Limiting Factors • Too much or too little of a single physical factor can adversely affect the function of an organism. • Limiting factors are physical or biological necessities whose presence or absence in inappropriate amounts limits the normal action of the organism.
Light is needed for photosynthesis and vision.• Blue light penetrates deepest.• Limited also by particles in the water.
Temperature influences the metabolic rate,the rate at whichreactions proceed within an organism.
• Most marine organisms are ECTOTHERMIC having an internal temperature that stays very close to that of their surroundings.• A few complex animals (mammals & birds) are ENDOTHERMIC, meaning they maintain a stable internal temperature.• Ocean temperature varies in both depth and latitude.• Ocean temperatures vary less than on land.
Salinity greatly affect cell membranes and protein structure.• Disrupts cells osmotic pressure.• Varies because of rainfall, evaporation and runoff from land.
Dissolved Gases are necessary for photosynthesis and respiration.• CO2 dissolves more easily in water than O2.• CO2 is more abundant in deep waters than surface water.• O2 decrease dramatically where light penetration decreases.
Dichotomous keys• Use this key to classify a tree
2.3.2 Abundance of organisms. Methods for Estimating Population Size 1. Quadrats 2. Capture/Mark/Release/Recapture (Lincoln Index)
• Knowing population size is important in making environmental decisions that would affect the population.• Making a decision on an estimate that is too high extinction.• Making a decision on an estimate that is too low unnecessarily hurt people that depend on the animals for food & income.
• When estimating population size it is important to collect RANDOM SAMPLES.• A sample is a part of a population, part of an area or part of some other whole thing, chosen to illustrate what the whole population, area or other thing is like.• In a random sample every individual in a population has an equal chance of being selected.
Using Quadrats1. Mark out area to be sampled.2. Place quadrates (1m2, 10m2) randomly within the area.3. Count how many individuals are inside each of the quadrates.4. Calculate the mean number of individuals per quadrate. 5. Pop. Size = mean x total area area of each quadrat
RANDOM SYSTEMATIC QUDRATS QUDRATS Quadrat sampling is suitable for plantsthat do not move around and are easy to find.
Quadrat method can be used to determine: POPULATION DENSITY = number of individuals of each species per area. PERCENTAGE FREQUENCY = percent of each species found within an area. PERCENTAGE COVER = percent of plant covering a given area.
Lincoln index - Capture/Mark/Release/Recapture1. Capture as many individuals as possible in the area occupied by the animal population, using netting, trapping or careful searching. 2. Mark each individual, without making them more visible to predators and without harming them.
3. Release all the marked individuals and allow them to settle back into their habitat.4. Recapture as many individuals as possible and count how many are marked and how many are unmarked. 10 marked 14 unmarked
5. Calculate the estimated population size by using the Lincoln Index: population size = N1 X N2 N3N1 = number caught and marked initiallyN2 = total number caught in 2nd sampleN3 = number of marked individuals recaptured Most suitable for animals that move around and are difficult to find.
Assumptions: 1. The population of organisms must be closed, with no immigration or emigration. 2. The time between samples must be very small compared to the life span of the organism being sampled. 3. The marked organisms must mix completely with the rest of the population during the time between the two samples. 4. Organisms are not hurt or disadvantaged by being caught and marked and therefore all organisms have an equal opportunity of being recaptured
Change in the relative abundance of a species over an area or a distance isreferred to as an ECOLOGIAL GRADIENT Also known as Zonation.
Changes in the distribution of animals withelevation on a typical mountain in Kenya. Another example of Zonation
DIVERSITY is a generic term for heterogeneity. If may refer to: 1. Genetic diversity is the total number of genetic characteristics of a specific species. 2. Habitat diversity is the diversity of habitats in a given unit area. 3. Species diversity a. Species richness – total number of species. b. Species evenness – relative abundance of each species. c. Species dominance – the most abundant species.
Figure aand b have the same species richness, but different species evenness.
Simpson’s diversity index- High value means high diversity • D is a measure of the diversity • N = total number of species • n = total number of individuals • Range is 0 to 1 (1 the best)
How would you interpret this graph?• Higher species diversity, means better change of surviving disease?• Areas of high infection have killed off a lot of species?