# 02-12 - Announcements Homework 2 due Wednesday Feb 17...

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Announcements • Homework 2- due Wednesday, Feb 17. Includes Stella Assignment #1, which is posted on Blackboard. • Quiz on Friday, February 19.

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Define Diversity as: diversity is high in fresh (unpolluted) waters and low in polluted waters. Usually: # of organisms (total) number of different species Diversity decreases in response to either: a. toxic (___________) factors b. stimulatory (___________) factors Quantifying Diversity: define diversity index = d let N.S. = number of individual species and let N.O. = total number of organisms abiotic biotic a function of : # species # organisms
Then d= alternate or d= definitions that have been used or d= all of these depend on sample size. Ex. 10 species in equal numbers if sample 10 organisms, d= if sample 100 organisms, d= N.S. / N.O. (N.S. - 1) / ln N.O. N.S. / (N.O.) 1/2 10/10 = 1 10/100 = 0.1 Using the first of the above definitions of d Richness and equitability combine to determine diversity. Example: Case 1: 10 species in equal numbers Case 2: 10 species– more than 50% of individuals in species 1, less than 5% in each of the other species.

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An index which is independent of sample size is where n i = Ex . if sample 2 species in equal numbers if sample 10 species in equal numbers d = 2.3 if sample 100 species in equal numbers d = 4.6 Note all of the above indices increase with increase in diversity. Number of organisms of species i d = d = . O . N n ln . O . N n i . S . N 1 i i i i 2 1 i i i n 2 n ln n 2 n = -2 (1/2) ln(1/2) = 0.69
Biotoxicity So far we've discussed a stimulatory pollutant (sewage discharge to a stream). Some pollutants produce toxic effects. How do we deal with these? Quantifying toxicity: What problems can you anticipate with this type test? 1. 2. 3. It does not measure sublethal effects such as chronic toxicity or diminishing function. Interaction

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02-12 - Announcements Homework 2 due Wednesday Feb 17...

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