Landscape structured by physical settings and benthic polychaete and avifauna habitat uses in a mangrove-vegetated estuary

Abstract

Mangrove expansion monopolizes estuarine landscapes by diminishing habitat diversity and hence biodiversity. Physical landcover types, including mangrove vegetation, influence polychaete and avifauna habitat uses. The connections between the physical to biota-associated landscapes warrant investigation. We determine how to best describe the landscape in a mangrove-vegetated wetland according to the physical, polychaete and bird domains and identify what physical attributes would affect the biota-associated landscapes. Differences among the physical and biota-associated landscapes were evaluated using multivariate ordination analyses. Six physical landcover types were aligned along elevation, inundation and sedimentary gradients. The polychaete-associated landscape was structured by three landcover types, mainly mangroves and tidal flats with intermediate and high inundation. Deposit-feeding spionid and nereid, carnivorous goniadid and suspension-feeding sabellid polychaetes depended on the different landcover types. Shorebirds occurred distinctively in tidal flats with large, open surface areas. Egrets characterized tidal flats and mangroves, and foliage and ground gleaners characterized mangroves. Open tidal flats are crucial to polychaetes, which are the main prey of shorebirds and are also important to egret foraging. Our results suggest that effective management strategies for conserving these migratory birds require the maintenance of open tidal flats in the landscape.