Top-down and bottom-up controls on southern New England salt marsh crab populations

PeerJ

article

Kenneth B. Raposa¹  Richard A. McKinney²  Cathleen Wigand²  Jeffrey W. Hollister²  Cassie Lovall¹  Katelyn Szura³  John A. Gurak⁴  Jason McNamee⁵  Christopher Raithel⁵  Elizabeth B. Watson⁶ 

[1] Narragansett Bay National Estuarine Research Reserve;ORD-NHEERL, Atlantic Ecology Division;Department of Biological Sciences, College of the Environment and Life Sciences, University of Rhode Island;The Scripps Research Institute;Rhode Island Department of Environmental Management;Department of Biodiversity, Earth and Environmental Sciences, Academy of Natural Sciences, Drexel University

关键词: New England;    Community assessment;    Sea-level rise;    Predation;    Crabs;    Salt marsh;   

DOI  :  10.7717/peerj.4876

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Southern New England salt marsh vegetation and habitats are changing rapidly in response to sea-level rise. At the same time, fiddler crab (Uca spp.) distributions have expanded and purple marsh crab (Sesarma reticulatum) grazing on creekbank vegetation has increased. Sea-level rise and reduced predation pressure drive these changing crab populations but most studies focus on one species; there is a need for community-level assessments of impacts from multiple crab species. There is also a need to identify additional factors that can affect crab populations. We sampled crabs and environmental parameters in four Rhode Island salt marshes in 2014 and compiled existing data to quantify trends in crab abundance and multiple factors that potentially affect crabs. Crab communities were dominated by fiddler and green crabs (Carcinus maenas); S. reticulatum was much less abundant. Burrow sizes suggest that Uca is responsible for most burrows. On the marsh platform, burrows and Carcinus abundance were negatively correlated with elevation, soil moisture, and soil percent organic matter and positively correlated with soil bulk density. Uca abundance was negatively correlated with Spartina patens cover and height and positively correlated with Spartina alterniflora cover and soil shear strength. Creekbank burrow density increased dramatically between 1998 and 2016. During the same time, fishing effort and the abundance of birds that prey on crabs decreased, and water levels increased. Unlike in other southern New England marshes where recreational overfishing is hypothesized to drive increasing marsh crab abundance, we propose that changes in crab abundance were likely unrelated to recreational finfish over-harvest; instead, they better track sea-level rise and changing abundances of alternate predators, such as birds. We predict that marsh crab abundance will continue to expand with ongoing sea-level rise, at least until inundation thresholds for crab survival are exceeded.

【 授权许可】

CC BY