IB Bio C.5

What type of factor is build-up of toxic by-products of metabolism

bottom up

What are density dependent factors

factors that have greater effect when the population density is higher

Define bottom-up limiting factors

factors that involve resources or lower trophic levels

outline the human practices that can disrupt bottom-up control of algae

fish, farming, fertilizer or sewage outflows cause eutrophication- algae populations increase rapidly due to the removal of nutrients as a limiting factor

Outline the environmental conditions experienced by algae that mean nutrients are a key limiting factor

-Algae depend on photosynthesis for nutrition -With key proteins such as chlorophyll in short supply, the rate of photosynthesis and hence algal growth is limited

Outline the transitional growth phase in terms of population growth

-As the population continues to grow, eventually competition increases as availability of resources is reduced -Natality starts to fall and mortality starts to rise, leading to slower rate of population increase

List ethical considerations for Marking

-Avoid making them more visible -Avoid damage

State two ways in which the Lincoln index can be used to estimate population size

-Compare populations of different species one time -Chart change in species over time

List ethical considerations for logistics

-Could the mark be washed off by accident

List ethical considerations for Animal Behavior

-Do they like the trap -More wary of humans

How does emigration affect population size?

Decreases as a result of loss of external populations

How does Mortality affect population size?

Decreases due to death

Outline the Plateau phase in terms of population growth

-Eventually, the increasing mortality rate equals the natality rate and population size becomes constant. The population has reached the carrying capacity (K) of the environment -Limited resources, predation and disease all contribute to keeping the population size balanced-While the population size at this point may not be static, it will oscillate around the carrying capacity to remain relatively even

Outline the main difficulty with estimating fish populations

-Fish are very mobile - they pursue what is frequently mobile food -they are often in schools and unevenly distributed

List 4 density dependent limiting factors

-Food and Water availability -Space for territories and nesting -Availability of mates -Disease -Predation

Describe how the age structure of a population acts an indicator of future growth or decline

-If a population is growing, then the relative number of younger fish will be higher -If the population is in decline then the proportion of older fish will be higher

List ethical considerations for capturing

-Injury or death -Damaging habitat

Explain why it is necessary to use sampling techniques to estimate population size

-It is only feasible to count populations directly when individuals are large and area is small. Since this is rarely the case, researchers need to use sampling techniques to estimate the population by measuring density in small parts of the study

List density independent factors that can affect the population size

-Natural disasters -Climate -Light

Outline the practices used to try to ensure fish can breed before being caught

-Regulations often restrict the net mesh size allowing younger fish to escape -Closed seasons are declared to allow undisturbed breeding

Control of algal blooms can be used as an example of top-down and bottom up control, why?

-Shortage of nutrients is normally a key bottom-up factor preventing algal blooms -Parrot fish are herbivores that feed on the algal blooms at a lower trophic level

Outline the exponential growth phase in terms of population growth

-There is a rapid increase in population size / growth as the natality rate exceeds the mortality rate -This is because there are abundant resources and limited environmental resistance

Explain the importance of sustainable fishing practices and the role of fisheries

-Up to maximum sustainable yield (MSY), sufficient individuals are replaced in the stock year-on-year so that there is no overall population decline -Overfishing depletes stocks to the point where there is an overall decline in resources -Collection of data for setting annual catch limits is difficult -Data collected include: average fish size, estimates of age, catch per unit effort, characteristics of the 'by catch' -Conservative (below MSY catch-limits are safer, due to limitation of data collected and to ensure no overall population decline)

Define the term population

A group of organisms of the same species in the same area at the same time

How are fish catches used

Age structure of landed fish can be used to estimate population size

Outline the type of environment in which exponential growth occurs

All individuals survive to reproduce successfully Unlimited resources Therefore, there is no competition and no limit to the population

Which factor has the greatest importance to population growth

Birth

How is echo sounders used

Can be used to estimate the size of fish schools

Describe the process of the Lincoln Index

Capture a sample and mark the sample Release sample Come back later and capture second sample Count how many are marked and unmarked

Outline why it is important to accurately estimate fish populations

Ecological impact: -Interdependence of species -Loss of diversity and productivity -r-strategists and pests could proliferate Economical &social impacts: -Long term recession of the industry -Unemployment -Loss of food source -Damage to communities and culture

Define the term limiting factor

Environmental factors that controls the maximum rate at which a process such as population growth can occur

What are the phases in sigmoidal graphs

Exponential phase: first part increasing Transitional phase: beginning to plateau Plateau phase: oscillates up and down making each year even

How is capture-mark-release-recapture used

Fish are temporarily stunned with electric shocks and then counted

Describe the consequences of coastal marine communities, such as coral reefs, of an algal loom that results from the disruption of bottom-up and or top-down control

Free living algal blooms can disrupt coral reef communities by blocking sunlight and preventing photosynthesis in the symbiotic zooxanthellae causing coral bleaching and death of coral reefs

State factors that can affect the mortality of a population

Genetics: The more genetically diverse the more likely they are to survive Density independent factors

Explain the importance of the age of mortality has to population growth

If individuals die before reproducing the population size of next population is reduced. Higher age = larger population

How does immigration affect population size

Increase in population size from external populations

State the effect quotas have on age structure of fish population

Increase the number of younger fish to encourage growing population

How does Natality affect population size?

Increase to population through reproduction

State the type of growth curve that shows exponential growth

J-shaped

Explain how a keystone species exerts top-down influence on its community

Keystone species applies these pressures by preventing species at lower trophic levels from monopolizing critical resources, such as a competition for space or food sources

Explain why nutrients are a limiting factor on a photosynthetic organism such as algae

Nutrients are essential for synthesis of key proteins and other compounds

When and what are the limitations of echo sounders

Only useful for schooling fish species

Describe the top down control of algal blooms by a named example of fish

Parrot fish are herbivores that feed on the algal blooms at a lower trophic level

How can the population size be determined formula

Population size = (natality + Immigration) - (Mortality + Emigration)

outline the human practices that can disrupt top-down control of algae

Remove parrot fish

What type of graph models population growth

Sigmoidal

Define maximum sustainable yield

The largest catch possible without adversely affecting the ability of the population to recover

Define the term carrying capacity

The largest population size that an environment can support

Explain how genetic diversity helps a population limit how much a population is affected by environmental resistance

The more diverse, the more likely they are to have fit individuals in the population

Apart from size describe how scientists can estimate fish age

The otolith (ear bone) contains rings, similar to the rings of a tree

State the conditions necessary for exponential growth

The population is very small The organism has just colonized a new environment

What age groups are density independent factors likely to affect the most and how will this impact the future

The young, old and weak will be more affected. This will decrease the population growth since the young population will be gone

Explain how this calculation uses the recapture data

This calculation use the recapture data to determine the proportion of the actual population as sampled on the first capture "How much of the actual population did we catch in the first capture"

What type of factor is availability of mates

Top-Down

What type of factor is space for territories and nesting

Top-Down

What type of factor is a disease

Top-down

When is capture-mark-release-recapture used and what are the limitations

Used in lakes and rivers, but recapture numbers are too small to be useful in open waters

State how the Lincoln Index is used as a sampling method

Used to estimate population of animal species in a given area at a given time

What is coral bleaching

When the coral releases zooxanthellae causing the coral to die

Define algal blooms

a rapid increase or accumulation in the population of algae in a water system

What are keystone species

a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.

Lincoln Index Equation

population size = N1 x N2 divided by N3 N1 = first capture N2 = second capture (marked only) N3 = Second Capture total

Define top-down limiting factors

pressures applied by other organisms at higher trophic levels

What type of factor is food and water availability

top down because keystone species controls food and water availability

When and what are the limitations of fish catches

violators of fishing regulations often do not repot what they landed or they dump the restricted fish causing a bias in the estimates