Modeling Small Fish Biomass Production and Dispersal

Adaptive life history strategies allow small fish communities in the subtropical freshwater Everglades to thrive despite seasonal contraction and expansion of habitat due to seasonally varying rainfall.  Understanding relationships between hydroperiod and spatial and temporal biomass production patterns will greatly aid conservation and management objectives.  We simulated population dynamics (growth, mortality, predation, movement patterns, and resource competition) of three small fish functional groups across a grid-based spatially-explicit, heterogeneous, two-dimensional marsh slough landscape using hydrologic variability as the primary driver for macro-spatial scale movement.  These groups were characterized by unique life history traits (F1, opportunistic; F2, intermediate; F3, conservative).  Simulations mapped fish biomass production in wet spatial cells and stranding as cells dried.  A permanent waterbody (canal) was included as a dry-season refuge treatment.  The model predicts the spatio-temporal pattern of fish biomass stranded (thus easily available for wading birds) as water levels decline.  Model output shows a broad distribution of stranded biomass throughout the slough system, and slightly elevated levels in the canal.  The opportunistic group (F1) accumulated the greatest total stranded biomass, while the intermediate (F2) and conservative (F3) groups left 0.18 and 0.55 less, respectively.