Ecosystems and the Biosphere

3 types of ecosystems

freshwater (least common), marine (most common), and terrestrial (grouped into biomes)

food chain

linear sequence of organisms through which nutrients and energy pass as one organism eats another

food web

concept that accounts for the multiple trophic (feeding) interactions between each species and the many species it may feed on, or that feed on it

grazing food web

plants or other photosynthetic organisms at its base

why do grazing food webs have detrital food webs associated with them?

Grazing food webs have detrital food webs associated with them because not all energy and matter in an ecosystem is consumed by herbivores or predators — a lot of it becomes waste or dead material, which detrital food webs break down and recycle.

detrital food web

base of organisms that feed on decaying organic matter.  Includes decomposers - break down dead and decaying organisms, and detritivores – consume organic detritus.  Examples: bacteria, fungi, invertebrates like earthworms; 

equilibrium

dynamic state of an ecosystem in which, despite changes in species numbers and occurrence, biodiversity remains somewhat constant

resistance

ability of an ecosystem to remain at equilibrium despite disturbances

resilience

speed at which an ecosystem recovers equilibrium after being disturbed

trophic level

feeding level

Living things acquire energy in two ways

make their own or consume those that make their own

The vast majority of energy in most ecosystems enter as?

sunlight

chemotrophs

use inorganic molecules for a much smaller number of ecosystems

producers

 autotrophs that are capable of making their own food

photoautotrophs

use sunlight

chemoautotrophs

use inorganic molecules

Photoautotrophs include

plants, photosynthetic bacteria, and algae

Chemoautotrophs include

bacteria and archaea in dark caves and hydrothermal ocean vents

heterotrophs

acquire energy by consuming/eating producers.  Primary, Secondary, and Tertiary Consumers are all heterotrophs.  As one organism eats another, there is a loss of usable energy.

primary productivity

rate at which photosynthetic producers incorporate energy from the sun

biomagnification

increasing concentration of toxic substances that are fat soluble, not water soluble

these toxins are stored in the organisms’ fat reserves.  As they are consumed by higher trophic levels, the toxins are magnified.  One example is the use of the pesticide DDT

Which organism was affected by DDT because it caused their eggs to be fragile?

birds

6 important common elements in an ecosystem

carbon, nitrogen, hydrogen,  oxygen, phosphorus, and sulfur

biogeochemical cycle

recycling of inorganic matter between living organisms and their nonliving environment

how much of earths water is salt water?

97.5%

how much % of humans are water?

70

evaporation

heat from the sun causes surface water to evaporate into the atmosphere

sublimation

ice directly to water vapor

condensation and precipitation

water vapor condenses in the clouds and falls as rain or snow

subsurface water flow

groundwater exists between fissures in rocks or between particles in sand and gravel; groundwater replenishes the streams groundwater exists between fissures in rocks or between particles in sand and gravel; groundwater replenishes the streams

surface runoff and snowmelt

rainwater or melting snow travels to streams, then lakes, finally ocean.

streamflow

streams

lakes

ocean

carbon is the _ most abundant element in living things

4th

photosynthesis

takes carbon dioxide out of the atmosphere and converts it into sugar

cellular respiration

breaks down sugar to produce energy, but produces carbon dioxide as a waste product

the atmosphere is mostly what?

nitrogen gas 78%

cannot be used as plants or animals in this form

what fixes nitrogen gases into usable forms?

bacteria

ammonification

converts nitrogenous waste into ammounium

nitrification

converts ammonia into nitrites and nitrates

dentrification

converts nitrates back into nitrogen gas

what is the order of the carbon cycle?

nitrogen fixation

nitrification

assimilation

ammonification

dentrification

Why do living things need nitrogen?

Essential for life-sustanining molecules: makes up proteins, DNA and RNA, and it helps plants grow because nitrogen is in chlorophyll

how does phosphours occur in nature as the phosphate ion?

weathering rocks release the ion into rivers, lakes, and oceans

how do humans produce excess phosphours?

fertilizer runoff and sewage

causes overgrowth of algae, which depletes oxygen and leads to death of fish, which causes dead zones

dead zone

areas in bodies of water with very low oxygen

why do we need phosphours in our cells?

energy- ATP

genetics- DNA/RNA

cell structure- membranes

skeletal strenght

eutrophication

nutrient runoff causes the overgrowth of algae and a number of consequential problems

sulfur enters the atmosphere in 3 ways

decomposition of organic molecules, volcanic activity and geothermal  vents, and burning of fossil fuels

sulfur is deposited in four ways

precipitation

rock weathering

fallout from atmosphere

geothermal vents

what do fossil fuels release

hydrogen sulfide gas- leads to acid rain

what are biomes determined by?

temperature and precipitation

tropical rainforests

tropical wet forests, near the equatorial regions, most diverse of the terrestrial biomes, stable temperatures and not much variation from month to month, high net productivity, average annual rainfall 250cm-450cm, vertical layers of vegetation with distinct habitats within each layer

forest floor (tropical)

sparse plants and decaying plant matter

understory (tropical)

short shrubby foliage, trees

canopy

uppermost layer of branches and leaves

savannas

grasslands with scattered trees, hot tropical areas with an extensive dry season (fires), plants have a well-developed root systems to quickly sprout after a fire. (Africa, South America, Australia)

subtropical deserts

between 15^◦ and 30^◦ north and south latitude (Tropic of Cancer and Tropic of Capricorn), low precipitation, large temperature differences between day and night because there is so little humidity, little species diversity, not many perennial plants, but the few that exist have adaptation allowing for survival in a dry climate. (Sahara and Namib – Africa; Mohave and Sonoran – US; Outback – Australia

chaparral

“shrub forest” rainfall 65-75cm, very dry summers, many seeds only germinate after a hot fire, fire is a natural maintenance of this biome. (California, Mediterranean Sea, Southern coast of Australia)

temperate grasslands

prairies or steppes, hot summers and cold winters, grasses and few trees near rivers or streams, growing season during warm months, fires by lightning or humans (Central North America, Eurasia)

temperate forests

mid-latitude, temperatures -30C and 30C, defined growing season, precipitation constant throughout year, deciduous (lose their leaves) trees are dominant, leaf litter provides a habitat for invertebrates and their predators. (Eastern North America, Western Europe, Eastern Asia, Chile, New Zealand)

boreal forests

Taiga or Coniferous Forests, 50^◦ – 60^◦ North latitude, cold dry winter and short wet summers, Evergreens like pines, spruce and fir trees, needle leaves decompose slowly and return fewer nutrients to the soil. (Canada, Alaska, Russia, northern Europe)

artic tundra

Arctic regions of Northern Hemisphere, above tree line on mountains, low annual precipitation, short growing season, shrubs, grasses, lichens, and small flowering plants, permafrost – perennially frozen state and roots cannot penetrate into the soil.

oceans

include different zones based on depth and light

interidal zone

closest to land

tide causes inundation with water followed by dry period

neritic zone

depths of 200 m at edge of continental shelf, enough sunlight for photosynthesis, well oxygenated water, low pressure, stable temp., highest productivity and biodiversity in the ocean

phytoplaknton

photosynthetic bacteria and algae

zooplankton

feed on these producers and secondary consumers feed on these organisms

oceanic zone

nutrients are scare, less productive part

abyssal zone

depths of 4000 m., very cold with high pressure, invertebrates and fish, but no photosynthetic organisms, chemosynthetic bacteria use hydrogen sulfide as energy source.

coral reefs

formed by invertebrates in warm shallow waters, 30 north and south of equator.   Reef is composed of calcium carbonate skeletons of the invertebrates.  The invertebrates need mutualism because the water is nutritionally poor.  Very diverse.

estuaries

fresh water meets ocean (salt) water.  (Brackish water).  Many crustaceans, mollusks and fish begin their lives here.

freshwater biomes

lakes, ponds, wetlands, rivers, and streams

lakes/ponds

still/slow

deeper (lakes)

algae, plankton, fish, frogs, aquatic plants

habitat zones

wetlands

still/slow

shallow

highly productive

water purification

rivers/streams

flowing

depth varies with flow

biodiversity changes with flow

nutrient transport