Topic 2.2 and 2.3

1. Topic 2.2 and 2.3 Measuring biotic and a-biotic components of the system

2. List the significant a-biotic factors of an ecosystem • Temperature • Pressure • Light intensity • Oxygen availability • Water availabilty • Carbon dioxide concentration • Salinity • pH • Flow rate / wind speed • Turbidity • Drainage • Mineral content • Slope

3. Describe and evaluate methods for measuring a-biotic factors within an ocean ecosystem • Temperature- Think! How would you get these readings? How accurately? http://www.frfrogspad.com/layers.gif http://prairieecosystems.pbworks.com/f/1179343887/crerar%20temperature%20variation.jpg http://www.rrsjamescook.com/ArticleImages%5COceanography%20-%20deep%5Ctemperature_depth.jpg

4. Oxygen availability: http://oceanexplorer.noaa.gov/explorations/04alaska/logs/aug17/media/oxygraph_600.jpg http://www.envcoglobal.com/files/MO-YSI-55.jpg

5. pH http://rst.gsfc.nasa.gov/Sect16/_45556228_ph_levels_oceans_466in.gif http://www.carlroth.com/media/_en-de/Graphics/00029324_0.jpg

6. Turbidity Shine a light through a sample. The less light that passes through the more turbid the water. http://img.directindustry.com/images_di/photo-g/turbidity-meters-408924.jpg http://www.fondriest.com/fileshare/subpages/science_library/turbidity.jpg

7. Salinity http://www.rickly.com/wqi/images/YSI63MET.JPG This works by measuring the amount of electricity can flow through the water. The more electricity that flows the higher the salinity. http://www.google.com.ph/imglanding?q=salinity+of+ocean+water&um=1&hl=en&rlz=1R2ADBF_enPH376&biw=815&bih=732&tbs=isch:1&tbnid=e9NNCkeNiSz5eM:&imgrefurl=http://www.windows2universe.org/earth/Water/salinity_depth.html&imgurl=http://www.windows2universe.org/earth/Water/images/sm_salinity_depth.jpg&ei=zTJKTajZNcOVcbyDsMsL&zoom=1&w=270&h=374&iact=hc&oei=zTJKTajZNcOVcbyDsMsL&esq=1&page=1&tbnh=139&tbnw=100&start=0&ndsp=13&ved=1t:429,r:6,s:0

8. Identification keys http://gottalovebio.wikispaces.com/file/view/candy_class._key.jpg/162207257/candy_class._key.jpg http://www.field-studies-council.org/publications/resources/ks3/images/Liqorice-key.jpg

9. Measuring abundance of organisms • If the organism is fixed use quadrats to measure how many there are or the % cover in a known area and extrapolate • If the organism is mobile use the Lincoln Index (Capture, mark, release, recapture method) Where: http://www.offwell.free-online.co.uk/lincoln.htm

10. Measuring Biomass • Get a sample of the organisms, dry them out completely (to remove all water!), find the mass and extrapolate : • If you catch 10 frogs, dry them out and find their average dry biomass to be 20g, what would the biomass of a population of 2500 frogs be? • 50,000g

11. Diversity • The two main factors taken into account when measuring diversity are richness and evenness. Richness is a measure of the number of different kinds of organisms present in a particular area. For example, species richness is the number of different species present. However, diversity depends not only on richness, but also on evenness. Evenness compares the similarity of the population size of each of the species present. 1.Richness • The number of species per sample is a measure of richness. The more species present in a sample, the 'richer' the sample. • Species richness as a measure on its own takes no account of the number of individuals of each species present. It gives as much weight to those species which have very few individuals as to those which have many individuals. Thus, one daisy has as much influence on the richness of an area as 1000 buttercups. 2.Evenness • Evenness is a measure of the relative abundance of the different species making up the richness of an area. http://www.countrysideinfo.co.uk/simpsons.htm

12. To give an example, we might have sampled two different fields for wildflowers. The sample from the first field consists of 300 daisies, 335 dandelions and 365 buttercups. The sample from the  second field comprises 20 daisies, 49 dandelions and 931 buttercups (see the table below). Both samples have the same richness (3 species) and the same total number of individuals (1000). However, the first sample has more evenness than the second. This is because the total number of individuals in the sample is quite evenly distributed between the three species. In the second sample, most of the individuals are buttercups, with only a few daisies and dandelions present. Sample 2 is therefore considered to be less diverse than sample 1. • A community dominated by one or two species is considered to be less diverse than one in which several different species have a similar abundance. • As species richness and evenness increase, so diversity increases. Simpson's Diversity Index is a measure of diversity which takes into account both richness and evenness. http://www.countrysideinfo.co.uk/simpsons.htm http://www.countrysideinfo.co.uk/simpsons.htm

13. Simpson’s biodiversity index D= N(N-1) ∑n(n-1) • D = diversity index • N = total number of organisms of all species found • n = number of individuals of a particular species You are not required to memorize this formula but must know the meaning of the symbols. D is a measure of species richness. A high value of D suggests a stable and ancient site, and a low value of D could suggest pollution, recent colonization or agricultural management. The index is normally used in studies of vegetation but can also be applied to comparisons of animal (or even all species) diversity. (IBO ESS syllabus)

14. Using the earlier example: D= N(N-1)Put the figures for sample 1 into the formula ∑n(n-1) D= 1000(999) =2.98 (300x299)+(335x334)+(365x364)

15. For Sample 2: D= N(N-1)Put the figures for sample 2 into the formula ∑n(n-1) D= 1000(999) =1.15 (20x19)+(49x48)+(931x930)

16. Sample 1 has a higher Simpson’s Biodiversity index than Sample 2 even though it has the same number of species present and the same number of total individuals because there is more even distribution of the organisms through the species.