Environmental Science Chpt. 3.1, 3.2, 3.3, 3.4 - Lauren Antonacci

What is an ecosystem?

A community of organisms and their abiotic (non-living) environment.

What are the three categories of ecosystems? Give some information about them.

1) Freshwater - Least common ecosystem, comprises of lakes, rivers, streams, and springs.

2) Marine - Most common ecosystem, comprises of three basic types of ecosystem: shallow ocean, deep ocean, and deep ocean bottom.

3) Terrestrial - Are grouped into large categories called biomes.

• A biome is a large-scale community of organisms, primarily defined on land by the dominant plant types that exist in geographic regions of the planet with similar climatic conditions.

• Examples of biomes include tropical rainforests, savannas, deserts, grasslands, temperate forests, and tundras

What is a food chain?

A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another.

• Divided into levels: Producers, primary consumers, higher-level consumers, and decomposers

Give an Example of a Food Chain Using the Proper Names:

Grey Wolf - Tertiary (Apex) Consumer

Hare - Secondary Consumer

Grasshopper - Primary Consumer

Grass - Producer

How is energy moved between trophic levels?

Energy is lost at each trophic level and between trophic levels as heat, and in the transfer to decomposers.

• After a limited number of trophic energy transfers, the amount of energy remaining in the food chain may not be great enough to support viable populations at higher trophic levels.

What is a food web?

A food web is a concept that accounts for the multiple trophic (feeding) interactions between each species.

There are Two Types of Food Webs:

• A grazing food web has plants or other photosynthetic organisms at its base, followed by herbivores and various carnivores.

• A detrital food web consists of a base of organisms that feed on decaying organic matter (dead organisms), including decomposers (which break down dead and decaying organisms) and detritivores

What are photoautotrophs? What are chemoautotrophs?

Photoautotrophs: Use sunlight as an energy source.

Chemoautotrophs: Use inorganic molecules as an energy source.

What is Gross Primary Productivity (GPP)?

GPP is the rate at which photosynthetic producers incorporate energy from the Sun.

What is Net Primary Productivity (NPP)?

NPP is the energy that remains in the producers after accounting for these organism’s metabolism and heat loss.

What is biomagnification?

Biomagnification is the increasing concentration of persistent, toxic substances in organisms at each successive trophic level. (Think of fish containing high mercury - the larger tertiary/secondary consumers have more mercury because of eating primary consumers - the toxic substances add up).

What are Biogeochemical Cycles?

It is the recycling of inorganic matter between living organisms and their nonliving environment.

• Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during energy transformation between trophic levels.

What is the hydrosphere?

The hydropshere is the area of Earth where water movement and storage occurs.

What is the water cycle?

The water cycle is driven by the Sun’s energy as it warms the oceans and other surface waters.

• This leads to evaporation (liquid water to water vapor) of liquid surface water and sublimation (ice to water vapor) of frozen water, thus moving large amounts of water into the atmosphere as water vapor.

• Over time, this water vapor condenses into clouds as liquid or frozen droplets and eventually leads to precipitation (rain, snow, hail), which returns water to Earth’s surface.

• Rain reaching Earth’s surface may evaporate again, flow over the surface, or percolate into the ground. Most easily observed is surface runoff: the flow of freshwater over land either from rain or melting ice. Runoff can make its way through streams and lakes to the oceans.

What is transpiration and evapotranspiration?

Transpiration: water enters the vascular system of plants through the roots and evaporates, or transpires, through the stomata (small microscope openings) of the leaves. Ecologists combine transpiration and evaporation into a single term that describes water returned to the atmosphere: evapotranspiration

What is the Carbon Cycle?

The carbon cycle is most easily studied as two interconnected subcycles: one dealing with rapid carbon exchange among living organisms and the other dealing with the long-term cycling of carbon through geologic processes.

• Carbon dioxide gas exists in the atmosphere and is dissolved in water.

• Photosynthesis converts carbon dioxide gas to organic carbon, and respiration cycles the organic carbon back into carbon dioxide gas.

• Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized.

What is respiration? What does it have to do with the Carbon Cycle?

Respiration is a process in which organic molecules are broken down to release energy by other organisms. As these organic molecules are broken down, carbon is removed from food molecules to form CO2, a gas that enters the atmosphere. CO2 is a byproduct of respiration.

What is the Nitrogen Cycle?

• Nitrogen enters the living world from the atmosphere via nitrogen-fixing bacteria.

• This nitrogen and nitrogenous waste from animals is then processed back into gaseous nitrogen by soil bacteria, which also supply terrestrial food webs with the organic nitrogen they need.

What is the Phosphorus Cycle?

• Weathering of rocks and volcanic activity releases phosphate into the soil, water, and air, where it becomes available to terrestrial food webs.

• Phosphate enters the oceans in surface runoff, groundwater flow, and river flow.

• Phosphate dissolved in ocean water cycles into marine food webs. Some phosphate from the marine food webs falls to the ocean floor, where it forms sediment.

What is a Dead Zone?

A dead zone is an area in lakes and oceans near the mouths of rivers where large areas are periodically depleted of their normal flora and fauna. These zones are caused bu eutrophication coupled with other factors like oil spills/ dumping toxic waste.

What is the Sulfur Cycle?

• Sulfur dioxide from the atmosphere becomes available to terrestrial and marine ecosystems when it is dissolved in precipitation as weak sulfuric acid or when it falls directly to Earth as fallout.

• Weathering of rocks also makes sulfates available to terrestrial ecosystems.

• Decomposition of living organisms returns sulfates to the ocean, soil, and atmosphere.

Human activity has played a major role in altering the sulfur cycle, causing Acid rain - a corrosive rain caused by rainwater falling to the ground through sulfur dioxide gas, turning it into weak sulfuric acid, which causes damage to aquatic ecosystems.

What are the eight major terrestrial biomes?

1) Tropical Rainforests

2) Savannas

3) Subtropical Deserts

4) Chaparral

5) Temperate Grasslands

6) Temperate Forests

7) Boreal Forests

8) Artic Tundra

What are Biomes?

Biomes are large-scale environments that are distinguished by characteristic temperature ranges and amounts of precipitation.

What makes up a Tropical Rainforest? Describe the biome.

Tropical rainforests are found in equatorial regions, and are the most biodiverse terrestrial biome.

• The vegetation is characterized by plants with spreading roots and broad leaves that fall off throughout the year (as compared to deciduous forests which loose their leaves in one season)

• Month to month temperatures are constant in tropical rainforests, this lack of temperature shifts/seasonality leads to year-round rapid plant growth

• Tropical rainforests have high net primary productivity because the annual temperatures and precipitation values support fast plant growth - though the heavy rainfall takes away nutrients in the soil

• Tropical rainforests have a vertical layering of vegetation, with distinct habitats in each layer: the forest floor, the understory, and the upper canopy

What makes up a Savanna? Describe the biome.

Savannas are grasslands with scattered trees, and are found in Africa, South America and northern Australia.

• Savannas are hot, tropical areas that have an extensive dry season and consequent fires. As a result, there are few trees scattered in the grasses and forbs within the savanna

• Due to the constant fires, the plant life have adapted by having deep roots that allow them to grow back faster

What makes up a Subtropical Desert? Describe the biome.

Subtropical deserts are located on the downwind, or lee side of mountain ranges, which create a rain shadow after winds drop their water content on the mountains. Subtropical deserts are very dry, evaporation exceeds precipitation.

• These places are characterized by low annual precipitation, with little monthly variation, and lack of predictability in rainfall (some years have plenty rainfall, some don’t)

• There’s low species diversity in this biome, directly caused by it’s unpredictable precipitation. These species adapt to their environment - plants are either annuals that grow/repoduce/quickly, or are perennials which conserve water.

• Animals in this habitat adapt to nocturnal life, spending the hot daytime underground.

(Cold deserts that experience freezing temperatures during the winter and any precipitation is in the form of snowfall.)

What makes up a Chaparral? Describe the biome.

Chaparral’s are also called scrub forests, and the vegetation is dominated by shrubs and is adapted to periodic fires.

• The ashes left behind from fire puts nutrients (like nitrogen) into the soils, fostering plant regrowth (fire is a natural maintenance in this biome).

What makes up a Temperate Forests? Describe the biome.

Temperate forests are most commonly found in mid-latitude regions. Temperatures change constantly, causing a range of seasonality. These temperatures mean that this biome has defined growing seasons during the spring, summer, and early fall.

• Deciduous trees are the dominant plant in this biome, these trees lose their leaves each fall and are leafless in the winter. Little photosynthesis occurs during these colder months.

• Due to the thick layer of leaf litter on the forest floors, the litter decays and nutrients return to the soil, the ground is insulates, and habitats are provided to smaller critters.

What makes up a Boreal Forest (Taiga)? Describe the biome.

The Boreal Forest has cold, dry winters and short, cool, wet summers. Precipitation normally takes the form of snow, and relatively little evaporation occurs due to the cool temperatures.

• The long and cold winters have led to the predominance of cold-tolerant coniferous trees, which retain their needle-shaped leaves year round.

• Evergreen’s and photosynthesize earlier in the spring than deciduous trees, and grow faster than deciduous trees in the Boreal Forest

• The net primary productivity of Boreal Forests is low, due to the slow growing trees that procure biomass over time.

What makes up a Tundra? Describe the biome.

The Artic tundra lies north of the subartic forests and is located throughout the Artic regions of the Northern Hemisphere.

• Plants in the Tundra have short growing seasons of around 60 days. However, during this time these plants have 24 hours of daylight - causing rapid plant growth

• Precipitation and evaporation in the Tundra is low, due to the bitter cold

• Plants in the Tundra are low to the ground and include low shrubs, grasses, lichens and small flowering plants. There is little species diversity, low net primary productivity, and low above ground biomass.

• Soil in the Tundra may remain in a perennially frozen state referred to as permafrost - making it impossible for roots to anchor

What are the zones of the ocean?

1) Pelagic Zone: Encapsulates the ocean’s open water.

2) Photic Zone: The portion of the ocean where light can penetrate.

3) Aphotic Zone: The portion of the ocean where light cannot penetrate.

What are the three Marine Biomes?

1) Ocean

2) Corral Reefs

3) Estuaries

What makes up the Ocean? Describe the biome.

The Ocean is the largest marine biome, it’s a continuous body of saltwater that stretches across the globe. Within the ocean, there are the biomes of coral reefs and estuaries.

The ocean is categorized into different zones based on how far light reaches into the water.

• Intertidal Zone: Organisms are exposed to air and sunlight at low tide and are underwater most of the time, especially during high tide

• Neritic Zone: Extends from the intertidal zone to depths at the endge of the continental shelf. Because light can penetrate this depth, photosynthesis can occur. The water is well-oxygenated, low pressure, and stable in temperature

• Oceanic Zone: Within the oceanic zone there is thermal stratification where warm and cold waters mix because of ocean currents. Abundant plankton serve as the base of the food chain for larger animals such as whales and dolphins. Nutrients are scarce and this is a relatively less productive part of the marine biome

• Benthic Zone: Comprises of sand, silt, and dead organisms. This is a nutrient-rich portion of the ocean because of the dead organisms that fall from the upper layers of the ocean. Because of this high level of nutrients, a diversity of sponges, sea anemones, marine worms, sea stars, fishes, and bacteria exist

What makes up the Coral Reefs? Describe the biome.

Coral Reefs are characterized by high biodiversity and the structures created by invertebrated that live in warm, shallow waters within the photic zone of the ocean.

• The coral organisms are colonies of saltwater polyps that secrete a calcium carbonate skeleton. These calcium-rich skeletons slowly accumulate, forming the underwater reef

• Corals found in shallower waters have a mutualistic relationship with photosynthetic unicellular algae - this relationship provides corals with the majority of the nutrition and energy they require

• Due to global warming and rising ocean acidity, these coral algae die, causing coral bleaching

What makes up Estuaries? Describe the biome.

Estuaries are biomes that occur where a source of fresh water, such as a river, meets the ocean. Therefore, both fresh water and salt water are found in the same vicinity; mixing results in a diluted saltwater.

• Salinity is a very important factor that influences the organisms and the adaptations of the organisms found in estuaries. The salinity of estuaries varies, and is based on the rate of flow of its freshwater sources (high tides bring salt water in, low tides reverse the current of salt water)

• Many plants that live in estuaries are halophytes - plants that can tolerate salty conditions. Halophytic plants are adapted to deal with the salinity resulting from saltwater on their roots or from sea spray

What are the three types of Freshwater Biomes?

1) Lakes/Ponds

2) Rivers/Streams

3) Wetlands

What makes up Lakes and Ponds? Describe the biome.

Lakes and ponds can range in area from a few square meters to thousands of square kilometers. Lakes and ponds are places with standing water (still water).

• Temperature is essential in lakes/ponds, light can penetrate within the photic zone of the lake or pond, allowing for photosynthesis

• Phytoplankton and Zooplankton carry out photosynthesis in these waters

• When there is a large input of nitrogen and phosphorus (from sewage/fertilizer), algal blooms happen - blocking out light and stalling photosynthesis

What makes up Rivers and Streams? Describe the biome.

Rivers/Streams are continuously moving bodies of water that carry large amounts of water from the source, or headwater, to a lake or ocean.

• Streams begin at a point of origin referred to as source water -usually a cold/clear stream of water- with a fast current. These fast waters results in minimal silt accumulation at the bottom of the river

• As the river or stream flows away from the source, the width of the channel gradually widens, and the current slows. This slow-moving water has more sedimentation, making more murky

What makes up Wetlands? Describe the biome.

Wetlands are environments in which the soil is either permanently or periodically saturated with water.

• Wetlands are different from lakes because wetlands are shallow bodies of water that may periodically dry out

• Emergent vegetation consists of wetland plants that are rooted in the soil but have portions of leaves, stems, and flowers extending above the water’s surface