Changes in hydrology of the Everglades over the last several decades have reduced the hydroperiod in some areas and may have diminished the community of small-bodied fish, chief forage base of wading birds. One of the ways toward restoration of historic fish productivity is to understand and to improve spatio-temporal water patterns in the wetlands. Therefore, we investigated the biomass dynamics with a spatially-explicit simulation model of an aquatic food web in an Everglades marsh landscape with the following components: primary producer, detritus, invertebrates, fish consumers and nutrients. We imposed annual fluctuations in water level as sinusoidally changing hydrology on the whole system, which resulted in dynamic patterns of flooded and non-flooded areas. The fish were allowed to disperse spatially in response to changing water levels. We performed long-term simulations over a period of 10 years and observed how the organizational levels reacted to the seasonal changes in water level.
Results/Conclusions
- Temporally and spatially varying patterns of trophic cascades could be discerned in the simulations, but they were relatively weak compared to such cascades that are observed in some lake ecosystems.
- The fish showed distinctive pulses at the edge of the drying front as water levels declined. The retreating fish added to the fish already in the present in the still-flooded cells, forming a pulse of fish retreating towards the persisting bodies of water. Pulselike behavior could also be observed following the flooding front during rising water level, but the pulses were much smaller.
- Biomass levels, averaged over the whole model, tended to increase moderately with the amplitude of water level fluctuations. However, the piscivore biomass always reached a peak at some fluctuation amplitude and then declined with further increase in amplitude.
- We discuss the consequences of these results for management and restoration of the Everglades aquatic communities.
