Freshwater Ecology Exam 1 Vocabulary Flashcards

A comprehensive collection of 152 vocabulary flashcards for Freshwater Ecology Exam 1, faithfully created from lecture notes.

Inland Water Proportion in Lakes and Rivers

Inland water makes up $1.51\%$ in lakes and $0.01\%$ in rivers and groundwater (which is poorly monitored and quantified).

Accessible Water Supply

Out of a total water supply of $\sim 39{,}000\,\text{km}^3\,\text{y}^{-1}$, only $\sim 9{,}000\,\text{km}^3\,\text{y}^{-1}$ is geographically and temporally accessible, of which humans currently use $\frac{1}{2}$.

Per Capita Water Use Rates

Per capita water use in the U.S. is $\sim 2{,}000\,\text{m}^3\,\text{y}^{-1}$ compared to $\sim 500\,\text{m}^3\,\text{y}^{-1}$ in Israel.

Primary Water Use Categories

The main ways humans use water, listed in comparison to home use, are industry and irrigation.

Climate Change Impacts on Freshwater

Key effects include changes in timing and form of precipitation, increased nutrient inputs, altered ice duration, altered mixing patterns, shifts in species assemblages, and changes in phenology.

Hydrogen Bonds in Water

Intermolecular bonds that influence water density, temperature, flow, velocity, and spatial distribution.

Maximum Water Density Temperature

The temperature at which pure water reaches its highest density, which is $3.98\,^{\circ}\text{C}$.

Salinity and Water Density

water density increases as salinity increases.

Universal Solvent Exception

hydrophobic solids.

Solid Solubility and Temperature

The relationship where solubility of solids increases with temperature (does not apply to hydrophobic solids).

Gas Solubility and Temperature

Gas solubility decreases as temperature increases.

Temperature Effect on Dissolved Oxygen

Colder water holds more dissolved oxygen, whereas hotter water holds less dissolved oxygen.

Heat of Fusion in Water

Energy process related to the calorie (energy required to raise $1\,\text{g}$ $H_2O$ by $1\,^{\circ}\text{C}$), buffering rapid temperature changes and dictating the time required for a lake to freeze or warm up between $0\,^{\circ}\text{C}$ and $100\,^{\circ}\text{C}$.

Heat of Vaporization

Thermal property of water responsible for evaporative cooling, also known as perspiration.

Surface Tension Causes

Surface tension at the air/water interface created by tight hydrogen bonds, cohesion, and adhesion.

Cohesion

The property of water molecules sticking together.

Adhesion

The property of water molecules sticking to other objects.

Temperature Effect on Surface Tension

An inverse relationship where surface tension decreases as water temperature increases.

Temperature Effect on Cohesion

An inverse relationship where cohesion decreases as water temperature increases.

Hydrostatic Pressure with Depth

Pressure increases by $1\,\text{atm}$ per $10\,\text{m}$ of depth (where $0\,\text{m} = 1\,\text{atm}$ and $10\,\text{m} = 2\,\text{atm}$).

Pressure at Depth Equation

Formula expressed as $P_x = P_{\text{atm}} \cdot \rho \cdot g \cdot x$, where $P_x$ is pressure at depth $x$, $P_{\text{atm}}$ is atmospheric pressure, $\rho$ is density, $x$ is depth, and $g$ is gravity constant.

Brownian Motion

Random, independent movement of individual molecules occurring at the smallest scale.

Large-Scale Fluid Flows

Laminar and turbulent flows that occur at large scales as a function of viscosity and inertia.

Laminar Flow

Fluid flow characterized by smooth, parallel layers with no disruption between layers, moving in a single direction.

Turbulent Flow

Fluid flow characterized by chaotic changes in pressure and flow velocity, moving in multiple directions with swirls and eddies.

Viscosity

Resistance of a fluid to change in form, described as internal friction.

Inertia

Resistance of a body or fluid to change in its state of motion.

Reynolds Number ($Re$)

A dimensionless ratio comparing relative inertia to relative viscosity.

Inertial Force Formula ($F_i$)

Defined as $F_i = \rho \cdot S \cdot U^2$, where $\rho$ is density, $S$ is surface area, and $U$ is velocity.

Viscous Force Formula ($F_v$)

Defined as $F_v = \frac{\mu \cdot S \cdot U}{l}$, where $\mu$ is dynamic viscosity, $S$ is surface area, $U$ is velocity, and $l$ is length.

Reynolds Number Formula ($Re$)

Calculated as $Re = \frac{F_i}{F_v} = \frac{\rho \cdot U \cdot l}{\mu}$.

Dynamic Viscosity Symbol ($\mu$)

Represented by $\mu$, which is the standard dynamic viscosity value for water.

Velocity Increase Effect on Reynolds Number

As fluid velocity ($U$) increases, the Reynolds number ($Re$) becomes bigger.

Velocity Decrease Effect on Reynolds Number

As fluid velocity ($U$) decreases, the Reynolds number ($Re$) becomes smaller.

Flow Boundary Layer

A layer created by friction between moving water and fixed structures where flow velocity slows down and transitions from turbulent to laminar flow.

Reynolds Number in Turbulent Water

Reynolds number increases in turbulent water due to the higher fluid velocity.

Reynolds Number in Streamlined Flow

Reynolds number is lower in streamlined, laminar forms due to lower velocity.

Vortices

Swirling structures that create turbulent flow, often formed by obstacles such as rocks in a stream.

Spatial Scale Effect on Viscosity

An inverse relationship where viscosity dominates at very small spatial scales; as spatial scale decreases, viscosity increases.

Temperature Effect on Viscosity

An inverse relationship driven by tighter hydrogen bonds; as temperature increases, viscosity decreases.

Water Movement Effect on Viscosity

A positive relationship where an increase in water movement results in an increase in viscosity.

Factors Positively Correlated with Inertia

Inertia has a positive relationship with spatial scale, size, density, and velocity.

Spider Web Analogy for Scale

An analogy illustrating how hydrogen bonds act like spider webs relative to scale: small organisms (flies) are stopped by viscosity, while large entities (humans) pass through unaffected.

Diffusion across Gradients

Movement of materials from a lower concentration to a higher concentration across a gradient (or changes in concentration over space and time).

Ecological Adaptations to Inertia and Viscosity

Includes specialized food collection methods, swimming speed challenges, streamlining (around $1\,\text{mm}$ in size), particle settling, and groundwater movement.

Shear Stress

Force exerted on attached substrate objects or organisms; as velocity increases, boundary layer thickness decreases and shear stress increases.

Stokes' Law

Law dictating particle sinking rates as a function of sphere size and density, along with water viscosity and density.

Forces Driving Water Movement

Solar heating and evaporation, gravity (streams/rivers), wind (lake/pond mixing), Coriolis effect (lakes $> 100\,\text{km}$), and bioturbation by organisms.

Coriolis Effect in Lakes

Circulation cycles in Northern and Southern hemispheres caused by Earth's rotational momentum, affecting large lakes ($> 100\,\text{km}$).

Advective Transport vs. Molecular Diffusion

Molecular diffusion (Brownian motion) is very slow, whereas advective transport involves eddy diffusion or transport diffusion.

Fick's Law of Diffusion

Formula expressing diffusion rate as $\text{Flux} = \text{constant} \cdot \frac{\Delta C}{\Delta X}$.

Diffusion Boundary Layer

A layer surrounding objects/organisms dominated by molecular diffusion, functioning as both a biogeochemical and physiological constraint.

Isotope

A variant of a chemical element containing the same number of protons but a different number of neutrons.

Water Diffusion Rate Constraint

Diffusion of materials in water is approximately $10^4 \times$ slower than in air.

Submerged Plant Photosynthesis and Carbon Isotopes

Submerged plants preferentially use lighter $^{12}\text{C}$ over $^{13}\text{C}$; a thicker boundary layer slows diffusion and forces usage of $^{13}\text{C}$, while a thinner layer increases $CO_2$ or $HCO_3^-$ availability.

Bacterial Surface Area to Volume Ratio

Small organism size provides a high surface-area-to-volume ratio, enabling direct oxygen uptake across the cellular membrane via diffusion.

Heating of Water by Light

Water is heated by light absorption by H2O molecules and suspended substances, alongside surface reflection and light transmission.

Refraction

The bending of light as it passes through the air-water interface.

Attenuation

The gradual loss of light intensity with distance through a medium.

Logarithmic Light Attenuation Pattern

Light intensity drops to $\frac{1}{10}$ after $1\,\text{m}$, $\frac{1}{100}$ after $2\,\text{m}$, and $\frac{1}{1000}$ after $3\,\text{m}$.

Light Attenuation Coefficient Formula ($\eta$)

Calculated as $\eta = \frac{\ln(I_1) - \ln(I_2)}{z_2 - z_1}$, where $I$ is light intensity and $z$ is depth.

Pure Water Light Transmission

Pure water transmits blue light most efficiently and absorbs red light.

Green Algae Light Absorption

Green algae contain chlorophyll that absorbs red and blue light most efficiently while reflecting green light.

Cyanobacteria Pigments

Cyanobacteria possess phycobilin pigments that allow them to utilize green light.

Humic Waters

Water bodies characterized by high concentrations of various organic dissolved substances.

Algal Bloom Sequence

Green algae increase -> green light reflected -> cyanobacteria use green light -> cyanobacteria increase -> toxins in water increase.

Eutrophic Lakes

Lakes characterized by high nutrient concentrations.

Mesotrophic Lakes

Lakes characterized by intermediate nutrient concentrations.

Oligotrophic Lakes

Lakes characterized by low nutrient concentrations.

Light Attenuation in Lakes

The gradual decrease in light brightness or intensity as it travels deeper through lake water.

Secchi Depth

A standard measurement of water clarity correlated with the light extinction coefficient.

Extinction Coefficient by Trophic State

Oligotrophic lakes have the lowest extinction coefficient, whereas eutrophic lakes have the highest extinction coefficient.

Phytoplankton Effect on Light

Phytoplankton decrease light intensity beneath the water surface by absorbing and scattering sunlight using cellular pigments.

Trophic Status and Light Transmission

Eutrophic lakes have lower light transmission across depths due to higher light-absorbing nutrients; oligotrophic lakes have higher light transmission.

Heat Sources for Lakes

Dominant source is solar radiation, supplemented by atmospheric diffusion, groundwater inflow, and anthropogenic sources.

Heat Loss Processes in Water

Heat is lost via atmospheric reflection/back radiation, evaporation, and cool water inflow (e.g., groundwater or anthropogenic inputs).

Heat Transfer Mechanisms in Water

Heat is transferred within water through diffusion and advection (described by modified Fick's equations) and light reaching the substrate.

Exothermic Ice Formation

The process where liquid water releases thermal energy into its surroundings as it freezes into solid ice.

Subjects of Lake Physiography

Includes size distribution, geological formation processes, habitats and morphometry, stratification, and water movement/currents.

Intermittent Lakes

Water bodies that completely dry up or shrink significantly during specific parts of the year.

Perennial Lakes

Permanent bodies of standing water retaining water year-round, most commonly found in glaciated regions.

Lake Size and Abundance Distribution

Most lakes on Earth are small, while a small number of extremely large lakes account for most total lake area.

Benthos

The bottom substrate layer of a lake body.

Littoral Zone

The shallow lake area where sunlight reaches the benthos.

Pelagic Zone

Open water area of a lake where light does not reach the benthos.

Limnetic Zone

The open water area of a lake where light penetrates.

Profundal Zone

Deep pelagic water where no light penetrates.

Lake Volume Formula

Calculated basic formula as $\text{Volume} = \text{Area} \cdot \text{mean depth}$.

Water Retention Time

Calculated as $\text{Retention time} = \frac{\text{Volume}}{\text{Discharge}}$.

Lake Stratification

The formation of distinct water layers caused by density differences driven by temperature and salinity.

Inter-Layer Transport during Stratification

When a lake is stratified, transport of materials between layers occurs primarily via molecular diffusion.

Isothermal Lakes

Lakes maintaining a uniform temperature throughout the water column.

Monomictic Lakes

Lakes that mix completely once per year (found in temperate and subtropical regions).

Amictic Lakes

Non-mixing lakes with permanent ice cover that are colder near the surface.

Meromictic Lakes

Lakes containing two distinct layers that never mix due to density differences from salinity.

Polymictic Lakes

Shallow, tropical lakes that mix multiple times a year due to greater density differences at $20\text{--}25\,^{\circ}\text{C}$ than at $10\text{--}15\,^{\circ}\text{C}$.

Dimictic Lakes

Temperate lakes that turn over and mix twice per year.

Isothermal Periods in Stratified Lakes

Periods during spring mixing and fall mixing when thermally stratified lakes become isothermal.

Thermally Stratified Lake Seasons

Seasons during which thermal stratification layers exist in dimictic lakes, specifically summer and winter.

Fetch

The uninterrupted continuous distance of open water over which wind blows, transferring energy to generate waves and currents.