Stratified vertical sediment profiles increase burrowing crab effects on salt marsh edaphic conditions

Abstract

Burrowing animals can profoundly affect the biological structure and ecosystem functions of their environments. For instance, burrowing crabs increase sediment deposition and facilitate sediment homogenization and turnover, with potential impacts to sediment biogeochemistry. However, the relative importance of burrowing crabs on sediment dynamics can vary considerably between, and within, habitats. Sediment properties influence how burrowing crabs will affect edaphic conditions, but these studies often assume homogenous sediment conditions and fail to consider how sediment properties change with depth.Thus, understanding how burrowing crab effects on sediment properties are influenced by the vertical sediment profile should inform where burrowing crabs structure edaphic conditions. Here, we conducted an intensive field survey across three tidal salt marshes with variable sediment properties to understand if marsh vertical sediment profiles can help predict the nature of burrowing crab-sediment relationships. We found that burrowing crabs homogenize sediments in all marshes, but their effects on sediment homogenization and edaphic conditions were greater in marshes with highly stratified vertical sediment profiles. Our study suggests that understanding the vertical sediment profile of a salt marsh may provide critical insights into how crab burrowing may influence the edaphic conditions and physical characteristics of marsh surface sediments-especially in restored, created, and managed salt marshes.

Researcher effects on the biological structure and edaphic conditions of field sites and implications for management

“…We used measurements taken at the end of each region's growing season (AL = October; CA = September) in all ANOVAs; thus, time was not a factor in any of our models. All temporal data are available in Rinehart, Dybiec, Richardson, et al (2023).…”

“…AL‐CON was initially constructed in 1987 by harvesting pine savanna habitat and excavating topsoil down to a clay layer that intercepted the water table and was 0.27 m above mean sea level (NAVD88 datum). AL‐CON and AL‐NAT are separated by an approximately 0.5‐km thick pine savanna and have distinct hydrodynamics and biological structure (Dybiec et al, 2023; Ledford et al, 2021; Rinehart, Dybiec, Mortazavi, et al, 2023; Tatariw et al, 2021). The site was then planted with needlerush ( Juncus roemerianus ) and smooth cordgrass ( Spartina alterniflora ) in 1988 (Vittor et al, 1987).…”

“…The site was then planted with needlerush ( Juncus roemerianus ) and smooth cordgrass ( Spartina alterniflora ) in 1988 (Vittor et al, 1987). Today, both AL sites are almost entirely dominated by needlerush (Ledford et al, 2021; Rinehart, Dybiec, Mortazavi, et al, 2023; Tatariw et al, 2021), although the subordinate species, Distichlis spicata , is also common at AL‐NAT. Burrowing crabs, fiddler crabs (i.e., Minuca longisignalis , Minuca minax , Leptuca panacea , and Leptuca spinicarpa ), and marsh crabs ( Sesarma reticulatum ) are common and have known effects on needlerush productivity and sediment conditions (Rinehart, Dybiec, Mortazavi, et al, 2023).…”

“…Data (Rinehart, Dybiec, Richardson, et al, 2023) are available from Dryad: https://doi.org/10.25338/B84H18.…”

“…Soil coring and soil pits may also adversely affect environmental processes. Specifically, coring sediments and soils may be analogous to animal burrowing, increasing sediment homogenization and oxygenation (Bertness, 1985; Bortolus & Iribarne, 1999; Kristensen & Alongi, 2006; Rinehart, Dybiec, Mortazavi, et al, 2023).…”