Lecture 3: The Physical and Chemical Environment-Part 2

Properties of Water

• strong hydrogen bonds
• high specific heat
• high boiling point
• needs a lot of energy to evaporate
• expands when freezes

Polar

Molecule with partial charges. Mixes with water.

Hydrogen Bond

Weak attraction between a hydrogen atom and another atom

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid

Viscosity

A liquid's resistance to flowing

Solar Radiation

Transmission of energy from the sun in the form of electromagnetic waves.

Radient Energy

Energy carried by an electromagnetic wave

Stratification

The vertical layering of habitat; the arrangement of vegetation in layers.

Epilimnion

An upper layer of warm water with high levels of dissolved oxygen

Hypolimnion

The lower layer of water in a stratified lake, typically cooler than the water above and relatively stagnant.

Thermocline

A steep temperature gradient in a body of water such as a lake, marked by a layer above and below which the water is at different temperatures.

Phytoplankton

Microscopic, free-floating, autotrophic organisms that function as producers in aquatic ecosystems

Spring Bloom

A middle-latitude bloom of phytoplankton that occurs during the spring and is limited by the availability of nutrients.

Summer Stagnation

Hot, still, dry weather can lead to a build-up of pollutants in the air we breathe

Zooplankton

Small free-floating animals that form part of plankton

Upwelling

The movement of deep, cold, and nutrient-rich water to the surface

Field Capacity

The maximum amount of water held by soil particles against the force of gravity

Permanent Wilting Point

The point at which a plant can no longer recover from a lack of water

Evapotranspiration

The evaporation of water from soil plus the transpiration of water from plants.

Potential Evapotranspiration Rate

Measures how much water plants "need" given the local climate.

Beer's Law

Explains the relationship between absorbance, at a given wavelength and concentration, A = εbc

Holdridge's Life Zone Classification

A system of ecological zoning based on the identification of bioclimatic units (life zones) that employs the variables of biotemperature, precipitation, potential evapotranspiration (EVP), EVP/P ratio, latitude, and altitude

Net Primary Production

The gross primary production of an ecosystem minus the energy used by the producers for respiration.

Osmolarity

Total concentration of all solute particles in a solution

Salinity

A measure of the amount of dissolved salts in a given amount of liquid

Saline Lakes

Salt lake; commonly caused by interior stream drainage in an arid environment

Brackish Water

A mix of freshwater and seawater which commonly occurs in estuaries where a river enters the ocean

Lagoons

A stretch of salt water separated from the sea by a low sandbank or coral reef.

Isotonic

When the concentration of two solutions is the same

Hypotonic

Having a lower concentration of solute than another solution

Hypertonic

Having a higher concentration of solute than another solution.

Stenohaline

Animals that cannot tolerate substantial changes in external osmolarity

Euryhaline

Animals that can survive large fluctuations in external osmolarity

Osmoregulatory Response

The physiological processes that maintain a fixed concentration of cell membrane-impermeable molecules and ions in the fluid that surrounds cells

Osmoconformers

An organism that allows its internal salt concentration to change with the salinity of the surrounding water

Homeotherms

Organisms that maintain a consistent body temperature

Poikilotherm

An animal whose body temperature varies with the temperature of its surroundings

Endotherms

Animals (such as birds or mammals) that can regulate their body temperature.

Ectotherms

An animals that warms itself mainly by absorbing heat from its surroundings

Thermoneutral Zone

Range of environmental temperatures within which the metabolic rates are minimal

Temperature Threshold

The highest or lowest temperature at which an organism can live.

Physiological Time

Amount of heat required over time to complete development or life stages