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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14231

Effects of season and latitude on the diet quality of the invasive Asian shore crab, Hemigrapsus sanguineus

Tanner C. Reese, Jill Alder, Emily Gail Asay, April M. H. Blakeslee, Doreen Cabrera, Laura C. Crane, Laura S. Fletcher, Emily Pinkston, Michele F. Repetto, Nanette Smith, Carter Stancil, Carolyn K. Tepolt, Benjamin J. Toscano, Blaine D. Griffen*

*Corresponding author:

ABSTRACT: Invasive species alter invaded ecosystems via direct impacts such as consumption. In turn, an invasive species’ ability to thrive in new habitats depends on its ability to exploit available resources, which may change over time and space. Diet quality (what is eaten) and quantity (how much is eaten) are indicators of a consumer’s consumptive effects and can be strongly influenced by season (time) and latitude (space). We examined the effects of season and latitude on the diet quality and diet quantity of the invasive Asian shore crab, Hemigrapsus sanguineus, throughout a non-winter sampling year at five different sites spanning 8° of latitude across its invaded United States range. We found that diet quality, averaged through time, largely follows an expected latitudinal cline with higher diet quality in the center of its range and lower diet quality toward the southern and northern edges. We also found that while some sites show similar patterns of diet quality variation with season, no pattern is consistent across all latitudes. Finally, we found that crabs at sites with low diet quality during summer reproductive months did not compensate by increasing total consumption. Because the Asian shore crab is an important consumer in its invaded ecosystems, understanding how its diet quality and quantity vary with season and latitude can help us better understand how this species influences trophic interactions and community structure, how it has been able to establish across a wide ecological and environmental range, and where future range expansion is most likely to occur.