Unit 1: Interactions in Ecosystems

watershed

the area of land that drains into a body of water

runoff

water that flows over the ground/surface

inflitration

water that seeps into the ground

local watersheds in our area

• potomac river

• chesapeake bay watershed

types of watershed pollution

• salt pollution

• nutrient pollution

• sediment pollution

why does salt pollution occur

salt from roads in the winter is washed into the watershed

impacts of salt pollution

• degradation of nearby plant life

• salt-contaminated soil harms soil microbes and plants

• salted water kills aquatic plant + animal life

• contaminated streams harm land animals who drink from them

• degradation of infrastructure

• contaminates our drinking water

why does nutrient pollution occur

nutrients (fertilizer) applied to yards and farms is washed into the watershed

impact of nutrient pollution

eutrophication

eutrophication

the process whereby excessive nutrients in water bodies lead to increased plant growth, resulting in oxygen depletion and harm to aquatic life - oxygen free dead zones caused by algae blooms

process of eutrophication

• 1) excess nutrients flow into surface waters

• 2) algae blooms and covers the whole surface of the water

• 3) light cannot get through the algae mat

• 4) underwater plants cannot photosynthesize and die

• 5) bacteria eat the dead plants and use up oxygen

• 6) oxygen levels fall and underwater animals cannot perform cellular respiration and die

• 7) bacteria eat more dead stuff and use more oxygen

• 8) an oxygen free dead zone forms and nothing can survive

sediment pollution

any exposed soil can be washed away

impacts of sediment pollution

• decreased underwater photosynthesis due to lack of light

• creek bed “nooks and crannies” are smothered

• irritates aquatic animals gills

land use impacts on watershed

• 1) impervious surfaces

• 2) urbanization

• 3) landscaping

• 4) agriculture

• 5) excess soil (agriculture, construction, etc.)

impervious surfaces

surfaces that do not allow water to infiltrate, leading to increased runoff and potential erosion in watersheds

urbanization’s impact on watersheds

more salt used during winter to prevent snow from sticking which leads to more salt pollution

landscaping’s impact on watersheds

less infiltration and more runoff due to the use of fertilizers and pesticides

agriculture’s impact on watersheds

more nutrient pollution because of fertilizers

excess soil’s impact on watersheds

increased sediment pollution

impacts of poorly managed watersheds

• flooding

• erosion

• contanimates drinking water

solutions for poorly managed watersheds

• rain barrels

• rain gardens

• pervious surfaces

• buffer strips

• reforestation

• wetland restoration

rain barrels

containers used to collect and store rainwater for irrigation and conservation purposes

pervious surfaces

materials that allow water to infiltrate, reducing runoff and promoting groundwater recharge

buffer strips

areas of vegetation planted between fields and water bodies to filter pollutants and reduce erosion

reforestation

the process of replanting trees in deforested areas to restore ecosystems and improve biodiversity

wetland restoration

the process of recovering and rehabilitating wetland ecosystems that have been degraded or converted to other uses, enhancing their ecological functions

concentration

the measure of how many molecules are in a given area

concentration gradient

the gradual change in the concentration of solutes in a solution between two regions

solution

a mixture of two or more substances - a solute is dissovled in a solvent

solute

gets dissolved in a solution

solvent

dissolves a solute - results in solution

selectively permeable

a layer that only certain molecules can pass through

diffusion

movement of molecules from areas of high to low concentration

osmosis

the movement of water from high to low concentrations across a semi-permeable membrane

hypertonic solution

a solution that causes water to exit the cell (higher concentration of solute outside the cell)

hypotonic solution

a solution that causes water to enter the cell (there is a higher concentration of solute inside the cell)

isotonic solution

a solution that causes water to move across the cell membrane both ways (equal concentration of solute inside and outside the cell)

what do hypertonic cells look like?

shriveled due to the loss of water as it moves out of the cell

what do hypotonic cells look like?

swollen due to the water entering the cell

what do isotonic cells look like?

maintain normal shape with no net water movement, balanced internal and external solute concentrations

matter

anything that takes up space and has mass

energy

the ability to do work or cause change

food chain

a linear sequence of organisms where energy and matter is passed as one eats another

food web

an interconnected diagram that shows all eating relationships and matter and energy transfers through an ecosystem

organisms in food webs

• producers

• consumers

• herbivores

• omnivores

• carnivores

• detritivores

• decomposers

producers

organisms that make their own food (plants)

consumers

organisms that eat other things to get energy

herbivores

organisms that eat plants

omnivores

organisms that eat plants and animals

carnivores

organisms that eat animals

detritivores

organisms that eat dead material and digest it internally

decomposers

organisms that eat dead materials and digest them externally

trophic pyramids

diagrams that show how much energy is distributed in an ecosystem and how its passed from organism to organism

levels of trophic pyramids

• tertiary consumers

• secondary consumers

• primary consumers

• producers

producers in trophic pyramids

store the greatest amount of energy

primary consumers

eat the producers (herbivores)

secondary consumers

eat the primary consumers (omnivores or carnivores)

tertiary consumers

top of the food chain - eats secondary consumers (omnivores or carnivores)

direct effect

change in one population causes a change to another that is directly connected to that species

indirect effect

change to one population causes a change to another population that isn’t directly connected to that species

trophic cascade

indirect changes to the ecosystem that are triggered by the addition/removal of a top predator

foundation species

habitat forming species that has a strong role in structuring the ecosystem (producer)

keystone species

species in high trophic levels that maintain biodiversity in the ecosystem - when removed, the ecosystem collapses

indicator species

an organism/species whose presence, absence, and population size reflects a specific environmental condition

population

all members in a group of the same species

sample

a subset of members in a specified population

sampling

testing a subset to make conclusions about the whole population

why sample?

• we cannot count the whole population

• we need information quickly

what can be measured by sampling?

• population size

• population density

• percentage affected by something

types of population sampling

• quadrat sampling

• transect sampling

• mark and recapture sampling

• indirect sampling

quadrat sampling

testing random areas in a sampling region the size of one quadrat to calculate population density or size

what is quadrat sampling good for?

• non-moving populations (plants)

• evenly distributed populations

• determining population size and density

what is quadrat sampling bad for?

• moving populations (animals)

• clumped populations

• large survey areas

transect sampling

stretching a line across a sampling site and counting organisms at even intervals along the line - repeat with other parallel lines

what is transect sampling good for?

• non-moving populations

• populations distributed in a gradient or pattern

• determining a rough survey of the biodiversity in an area

what is transect sampling bad for?

• moving populations

• large survey areas

• determining population size/density

mark and recapture sampling

a method used to estimate an animal population's size by capturing, marking, releasing, and recapturing individuals to see how many are marked - total population = # first capture x # second capture / # of marked animals in recapture

what is mark and recapture sampling good for?

• moving populations of non-dangerous animals

what is mark and recapture sampling bad for?

• dangerous animals

• animals that may be harmed by human interaction

• animals in clumped populations

• populations with lots of immigration/emmigration

indirect sampling

counting specific animal traces in an area (tracks and scat) without interacting with the population to determine the population size/density

what is indirect sampling good for?

• moving animals that are elusive

• dangerous animals

• animals who may be harmed by human interaction

what is indirect sampling bad for?

• determining accurate population size/density

how to sample well

• make sure it is representative of the whole group

• random sampling

• the larger the sample the more accurate

• sampling shouldn’t disturb the population

population density

the number of individuals per unit in an area

equation for population change

(births + immigration) - (deaths + emigration) = population change

what will happen to the population if births are greater than deaths?

the population will grow

what will happen to the population if deaths are greater than births?

the population will shrink

equation for the new population

initial population + births - deaths = new population

exponential growth

the growth rate of a population stays the same as the population size increases so it grows faster and faster as time goes on

logistic growth

population growth rate gets smaller and smaller as the population size approaches a maximum

limiting factor

something that limits growth, abundance, or distribution of a population

examples of limiting factors

• food

• space

• disease

• natural disaster and climate

• competition for resources and mates

• predators

density dependent factor

the effect it has on the population size/growth may vary depending on the population density

density independent factor

the effects on the size/growth of a population do not change with the population density

what letter represents carrying capacity

k

carrying capacity

the maximum number of organisms the environment can stably handle

growing populations typically _____________ around the carrying capacity

fluctuate

population growth steps

• initial growth

• growth rate speeds up

• grow too fast and overshoot k

• fall and undershoot

• continue to regularly fluctuate

when can k increase

• if more space becomes available

• if more food becomes available

what impacts the carrying capacity of an environment?

• resource availability

• habitat availability

• change in limiting factors

• human disturbance