waxy coating to prevent water loss• Spines deter thirsty animals from eating plant’s juicy flesh• Roots are shallow and spread out widely• Plants are adapted to drought, will die when it is too dry,

drop their seeds which lie dormant until the next rainfall when they germinate, grow and bloom before the soil becomes dry again (drought-resistance) ); adapted to survive even when their water content falls below 30% of their mass (water levels between 50% to 75% are fatal for most plants)

Deserts: Animal Adaptations

• Reptiles (gila monsters, rattlesnakes) have thick, scaly skins that prevent water loss

• Amphibians (spadefoot toad) survive scorching desert summers by burying themselves in the ground and sleeping through the dry season (estivating)

• Insects and spiders are covered with body armor to help them retain water

• Most animals are activate at night or at dusk, when the air is cooler

Threats to the Desert

• In the American West, residential development encroaches upon the desert areas

• Off-road and all-terrain vehicles kill desert vegetation, destroying habitats of endangered animals (desert tortoise)

• Humans removing desert plants endanger plant populations

Tundra

• Lies north of the Arctic Circle; has no tall trees• Frozen soil supports mostly tough grasses and

shrubs• Summers are short; only a few inches of the soil

thaws; becomes dotted with bogs and swamps during the thaw periods; makes an ideal breeding ground for huge numbers of swarming insects (mosquitoes, blackflies) and birds that feed on them

• Under soil lies the permafrost (permanently frozen soil)

Tundra: Plant Adaptations

• Mosses and lichens cover acres of rocks (don’t need soil to grow)

• Where soil (thin) exists, plants have shallow, wide roots which anchor them against arctic winds

• Flowering plants (moss campion, gentian) are tiny and hug the ground for warmth and to stay out of the wind

• Woody plants and perennials (willow, junipers) have evolved dwarf forms and grow flat or trailing

• Plants grow and flower quickly (short summers)

Tundra: Animal Adaptations

• Millions of migratory birds breed during the short summer because of the abundant food supply (plants, mollusks, worms, insects)

• Caribou and reindeer migrate; wolves prey on the caribou, deer, moose, lemmings, mice and rabbits.

• Rodents burrow underground during winter• Year-round residents (arctic fox) have white fur in

winter; coats are extremely well insulated (musk ox)

Threats to the Tundra

• One of the most fragile biomes on Earth• Food chains are relatively simple and can be

disrupted easily• Conditions are so extreme, land is easily

damaged and slow to recover.• Oil extraction and transport across land has

brought humans to the area, which has disturbed the delicate balance of the biome

4.6 Freshwater Ecosystems

• The types of organisms in an aquatic ecosystem are mainly determined by the water’s salinity; The amount of dissolved salts the water contains

• Divided into two aquatic groups depending on the salinity: freshwater ecosystems and marine ecosystems

• Freshwater ecosystems include sluggish waters of lakes and ponds, moving waters of rivers and streams and areas where land and water come together

Lakes and Ponds

• Littoral zone – where aquatic life close to shore is diverse and abundant; nutrient-rich area

• Further out, where there is still sunlight for photosynthesis, live the phytoplankton (plants) and zooplankton (tiny animals)

• Deep lakes and ponds (too little light) contain a few fish adapted to cooler water and bacteria (decompose the dead plants and animals)

• Benthic Zone – bottom of a body of water; inhabited by decomposers, insect larvae, clams

• Lakes with large amounts of plant matter are eutrophic (plants and algae grow in large quantities; bacteria break down dead matter using up oxygen; diversity of species decline).

Characteristics of Aquatic Ecosystems

• Plant and animal life depends on depth of water; how fast water moves; amount of sunlight, mineral nutrients, oxygen and temperature

• Contain several types of organisms, grouped by their location and by their adaptations: plankton (float near the surface and include phytoplankton, zooplankton); nekton (free swimming organisms such as fish, turtles, whales); and benthos (bottom dwelling organisms such as mussels, worms, barnacles)

• Decomposers are also a type of aquatic organism

Lakes and Ponds: Plant and Animal Adaptations

• • Lakes, ponds, wetlands, rivers and streams make up the various types of freshwater ecosystems

• • Lakes, ponds and wetlands form naturally where groundwater reaches Earth’s surface

• • Littoral zone – where aquatic life close to shore is diverse and abundant; nutrient-rich area (plants: cattails, reeds: rooted in water, upper leaves and flowers above the water)

• • Further out, where there is still sunlight for photosynthesis, live the phytoplankton (plants) and zooplankton (tiny animals)

Lakes and Ponds: Plant and Animal Adaptations

• Deep lakes and ponds (too little light) contain a few fish adapted to cooler water and bacteria (decompose the dead plants and animals)

• Benthic Zone – bottom of a body of water; inhabited by decomposers, insect larvae, clams

• Animals the live in lakes and ponds have adaptations that help them obtain what they need to survive (ex: water beetles: hairs under their bodies trap surface air used to breathe during dives; whiskers on catfish: sense food)

Lakes and Ponds: Plant and Animal Adaptations

• Lakes with large amounts of plant matter are eutrophic (plants and algae grow in large quantities; bacteria break down dead matter using up oxygen; diversity of species decline). Happens naturally over time, however, eutrophication can be accelerated by runoff that carries sewage, fertilizers, or animal waste

Wetlands:

• Areas that are covered by water for at least part of the year• Two main types:

• Marshes: contain non-woody plants (cattails)• Swamps: contain woody plants or shrubs (trees and shrubs)

• Perform several important environmental functions: serve as filters or sponges (absorb and remove pollutants from water that flows through them); control flooding; serve as spawning and feeding grounds for game fish; providing homes for native and migratory wildlife (including endangered and threatened species); vegetation traps carbon which would otherwise be released back into the atmosphere as carbon dioxide; produces commercial products such as cranberries, blueberries, peat moss

Wetlands: Marshes

• Most freshwater wetlands are located in southeastern US. Florida Everglades is the largest freshwater wetland in the US; Everglades once covered 8 million acres in S. Florida, today it covers less than 2 million acres

• Several kinds of marches, each with its own characteristics: brackish marshes (slightly salty); salt marshes (saltier water)

• Occur on low, flat lands with little water movement

• In shallow waters, plants (reeds, rushes and cattail) root to the bottom, leaves above the water year-round

Wetlands: Marshes

• Benthic zones are nutrient rich, contain plants, numerous types of decomposers and scavengers

• Waterfowl (ducks, grebes) have flat beaks to sift through water; water birds (herons) have spear-like beaks to grasp small fish and frogs; attract migratory birds from temperate and tropical habitats

Wetlands: Swamps

• Occur on flat, poorly drained land, near streams• Dominated by shrubs or water-tolerant trees (red

maple, cedar, oak, cypress – depending on latitude and climate)

• Mangrove swamps occur in warm climates near ocean (more saline water)

• Ideal habitat for amphibians (green frog, salamanders) and attract birds (wood ducks) that nest in hollow trees; reptiles (alligator) are the predator of the swamp and will eat almost any organism that crosses its path

Threats to Wetlands

• Used to be considered wastelands (breeding grounds for pesky insects) so people “improve” them by draining and clearing them for farms, residential or commercial development

• However, we now view them as purifiers (wastewater and absorbers of hazardous flood waters)

• Vital habitats for wildlife for breeding (herons, storks, other birds)

• Home to many amphibians and reptiles (alligators, crocodiles)

• Federal government now prohibits the destruction of wetland areas

4.7 Rivers

• Originate from snowmelt in mountains• Headwaters-water is usually very cold and highly

oxygenated; runs swiftly; shallow• As it moves down the mountain, it broadens; water

is warmer, loses oxygen and flows more slowly• Characteristics vary depending on land and climate• Runoff wash nutrients and sediment from

surrounding land into a river, thus affecting growth and health of organisms in the river

Rivers: Plant and Animal Adaptations

• Near headwaters, mosses anchor themselves to the rocks

• Mayflies use hooks on their legs to cling to any stable surface

• Trout (streamlined bodies, powerful swimmers) and minnows are adapted to live in the cold, highly oxygenated water

• Downstream – catfish, carp (adapted to glide over river bottom) prefer warmer, calmer water

• Freshwater aquatic plants (crowfoot) set roots in soil; many have arrowhead shaped leaves depending on the speed of the water

Threats to Rivers

• Industries use river water in manufacturing processes and as a receptacle for waste

• People have used rivers to dump sewage and garbage

• These practices have polluted the rivers with toxins; killing river organisms and making the fish inedible

• Runoff from the land is putting pesticides and other poisons into the rivers and coats the riverbeds with toxic sediments

• Dams alter river flows and destroy fish habitats

4.8 Marine Ecosystems

• The oceans of the world contain a wide variety of plants and animal communities

• The types of organisms present in marine ecosystems depend on temperature and the amount of sunlight and nutrients are available.

Coastal Wetlands

• Land areas covered by salt water for all or part of the time are known as coastal wetlands

• Provide habitat and nesting areas for fish and wildlife

• Also absorbs excess rain, protects areas from flooding, filters out pollutants and sediments, and provides recreational areas for boating, fishing and hunting

Estuaries

• Many coastal areas form in estuaries• An ecosystem where fresh water from rivers

mixes with the salt water from the ocean; as the two bodies of water meet, currents form and cause mineral rich mud and nutrients to fall to the bottom and become a nutrient trap; constantly getting fresh nutrients

• Among the most productive ecosystems; contain plenty of light, nutrients for plants

Estuaries: Plant and Animal Adaptations

• One week each spring, huge snowshoe crab crawl out of the ocean onto the beaches of the Delaware Bay to mate and lay their eggs. Shorebirds wait for them and millions of migrating birds will stop there to gorge on the eggs

• Rivers supply nutrients washed from the land; water is shallow; sunlight reaches the bottom; in shallow areas, marsh grass grows

• Can support large amounts of plants, phytoplankton and zooplankton which provide food for larger animals (fish, dolphins, manatees, seals, other mammals)

Estuaries: Plant and Animal Adaptations

• Oysters, barnacles, clams live anchored to marsh grass or on the bottom and filter algae and debris out of the water

• Organisms can tolerate variations in salinity as the content of the water varies as fresh water and salt water mix (tides)

• Provide protected harbors, access to oceans and connections to rivers, as a result, many of the world’s major ports are built on estuaries; six of the ten largest urban areas in the world (Tokyo, New York, Shanghai, Buenos Aires, Rio de Janeiro, Bombay)

Threats to Estuaries

• Were used as dumping grounds, filled and then used as building sites, occurred extensively in California; now, plans are to restore them to estuary wetlands

• Industrial waste (toxic chemicals), sewage, agricultural runoff containing pesticides and fertilizers have damaged estuaries

• Most of the pollutants will break down over time, but estuaries cannot cope with the large amounts produced by dense human populations

• Dominate much of the shoreline of the Gulf of Mexico, Atlantic Coast of US; absorb pollutants and protect inland areas

• Develop in estuaries where rivers deposit their load of mineral rich mud; support clams, fish, and aquatic birds

• Acts as a nursery for shrimp, crabs and fish when they are small; later to be eaten by larger fish or caught by commercial fisheries

Salt Marshes

Mangrove Swamps

• Located along coastal areas of tropical and subtropical zones; help to protect the coastline from erosion, reduce damage from storms

• Mangrove trees dominate the mangrove swamps; grow partly submerged in the warm, shallow, protected salt water

• Provide breeding and feeding grounds for about 2000 animal species

Coral Reefs

• Limestone islands in the sea that are built by coral animals called polyps (very slow growing); thousands of species of plants and animals live in the cracks and crevices; among the most diverse ecosystems on Earth

• Corals live in only warm salt water; a lot of light for photosynthesis; shallow, tropical seas

• Only outer layer of coral is living

Coral Reefs: Animal Adaptations

• Coral Polyps are predators that never chase their prey; use stinging tentacles to capture small animals that float or swim too close

• Provide habitats for a variety of tropical fish, snails, clams, sponges

• Parrotfish have teeth fused into their beaks which they use to scrape algae and corals off the reefs to eat

Threats to Coral Reefs

• Coral Reefs are productive but fragile ecosystems• Estimated 27% of coral reefs are in danger of

destruction from human activities• If they get too hot or too cold, or fresh water

drains into the water surrounding the reef, corals cannot produce limestone needed to survive

• If it is too muddy, too polluted, too high in nutrients, algae will die or grow out of control and smother the corals

Threats to Coral Reefs

• Oil spills, sewage, pesticides, silt runoff are linked to coral-reef destruction

• Overfishing can devastate fish populations, upsetting the balance

• Coral reefs grow very slowly and cannot repair itself after being destroyed by careless divers, shipwrecks, anchors, people breaking off pieces

4.9 The Ocean

• Covers nearly ¾ of Earth’s surface• Plants only grow where there are nutrients and

light; most life is in shallow water around the edges of continents; abundant with plants and animals in these areas

• Open ocean, phytoplankton grows near the surface (sunlight) if there are nutrients; one of the least productive of all ecosystems

• The depths of the ocean are dark and most of the food consists of dead organisms (falling from the surface)

Ocean: Plant Adaptations

• No flowering plants except around the edges

• Food for herbivores in the open ocean are phytoplankton (floating by being buoyant or having long spines; whip-like flagella; oil droplets)

• When they die, they sink to the bottom

Ocean: Animal Adaptations

• Smallest herbivores are the zooplankton (jellyfish, tiny shrimp, fish larvae) which live near the surface; others (oysters, lobsters) live at the bottom

• Dozens of fish, as well as seals and whales (mammals) feed on plankton

• Evolved sleek, tapered shapes for moving through dense water; silvery color (protective camouflage); buoyancy devices to stay at one level (sharks –oily livers; bony fish – gas-filled swim bladders; mammals – lungs

• The depths of the ocean are perpetually dark; decomposers, filter feeders and organisms that eat them live here

• Poor visibility at these depths so organisms use “light” to communicate (luminous) or sound (whales – “songs”; dolphins – clicks and calls

Threats to the Ocean

• Pollution – comes from the land; same as the pollutants on the land (fertilizers causing toxic algal blooms; industrial waste; sewage discharged into rivers, particularly from nuclear power plants)

• Overfishing and some fishing methods have destroyed fishing grounds, nets entangling every living thing bigger than the holes (most of the catch are not used and are thrown back, dead); marine mammals drown; fishing lines are discarded in the ocean and strangle fish, seal

• All of these things are reducing reproduction thus endangering many species

Polar Ecosystems

• Ice covered North and South Pole are considered marine ecosystems because most of the food supply is phytoplankton

• South Pole lies on the continent of Antarctica and is covered with a permanent icecap (melts only around the edges); North Pole is not on land at all; lies in the Arctic Ocean, frozen into a huge iceberg throughout the year with little icebergs floating around it

The Arctic

• Relatively shallow; rich in nutrients; supports large populations of plankton

• This provides food for a diversity of fish, whales, ocean birds (who prey on the fish), seals

• The birds and seal bear their young on the ice; they provide food for the few humans that live there and for the polar bear

The Antarctic

• Only continent never colonized by humans• Used mainly for research on the unusual animals

that live there• Only a few plants live there• Plankton forms basis of the food chain; feeds fish,

whales, penguins

Threats to Polar Ecosystems

• Contains reserves of minerals (oil) whose extraction would disrupt this large untouched ecosystem

• Conservationists want it made into a world wildlife refuge

• Main threat is tourism (garbage left behind, does not decay because it is so cold)

• They are working to solve that problem