Distribution of crabs along a habitat gradient on the Yellow Sea coast after Spartina alterniflora invasion.

Pan Chen,Yan Zhang,Changhu Lu,Xiaojing Zhu

doi:10.7717/peerj.6775

Abstract

The effects of Spartina alterniflora invasion on macrobenthos have long been of concern; however, there is currently no unified conclusion regarding these effects. Most studies on crabs focus on one species or limited habitat types, and assessments of the community-level effects of S. alterniflora invasion considering multiple species and habitat types have rarely been conducted. In this study, we sampled crabs along a habitat gradient from the shoreline to inland areas on the Yellow Sea coast, including the mudflat, S. alterniflora marsh, Suaeda salsa marsh and Phragmites australis marsh. A total of 10 crab species were found among all habitats, with five species in the mudflat, six species in S. alterniflora marsh, seven species in S. salsa marsh and four species in P. australis marsh. The Shannon index values for the crab communities were similar between S. alterniflora marsh and S. salsa marsh, and these values were significantly higher than those for the mudflat and P. australis marsh. However, the total biomass of crabs was highest in the mudflat, and Metaplax longipes, Philyra pisum and Macrophthalmus dilatatus exclusively preferred the mudflat. The analysis of principal components and similarities showed that the crab community structure in S. alterniflora marsh was most similar to that in S. salsa marsh, while the crab community structure in the mudflat was most different from that in the other habitat types. Our results demonstrate that the distribution of crabs varies across a habitat gradient after S. alterniflora invasion and that the crab community in S. alterniflora marsh is slightly different from that associated with the local vegetation but shows a large difference from that in the mudflat. This study indicates that some crab species may have adapted to habitat containing alien S. alterniflora, while other crab species reject this new marsh type. The effects of the distribution of crabs after S. alterniflora invasion on the regional ecosystem need further study in the future.

Highlights

Biological invasions often threaten the existence of native species and potentially destroy the structure and function of ecosystems, which is one of the essential causes leading to the loss of global biodiversity (Butchart et al, 2010; Genovesi et al, 2015)
Composition of crab species A total of 10 crab species were found among all habitats, with five species in the mudflat, six species in S. alterniflora marsh, seven species in S. salsa marsh and four species in P. australis marsh
Many studies have suggested that S. alterniflora invasion has resulted in local biodiversity loss and ecosystem degradation (Li et al, 2009; Yang et al, 2017), a unified conclusion regarding the effects of S. alterniflora invasion on macrofaunal species has not been reached (Quan et al, 2016)

Summary

Introduction

Biological invasions often threaten the existence of native species and potentially destroy the structure and function of ecosystems, which is one of the essential causes leading to the loss of global biodiversity (Butchart et al, 2010; Genovesi et al, 2015). Distribution of crabs along a habitat gradient on the Yellow Sea coast after Spartina alterniflora invasion. Spartina alterniflora (Poaceae), which is native to the Atlantic and Gulf coasts of North America, is one of the most notable plant invaders, with strong fecundity and ecological adaptability (Nishijima, Takimoto & Miyashita, 2016). S. alterniflora often shows strong competitiveness and rapidly replaced native plants, reshaping the landscape pattern in invaded areas (Yang et al, 2017). Extensive S. alterniflora invasion has caused a series of ecological consequences to native plants, birds and microbenthic invertebrate communities, especially decreased biodiversity and the degradation of native habitats (Liu et al, 2012)

Methods

Discussion

Conclusion