Quantitative food web modeling unravels the importance of the microphytobenthos-meiofauna pathway for a high trophic transfer by meiofauna in soft-bottom intertidal food webs.
Meiofauna are known to have an important influence on several ecological processes, still, their role in food web dynamics is often poorly understood. Here, we are using qualitative food web modeling integrating detailed information about this compartment to unravel their role in food web dynamics. The highly productive microphytobenthos and meiofauna compartments play an important role in the carbon fluxes of five soft-bottom intertidal habitats, as highlighted by food web models. Flows of carbon were determined using the linear inverse model-Markov chain Monte Carlo technique. New data on biomass and feeding ecology of meiofauna was integrated into existing food web models from the Marennes-Oléron Bay and the Sylt-Rømø Bight. Ecological network analyses provided insights on food web characteristics, e.g. cycling, throughput and redundancy, which were compared between the modeled systems. The pathway from microphytobenthos to meiofauna was the largest flow in all habitats, with little influence of variations in availability and productivity of food sources. This resulted in high production and short turnover time of meiofauna. Macrofauna relied on a wider range of food sources and had a much longer turnover time. All trophic groups of meiofauna, except for selective deposit feeders, had a very high dependency on microphytobenthos. Selective deposit feeders relied instead on a wider range of food sources, with varying contributions of bacteria, microphytobenthos and sediment organic matter. Splitting meiofauna compartments and aggregating macrofauna compartments, resulting in a similar number of compartments for all food webs, reduced the food web model cycling and increased the redundancy.