ECOLOGYCore Concepts 1. Ecology is the scientific study of interactions among organisms and between organisms and their environment. 2. Biotic and abiotic factors influence life in the biosphere, such as the distribution of biological communities. 3. An organism’s niche refers to the conditions in which an organism lives and the way in which the organism uses those conditions. 4. Ecosystems constantly change in response to natural or human disturbances. 5. Energy flows through an ecosystem in one direction: from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers).
ECOLOGY- study of the interactions between organisms and their environment (both living and non-living)- “oikos” (house) + “logos” (study)- scope of ecology: organism population community ecosystem biosphereECOSYSTEM - biological community + physical environment (biotic and abiotic factors)
ECOLOGICAL NICHE - the status/role of an organism in its environment - Competitive Exclusion Principle: a fundamental rule in ecology stating that no two organisms can occupy the exact niche for an indefinite amount of time because competition for resources would lead to the death of one.ECOLOGICAL SUCCESSION - the sequence of communities that develops in an area from the initial stages of colonization until a stable climax community is achieved - series of changes in the species composition of living communities, often following ecological disturbance of the community - pioneer species vs. climax community - primary vs. secondary succession
BIOMES- an environment that has a characteristic climax community- organisms are of the same general type, being adapted to the particular conditions in which they occur
BIOMES A. Land Biomes 1. Tundra 2. Taiga 3. Temperate deciduous forest 4. Grassland 5. Tropical rainforest 6. Desert B. Aquatic Biomes 1. Freshwater 2. Marine 3. Estuary
Characteristics used to distinguishTypes of Land Biomes/Ecosystems: Climatic conditions Temperature precipitation/rainfall location, altitude, topography, etc. Climax community Vegetation Animals Adaptations of Flora and Fauna
Matter/Biogeochemical Cycles Carbon cycle Nitrogen cycle Water cycle Mineral cycles: Phosphorus Calcium Sulfur etc.
Energy Flow Trophic levels: producers, consumers Feeding relationships: food chains, food webs Ecological pyramids: Energy pyramid Pyramid of Biomass Pyramid of Numbers
Terrestrial vs. Aquatic ecosystems Evolution and Ecological Succession Life originated in water and evolved there for almost 3Billion years before plants and animals began moving onto land. Coverage Aquatic Biomes occupy the largest part of the biosphere covering about 75% of the Earth’s surface Aquatic biomes are less affected by climate change than land ecosystems. Why? Nature of water
Abiotic and Biotic Factors of Aquatic Biomes Water Chemistry Salinity of Aquatic Biomes: Salinity, pH, ions, nutrients, <1% - 3% pollutants Freshwater – about <1% Temperature Estuary – variable (Why?) Depth of Water Marine – about 3% Light penetration BOD Turbidity O2 content Biological Oxygen Demand Wind action Eutrophication Water current/flow rate Turn-over/Upwelling Microbial action Water pressure
Zonations and Thermal Stratification Affect Interactions in Aquatic Ecosystems/Biomes
Standing (Lentic)water :ponds, lakesIsolated/land-locked ;low species diversity
Life Zones/Zonations based on:Light Penetration: Photic Zone Aphotic ZoneDistance from shoreline, Depth, Sunlight, Temperature: Littoral Zone: near shore; sunlight abundant; photosynthesis high ; high species diversity Limnetic Zone: near-surface open water ; w/ plankton at the base of food chain Profundal Zone: deep water ; aphotic; low temp; no photosynthesis; no O2 (only anaerobic organisms live here), low species diversityThermal Stratification: Eutrophic vs. Oligotrophic vs. Mesotrophic Lakes Epilimnion Thermocline Hypolimnion
Abiotic - Biotic Interactions inFreshwater based on Life Zones
Oligotrophic lakes are generally newly formed lakes withrelatively small supply of nutrients (poorly nourished); they areoften deep, with steep banks. They are usually crystal-clear blueor green water due their relatively low net primary productivity.
Spring overturnIn spring, when the atm. warms, the lake’s surface water warms to 40C, reaches maximumdensity, and sinks through and below the cooler, less dense water, bringing the bottomwater to the surface. During this spring turnover, DO in the surface layer is moveddownward, and nutrients released by decomposition on the lake bottom are movedupward toward the surface.
The Thermocline acts as a barrier to the transfer of nutrientsand dissolved O2 from the epilimnion to the hypolimnion.
In summer, such lakes become stratified into different temperature layersthat resist mixing. These lakes have and epilimnion, an upper layer of warmwater with high levels of dissolved O2 (DO ), and a hypolimnion, a lowerlayer of colder,denser water, usually with a lower concentration of dissolvedO2, because it is not exposed to the atmosphere.
In the fall the temp. begin to drop, the surface layer sinks to the bottomwhen it cools to 40C and the thermocline disappears. This mixing or fallturnover, brings nutrients from bottom sediments to the top and sends DOfrom the top to the bottom.
Water is densest as liquid at 40C(390F) or Solid ice at 00C (320F)is less dense thanliquid water at 40C, which is why ice floats on water. This is fortunate for us andmost freshwater organisms; otherwise, lakes and other bodies of freshwater incold climates would freeze from bottom up instead of from surface down, whichwould push fish and other organisms to the top, killing them. This unusualproperty of water causes thermal stratification of deep lakes in northerntemperate areas with cold winters and warm summers.
Flowing (Lotic) water: streams, rivers ;conditions at different points (headwater, middle reaches, lower reaches) with different adaptations of organisms depth + width high species diversity Slow flow low O2 low species diversity (e.g., catfish, carp) slow flow high sediments low light low photosynthesis low species diversity fast flow animals w/ hooks, suckers, flattened bodies Slow flow species similar to pond/lake inhabitants
Marine Biome Salinity: >3%Distance from shoreline, depth, sunlight, temp determine life zones: Spray zone: constantly sprayed with salt water by wave action in the intertidal zone Intertidal zone: low/high tide area constantly changing conditions constantly changing communities high light + highO2 + high nutrients highly productive ecosystem Pelagic zone: open ocean producers limited to photic zone remains sink to ocean floor low nutrients (unless there is an upwelling) Benthic zone: ocean floor high remains + decomposers low nutrients (stuck here) Abyssal zone: deep ocean Low temp (3oC) + high PH2O + no light very low species diversity hydrothermal vents w/ chemosynthetic bacteria (use H 2S)