1.1 - Intro

Ecosystem Basics

• Individual: one organism

• Population: group of individuals of same species

• Community: all living organisms in an area

• Ecosystem: all living and non-living things in an area

• Biome: the plants and animals found in a given region

Organism Interactions

• Competition: organisms fighting over a resource like food or shelter → limits population size

• Predation: one organism using another organism as an energy source (hunting, parasitism)

• Mutualism: relationship that benefits both organisms

• Commensalism: relationship that benefits one organism and doesn’t affect the other

Predation

• Herbivores → eat plants for energy

• True predators → kills and eats prey for energy

• Parasites → uses a host organism for energy

• Parasitoids → lay eggs inside host organism; eggs hatch and larvae eat host for energy

Symbiosis

• Symbiosis → any long-term, close interaction between two organisms of different species (predation, mutualism, commensalism, parasitism)

Competition

• Competition → reduces population size since there are fewer resources available & fewer organisms can survive

• Resource partitioning → different species using the same resource in different ways to reduce competition

  • Temporal competition → using resources at different times (wolves hunting during day, coyotes hunting at night)

  • Spatial partitioning → using different areas of the same habitat

  • Morphological partitioning → using different resources based on different evolved body features

1.2 - Terrestrial Biomes

Biomes

• Biome → the plants and animals found in a region; based on yearly temp, & climate (rain forest, tiaga, grasslands)

• The community of organisms in a biome are uniquely adapted to live in that biome

Nutrient availability

• Plants need soil nutrients to grow, so availability determines which plants can survive in a biome

  • Tropical RF = nutrient-poor soil (high temp. & rainfall → rapid decomposition of org. matter; acidic soil + high rainfall → nutrient leaching)

  • Boreal forest = nutrient-poor soil (low temp. & low decomp. rate of dead organic matter)

  • Temp. forest = nutrient-rich soil (lots of dead organic matter - leaves & warm temp/moisture for decomposition)

Shifting biomes

• Biomes can shift in location as the Earth’s climate changes

1.3 - Aquatic Biomes

Characteristics of an aquatic biomes

• Salinity → the amount of salt in a body of water determines which species can survive & usability for drinking

• Depth → influences how much sunlight can penetrate and reach plants below the surface for photosynthesis

• Flow → determines which organisms can survive; how much O₂ can dissolve into water

• Temperature → warmer water holds less dissolved O₂ so it can support fewer aquatic organisms

Freshwater: Rivers & Lakes

• Rivers have high oxygen due to flow mixing water and air; also carry nutrient-rich sediments (deltas & flood plains = fertile soil)

• Lakes → standing bodies of water (Key drinking water source)

  • Littoral → shallow water w/ emergent plants

  • Limnetic → where light can reach (photosynthesis)

    • No rooted plants, only phytoplankton

  • Profundal → too deep for sunlight; no photosynthesis

  • Benthic → murky bottom where bugs live; nutrient rich sediments

Freshwater: Wetlands

• Wetland → area with soil submerged/ saturated in water for at least part of the year, but shallow enough for emergent plants

• Benefits of wetlands

  • Stores excess water during storms

  • Recharges ground water by absorbing rainfall into soil

  • Roots of wetland plants filter pollutants from water draining through

  • High plant growth rate due to lots of water and nutrients in sediment

Estuaries

• Estuaries → areas where rivers dump into an ocean

• Brackish water

• Salt marsh → estuary habitat along coasts in temperate climates

  • Breeding ground for many fish and shellfish species

• Mangrove swamps → estuary habitat along coasts of tropical climates

  • Mangrove tree roots stabilize shoreline and provide habitats for fish and shellfish

Coral Reef

• Warm, shallow waters beyond the shoreline; most diverse marine biome

Intertidal Zones

• Narrow band of coastline between high and low tide

• Species must be adapted to crashing waves and direct sunlight/heat during low tide

Open Ocean

• So large that algae and phytoplankton can produce a lot of Earth’s oxygen and absorb a lot of atmospheric carbon

• Algae and plankton can only survive in photic zone

  • Photic zone → area where sunlight can reach

  • Aphotic zone (abyssal) → area too deep for sunlight

1.4 - Carbon Cycle

Overview

• Carbon cycle → movement of molecules that contain carbon glucose between sources and sinks

• Some steps are very quick (fossil fuels and combustion) while some are very slow (burial and sedimentation)

• The atmosphere is a key carbon reservoir; increasing levels of carbon in the atmosphere leads to climate change

• Carbon sink → a reservoir that takes in more carbon than it releases

  • Ocean (algae and sediments), plants, and soil

• Carbon source → a reservoir that releases more carbon than it takes in

  • Fossil fuel combustion

  • Animal waste (cow farts, basically)

  • Deforestation (released carbon dioxide from trees)

Photosynthesis and Cellular Respiration

• Photosynthesis

  • Plants, algae, and phytoplankton

  • Removes carbon dioxide from the atmosphere and converts it into glucose

  • Carbon dioxide sink

• Cellular Respiration

  • Done by plants and animals to release stores energy

  • Uses oxygen to break down glucose and release energy

  • Releases carbon dioxide into the atmosphere

  • Carbon dioxide source

• Both processes are very quick

• Cycles carbon between biosphere and atmosphere in balanced amount (no net carbon increase in atmosphere)

Ocean and Atmosphere

• Direct exchange → carbon dioxide moves directly between atmosphere and ocean by dissolving into and out of ocean water at the surface

• Because of direct exchange, increasing atmospheric carbon dioxide also increases ocean carbon dioxide, leading to ocean acidification

• Algae and phytoplankton: take carbon dioxide out of the ocean and atmosphere through photosynthesis

  • Coral, mollusks, and some zooplankton also take carbon dioxide out of the air to make calcium carbonate exoskeletons

• Sedimentation → calcium carbonate precipitates out as sediment and settles on the ocean floor

  • Burial → over long periods of time, pressure of water compresses carbon-containing sediments on the ocean floor into sedimentary rock (long term carbon reservoir)

Burial, Extraction, and Combustion

• Slow, geological process that store carbon in underground sinks (sedimentary rock or fossil fuels)

• Fossil Fuels → formed from fossilized remains of organic matter into coal or oil; their decomposition produces natural methane gas

• Extraction and combustion → digging up or mining fossil fuels and burning them as an energy source; releases carbon dioxide into the atmosphere