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Generalists and competition may be important in limiting range expansion, evidence from the frontlines of climate change
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  • Herbert Leavitt,
  • Alexander Thomas ,
  • Jennifer Doerr,
  • David Johnson,
  • James Nelson
Herbert Leavitt
University of Georgia

Corresponding Author:[email protected]

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Alexander Thomas
University of Georgia
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Jennifer Doerr
NOAA Fisheries Service
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David Johnson
Virginia Institute of Marine Science
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James Nelson
University of Georgia
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Abstract

Climate-driven range expansions of individual species are well-documented; however, corresponding community shifts are not. This lack of widespread community change may indicate communities can resist wholesale change with the arrival of new species. In the northern Gulf of Mexico, climate change is driving the expansion of black mangroves (Avicennia germinans) into areas traditionally dominated by smooth cordgrass (Spartina alterniflora). This study investigates the effects of these changes on the species composition of animals and habitat structure in Louisiana, U.S. with implications for how species expand their range under shifting climactic regimes. Using quantitative nekton sampling and satellite imagery analysis over two decades, we observed a substantial increase in winter temperatures of 3.5°C and a significant regime shift from marsh to mangrove habitats. Despite these remarkable physical and habitat changes, the species composition remained stable, suggesting that local species interactions may mitigate the effects of climate-driven range expansions. Our findings highlight the resilience of estuarine communities to rapid environmental changes and emphasize the need for further research on the indirect effects of habitat shifts on food web dynamics.