aquatic-benthic.html: 50_17AquaticBiomes-benthic.jpg
The marine benthic zone consists of the seafloor below the surface waters of the coastal, or neritic,
zone and the offshore, pelagic zone.
The very deep benthic, or abyssal, zone are adapted to continuous cold and extreme pressures.
Around deep-sea hydrothermal vents, which are sites of volcanic activity on mid-ocean ridges, the producers are chemoautotrophic prokaryotes that obtain energy by oxidizing H2S formed by a reaction of hot water with dissolved sulfate (SO42-).
A diverse community
of exotic organisms
live in this lightless world.
aquatic-coral.html: 50_17AquaticBiomes-coral.jpg
_MID_CoralReef-V.swf 0 Coral_Reef
A coral reef is formed from the calcium carbonate skeletons of corals in the photic zone of marine
environemnts with high water quality.
It begins as a fringing reef on young islands, forming an offshore barrier reef as the island submerges, and eventually becoming an atoll with an inner lagoon.
Dinoflagellate algae live symbiotically within the tissues of coral animals.
Red and green algae also contribute photosynthetic activity to this biome, making it the most productive of all the biomes.
aquatic-estuary.html: 50_17AquaticBiomes-estuary.jpg
An estuary is a transition area between river and sea, often bordered by mudflats and salt marshes.
The mixing of fresh and saline water in this ecotone, together with nutrients from the river,
make estuaries among the most productive biomes.
aquatic-intertidal.html: 50_17AquaticBiomes-intertidal.jpg
An intertidal zone is periodically submerged and exposed by the tides.
Organisms must adapt to either rocky or sandy substrates that have fluctuating levels of water.
aquatic-lake.html: 50_17AquaticBiomes-lake.jpg
Standing bodes of water range from small ponds to large lakes.
Oligotrophic lakes are nutrient-poor and generally oxygen-rich.
Eutrophic lakes are nutrient rich and often depleted of oxygen.
Seasonal turnover in temperate regions allow mixing of oxygen and nutrients.
Rooted and floating aquatic plants live in the littoral zone, the shallow, well-lighted waters close to shore.
The limnetic zone is inhabited by phytoplankton and cyanobacteria.
aquatic-pelagic.html: 50_17AquaticBiomes-pelagic.jpg
The oceanic pelagic biome is a vast realm of open water
, mixed by wind-driven oceanic currents.
Nutrient levels are generally low, leading to low productivity.
aquatic-stream.html: 50_17AquaticBiomes-stream.jpg
Moving water (current) is characteristic of streams and rivers,
and they are often oxygen-rich.
Small aquatic organisms must adapt to the moving water to avoid being swept downstream,
and the presence of pollution-intolerant aquatic
macroinverbrates
are often used as an indicator of water quality.
aquatic-wetland.html: 50_17AquaticBiomes-wetland.jpg
A wetland has water-logged soil that supports aquatic plants.
Because of the high organic production and decomposition, both the waters and soils are low in dissolved oxygen.
Wetlands are ecotones between aquatic and terrestrial environments.
aquatic_zonation.html: 50_16AquaticZonation.jpg
| Zonation in a lake. Light penetration: photic, aphotic Distance from shore: littoral, limnetic Water depth: pelagic, benthic | Marine zonation. Light penetration: photic, aphotic Distance from shore: intertidal, neritic, oceanic Water depth: pelagic, benthic, abyssal |
biogeography.html: 50_06GeogDistribLimits.jpg
Flowchart of factors limiting geographic distribution.
As ecologists study the factors limiting a species' distribution, they often consider a series of questions like these.
climate_change.html: 50_14ClimatChangTreeDist.jpg
Current range and predicted range for the American beech (Fagus grandifolia) under two scenarios of climate change.
Climate is the prevailing weather conditions in a particular area.
ecology.html: 50_03EcologySubfields.jpg
grackle.html: 50_07GrackleSpread.jpg
Spread of breeding populations of the great-tailed grackle in the United States from 1974 to 1996.
The grackle expanded its breeding range substantially in just 22 years.
kangaroo.html: 50_02KangarooDistribution.jpg
Red kangaroos do not live in regions around the periphery of Australia,
where the climate varies from moist to wet.
They are most abundant in a few areas where the climate is drier and more variable from year to
year.
mountain.html: 50_12RainShadow.jpg
When warm, moist air approaches a mountain, the air rises and cools, releasing moisture
on the windward side.
On the leeward side, cooler, dry air descends, absorbing moisture and
photic.html: 50_16AquaticZonation.jpg
The photic zone is a zone of sunlight penetration, approximately 200 meters under ideal conditions.
rain.html: 50_10AirCircRainPatterns.jpg
GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS
High temperatures in the tropics evaporate water.
Warm, wet air rises, creating abundant precipitation.
Dry air descend and create an arid climate at around 30° latitude.
The air masses again rise and release moisture
in the vicinity of 60° latitude.
Cold, dry air then flows to the poles, where it descends, creating dry and cold climates.
realms.html: 50_05BiogeographicRealms.jpg
Biogeographic realms.
Continental drift and barriers such as deserts and mountain ranges all contribute to the distinctive flora and fauna found in
Earth's major biogeographic realms. The realms are not sharply delineated but grade together in zones where species from adjacent realms coexist.
seasons.html: 50_10SunIntensSeasonVar.jpg sunlight.html: 50_10SunIntensityLatVar.jpg terrestrial-broadleaf.html: 50_20TerrestrialBiomes-broadleaf.jpg terrestrial-chaparral.html: 50_20TerrestrialBiomes-chaparral.jpg terrestrial-coniferous.html: 50_20TerrestrialBiomes-coniferous.jpg terrestrial-desert.html: 50_20TerrestrialBiomes-desert.jpg terrestrial-grassland.html: 50_20TerrestrialBiomes-grassland.jpg terrestrial-savanna.html: 50_20TerrestrialBiomes-savanna.jpg terrestrial-tropical.html: 50_20TerrestrialBiomes-tropical.jpg terrestrial-tundra.html: 50_20TerrestrialBiomes-tundra.jpg terrestrial.html: 50_18Climograph.jpg turnover.html: 50_13LakeStratTurnover_1.jpg turnover2.html: 50_13LakeStratTurnover_2.jpg turnover3.html: 50_13LakeStratTurnover_3.jpg turnover4.html: 50_13LakeStratTurnover_4.jpg urchin.html: 50_08PredatLimitsSeaweed.jpg water.html: 50_11WaterModeratesTemp.jpg wind.html: 50_10WindPatterns.jpg wind2.html: 50_09WindEffectsTrees.jpg
SEASONAL VARIATION IN SUNLIGHT INTENSITY
Because the planet is tilted on its axis
by 23.5
LATITUDINAL VARIATION IN SUNLIGHT INTENSITY
Earth’s curved shape causes latitudinal variation in the intensity of sunlight.
Because sunlight strikes the equator perpendicularly, the most heat and light
per unit of surface area are delivered there.
Temperate broadleaf forests are found in regions of temperate temperatures and
precipitation
(70 - 200 cm annually).
In the Northern Hemisphere, deciduous trees dominate the forest composed of distinct and diverse vertical layers,
including a closed canopy, understory, a shrub layer, and an herbaceous floor.
In Australia, evergreen eucalyptus trees dominate these forests.
This biome occurs in midlatitude coastal regions, and is called
chaparral in North America,
matorral in Spain,and Chile,
garigue and maquis in southern France, and
fymbos in South Africa.
Precipitation is highly seasonal, with dry summers and rainy winters whose temperatures are moderated by
coastal waters;
this climate pattrern is also known as Mediterranean in Europe.
Shrubs and small trees dominate the landscape; organisms are well adapted to drought and fire regimes.
The northern coniferous forest , or taiga is the largest terrestrial biome,
with cold and long winters.
Cone-bearing and conical shaped trees, such as pine, spruce, fir, and hemlock, dominate, often excluding other plants.
The reduced diversity in plant species makes these forests vulnerable to periodic insect outbreaks.
Deserts occur in a band near 30° north and south latitude or in the interior of
continents, generally with less than 32 cm per year of precipitation.
Organisms must adapt to the heat and dessication found in this biome.
Temperate grasslands occur in temperate plains:
the veldts of South Africa,
the puszta of Hungary,
the pampas of Argentina and Uruguay,
the steppes of Russia, and the plains
and prairies of central North America.
Precipitation is moderate
(30 - 100 cm per year) but highly with seasonal: relatively cold, dry winters and hot, wet summers with periodic droughts.
Grasses and forbs dominate the landscape and are adapted to the periodic droughts and fires
and prevent establishment of woody shrubs and trees.
The savanna has warm (24-29°C) and dry (30-50 cm rain per year) climate,
with scattered trees and periodic fires in a grass-dominated landscape.
Insects, especially termites, are the dominant herbivores. Larger grazing mammals must migrate during seasonal droughts.
In tropical rain forests, 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.
The diversity of life in tropical rain forests is higher than in any other biome.
Tundra occupy the cold expanses of the polar
(arctic tundra) and high mountains
(alpine tundra) regions.
A permanently frozen layer of soil called permafrost prevents water infiltration.
Plants are small and herbaceous, consisting of lichens, mosses, grasses, and forbs, with few shrubs and trees.
1
In winter, the coldest water in the lake (0°C) lies just
below the surface ice; water is progressively warmer at deeper levels of the lake, typically 4–5°C at the bottom.
2
2
In spring, as ice melts, the surface water warms to 4°C and sinks, eliminating the thermal stratification.
Spring winds mix the water, bringing oxygen (O2) to the bottom waters and nutrients to the surface.
3
3
In summer, the lake regains a distinctive thermal profile,
with warm surface water separated from cold bottom water by a narrow vertical zone of rapid temperature change,
called a thermocline.
4
4
In autumn, surface water cools and sinks below the underlying layers,
remixing the water until the surface begins to freeze and the winter temperature profile is reestablished.
1
In Australia, urchins and limpets feed on seaweed.
Selective removal of these predators from the habitat shows that urchins have a much greater effect
than limpets in limiting seaweed distribution.
During a warm summer day, hot air rises over the land, drawing a cool breeze from the water.
At night, air over the now warmer water rises,
reversing the circulation and drawing cooler air from the land out over the water
.
GLOBAL WIND PATTERNS due to the Coriolis Effect.
As Earth rotates on its axis, land near the equator moves faster than that at the poles, deflecting
winds
in prevailing bands.
Easterlies (trade winds) blow from east to west in the tropics.
Westerlies blow from west to east in temperate zones,
the regions between the tropics and the Arctic Circle or the Antarctic Circle.