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Abstract:
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Habitat fragmentation is often regarded as a biodiversity threat associated with habitat degradation ; however , research has also revealed beneficial effects on biodiversity as well , depending on the ecosystem and species community . This study examined the biodiversity of small nekton residing in seagrass meadows characterized by three levels of habitat fragmentation , and as a habitat gradient comprised of measures such as habitat amount , connectivity , patch shape , and proximity . Landscapes were mapped using recent advances in GPS and GIS technology , and analyzed using established methods from research in terrestrial ecosystems . Species richness was not significantly different as a function of fragmentation regardless of season , suggesting that the amount of habitat and configuration of several patches in fragmented habitats is sufficient to support comparable numbers of species in several patches compared to communities in large , continuous seagrass meadows . Species evenness declined significantly in fragmented habitats versus continuous ones in both seasons . Within fragmented landscapes , evenness progressively declined as habitat amount and connectivity decreased and patch isolation and density increased , suggesting that changes in landscape qualities can differentially impact processes supporting metapopulations such as dispersal and reproduction in certain species , thereby influencing community structure . Analyses that included measures of habitat connectivity , proximity , and patch density in addition to habitat amount accounted for more variability in species evenness than those just containing percent cover , and showed that fragmentation’s impacts can differ geographically . These data suggest that community resilience to fragmentation can differ between similar animal communities residing in separate locations , and that landscape configuration plays an important role in determining how communities respond to fragmentation after a threshold of change in habitat amount has been exceeded . |