52 Introduction of Ecology and the Biosphere

Question 1

What is ecology divided into?

Answer 1

Global ecology, landscape ecology, ecosystem ecology, community ecology, population ecology and organismal ecology.

Question 2

What is global ecology?

Answer 2

The study of how the regional exchange of energy and materials influences the functioning and distribution of organisms across the biosphere.

Question 3

What is landscape ecology?

Answer 3

The study of the factors controlling exchanges of energy, materials, and organisms across multiple ecosystems.

Question 4

What is ecosystem ecology?

Answer 4

The study of the community of organisms in an area and the physical factors with which those organisms interact.

It emphasises energy flow and chemical cycling between organisms and the environment.

Question 5

What is community ecology?

Answer 5

The study of how interactions between species, such as predation and competition, affect community structure and organization.

Question 6

What is population ecology?

Answer 6

The analysis of factors that affect population size and how and why it changes through time.

Question 7

What is organismal ecology?

Answer 7

The study of how an organism’s structure, physiology, and behavior meet the challenges posed by its environment.

It is further divided into physiological ecology, evolutionary ecology and behavioural ecology.

Question 8

Define ecology?

Answer 8

The scientific study of the interactions between organisms and the environment.

Question 9

What is the global ecosystem called?

Answer 9

The biosphere

Question 10

Define biosphere.

Answer 10

The sum of all the planet’s ecosystems and landscapes

Question 11

Define landscape

Answer 11

A mosaic of connected ecosystems

Question 12

What is the marine equivalent of ‘landscape’?

Answer 12

A ‘seascape’

Question 13

Define ecosystem.

Answer 13

The community of organisms in an area and the physical factors with which those organisms interact

Question 14

Define community

Answer 14

A group of populations of different species in an area.

Question 15

Define population.

Answer 15

A group of individuals of the same species living in an area.

Question 16

What is an example of a question asked in global ecology?

Answer 16

How does ocean circulation affect the global distribution of crustaceans?

Question 17

What is an example of a question asked in landscape ecology?

Answer 17

To what extent do the trees lining a river serve as corridors of dispersal for animals?

Question 18

What is an example of a question asked in ecosystem ecology?

Answer 18

What factors control photosynthetic productivity in a temperate grassland ecosystem?

Question 19

What is an example of a question asked in community ecology?

Answer 19

What factors influence the diversity of species that make up a forest?

Question 20

What is an example of a question asked in population ecology?

Answer 20

What environmental factors affect the reproductive rate of locusts?

Question 21

What is an example of a question asked in organismal ecology?

Answer 21

How do hammerhead sharks select a mate?

Question 22

What is the north most tropic called?

Answer 22

The Tropic of Cancer

Question 23

What is the south most tropic called?

Answer 23

The Tropic of Capricorn

Question 24

Why are equatorial regions typically warmer?

Answer 24

When sun hits the equators it is more or less overhead. In the poles this light is at a oblique angle so not as intense.

Question 25

What causes the global air currents?

Answer 25

As air warms at the equators it rises. This updraft forces it north or south where it cools and sinks.

The suction causes by the air rising at the equator pulls the air from the north/south back down to the equator forming a current.

Question 26

What is a typical pattern of rain forests and deserts on dart?

Answer 26

Rain-forests are often located at the equator. Areas on the tropics of cancer and capricorn are typically deserts.

Question 27

How many degrees form the equator is the tropic of capricorn?

Answer 27

23.5º S

Question 28

Why are deserts typically found at the tropics and rain forests at the equator?

Answer 28

The air what rises at the equator loses its water as it rises. This cause rain to fall on the equator.

As this wire reaches the desert regions at the tropic it picks up the air and carries it to the equator.

Thus water is carried from the deserts to the rainforest regions.

Question 29

What are the main winds called?

Answer 29

The ‘westerlies’ are from the tropic of cancer to the north pole and from the topic of capricorn to the south pole.

The ‘northeast trades’ are from the tropic of cancer to the equator.

The ’south east trades’ are from the tropic of capricorn to the equator.

Question 30

What does the name of a wind i.e. ‘westerly’ mean?

Answer 30

This states the direction it is FROM. Therefore a westerly wind would come from the west to the east.

Question 31

At what degree of latitude is the arctic circle?

Answer 31

60ºN

Question 32

At what degree of latitude is the antarctic circle?

Answer 32

60ºS

Question 33

Define climate.

Answer 33

The long term prevailing weather conditions of a region.

Question 34

What are the main factors of climate?

Answer 34

Temperature, precipitation, sunlight and wind.

Question 35

What is climate divided into?

Answer 35

Microclimate and Macroclimate.

Question 36

Define ‘macroclimate’

Answer 36

Climate patterns on the global, regionally and landscape level.

Question 37

Define ‘microclimate’

Answer 37

Very fine, localized patterns, such as those encountered by the community of organisms that live in the microhabitat beneath a fallen log

Question 38

What are currents that exist in a circle called?

Answer 38

‘Gyre’s

Question 39

What are the main Gyres?

Answer 39

The North Pacific Gyre, South Pacific Gyre, North Atlantic Gyre, South Atlantic Gyre and the Indian Ocean Gyre

Question 40

Besides the Gyres, what are the major ocean currents?

Answer 40

The ‘antarctic circumpolar current’ which circumnavigates the pole.

the ‘labrador’ current’ which travels south from Canada.

Question 41

What causes the seasons?

Answer 41

As the earth orbits the sun it has a content tile tot 23.5º

As the earth moves this tilt means that for some portion of the year the southern hemisphere is leaning away and the northern hemisphere is leaning towards the sun. In this case the northern hemisphere is in summer.

Question 42

What are the days that represent a turning point in the seasons called?

Answer 42

The March equinox, September equinox, June solstice and December solstice.

Question 43

What happens during an equinox?

Answer 43

The earth is arranged so that neither hemisphere is pointing towards or away form the sun.

Therefore in both hemispheres the day is exactly 12 hours.

Question 44

What happens during a solstice?

Answer 44

The earth is arranged so that one hemisphere is leaning the most prominently to the sun. The other hemisphere is as tilted in the opposite direction as it ever will be.

Therefore one hemisphere will experiences its longest day and the other will have its shortest day.

Question 45

How does the June solstice differ from the December solstice?

Answer 45

In the June solstices the Northern hemisphere has its longest day while the Southern hemisphere has its shortest,

The December solstice is the opposite: Northern has shortest day, Southern longest.

Question 46

How do mountains affect climate?

Answer 46

As winds hit the mountains the air flows up the mountain. This causes them to cool and drop precipitation.

Therefore the front side receives hight precipitation. This means that when the is at the ‘leeward side’ on the other side it has less moisture. Therefore the ‘leeward side’ is in a ‘rain shadow.’

Question 47

What can factors that affect a microclimate be divided into?

Answer 47

Abiotic and biotic

Question 48

What are some examples of microclimates?

Answer 48

The area under a tree is sheltered from light and rain.

A fallen log provides shelter for many insects.

A cleared area has more direct sunlight so is often warmer.

Question 49

How can global warming affect trees?

Answer 49

It can affect air current and thus precipitation and thus causes trees to move away form drier areas.

The change in temperature limits the range in which their pollinators live and thus the range in which they can live.

Question 50

What is the are in which a species lives in called?

Answer 50

Its ‘range’

Question 51

How can the climate of a region be predicted?

Answer 51

With a ‘climograph’

Question 52

How does a climograph work?

Answer 52

It has annual mean precipitation on the x axis and mean temperature on the y axis.

Within the plot of the graph are shaded areas that specify a climate type.

The region is then plotted on the graph with the shaded area it falls in predicting its climate.

Question 53

What is a ’biome’?

Answer 53

A major life zone characterized by vegetation type (in terrestrial biomes) or by the physical environment (in aquatic biomes)

Each biome is characterised by microorganisms, fungi, and animals adapted to that particular environment.

Question 54

In what biome is arbuscular mycorrhizae most frequently found?

Answer 54

Temperate regions.

Question 55

What are the boundaries between terrestrial biomes called?

Answer 55

‘Ecotones’

Question 56

What is an ‘ecotone’?

Answer 56

The boundary between two terrestrial biomes

Question 57

How wide is a typically ecotone?

Answer 57

It varies considerably.

Question 58

What are the major terrestrial ecosystems?

Answer 58

Tropical forrest, desert, savanna, chaparral, temperate grassland, northern coniferous forest, temperate broadleaf forest and tundra

Question 59

How stable are biomes?

Answer 59

Not: they are dynamic and exist in a ‘dynamic equilibrium’ due to many ‘disturbances’.

Question 60

In terms of ecology, what is a disturbance?

Answer 60

A event that changes a community such as by removing organisms from it or affecting resource availability.

Question 61

What are some examples of ecosystem disturbances?

Answer 61

Fire, storms, pest outbreaks or human activity.

Question 62

Why are disturbances important to an environment?

Answer 62

• By removing a predator they can allow its prey to increase in population
• By burning the leaf litter, forest fires remove old trees and thus allow new ones to grow.
• It can expose new habitats such as a log falling of a tree during a storm.

Question 63

In what biomes are wildfires considered essential?

Answer 63

Grasslands, savannahs, chaparral and many coniferous forests.

Question 64

What is the distribution of tropical forests?

Answer 64

Equatorial and subequatorial regions

Question 65

What is the distribution of deserts?

Answer 65

Deserts occur in bands near 30° north and
south latitude or at other latitudes in the interior of continents (for instance, the Gobi Desert of north-central Asia).

Question 66

What is the distribution of savannah?

Answer 66

Equatorial and subequatorial regions

Question 67

What is the distribution of chaparral?

Answer 67

It is found across the world particularly in midlatitude coastal regions like California, South Africa and southern France.

Question 68

What is the distribution of temperate grasslands?

Answer 68

Across the world but primarily in the northern Hemisphere.

They are typically at the interior of continents such as at the centre of the US and in central Russia.

Question 69

What is the distribution of northern coniferous forests?

Answer 69

Extending in a broad band across northern

North America and Eurasia to the edge of the arctic tundra,

Question 70

What is the distribution of temperate broadleaf forests?

Answer 70

Found mainly at midlatitudes in the Northern Hemisphere, with smaller areas in Chile, South Africa, Australia, and New Zealand

Question 71

What is the distribution of tundra?

Answer 71

Tundra covers expansive areas of the Arctic, amounting to 20% of Earth’s land surface.

High winds and low temperatures produce simi- lar plant communities, called alpine tundra, on very high mountaintops at all latitudes, including the tropics.

Question 72

Where are the ‘Pampas’ found and what biome are they?

Answer 72

In Argentina and Uruguay. They are Temperate Grasslands.

Question 73

Where are ‘Puztas’ found and what biome are they?

Answer 73

In Hungary. They are Temperate Grasslands.

Question 74

What are ’Northern Coniferous Forests’ also called?

Answer 74

Taiga

Question 75

What does ’Taiga’ refer to?

Answer 75

A northern coniferous forest.

Question 76

What is the largest biome on earth by land area?

Answer 76

The northern coniferous forests i..e Taiga.

Question 77

What are the typical precipitation of Tropical Rainforests?

Answer 77

Rainfall is relatively constant, about 200–400 cm annually. In tropical dry forests, precipitation is highly seasonal, about 150–200 cm annually, with a six- to seven- month dry season.

Question 78

What are the typical precipitation of Deserts?

Answer 78

Low and highly variable, generally less than 30 cm per year.

Question 79

What are the typical precipitation of Savannah?

Answer 79

Rainfall is seasonal and averages 30–50 cm per year. The dry season can last up to eight or nine months.

Question 80

What are the typical precipitation of Chaparral?

Answer 80

Precipitation is highly seasonal, with rainy winters and dry summers. Annual precipitation generally falls within the range of
30–50 cm.

Question 81

What are the typical precipitation of Temperate Grassland?

Answer 81

Precipitation is often highly seasonal, with relatively dry winters and wet summers. Annual precipitation generally averages between 30 and 100 cm.

Periodic drought is common.

Question 82

What are the typical precipitation of Northern Coniferous Forests?

Answer 82

Annual precipi- tation generally ranges from 30 to 70 cm, and periodic droughts are common.

However, some coastal coniferous forests of the US have 300 cm of rain per year

Question 83

What are the typical temperature of Tropical Rainforests?

Answer 83

High year- round, averaging 25–29°C with little seasonal variation

Question 84

What are the typical temperature of Deserts?

Answer 84

Temperature is variable seasonally and daily. Maximum air temperature in hot deserts may exceed 50°C Often very cold at night

Iin cold deserts air temperature may fall below –30°C.

Question 85

What are the typical temperature of Savannah?

Answer 85

Warm year-round, averaging 24–29°C, but more seasonal variation than in tropical forests.

Question 86

What are the typical temperature of Chaparral?

Answer 86

Fall, winter, and spring are cool,with average temperatures in the range of 10–12°C.

Question 87

What are the typical temperature of Temperate Grassland?

Answer 87

Winters are generally cold, often below –10°C.

Summers, are hot, often approaching 30°C

Question 88

What are the typical temperature of Northern Coniferous Forests?

Answer 88

Winters are very cold, summers reasonably warm

Some in Siberia go from -50ºC in the winter to 20ºC in the summer.

Question 89

What are the typical plants of Tropical Rainforests?

Answer 89

Tropical forests are vertically layered with a canopy layer, one or two ‘subcanopy’ layers then shrubs at the bottom. There are generally fewer layers in tropical dry forests.

Broadleaf evergreen trees are dominant in tropical rain forests, whereas many tropical dry forest trees drop their leaves during the dry season.

Epiphytes such as bromeliads and orchids generally cover tropical forest trees but are less abundant in dry forests. Thorny shrubs and succulent plants are found in some tropical dry forests.

Question 90

What are the typical plants of Deserts?

Answer 90

Due to low water the vegetation is sparse. Most plants are shrubs and herbs that grow in the intermittent wet periods.

Most plants are succulent to store water between wet periods. This water is often protected with spines and chemical defences

Question 91

What are the typical plants of Savannah?

Answer 91

Vast grasslands with scattered trees, often with small leaves and spines.

Question 92

What are the typical plants of Chaparral?

Answer 92

Mostly shrubs and small trees, along with many kinds of grasses and herb.

Adaptations to drought include the tough evergreen leaves of woody plants to water loss.

Many shrubs produce seeds which only germinate during the frequent fires.

Question 93

What are the typical plants of Temperate Grassland?

Answer 93

Mostly grasses and ‘forbs’, Some grasses grow up to 2 metres.

The plants re well adapted to periodic droughts and fires.

Question 94

What are the typical plants of Northern Coniferous Forests?

Answer 94

Dominated by cone-bearing trees, such as pine, spruce, fir, and hemlock.

Question 95

What are the typical animals of Tropical Rainforests?

Answer 95

Extremely diverse with vast numbers of spiders, insects, amphibians, reptiles, birds and mammals

Question 96

What are the typical animals of Deserts?

Answer 96

Common desert animals include snakes and lizards, scorpions, ants, beetles, migratory and resident birds, and seed-eating rodents. Many species are nocturnal.

Water conservation is a common adaptation, with some species surviving solely on water from breaking down carbohydrates in seeds.

Question 97

What are the typical animals of Savannah?

Answer 97

Large plant-eating mammals, such as wildebeests and zebras, and predators, including lions and hyenas, are common inhabitants.

The most prevalent herbivores are insects like ’termites’ and locusts.

Question 98

What are the typical animals of Chaparral?

Answer 98

Mostly browsers, such as deer and goats, that feed on twigs and buds of woody vegetation

Also a high diversity of small mammals, amphibians, birds, reptiles and insects.

Question 99

What are the typical animals of Temperate Grassland?

Answer 99

Native mammals include large grazers such as bison and wild horses.

Temperate grasslands are also inhabited by a wide variety of burrowing mammals, such as prairie dogs in North America.

Question 100

What are the typical animals of Northern Coniferous Forests?

Answer 100

Many migratory birds nest in northern coniferous forests, other species reside there year-round. Also includes mammals such as moose, brown bears, and Siberian tigers.

Periodic outbreaks of insects that feed on the dominant trees can kill vast tracts of trees.

Question 101

What is a sub biome of tropical rainforest and how does it differ?

Answer 101

’Tropical dry forest’ in which the precipitation is slightly less but more seasonal with a 6-moth dry season.

Question 102

Why are deserts typically cold at night?

Answer 102

They are far from the sea which acts has a large SHC so warms the land during the night.

Question 103

What are non-woody, non-grass plants grouped as?

Answer 103

‘Forbs’

Question 104

What does ‘Forbs’ refer to?

Answer 104

Non-woody plants which aren’t grasses.

Question 105

In what biome is plant diversity greater: northern coniferous forests or temperate broadleaf?

Answer 105

Temperate Broadleaf

Question 106

What is the advantage of the conical shapes of pine cones?

Answer 106

They prevent snow from building up.

Question 107

Why do pine tress have needles?

Answer 107

They reduce water loss and prevent snow from piling up.

Question 108

What terrestrial ecosystem has the greatest animal diversity?

Answer 108

Tropical rainforest.

Question 109

What is the typical temperature of Temperate broadleaf forests?

Answer 109

Winter temperatures average around 0°C.

Summers are hot and humid at up to 35ºC

Question 110

What is the typical temperature of Tundra?

Answer 110

Winters are cold, with averages in some areas below –30°C.

Summer temperatures generally average less than 10°C.

Question 111

What is the typical precipitation of Temperate broadleaf forests?

Answer 111

Precipitation can average from about 70 to over 200 cm annually.

Significant amounts fall during all seasons, including summer rain and, in some forests, winter snow.

Question 112

What is the typical precipitation of Tundra?

Answer 112

Precipitation averages from 20 to 60 cm annually in arctic tundra but may exceed 100 cm in alpine tundra.

Question 113

What is a sub biome of Tundra?

Answer 113

Alpine tundra which is found on the side of mountains

Question 114

What are the typical animals of Tundra?

Answer 114

Large grazing musk oxen are resident, while caribou and reindeer are migratory. Predators include bears, wolves, and foxes.

Many bird species migrate to the tundra for summer nesting.

Question 115

What are the typical animals of Temperate Broadleaf Forests?

Answer 115

In the Northern Hemisphere, many mammals hibernate in winter, while many bird species migrate to warmer climates.

Mammals, birds, and insects make use of all the vertical layers of the forest.

Question 116

Besides rainforests, what biomes have multiple layer?

Answer 116

All forest biomes

Question 117

What are the typical plants of Temperate Broadleaf Forests?

Answer 117

mature temperate broadleaf forest has distinct
vertical layers, including a closed canopy, one or two strata of understory trees, a shrub layer, and an herb layer.

There are few epiphytes. The dominant plants in the Northern Hemisphere are deciduous trees, which drop their leaves before winter, when low temperatures would reduce photosynthesis and make water uptake from frozen soil difficult.

In Australia, evergreen eucalyptus trees dominate these forests.

Question 118

What are the typical plants of Tundra?

Answer 118

The vegetation of tundra is mostly herbaceous, consisting of a mixture of mosses,
grasses, and forbs, along with some dwarf shrubs and trees and lichens.

A permanently frozen layer of soil called permafrost restricts the growth of plant roots.

Question 119

What does ‘permafrost’ refer to?

Answer 119

A permanently frozen layer of soil

Question 120

What is a permanently frozen layer of soil called?

Answer 120

Permafrost

Question 121

What is an important property aquatic environments?

Answer 121

They have zones

Question 122

What are the zones in lake?

Answer 122

It has a ‘littoral zone’ which consists of the extremely shallow water. The rest of the water is in the ‘limnetic zone’

The top of the water is called the ‘photic zone’ as it can be reached by sunlight. The ‘aphasic zone’ below cannot be.

They water around the bottom of the lake is the ‘benthic zone’. The rest is the ‘pelagic zone’

Note that these zones are not mutual exclusive i.e ash organism can be in the photic zone and the limnetic zone simultaneously.

Question 123

What are the zones in the ocean?

Answer 123

It has a ’neritic’ which consists of the extremely shallow water. The rest of the water is in the ‘oceanic zone’

It has a ‘intertidal zone’ which is covered by water or not depending on the tide.

The top of the water is called the ‘photic zone’ as it can be reached by sunlight. The ‘aphasic zone’ below cannot be.

They water around the bottom of the lake is the ‘benthic zone’. The rest is the ‘pelagic zone’ if it is above 6000m or the ‘abyssal zone’ if it is below.

Question 124

What are the organisms which live in the benthic zone called?

Answer 124

The ‘Benthos’

Question 125

What does ‘benthos’ refer to?

Answer 125

The organisms that live in the benthic zone.

Question 126

What are the conditions in the photic zone?

Answer 126

• High sunlight
• High oxygen
• Relatively low detritus except in the Benthic zone

Question 127

What are the conditions of the benthic zone?

Answer 127

• Low sunlight
• Low oxygen
• Relatively low detritus except in the Benthic zone

Question 128

How does the temperature of a lake vary as the depth increases?

Answer 128

It is warm at the surface and drops suddenly below the photic zone. This sudden drop is called the ’thermocline’

Question 129

What dose ’thermocline’ refer to?

Answer 129

The sudden drop in temperature seen in lakes as depth increases.

Question 130

What is a major source of food for the ‘benthos’?

Answer 130

Detritus

Question 131

What is a major consequence of the ’thermocline’?

Answer 131

It leads to ’seasonal turnover’

Question 132

What is ’seasonal turnover’?

Answer 132

The seasonal movement of water between the layers of the lake.

Question 133

Why is seasonal turnover important?

Answer 133

By tuning over the water it provides oxygenated water to the bottom of the lake and brings up nutrient rich detritus to the surface from the benthic zone.

Question 134

How does ’seasonal turnover’ occur?

Answer 134

In winter, the coldest water in the lake (0°C) lies just below the surface ice; water becomes progressively warmer at deeper levels of the lake, typically 4°C at the bottom.

In spring, as the ice melts, the surface water warms to 4°C and mixes with the formerly cooler layers below, eliminating thermal stratification. Spring winds help mix the water, bringing oxygen to the bottom waters and nutrients to the surface.

In summer, the lake regains a distinctive thermal profile, with warm surface water separated from cold bottom water by a narrow vertical zone of abrupt temperature change, called a thermocline.

In autumn, as surface water cools rapidly, it sinks beneath the underlying layers, remixing the water until the surface begins to freeze and the winter temperature profile is reestablished.

Question 135

What are the major aquatic biomes?

Answer 135

Lakes, Wetlands, Streams/Rivers, Estuaries, Intertidal Zones, Oceanic Pelagic Zone, Coral Reefs and Marine Benthic zone.

Question 136

What is the physical environment of lakes?

Answer 136

Standing bodies of water range from ponds a few square meters in area to lakes covering thousands of square kilometers. Light decreases with depth, creating stratification.

Temperate lakes may have a seasonal thermocline; tropical lowland lakes have a thermocline year-round.

Question 137

What is the physical environment of wetlands?

Answer 137

A wetland is a habitat that is inundated by water at least some of the time and that supports plants adapted to water-saturated soil. Some wetlands are inundated at all times, whereas others flood infrequently.

Question 138

What is the physical environment of streams/rivers?

Answer 138

The main characteristic of streams and rivers is their current. Headwater streams are generally cold, clear, turbulent and swift.

Farther downstream, where numerous tributaries may have joined, forming a river, the water is generally warmer and more turbid because of suspended sediment.

Streams and rivers are stratified into vertical zones.

Question 139

What is the physical environment of estuaries?

Answer 139

They are a transition area between river and sea. Seawater flows up the estuary channel during a rising tide and flows back down during the falling tide.

Often, higher-density sea-water occupies the bottom of the channel and mixes little with the lower-density river water at the surface.

Question 140

What is the physical environment of intertidal zones?

Answer 140

An intertidal zone is periodically submerged and exposed by the tides, twice daily on most marine shores.

Upper zones experience longer exposures to air and greater variations in temperature and salinity.

Changes in physical conditions from the upper to the lower intertidal zones limit the distributions of many organisms to particular strata.

Question 141

What is the physical environment of oceanic pelagic zones?

Answer 141

The oceanic pelagic zone is a vast realm of open blue water, constantly mixed by wind-driven oceanic currents. Because of higher water clarity, the photic zone extends to greater depths than in coastal marine waters.

Question 142

What is the physical environment of coral reefs?

Answer 142

Coral reefs are formed largely from the calcium carbonate skeletons of corals. Shallow reef building corals live in the photic zone of relatively stable tropical marine environments with high water clarity, primarily on islands and along the edge of some continents.

They are sensitive to temperatures below about 18–20°C and above 30°C. Deep-sea coral reefs, found between 200 and 1,500 m deep, are less known than their shallow counterparts but harbor as much diversity as many shallow reefs do.

Question 143

What is the physical environment of marine benthic zones?

Answer 143

The marine benthic zone consists of the seafloor below the surface waters of the coastal, or neritic, zone and the off-shore, pelagic zone. Except for shallow, near-coastal areas, the marine benthic zone receives no sunlight.

Water temperature declines with depth, while pressure increases. As a result, organisms in the very deep benthic, or abyssal, zone are adapted to continuous cold (about 3°C) and very high water pressure.

Question 144

What is the chemical environment of lakes?

Answer 144

The salinity, oxygen concentration, and nutrient content differ greatly among lakes and can vary with season. Oligotrophic lakes are nutrient-poor
and generally oxygen-rich; eutrophic lakes are nutrient-rich and often depleted of oxygen in the deepest zone in summer and if covered with ice in winter.

The amount of decomposable organic matter in bottom sediments is low in oligotrophic lakes and high in eutrophic lakes; high rates of decomposition in deeper layers of eutrophic lakes cause periodic oxygen depletion.

Question 145

What is the chemical environment of wetlands?

Answer 145

Because of high organic production by plants and decomposition by microbes and other organisms, both the water and the soils are periodically low in dissolved oxygen.

Wetlands have a high capacity to filter dissolved nutrients and chemical pollutants.

Question 146

What is the chemical environment of streams/rivers?

Answer 146

The salt and nutrient content of streams and rivers increases from the headwaters to the mouth.

Headwaters are generally rich in oxygen. Downstream water may also contain substantial oxygen, except where there has been organic enrichment.

A large fraction of the organic matter in rivers consists of dissolved or highly fragmented material that is carried by the current from forested streams.

Question 147

What is the chemical environment of estuaries?

Answer 147

Salinity varies spatially within estuaries, from nearly that of fresh water to that of seawater. Salinity also varies with the rise and fall of the tides.

Nutrients from the river make estuaries, like wetlands, among the most productive biomes.

Question 148

What is the chemical environment of intertidal zones?

Answer 148

Oxygen and nutrient levels are generally high and are renewed with each turn of the tides.

Question 149

What is the chemical environment of oceanic pelagic zones?

Answer 149

Oxygen levels are generally high. Nutrient concentrations are generally lower than in coastal waters.

Because they are thermally stratified year-round, some tropical areas of the oceanic pelagic zone have lower nutrient concentrations than temperate oceans. Turnover between fall and spring renews nutrients in the photic zones of temperate and high-latitude ocean areas.

Question 150

What is the chemical environment of coral reefs?

Answer 150

Corals require high oxygen levels and are excluded by high inputs of fresh water and nutrients.

Question 151

What is the chemical environment of marine benthic zones?

Answer 151

Except in areas of organic enrichment, oxygen is usually present at sufficient concentrations to support diverse animal life.

Question 152

What are the geologic features of lakes?

Answer 152

Oligotrophic lakes may become more eutrophic over time as runoff adds sediments and nutrients.

They tend to have less surface area relative to their depth than eutrophic lakes.

Question 153

What are the geologic features of wetlands?

Answer 153

‘Basin’ wetlands develop in shallow basins, ranging from upland depressions to filled-in lakes and ponds.

‘Riverine’ wetlands develop along shallow and periodically flooded banks of rivers and streams.

‘Fringe’ wetlands occur along the coasts of large lakes and seas, where water flows back and forth because of rising lake levels or tidal action. Thus, fringe wetlands include both freshwater and marine biomes.

Question 154

What are the geologic features of streams/rivers?

Answer 154

Headwater stream channels are often narrow, have a rocky bottom, and alternate between shallow sections and deeper pools.

The downstream stretches of rivers are generally wide and meandering.

River bottoms are often silty from sediments deposited over long periods of time.

Question 155

What are the geologic features of estuaries?

Answer 155

Estuarine flow patterns combined with the sediments carried by river and tidal waters create a complex network of tidal channels, islands, natural levees, and mudflats.

Question 156

What are the geologic features of intertidal zones?

Answer 156

The substrates of intertidal zones, which are generally either rocky or sandy, select for particular behavior and anatomy among intertidal organisms.

The configuration of bays or coastlines influences the magnitude of tides and the relative exposure of intertidal organisms to wave action.

Question 157

What are the geologic features of oceanic pelagic zones?

Answer 157

This biome covers approximately 70% of Earth’s surface and has an average depth of nearly 4,000 m. The deepest point in the ocean is more than 10,000 m beneath the surface.

Question 158

What are the geologic features of coral reefs?

Answer 158

Corals require a solid substrate for attachment.

A typical coral reef begins as a ‘fringing reef’ on a young, high island, forming an offshore ‘barrier reef’ later in the history of the island and becoming a ‘coral atoll’ as the older island submerges.

Question 159

What are the geologic features of marine benthic zones?

Answer 159

Soft sediments cover most of the benthic zone. However, there are areas of rocky substrate on reefs, submarine mountains, and new oceanic crust.

Question 160

What are the autotrophs of lakes?

Answer 160

Rooted and floating aquatic plants live in the ‘littoral zone’, the shallow, well-lit waters close to shore.

Farther from shore, where water is too deep to support rooted aquatic plants, the ‘limnetic zone’ is inhabited by a variety of phytoplankton, including cyanobacteria.

Question 161

What are the autotrophs of wetlands?

Answer 161

Wetlands are among the most productive biomes on Earth.

Their water-saturated soils favor the growth of plants such as floating pond lilies and emergent cattails, many sedges, tamarack, and black spruce, which have adaptations enabling them to grow in water or in soil that is periodically anaerobic owing to the presence of unaerated water.

Woody plants dominate the vegetation of swamps, while bogs are dominated by sphagnum mosses.

Question 162

What are the autotrophs of streams/rivers?

Answer 162

Headwater streams that flow through grasslands or deserts may be rich in phytoplankton or rooted aquatic plants.

Question 163

What are the autotrophs of estuaries?

Answer 163

Saltmarsh grasses and algae, including phytoplankton, are the major producers in estuaries.

Question 164

What are the autotrophs of intertidal zones?

Answer 164

A high diversity and biomass of attached marine algae inhabit rocky intertidal zones, especially in the lower zone.

Sandy intertidal zones exposed to vigorous wave action generally lack attached plants or algae, while sandy intertidal zones in protected bays or lagoons often support rich beds of seagrass and algae.

Question 165

What are the autotrophs of oceanic pelagic zones?

Answer 165

The dominant photosynthetic organisms are phytoplankton, including photosynthetic bacteria, that drift with the oceanic currents.

Spring turnover renews nutrients in temperate oceans producing a surge of phytoplankton growth.

Because of the large extent of this biome, photosynthetic plankton account for about half of the photosynthetic activity on Earth.

Question 166

What are the autotrophs of coral reefs?

Answer 166

Unicellular algae live within the tissues of the corals, forming a mutualistic relationship that provides the corals with organic molecules.

Diverse multicellular red and green algae growing on the reef also contribute substantial amounts of photosynthesis.

Question 167

What are the autotrophs of marine benthic zones?

Answer 167

Photo- synthetic organisms, mainly seaweeds and filamentous algae, are limited to shallow benthic areas with sufficient light to support them.

Unique assemblages of organisms are found near deep-sea hydrothermal vents on mid-ocean ridges.

In these dark, hot environments, the food producers are chemoautotrophic prokaryotes that obtain energy by oxidizing H2S formed by a reaction of the hot water with dissolved sulfate (SO42–).

Question 168

What are the heterotrophs of lakes?

Answer 168

In the limnetic zone, small drifting heterotrophs, or zooplankton, graze on the phytoplankton.

The benthic zone is inhabited by assorted invertebrates whose species composition depends partly on oxygen levels.

Fishes live in all zones with sufficient oxygen.

Question 169

What are the heterotrophs of wetlands?

Answer 169

Wetlands are home to a diverse community of invertebrates, birds, and many other organisms.

Herbivores, from crustaceans and aquatic insect larvae to muskrats, consume algae, detritus, and plants.

Carnivores are also varied and may include dragonflies, otters, frogs, alligators, and herons.

Question 170

What are the heterotrophs of streams/rivers?

Answer 170

A great diversity of fishes and invertebrates inhabit unpolluted rivers and streams, distributed according to, and throughout, the vertical zones.

In streams flowing through temperate or tropical forests, organic matter from terrestrial vegetation is the primary source of food for aquatic consumers.

Question 171

What are the heterotrophs of estuaries?

Answer 171

Estuaries support an abundance of worms, oysters, crabs, and many fish species that humans consume.

Many marine invertebrates and fishes use estuaries as a breeding ground or migrate through them to freshwater habitats upstream.

Estuaries are also crucial feeding areas for waterfowl and some marine mammals.

Question 172

What are the heterotrophs of intertidal zones?

Answer 172

Many of the animals in rocky intertidal environments have structural adaptations that enable them to attach to the hard substrate.

The composition, density, and diversity of animals change markedly from the upper to the lower intertidal zones.

Many of the animals in sandy or muddy intertidal zones, such as worms, clams, and predatory crustaceans, bury themselves and feed as the tides bring sources of food. Other common animals are sponges, sea anemones, echinoderms, and small fishes.

Question 173

What are the heterotrophs of oceanic pelagic zones?

Answer 173

The most abundant heterotrophs in this biome are zooplankton. These protists, worms, copepods, shrimp-like krill, jellies, and small larvae of invertebrates and fishes graze on photosynthetic plankton.

The oceanic pelagic zone also includes free-swimming animals, such as large squids, fishes, sea turtles, and marine mammals.

Question 174

What are the heterotrophs of coral reefs?

Answer 174

Corals, a diverse group of cnidarians, are themselves the predominant animals on coral reefs.

However, fish and invertebrate diversity is exceptionally high. Overall animal diversity on coral reefs rivals that of tropical forests.

Question 175

What are the heterotrophs of marine benthic zones?

Answer 175

‘Neritic benthic’ communities include numerous invertebrates and fishes. Beyond the photic zone, most consumers depend entirely on organic matter raining down from above.

Among the animals of the deep-sea hydrothermal vent communities are giant tube worms, some more than 1 m long. They are nourished by chemoautotrophic prokaryotes that live as symbionts within their bodies.

Many other invertebrates, including arthropods and echinoderms, are also abundant around the hydrothermal vents.

Question 176

What is the word for a nutrient poor region?

Answer 176

‘Oligotrophic’

Question 177

What is the word for a nutrient rich region?

Answer 177

‘Eutrophic’

Question 178

What does ‘Eutrophic’ refer to?

Answer 178

A nutrient rich region

Question 179

What does ‘Oligotrophic’ refer to?

Answer 179

A nutrient poor region

Question 180

What does ‘gyre’ refer to?

Answer 180

A circular current