PiscesLogoSmallerStill Rank abundance plots

Top  Previous  Next


It is very useful to examine the pattern of relative abundance between species in your samples. The rank abundance plot is often a very useful way to summarise both equitability in abundance between species and species richness. Below we take you through all the stages of the analysis.


First open the data set called Hinkley annual fish.csv


This data set is for the fish community of the Bristol Channel, England. It is derived from monthly sampling over a 25 year period and is one of the largest data sets of its type available.


open Hinkley annual fish


Now from the Abundance tab choose Rank Abundance.


choose rank abundance


A graph showing the rank abundance plots for every year will be shown as follows:



Rank anundance plot


This shows a log-log plot, which is usually better than using normal axes because species typically vary in abundance over a number of orders of magnitude.


This plot is too cluttered, so you cannot see the difference between years. To select the samples (years) to plot click on the Select Data tab at the top of the graph.


select data tab


Now select 1985 and 1996 only, using the selection buttons between the two boxes holding the not selected and selected samples.


selection boxes


Now click on the Graph tab to display the graph for 1985 and 1996 The resulting graph clearly shows the difference in fish abundance and richness between the two years.



two year rank abundance plot

This change in fish community has been related to increases in average temperature and changes in the North Atlantic Oscillation.