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Title: A fiddler crab reduces plant growth in its expanded range

Species across the planet are shifting or expanding their ranges because of climate change. These are climate migrants. Although climate migrants are well documented, their impacts on recipient ecosystems are not. Climate migrants that are also ecosystem engineers (species that modify or create habitats) will likely have profound effects on ecosystems. The Atlantic marsh fiddler crab,Minuca pugnax, is a burrowing crab that recently expanded its range into the northeastern United States. In its historical range,M. pugnaxenhances the aboveground growth of the cordgrassSpartina alterniflora, a plant critical to marsh persistence. In a control‐impact study, however, we found thatSpartinaaboveground biomass was 40% lower whenM. pugnaxwas present. Thus, the positive effect ofM. pugnaxonSpartinaaboveground biomass flipped to a negative one in its expanded range.Spartinabelowground biomass was also 30% lower on average when crabs were present, a finding consistent with what is seen in the historical range. These impacts onSpartinaare likely due to burrowing byM. pugnax.Benthic microalgae was, on average, 45% lower when crabs were present. Fiddler crabs eat benthic microalgae, and these results suggest that fiddler crabs can control algal biomass via grazing. Because fiddler crabs reduced the biomass of foundational primary producers in its expanded range, our results imply thatM. pugnaxcan influence other saltmarsh functions such as carbon storage and accretion as they expand north. Most strikingly, our results suggest that as species expand or shift their range with climate change, not only can they have profound impacts in their new ranges but those impacts can be the inverse of what is seen in their historical ranges.

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Award ID(s):
1754259 1637630
Author(s) / Creator(s):
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Medium: X
Sponsoring Org:
National Science Foundation
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