Marine biology students want to study how the abundance and distribution of organisms on a rocky shore change with height above the low-tide mark.
Suggest a systematic sampling method they should use to investigate this distribution.
Explain one limitation of using a line transect compared to a belt transect for this investigation.
The students recorded the number of individuals of 5 marine species in a representative quadrat. Their data is shown in the table below:
| Marine species | Representative number of individuals (nnn) |
|---|---|
| Common limpet | 28 |
| Flat periwinkle | 16 |
| Dog whelk | 8 |
| Beadlet anemone | 12 |
| Toothed wrack | 16 |
Calculate the Simpson's Index of Diversity (DDD) for this data using the formula:
D=1−∑(nN)2 D = 1 - \sum \left(\frac{n}{N}\right)^2 D=1−∑(Nn)2Show your working. Give your final answer to 3 decimal places.
The students struggled to distinguish between different species of periwinkles and decided to group both flat periwinkles and rough periwinkles under the single category 'Flat periwinkle'.
Explain how this decision might affect the calculated value of DDD.
