Biological comparative tables - guidance notes

Structure of the spreadsheet
The biological comparative tables contain seven worksheets.  The two main ones are the "Comparative Table" worksheet, which contains a pivot table enabling a comparative overview over which species are frequently recorded in biotopes, and the "Extended Species Table", which contains additional information, such as the average abundance at which species are recorded within biotopes. The layout of these two worksheets is described in detail below.
The main pivot table (in the "Comparative Table" worksheet) has to process a large amount of species data. Depending on the filtering options chosen, and on the power of the computer being used, it may take a long time for some sets of biotopes to display. In order to enable users with slower processors to make full use of the tables, five additional worksheets were created, each containing information for a single broad habitat. These tables will display instantly. They have a similar layout to the "Comparative Table" worksheet, but without the filtering options. They do not contain any additional information over the main worksheets.

The Comparative Table worksheet

Each column in the main part of the pivot table represents a biotope, indicated by the biotope code in the column header. The rows contain information on species, with species names listed in taxonomic order down the left. The figures given in each cell represent the percentage of core biotope records within which a given species is recorded. To avoid the size of the table becoming unmanageable, species recorded in less than 20% of core records of a biotope are not shown. The biotopes which are displayed at any one time is user-defined, with a number of options available for filtering the data.
The last row and last column contain the sums of all the figures in the columns / rows, and should be ignored. They are part of the standard set-up of an Excel™ pivot table, but in this instance the figures they contain are meaningless.
The following filtering options are available:
Broad Habitat (top left corner of worksheet): The drop-down arrow enables the selection of biotopes from within a single broad habitat.
EUNIS Level (top left corner of worksheet): The drop-down arrow enables the selection of units from within a single hierarchical classification level (from broad habitat to sub-biotope). On the pivot table, the column headings containing biotope codes are coloured according to the standard classification colour scheme, which is used for the classification hierarchy throughout the website. The column headers are colour-coded irrespective of whether the "EUNIS Level" filter is in use or not.
Species Name: Clicking on the drop-down arrow opens up a ticklist, which enables the user to choose a single species or a defined subset of species for which information is to be displayed. The "(Show all)" option at the top of the list will re-display the entire list. Remember that whatever is clicked on or off in this filter, species are only ever shown if they occur in at least 20% of the core biotope records of at least one of the biotopes currently displayed on the table.
Biotope Code: As for the Species Name, clicking on the drop-down arrow opens up a ticklist, enabling the display of any combination of biotopes required.
There is an additional filtering button on the table, which is greyed out. This contains the hierarchical sort order of the biotopes, and has been included in the pivot table to ensure that the columns always appear in the correct classification sort order. The row containing the sort order has been hidden. There is also a hidden column, containing the taxonomic sort order for the species in the form of the alpha-numeric species codes taken from Howson & Picton (1997). Including this in the pivot table ensures that the species will always display in their correct taxonomic order.
If you wish to filter on one of the above options only, it is advisable to double-check all the other filters to make sure that the "show all" option is selected, to avoid inadvertently filtering data you want to include in the table.
Note that Excel™ worksheets are limited to a maximum of 256 columns. The number of biotopes in the classification exceeds this number, so please be aware that if none of the data filters are in use, only part of the classification will be displayed on the table. It is possible, however, to display all units for each broad habitat individually on a single sheet.

The Extended Species Table worksheet

This worksheet provides additional species data for each biotope, including the total number of core biotope samples, characterising species, average infaunal counts for infaunal species, and SACFOR abundances for all species.
The biotopes are displayed in rows rather than columns, which means that the limit of 256 does not apply, and all data can be displayed at the same time. There is a single row for each species in each biotope – i.e. if there are 10 species within the core records for a biotope, there will be 10 rows with that biotope code (note that the 20% percentage cut-off still applies). 
The information displayed in the columns is as follows, with the option to filter on any of them:
Biotope Code: Contains biotope codes, with the filtering option of displaying a single biotope at a time.
Biotope Sort Order: Allows biotopes to be displayed in the correct classification order.
EUNIS Level: Shows the EUNIS level for each classification unit. It is colour-coded in the standard colour scheme used throughout the classification website. Using the filter, it is possible to display units from a single level in the classification hierarchy.
Number of Core Biotope Records: This shows the number of core biotope records for each biotope. It is important to be aware of the number of records on which the information in the tables is based. There are some biotopes for which there are not a lot of records on the JNCC marine database, and which therefore have only a limited number of core records. When the information in the comparative tables is based on only a handful of core records, it needs to be treated with the appropriate level of caution.
Species Name: Lists the species which are recorded in 20% or more of the core biotope records. The filter allows information to be displayed for a single species at a time.
Taxonomic Sort Order: Contains the alpha-numeric taxon codes from Howson & Picton (1997), allowing the species to be displayed in correct taxonomic order.
Percentage Ocurrence: This column contains the same values as the "Comparative Table" worksheet, i.e. the percentage of core biotope samples within which each species is recorded.
Infaunal Density: Some biotopes have core records containing quantitative infaunal sample data. This column shows the average number per m2 for species recorded in quantitative infaunal samples.
SACFOR: Shows the average frequency of each species on the MNCR SACFOR scale, based on SACFOR data in the core biotope records. Details on the SACFOR scale are included in the introductory text for the classification.
Percentage Occurrence Score: This column is intended to provide a rapid visual assessment of the percentage occurrence of species within core biotope records. It is based on the information in the Percentage Occurrence column, with categories broken down as follows:
20-40%                 nn
40-60%                 nnn
60-80%                 nnnn
80-100%               nnnnn
Broad Habitat: Contains the broad habitat code for each biotope, enabling the selection of data from within a single broad habitat through use of the filter.
If you wish to filter on one of the above options only, it is advisable to double-check all the other filters to make sure that the "show all" option is selected. This will avoid inadvertently filtering out data you want to include.

Biotopes which do not appear in the biological tables

Every species which appears in 20% or more of the core records of a biotope is displayed in the comparative tables, but any species which occurs in fewer than 20% of the core records is not shown. This cut-off percentage was used to keep the tables within manageable size limits.
There are a limited number of biotopes for which no species at all are recorded in 20% of the core biotope records. These biotopes were not picked up in the generation of the tables. This has happened where biotopes are extremely species-poor, or they have no core biotope records. The species-poor biotopes have core records containing physical information, which means that these biotopes are featured in the physical tables even though they do not appear in the biological tables. Biotopes with no core records, on the other hand, were included in the classification based on information from sources other than the JNCC marine database. For these biotopes, there is no information in the physical comparative tables, either.
The biotopes (and broader units) which do not appear in the biological comparative tables are listed here.
Biotopes with no core records (appear neither in the biological nor physical comparative tables):
Species-poor biotopes (appear in the physical, but not in the biological comparative tables):

Download the comparative tables

Comparative tables guidance - File format pdf (45KB)
Physical comparative tables - File format zip (148KB)
Biological comparative tables - File format zip (945KB)