Unit 4.1 (BIOL 1010)
The saltiness of estuaries ranges, across their length, from nearly that of fresh water to that of the ocean. With their waters enriched by nutrients from a river, estuaries are among the most productive biomes on Earth. Oysters, crabs, and many fishes live in estuaries or reproduce in them. Estuaries are also crucial nesting and feeding areas for waterfowl
Explain estuaries [SPW]
They range from marshes to swamps and bogs. They're high in species diversity. They provide water storage areas that reduce flooding and improve water quality by filtering pollutants. Recognition of their ecological and economic value has led to government and private efforts to protect and restore wetlands
Explain freshwater wetlands [DSV]
Aphotic zone
It's below the photic zone of the ocean
Solar energy
It's from sunlight, captured during photosynthesis and powers most ecosystems
Savanna
A biome dominated by grasses & scattered trees
Estuary
A biome that occurs where a freshwater stream or river merges with the ocean
Landscapes
Arrays of ecosystems usually visible from the air as distinctive patches
Northern coniferous forests
As global temperatures continue to rise, which biome will most likely replace arctic tundras?
The scarcity of food probably explains the strangely outsized mouths of the angler and other fishes that inhabit this region of the ocean, a feature that allows them to grab any available prey. Inwardly angled teeth ensure that once caught, prey don't escape. The angler fish improves its chances of encountering prey by dangling a lure lit by bioluminescent bacteria
Explain angler fishes
This extends from the atmosphere several kilometers above Earth to the depths of the oceans. It's all of Earth that is inhabited by life
Explain biospheres in ecology
An assemblage of all the populations of organisms living close enough together for potential interaction - all of the biotic factors in an environment
Explain communities in ecology
A reef is built up slowly by successive generations of coral animals and by multicellular algae encrusted with calcium carbonate. Unicellular algae live within the corals, providing the corals with food
Explain coral reefs [BA]
This includes both the biotic & abiotic components of the environment. Some critical questions at the ecosystem level concern how chemicals cycle and how energy flows between organisms & their surroundings
Explain ecosystems in ecology
Phytoplankton
Microscopic algae & cyanobacteria
Inorganic nutrients
Plants obtain these from the soil (eg.: nitrogen & phosphorus)
Differentiation
The conversion of semi-arid regions to desert that is a significant environmental problem
Wetlands
They constitute a biome that is transitional between an aquatic ecosystem and a terrestrial ecosystem
Freshwater biomes
They cover less than 1% of Earth's surface and contain a mere 0.01% of its water. But they harbor a disproportionate share of biodiversity - an estimated 6% of all described species
Trout
They locate their insect prey mainly by sight in the clean water, and are often the predominant fishes
Tropical forests
They occur in equatorial areas where the temperature is warm and days are 11-12 hours long year round
Watertight coverings
They were key evolutionary adaptations enabling plants & vertebrates to be successful on land
Pelagic realm
This includes all open water
Intertidal zone
This is where the ocean meets land
Drinking water, crop irrigation, sanitation, and industry
What activities depend on freshwater biomes?
Monkeys, birds, insects, snakes, bats, and frogs find food & shelter many meters above the ground
What animals live in tropical rain forests?
Tropical forests, savannas, deserts, chaparrals, temperate grasslands, temperate broadleaf forests, northern coniferous forests, tundras, and high mountains (coniferous forest & alpine tundra)
What are the nine major types of terrestrial biomes?
Standing water (lakes & ponds) and flowing water (rivers & streams)
What are the two categories of freshwater biomes?
The species may have evolved from ancestors living in that location, or it may have dispersed to that location & been able to survive once it arrived
What are the two possible explanations of a species' presence in a particular place?
They describe the distribution & abundance of organisms - where they live and how many live there
What do ecologists describe? [D&A]
To explain the distribution of organisms
What is one of the fundamental goals of ecology?
Lack of sunlight
What is the most important factor limiting plant growth for terrestrial ecosystems?
The individuals whose phenotypes are best suited to the environment will pass their alleles to the next generation. But individuals with other phenotypes may not
What is the role of the environment in adaptive evolution?
Low levels of nitrogen & phosphorus
What limits the growth of algae & photosynthetic bacteria?
Nitrogen & phosphorus
What minerals typically determine the amount of phytoplankton growth in a lake or pond?
Sponges, burrowing worms, clams, sea anemones, crabs, and echinoderms
What organisms inhabit the benthic realm of the photic zone?
Salinity, current, and tides
What three factors play a role in aquatic ecosystems?
Soil structure, pH, and nutrient content
What three factors play major roles in determining the distribution of plants?
Zooplankton, fishes, marine mammals, and many other types of animals
What types of animals are abundant in the pelagic photic zone?
Between 200 - 1000 m
Where is light still attainable in the aphotic zone?
Estuaries, wetlands, and coral reefs
Which places are very vulnerable to pollution/damage/overfishing?
Ecologists hypothesize that the selection pressure of the cheetah's pursuit led to the pronghorn's blazing speed, which far exceeds that of its main present-day predator, the wolf.
Why are American cheetahs now extinct?
As ectotherms, reptiles other than birds and amphibians don't have adaptations that enable them to withstand the cold temperatures of the alpine habitat
Why are birds and mammals found in Himalayan alpine meadows, but non-bird reptiles and amphibians are not?
Climate conditions favor rapid decomposition of organic litter in the soil and immediate uptake of the resulting nutrients by vegetation that is cleared away before farming rather than being stored in the soil
Why are the soils in most tropical rain forests so poor in nutrients that they can only support farming for a few years after the forest is cleared?
The sewage adds nutrients (eg.: nitrogen & phosphorus) that stimulate the growth of algae
Why does sewage cause algal blooms in lakes?
Because deserts are defined by low precipitation and dry soil, not by temperature
Why isn't cold desert an oxymoron?
Coral animals
A diverse group of cnidarians that secrete a hard external skeleton
Coral reefs
A visually spectacular & biologically diverse biome that are scattered around the globe in the photic zone of warm tropical waters above continental shelves. They support a huge variety of invertebrates & fishes
Temperature
An important abiotic factor because of its effect on metabolism
Deposit feeders
Animals that consume dead organic matter on the substrate
Zooplankton
Animals that drift in aquatic environments
In lakes & large ponds, the communities of plants, algae, and animals are distributed according to the depth of the water and its distance from the shore. If a lake/pond is deep/murky enough, it has an aphotic zone where light levels are too low to support photosynthesis. In the benthic realm, large populations of microorganisms decompose dead organisms that sink to the bottom. Respiration by microbes removes oxygen from water near the bottom, and in some lakes, benthic areas are unsuitable for any organisms except anaerobic microbes
Explain lakes & ponds (standing water) [DABR]
Covered with water either permanently or periodically, wetlands support the growth of aquatic plants. Mudflats & salt marshes are coastal wetlands that often border estuaries and experience tidal fluctations
Explain marine wetlands [GM]
Ecologists may examine how one kind of organism meets the challenges and opportunities of its environment through its physiology or behavior
Explain organisms in ecology [CO]
They're a group of individuals of the same species living in a particular geographic area
Explain populations in ecology
A river/stream changes greatly between its source and the point at which it empties into a lake or the ocean. Near the source, the water is usually clear, cold, and oxygen-rich, with a swift current that inhibits the growth of phytoplankton. Most of the organisms found here are supported by the photosynthesis of algae attached to rocks or by organic material, such as leaves, carried into the stream from the surrounding land. The most abundant benthic animals are usually arthropods, such as small crustaceans & insert larvae, that have physical & behavioral adaptations that enable them to resist being swept away. Downstream, a river/stream generally widens & slows. The water is usually warmer, lower in oxygen, and may be murkier because of sediments and phytoplankton suspended in it. Worms & insects that burrow into mud are often abundant, as are waterfowl, frogs, catfish, and other fishes that find food more by scent and taste then by sight
Explain rivers & streams (flowing water) [CPBSM]
Light isn't uniformly available. Microorganisms & suspended particles absorb light and prevent it from penetrating beyond certain depths. As a result, most photosynthesis occurs near the water's surface
Explain solar energy in aquatic environments
Bacteria that extract energy from inorganic chemicals power ecosystems. Sulfur bacteria perform this function in hydrothermal vent communities
Explain solar energy in dark environments
They're grouped into nine major types of biomes, which are distinguished primarily by their predominant vegetation. By providing food, shelter, nesting sites, and much of the organic material for decomposers, plants build the foundation for the communities of animals, fungi, and microorganisms that are characteristic of each biome. The geographic distribution of plants, and thus of terrestrial biomes, largely depends on climate, with temperature and precipitation often the key factors determining the kind of biome that exists in a particular region
Explain terrestrial ecosystems
Below 1000 m, the ocean is completely and permanently dark. Adaptation to this environment has produced bizarre-looking creatures (eg.: angler fish)
Explain the "no light" zone in the aphotic zone [DB]
They're adapted to drought and extreme temperatures. Many live in burrows and are active only at night, when temperatures drop; and most have special adaptations that conserve water. Seed-eaters such as ants, many birds, and rodents are common in deserts. Lizards, snakes, and hawks eat the seed-eaters
Explain the animals in deserts
The dormant herbivores in savannas are actually insects, especially ants & termites. Also common are many burrowing animals, including mice, moles, gophers, snakes, ground squirrels, worms, and numerous arthropods. Many of the world's large herbivores and their predators inhabit savannas. African savannas are home to giraffes, zebras, and many species of antelopes, as well as to lions and cheetahs. Several species of kangaroo are the dominant mammalian herbivores of Australian savannas
Explain the animals of savannas
Most benthic organisms are deposit feeders. Crustaceans, annelid worms, sea anemones, and echinoderms (eg.: sea cucumbers, sea stars, & sea urchins) are common. Because of the scarcity of food, the density of animals is low - except at hydrothermal vents, where chemoautotrophic bacteria support an abundance of life
Explain the benthic organisms in the "non light" zone of the aphotic zone [FCD]
The pronghorn has a thick coat made of hollow hairs that trap air, insulating the animal in cold weather
Explain the characteristics of a pronghorn antelope
They occur in equatorial areas where the temperature is warm and days are 11-12 hours long year round. Rainfall in these areas is quite variable, and this variability generally determines the vegetation that grows in a particular tropical forest. In areas where rainfall is scarce or there is a prolonged dry season, tropical dry forests predominate
Explain the conditions in tropical forests
The large deserts in central Australia & northern Africa have average annual rainfalls of less than 2 cm, and in the Atacama Desert, there is often no rain at all for decades at a time. But not all desert air is dry. Coastal sections of the Atacama and of the Namib Desert are often shrouded in fog, although the ground remains extremely dry. Some deserts are very hot, with daytime soil surface temperatures above 60°C and large daily temperature fluctuations. Other deserts, are relatively cold: air temperatures in cold deserts may fall below -30°C
Explain the conditions of deserts
The temperature is warm all-year round. Rainfall averages 30-50 cm (12-20 in) per year, almost all of it during a relatively brief rainy season. Poor soils & lack of moisture prevent the establishment of most trees. Grazing animals & frequent fires, caused by lightning or human activity, further limit invasion by trees. Grasses survive burning because the growing points of their shoots are below ground
Explain the conditions of savannas
Tropical rain forests are found in very humid equatorial areas where rain fall is abundant. The forest structure consists of distinct layers that provide many different habitats: emergent trees growing above a closed upper canopy, one or two layers of lower trees, a shrub understory, and a sparse ground layer of herbaceous plants. Because of the cloud canopy, little sunlight reaches the forest floor. The soils of tropical rain forests are typically poor. High temperatures & rainfall lead to rapid decomposition and release of nutrients. However, the nutrients are quickly taken up by the luxuriant vegetation or washed away by the frequent rains
Explain the conditions of tropical rain forests
Many lakes & ponds receive large inputs of nitrogen & phosphorus from sewage & runoff from fertilized lawns & farms. These nutrients may produce a heavy growth of algae, which reduces light penetration. When the algae die and decompose, a pond/lake can suffer severe oxygen depletion, killing fish that are adapted to high oxygen conditions
Explain the effect of nitrogen & phosphorus on lakes & ponds [RAD]
Few organisms can maintain a sufficiently active metabolism at temperatures close to 0°C, and temperatures above 45°C destroy the enzymes of most organisms. Archaeans living in hot springs have enzymes that function optimally at extremely high temperatures. Mammals & birds can remain considerably warmer than their surroundings and can be active at a fairly wide range of temperatures. Amphibians & reptiles gain most of their warmth by absorbing heat from their surroundings (have limited distribution)
Explain the effect of temperature in organisms [MABR]
Aquatic organisms are surrounded by water; their problem is solute concentration. Freshwater organisms live in a hypotonic medium, while the environment of marine organisms is hypertonic. Animals maintain fluid balance by a variety of mechanisms
Explain the effect of water in aquatic environments
Its present-day habitat is arid, windswept, and subject to extreme temperature fluctuations both daily & seasonally
Explain the environment of a pronghorn antelope
It's an ongoing source of concern. It's a common practice to clear the forest for lumber, or simply to burn it, farm the land for a few years, and then abandon it. Mining has also devastated large tracts of rain forest. Once stripped, the tropical rain forest recovers very slowly because the soil is so nutrient-poor
Explain the human impact on tropical rain forests
The shore is pounded by waves during high tide and exposed to the sun and drying winds during low tide. The rocky intertidal zone is home to many sedentary organisms, such as algar, barnacles, and mussels, which attach to rocks and thus resist being washed away when the tide comes in. On sandy beaches, suspension-feeding worms, clams, and predatory crustaceans bury themselves in the ground
Explain the intertidal zone [SRB]
Field research is fundamental to ecology. But ecologists also test hypotheses using laboratory experiments, where conditions can be simplified & controlled. Some ecologists take a theoretical approach, devising mathematical & computer models that enable them to simulate large scale experiments that are impossible to conduct in the field
Explain the laboratory & theoretical approach of ecologists [FRLETA]
The pronghorn's main foods are small broadleaf plants, grasses, and woody shrubs. The teeth of a pronghorn are specialized for biting & chewing tough plant material. The pronghorn's stomach contains cellulose-digesting bacteria
Explain the nutrition of a pronghorn antelope
The cycles of growth & reproduction in the desert are keyed to rain fall. The driest deserts have no perennial vegetation at all, but less arid regions have scattered deep-rooted shrubs, often interspersed with water-storing succulents such as cacti. The leaves of some plants have a waxy coating that prevents water loss. Desert plants typically produce great numbers of seeds, which may remain dormant until a heavy rain triggers germination. After periods of rainfall, often in late winter, annual plants in deserts may display spectacular blooms
Explain the plants in deserts
The plants found there are a mixture of thorny shrubs and deciduous trees and succulents
Explain the plants in tropical forests
They're among the most complex of all biomes, harboring enormous numbers of different species. Up to 300 species of trees can be found in a single hectare. Many trees are covered by woody vines growing toward the light. Other plants, including bromeliads & orchids, gain access to sunlight by growing on the branches or trunks of tall trees. Many of the animals also dwell in trees, where food is abundant
Explain the plants in tropical rain forests
Savanna plants have been selected for their ability to survive prolonged periods of drought. Many trees & shrubs are deciduous, dropping their leaves during the dry season, an adaptation that helps conserve water. Grasses & forbs (small broadleaf plants) grow rapidly during the rainy season, providing a good food source for many animal species. Large grazing mammals must migrate to greener pastures and scattered watering holes during seasonal drought
Explain the plants of savannas
The dimly lit world is dominated by a fascinating variety of small fishes & crustaceans. Food sinking from the photic zone provides some sustenance for these animals. In addition, many of them migrate to the surface at night to feed. Some fishes in the twilight zone have enlarged eyes, enabling them to see in the very dim light, and luminescent organs that attract mates and prey
Explain the twilight zone in the aphotic zone [CFEO]
Wind
It increases an organisms' rate of water loss by evaporation. The resulting increase in evaporation cooling can be advantageous on a hot summer day, but it can cause dangerous wind chill in the water
They must depend on oxygen dissolved in water. Some species of fish (eg.: trout) require high levels of dissolved oxygen. Cold, fast-moving water has a higher oxygen content than warm/stagnant water
How do aquatic organisms acquire oxygen?
By repeatedly preventing the spread of trees and other woody plants, grasses survive because the growing points of their shoots are underground
How do fires help to maintain savannas as grassland ecosystems?
Photosynthesis by phytoplankton and multicellular algae provides energy and organic carbon for a diverse community of animals
How do sunlit regions obtain energy?
Continental shelves
Shallow areas such as the submerged parts of continents
Convergent evolution
The appearance of similar traits in independently evolved species living in similar environments
Photic zone
The depth of light penetration (a maximum of 200 m [656 ft])
Pronghorn antelope
The descendant of ancestors that roamed the open plains and shrub deserts of North America more than one million years ago. The animal is found nowhere else and is only distantly related to the many species of antelope in Africa
Deserts
The driest of all terrestrial biomes, characterized by low & unpredictable rainfall (<30 cn [12 in] per year)
Atacama Desert
The driest place on Earth, located in Chile
Biotic factors
The living component of the environment
Abiotic factors
The nonliving component of the environment
American cheetah
The now-extinct fleet-footed feline that bears some similarities to the more familiar African cheetah
Ecology
The scientific study of interactions between organisms and the environment
Habitat
The specific environment an organism lives in
Benthic realm
The substrate (seafloor)