Distribution of benthic macroinvertebrate living modes in European seas | Emodnet Biology

Distribution of benthic macroinvertebrate living modes in European seas

Data series

Several occurrence lists from EMODnet Biology were considered on the basis of compatible sampling protocol: sampling gear (grab or corer) and sieve mesh size (1 mm). This includes:

Data product

This series of products displays the main functional types of benthic macroinvertebrates derived from a multivariate analysis of 13 life history traits. Three main living modes were identified. The first one comprises species resistant to physical stress in natural conditions through a strong mobility, a short life cycle and a high offspring survival probability. The second one is composed of opportunistic species, also with a relatively short life span, among which many are pioneer species which are not very habitat-specific. The third group is composed of species which require many years or even decades to achieve a minimum of reproductive success. Population survival in the two first groups was shown to be unaffected by bottom trawling, whereas the response of the third species group is generally negative (ICES, 2017). Hence, these products provide information on the benthic ecology, but also on ecosystem vulnerability to human pressures, but it must be noted that vulnerable organisms like corals and sponges, which frequently occur at boreal latitudes are not considered in this product.


One representative species of each group illustrates this functional typology. Urothoe poseidonis is typical of the first group. This is a small crustacean which is very abundant in coarse sediments subjected to high tidal velocities and shear stress, as encountered in the Southern Bight and on the Dogger Bank in the North Sea, and areas of northwestern France and southwestern UK with similar habitat characteristics. It has an annual cycle and releases a few large offspring as miniature-adults which become sexually mature only a few months later.


Urothoe poseidonis


From the second group, Spiophanes bombyx is a small tubicolous worm which can cope with various environmental conditions, including constraining ones like oxygen depletion and salinity variation.


Spiophanes bombyx


In the third group, Arctica islandica is a very iconic species, famous for its very long life span that exceeds hundred years and can reach five centuries. It  matures and reproduces very late, at a large individual size which enables the production of a high number of small eggs. This large number compensates for the very high early mortality rates. Such a life cycle requires stable environmental conditions with low adult mortality. The very low metabolic rate of the species helps to survive naturally occurring stress from low food for prolonged periods. However, the species is very vulnerable to human disturbance causing direct adult mortality. Recovery from such disturbance is very slow.


Arctica islandica



Complementary maps in the data product show the underlying data used to delineate the three major types discussed above. Each of the 13 life history traits used in the analysis had different modalities. In total, 62 trait modalities have been documented over the 13 traits. Maps have been produced displaying the scores for each of these 62 trait modalities, both based on absolute and relative organism densities averaged per spatial location.

For example, the maps below show the maps of gridded burrowing depth, one of the 13 life history traits with 4 modalities: 0 cm, 0 - 5 cm, 5 - 15 cm, > 15 cm.

These maps are available for all traits.

The map below shows the distribution data of the three living modes.

Map showing the data distribution of the three living modes

A DIVAnd interpolated map of the relative distribution of the three living modes:

Map showing the relative distribution of the three living modes


Note that the relative error of this interpolation is quite large far from the coastline, and e.g. in the Spanish, Portuguese and in Mediterranean where no data was available:

Map showing the relative error of the interpolation



Firstly, the different occurrence lists were merged, and the validity of taxonomic names was checked with the World Register of Marine Species (WoRMS, www.marinespecies.org). Two measures were considered per geographic location: individual organism density and number of taxa, in two separated data frames.

Individual organism counts were summed per combination of location, sampling gear, sampling surface area, year, month and taxon. Sampling effort per location and sampling gear was calculated by summing the sampling surface areas of the different samples (when a location was sampled several times) and divided by the number of sampling times. This enabled the calculation of individual organism densities per sampling gear and per location, and finally per location (expressed in number of individuals per squared meters).

The number of taxa per location was calculated by successive averaging, firstly per combination of sampling gear, sampling surface area, year and month; then, per combination of sampling gear, sampling surface area and year, and so on until finally averaging per location.

Trait products are derived from the multiplication of the sample locations × taxa matrix by the taxa × trait modalities matrix explained in Beauchard et al. (2017) through the community weighted mean procedure (CWM). For a given community and within a trait, the modality score is the percentage of species expressing the considered modality; all modality scores within that trait sum to one.

Finally, all the final outcomes were interpolated by the DIVA (Data-Interpolating Variational Analysis) tool to create gridded output maps.


More information


Beauchard O., Veríssimo H., Queirós A.M., Herman P.M.J., 2017. The use of multiple biological traits in marine community ecology and its potential in ecological indicator development. Ecological indicators 76:81–96. https://doi.org/10.1016/j.ecolind.2017.01.011

ICES, 2017. Report of the Workshop to evaluate regional benthic pressure and impact indicator(s) from bottom fishing (WKBENTH), 28 February–3 March 2017, Copenhagen, Denmark. ICES CM 2017/ACOM:40, 233 p. http://ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/acom/2017/WKBENTH/01%20WKBENTH-Report.pdf

Code and methodology


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