The effect of community structure on the functioning of the ecosystem is an important issue in ecology due to continuing global species loss.
The influence of infaunal community structure on the functioning of marine systems is proposed here to act primarily through bioturbation of
the sediment. Nutrient concentration in the water column, generated by release from the sediment, was used as a measure of ecosystem
functioning. In situ and laboratory experiments showed a significant difference in nutrient concentrations with different species treatments.
Bioturbation profiles showing the incorporation of tracer particles also differed between communities with different dominant species. The
behavioural differences between infaunal species, generating different modes and rates of bioturbation, are therefore proposed to influence
nutrient release. The presence and quantity of bioturbating infauna also influenced the amount of sediment suspended in the water column.
The increase in surface area available for microbial activity may generate an increase in nutrient cycling. Abiotic influences on sediment
structure, such as flow, may have a similar effect on nutrient concentration. Annular flumes used in both laboratory and in situ experiments
to generate flow conditions produced a significant increase in ammonia (NH4
-N) production in macrofaunal treatments. Flow may influence
the behaviour of macrofaunal species, causing changes in NH4
-N production through modifying bioturbation of the sediment.