Marine Science 2016 Edition

Page 212 Chapter 8 Exercise 8.4 Simpson's Biodiversity Index Based on original ideas by Nancy Tsernjavski andAngela Colliver 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. Simpson's Diversity Index is a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species. As species richness and evenness increase, so diversity increases. n = the total number of organisms of a particular species N = the total number of organisms of all species The value of D ranges between 0 and 1. With this index, 1 represents infinite diversity and 0, no diversity. • To calculate Simpson's Index for Hypothetical Bay, two areas (natural vegetation and disturbed vegetation) were sampled using quadrats placed randomly or systematically. The number of plant species within each quadrat, as well as the number of individuals of each species should be noted. There is no necessity to be able to identify all the species, provided they can be distinguished from each other. • As an example, let us work out the value of D for a single quadrat sample of ground vegetation in the Hypothetical Bay dunes. Of course, sampling only one quadrat would not give you a reliable estimate of the diversity of the dune flora. Several samples would have to be taken and the data pooled to give a better estimate of overall diversity. The method used to optimise the sampling is the Optimum Quadrat Size technique. Species Number (n) n(n-1) Spinifex 2 2 Goats foot 8 8 Sea oak 1 0 Banksia 1 0 Wattle 3 6 N=15 ∑ n(n-1) = 64 • Now put the figures into the formula for Simpson's Index above Simpson's Index of Diversity = 0.7 Answer G roup discussion Form groups of about 5-6 and use the poster on Page 213 as a discussion starter to answer the questions below. Q uestions 1. The poster depicts a range of marine organisms in various habitats spanning coastal dune to intertidal zone, rock pool, reef and open ocean, through the zone of light and into the zone of perpetual darkness. What does your group think of the graphic, its characteristics and setting in attempting to explain species diversity? a. Make a list of the types of animals and plants you can identify. b. Classify them as best you can using the tree of marine life (Page 207). c. Make a list of the external features for each organism. 2. What is the difference between genetic, species and ecosystem diversity? Use the illustrations in the graphic to give an example of each. 3. Use the key on page 202 to devise a new key for the vertebrates shown in the graphic. 4. Draw up a two column table with temperate and tropical as headings. Now list under each heading where you think the animals and plants in the graphic would be found. 5. Study the images on pages 214 - 215 . a. Make a copy of each illustration and draw food webs for each. b. Using the tree of marine life, classify into animal and plant groups each of the marine organisms shown. c. Draw up a table to distinguish between the four different ecosystems shown. d. For each ecosystem, make a list of at least 4 individuals not shown. 6. Explain this statement: Food webs are one important type of interaction, but species can provide an attachment base for other species, can alter current or light patterns, provide camouflage or other forms of shelter or compete for space. (See page 210, para 5, for context). 7. What are the five kingdoms of marine life depicted and what characteristic/s separates them from each other? 8. Name one or more animals from the following groups in the illustration; Mammalia; Reptilia; Osteichthyes; Chondrichthyes; Amphibia; Mollusca; Cnidaria; Arthropoda; Mollusca; Echinodermata; Plantae.