MEPS 415:177-187 (2010)  -  DOI: https://doi.org/10.3354/meps08771

ABSTRACT: The effects of invasive cordgrass Spartina alterniflora on burrowing crab communities in the salt marshes of the Yangtze River Estuary, China, were studied. Crab abundance, distribution and diets were compared in native Phragmites australis and invasive S. alterniflora stands. Spartina-invaded stands had 42% higher crab density than did native P. australis stands, largely because 2 dominant grapsoid crabs, Helice tientsinensis and Chiromantes dehaani, thrived in S. alterniflora stands. Sediment grain size, water content and vegetation stem height were the main factors correlated with crab distributions. Crab diet analyses revealed that crab stomach fullness was similar in stands of different plant species, indicating that in Spartina-invaded stands crabs can find compatible food quantity as in native plant stands. Both H. tientsinensis and C. dehaani from S. alterniflora stands had significantly higher δ¹³C values than those from P. australis stands, suggesting that the crabs consumed S. alterniflora in the invasive marshes. This non-selective feeding may be driving the success of H. tientsinensis and C. dehaani in invasive Spartina stands.

KEY WORDS: Herbivores · Invasive species · Spartina alterniflora · Phragmites australis · Feeding habits · Gut contents · Stable isotopes · Yangtze River estuary