Freshwater Ecology Exam 5

outside the system, carbon dioxide in the atmosphere creates...

more acidic water

total dissolved solids (total amount of ions)

total mass of organic and inorganic material dissolved in water
ex: Calcium, phosphate, nitrates, potassium, chloride, sodium, clay particles

conductivity

measure of the ability of water to conduct an electric current

salinity

amount of salt dissolved in water

is water organ or inorganic?

inorganic

the more ions, the (higher/lower) conductivity?

higher

weathering

the breaking down of rocks, soils, & minerals as well as wood and artificial materials through contact with the Earth's atmosphere, water, and biological organisms

physical weathering

involves the breakdown of rocks and soils through the direct action of heat, water, ice, pressure, or other mechanical forces

chemical weathering

involves the direct action of atmospheric or biologically produced chemicals in the breakdown of rocks, soils, and minerals

physical location dictates water quality. (T/F)

true

Where does oxygen come from in freshwater environments?

- photosynthesis
- atmosphere

oxygen saturation

ration of the concentration of dissolved oxygen to the maximum amount of oxygen that will dissolve in that water body

the amount of oxygen that can be held by water depends on...

water temperature and pressure (main drivers) and also salinity (secondary)

what controls the rate of photosynthesis?

- light availability
- temperature
- nutrients
- water velocity
- organic compounds

when light availability goes up, O2 goes?

up

when temperature goes up, O2 goes?

down

when nutrients goes up, O2 goes?

up

when water velocity goes up, O2 goes?

up

where does O2 in freshwater environments go?

-respiration (main)
- oxidation (lesser)

how often does photosynthesis occur in a freshwater environment?

12 hrs a day (when the sun is up)

how often does cellular respiration occur in freshwater environments?

24 hrs a day

when is oxygen in a lake highest and lowest?

highest: dusk
lowest: sunrise

what is the desirable range of DO for warm water fish?

5-6 ppm

what DO level is considered hypoxic for warm water fish?

less than or equal to 2 ppm

if photosynthesis dominates, DO levels are high. what are the conditions?

need light, autotrophs

if respiration dominates, low levels of DO. what are the conditions?

cloudy day, ice cover, stagnant water, droughts, sewage discharges, eutrophication

high temperatures can exacerbate the problem of low DO because

1. oxygen solubility is lower at higher temps
2. metabolic rate is greater

eutrophications effects of DO

1. increase algal growth and leads to an increase in photosynthesis and respiration
2. death of algae leads to decomposition and lower DO

what is the most common cause of fish kills?

oxygen depletion

when are fish kills most prevalent?

late summer or fall turnover, but can happen at any time

earth is considered a _______________ system, meaning it can exchange energy, but not matter, with its surroundings.

CLOSED

the amount of matter on earth is fixed and finite, this means...

- resources are limited
- waste products remain within the confines of the earth

if changes are made in one part of the planet, the results of those changes...

eventually will affect other parts of the system

sink (reservoirs)

a place where matter is stored

residence time

average time something will spend in the reservoir

processes

chemical reactions that change matter from one form into another, sometimes referred to as "flows"

step 1 of the carbon cycle: carbon enters the atmosphere as _______________________ from ___________ and ________________.

carbon dioxide (inorganic); respiration; combustion

step 2 of the carbon cycle: carbon dioxide is absorbed by __________ to make glucose in __________________.

producers; phtosynthesis

step 3 of the carbon cycle: animals feed on the plant passing the carbon compounds along the food chain. Most of the carbon they consume is exhaled as ______________________ that was formed during ______________________. The animals and plants eventually die.

carbon dioxide; aerobic respiration

step 4 of the carbon cycle: decomposers break down dead organisms. decomposers respire. _______________ from dead organisms becomes available for other organisms.

organic carbon

organic carbon

includes carbon bonded with hydrogen, usually oxygen

inorganic carbon

carbon is not bonded to hydrogen
example: carbon dioxide

carbon cycle processes?

photosynthesis, respiration, decomposition, combustion

carbonic acid

H2CO3

bicarbonate ions

HCO3-

carbonate ions

CO3^-2

sources of excess inorganic carbon

- carbon dioxide from the atmosphere
- geology

carbon dioxide dissolved in water creates:

- carbonic acid
- bicarbonate ions
- carbonate ions

hard water is a...

natural buffer to changes in pH
- helps keep water less acidic

nutrient

any element required by an organism for growth
- typically used in reference to elements that are limiting to growth
ex: N, P, Fe, Silicon

all organisms have approximately the same nutrient requirements, which are

C:N:P
106:16:1

biological molecule require different amounts of nutrients:

- lipids are phosphorus rich
- amino acids and proteins require more nitrogen that most molecules
- nucleotides and nucleic acids require nitrogen and phosphorus
vertebrate bones require large amounts of phophorus

what is uptake

organisms ned to take nutrients in from the water surrounding them or from food

what is the prime determinant of uptake?

nutrient concentration

what is assimilation

once the nutrient enters the organism, it then needs to be incorporated into organic molecules used for growth

nitrogen gas

N2
- triple bond very hard to break

ammonia

NH3
- can be toxic as a gas, bad smell, fish excrete ammonia

ammonium

NH4+
- readily available for uptake, no smell

nitrate

NO3-

nitrite

NO2-
- plant, autotrophs, bacteria & cyanobacteria love this
- reacts badly with hemoglobin

organic nitrogen

Nitrogen that is bound with organic carbon and forms organic molecules
- easiest, found in meat

nitrogen fixation happens by

1. some bacteria, cyanobacteria, and archea
2. lighting
3. ??????????????

what is nitrogenase?

an enzyme used to convert N2 to ammonium

globally humans have _____ the rate of nitrogen fixation

doubled
- most caused by synthetic fertilizer
- 2nd burning of fossil fuels

what is nitrification?

a 2-step process by bacteria
1. nitrosomonas (convert ammonia to nitrite)
2. nitrobactor (convert nitrite to nitrate)
- import producer of nitrate

what is denitrification?

occurs in anoxic conditions
- by a diverse group of prokaryotes
- removes nitrate from the ecosystem and returns it to the atmosphere in gas form

what is anammox?

converts ammonium and nitrite into nitrogen gas and water
- specific phylum of bacteria in anoxic conditions

what is the easiest way to obtain nitrogen?

heterotrophy; organic nitrogen is found in the molecules of the tissues of the organisms that are being consumed

what is ammonification?

various fungi and prokaryotes convert organic nitrogen into ammonia via decomposition
- organic nitrogen inputs are death

paper conclusions:

1. microplastics were found across all locations
2. urban areas contribute significant amounts to lake ontario
3. authors hypothesized that microplastics are remaining in the sediment of the lake not on the surface

phosphorus cycle reservoirs?

1. rocks (inorganic)
2. soil (inorganic and organic)
3. plants and animals (organic)

what converts organic P to inorganic P in the soil so it is readily available for plants?

microbes

plants can only readily take in (inorganic/organic) phosphorus?

inorganic

what are the main organic phosphorus forms?

particulate: parts of cells, microbes
dissolved: phospholipids, nucleic acids

what are the main inorganic phosphorus forms?

particulate: mineral phosphorus
dissolved: orthophosphate (PO4^3-); readily available for uptake

what are the phosphorus cycle processes:

1. weathering
2. assimilation (heterotrophs absorb P)
3. remineralization (organic to inorganic) (completed by the microbial loop in aquatic ecosystems, regeneration of inorganic P, continues to cycle in epilimnion)

P cycle Processes in Freshwater Ecosystems?

1. orthophosphate inn solution can be absorbed/assimilated by autotrophs, becomes organic P
2. organic P is cycled through (heterotrophy, assimilation, and excretion)
3. dissolved organic P is remineralized via microbes into an inorganic form that is available to autotrophs

what are the P cycle forms?

organic P fertilizer:
- manure-biosolids
- dead plants
inorganic P fertilizer:
- chemical fertilizer
- phosphates in detergents

where does all the P go?

flows from land to water and is depositied

what is a legacy contaminant?

chemicals often produced through industrial or agricultural activities that remain in aquatic ecosystems long after they are first released into the environment

what are emerging contaminants

naturally occurring or manmade substances that present realized or potential risks to the structure and function of aquatic ecosystems

examples of legacy contaminants

- metals (lead and mercury)
- pesticides (DDT)
- PCBs

what is bioaccumulation?

An increase in the concentration of a chemical in a single organism over time

what is biomagnification?

an increase in the concentration of a chemical at higher trophic levels in the food web

emerging contaminants are emerging because...

1. we lack detailed info about the complexity of mixtures of contaminants in the environment
2. insufficient understanding of the sublethal impacts of contaminants on aquatic organisms
3. more research is needed to learn about consequences
4. more info on how environmental stressors may exacerbate or reduce the impact of exposure

examples of emerging contaminants:

- caffeine
- antihistamines
- amphetamines
- antibiotics
- antidepressants
- fracking fluid
- pesticides
- herbicides
- PFAs
- microplastics

silicon

needed for diatoms, major source: earth's crust

iron

key element for hemoglobin, enzymes, and electron transport

sulfur

component of amino acids

dimethyl sulfide is a gaseous byproduct of?

phytoplankton metabolism

how does acid rain happen?

sulfur oxides and nitrogen oxides that react with water in the atmosphere to produce sulfuric and nitric acids

what does acid rain do to the soil?

soil acidity and N availability increase, buffering ability and P availability decrease
- increased susceptibility to invaders

what does acid rain do to forests?

reduced tree growth, increased susceptibility to stress (drought, disease)

What does acid rain do to marble, limestone, and other minerals?

causes them to erode

what does acid rain do to water ecosystems?

lakes, rivers, and streams become acidified

what does acid rain do to freshwater ecosystems?

1. altered microbial activity (decompose rate declines, leading to greater rates of deposition)
2. efficient of energy transfer up the food web is lowered
3. impaired ability of fishes to survive and reproduce

what treats and stops acid rain?

- the clean air act required emission reductions of sulfur dioxide and nitrogen oxide from the power sector
- the addition of limestone to lakes to neutralize acidic waters is used

oligotrophic

few foods

eutrophic

many foods

cultural eutrophication

flux of excess nutrients from human activity are added into a local run-off which in turn speeds up the natural eutrophication