Introduction

Benthic species (i.e., species that live on and/or in the seafloor sediment) can provide important ecosystem services. For example, because regulate nutrient cycling, or create habitat. For these seafloor dwelling species 15 traits can be distinguished, such as their burrow width, pumping capacity, or the size of the construction that they build. With these traits, benthic species can be clustered into groups, based on their function in the ecosystem (i.e., “functional groups”). The 11 most important benthic functional groups that occur in the North Sea are displayed in the picture below.

Epibenthic vs burrowing

The most important distinction between benthic species can be made on the basis of whether they live on (‘epibenthic’) or in (‘burrowing’) the seafloor sediment.

Which of these functional groups represent epibenthic species?

Substratum depth distribution

The second most important distinction between these functional groups is based on the depth distribution where the species occur: 0 cm, 0-5 cm, 5-15 cm, 15-30 cm, over 30 cm deep. Sort the functional groups according to the depth at which they typically occur.

Hard substrate

Some species can only settle on a hard substrate, such as a stone, a(n empty) shell, or wind turbine. Can you guess which?

Habitat creation

Some species are called ‘ecosystem engineers’, which refers to the ability of a species to create habitat. For example, like corals, oysters create reefs with which they attenuate waves and currents. This makes oyster reefs a specific habitat for other species that do not like waves. Can you guess which of these functional groups create habitat?

Resource cycling

Some organisms also contribute to cycling of resources, such as oxygen, nitrogen, and carbon, or particles, such as sand or organic matter. Some important actions include: 1) sediment mixing, 2) irrigation (flushing the sediment with oxygenated water), and 3) downward conveying (downward displacement of material).

Can you guess which groups mix the sediment.

Can you guess which of these species irrigate the sediment by flushing it with ‘fresh’ water?

Downward displacement of material by benthic species can be an important function that couples the water column (pelagic) with the seafloor (‘benthic-pelagic coupling’). Some organisms actively pump water through their bodies, filtering out food particles. They deposit their waste directly onto the seafloor, thereby displacing material from the water column down to the seafloor. Can you guess which of these groups show this behaviour?

Names

Can you now match the names of the functional groups to the sketches?

Acknowledgements

The drawings were created as part of the BFIAT project (funded by the Dutch Science Foundation).