Lecture - Chapter 3/4 Aquatic and Terrestrial Environment Flashcards
Biosphere
Living things are found on every part of the Earth, from high mountains to deepest oceans and extreme environments.
But most occur within a thin layer of Earth’s surface, from the tops of trees to the surface soil layers, and within 200 meters of the surface of the oceans
Lithosphere
Earth’s surface crust and upper mantle
Troposphere
The lowest layer of the atmosphere
Aquatic environment
75-95% of all living cells are water. 75% of earths surface is water.
Aquatic systems are divided into two categories
Fresh water and saltwater (marine)
Hydrologic cycle
Freshwater -> terrestrial and marine ecosystems.
Driven by solar radiation by providing energy for evaporation of water
Evaporation
Transformation of water from liquid to gaseous state
Transpiration
Evaporation of water from living parts of plants
Evapotranspiration
Total evaporation = ground surface + transpiration
Transpiration
Happens through leaf openings called stomates and rates can be controlled by variation in degree of opening and number of stomates per leaf surface area
Physical Properties of Water
Polar covalent bonds Hydrogen bonds - high specific heat - can store lots of heat with small increase in temperature - less seasonal variability in temperature - aids thermal regulation of organisms Special density - ice less densethan water Cohesion - surface tension
Light decreases exponentially with depth
The ocean is blue because blue is absorbed less efficiently
More likely to be scattered back to the surface than other wavelengths
Red and UV light is most effectively absorbed by water
Temperature change with water depth
Water temperature declines with depth slower than the amount of solar radiation
Mixed layer/epilimnion
Warm, low density, temperature roughly same as surface water
Thermocline
Transition layer, rapid temperature and density change. Acts as physical barrier that prevents mixing of surface and deep layers. Causes stratification
Deep Water/Hypolimnion
Cold, high-density
Ocean benthic zones
Sparsely populated with temperatures near freezing, low light and very high pressure
Deep ocean adaptations
Bioluminescence
Coloration
Large eyes
Large teeth
Diffusion of oxygen
Oxygen diffuses from the atmosphere to the surface water
OXygen content may also stratify in the summer in temperate zone waters. Surface waters have highest O content due to diffusion at the surface an photosynthesis in the photic zone. Decomposers reduce O content in the benthic zone.
Moving water contains lots of oxygen.
OMZ
Oxygen minimum zones, regions below the productive surface layer of the ocean where oxygen is low at about 500-1000m
- no surface diffusion
- no photosynthesis
- separated from atmosphere by density stratification
- respriation of organic material sinking from above
Carbonic acid
regulated H20 PH
Uptake and release of CO2 shifts PH
Loss of CO2 offset by diffusion from the atmosphere
Terrestrial environment
The physical environment shapes the dominant terrestrial vegetation types of the earth, referred to as biomes. Such plant communities then determine the distribution and abundance of animals.
Biomes
Terrestrial biomes are characterized by growth forms of the dominant plants such as leaf deciduousness or succulence
Constraints on land
gravitational force
dessication
temporal and spatial variability
leaf area index
foliage density
the vertical gradient of light is determined by the foliage density
the toaly one-sided area of leaf tissue per unit ground surface area. The greater the LAI, the lower the light penetration through the canopy
How do nutrients enter the ecosystem?
Nutrients enter ecosystems through the chemical breakdown of minerals in rocks or through fixation of atmospheric gases
All nutrients are ultimately derived from abiotic sources: minerals in rocks and gases in the atmosphere
Minerals
solid substances with characteristic chemical rpoperties
rocks
collections of different minerals
weathering
elements are released from rock minerals by this physical and chemical breakdown
soil
a mix of mineral particles, organic matter, water and organisms.
ion exchange capacity
the abilit of ions to bind to soil aprticles depends on the total number of positively or negatively charged sites
Cation exchange capacity
the total number of negatively charged sites. a basic measure of soil quality
saturation
when soil has more water than the pore space can hold and excess water drains
field capacity
when the water fills all the pore spaces of the soil and is held by capillary forces
wilting point
when plants can no longer extract water from the soil
available water capcity
the amount of water retained between field capacity and wilting point
leaching
loss to ground water.
soil capacity to absorb cations measured by titrating with Hydrogen
