Floodplain Deforestation Effects on Fisheries Yields

Floodplains are among the most threatened ecosystems on the planet.  Floodplains dominate fish production rates among freshwater ecosystems largely because their vegetated habitats provide fish populations with important nursery and feeding opportunities.  Yet, the extent to which escalating changes on floodplain land-cover affect fisheries productivity is unknown.  We evaluated the effects of floodplain land-cover change on fisheries productivity in a region of the Amazon Basin where 56% of the forests have been converted into agricultural and cattle ranching lands.  We used linear regression methods to model multispecies fish capture per unit effort (CPUE) in 107 floodplain lakes as a function of the amount of herbaceous, shrub, aquatic macrophyte, and forest habitats surrounding them.  The floodplain lakes were distributed along a gradient of surrounding habitat conditions, from forested to highly-deforested.  Forest amount directly affected multispecies CPUE at a significance of p = 0.000005, and herbaceous amount inversely affected multispecies CPUE at a significance of p = 0.01.  These results indicate that removal of floodplain forests causes decreases in fish biomass available for harvesting and associated productivity of multispecies fisheries.  The herbaceous habitats that typically replace lost forests exacerbate such effects by causing further decreases in fish biomass and fisheries yields