Food web heterogeneity and succession in created saltmarshes

TitleFood web heterogeneity and succession in created saltmarshes
Publication TypeJournal Article
Year of Publication2015
AuthorsNordstrom M.C, Demopoulos A.WJ, Whitcraft C.R, Rismondo A., McMillan P., Gonzalez J.P, Levin L.A
JournalJournal of Applied Ecology
Volume52
Pagination1343-1354
Date Published2015/10
Type of ArticleArticle
ISBN Number0021-8901
Accession NumberWOS:000361186500025
Keywordsbiodiversity; communities; Ecosystem services; habitat heterogeneity; landscape; macroinvertebrates; Mediterranean climate; niche widths; nitrogen; Restoration; restoration ecology; stable isotopes; stable-isotope ratios; structure; temporal-changes; tidal wetland; Trophic; trophic interactions; vascular plants; Venice Lagoon
Abstract

Ecological restoration must achieve functional as well as structural recovery. Functional metrics for re-establishment of trophic interactions can be used to complement traditional monitoring of structural attributes. In addition, topographic effects on food web structure provide added information within a restoration context; often, created sites may require spatial heterogeneity to effectively match structure and function of natural habitats. We addressed both of these issues in our study of successional development of benthic food web structure, with focus on bottom-up-driven changes in macroinvertebrate consumer assemblages in the saltmarshes of the Venice Lagoon, Italy. We combined quantified estimates of the changing community composition with stable isotope data (C-13:C-12 and N-15:N-14) to compare the general trophic structure between created (2-14years) marshes and reference sites and along topographic elevation gradients within saltmarshes. Macrofaunal invertebrate consumers exhibited local, habitat-specific trophic patterns. Stable isotope-based trophic structure changed with increasing marsh age, in particular with regard to mid-elevation (Salicornia) habitats. In young marshes, the mid-elevation consumer signatures resembled those of unvegetated ponds. The mid-elevation of older and natural marshes had a more distinct Salicornia zone food web, occasionally resembling that of the highest (Sarcocornia-dominated) elevation. In summary, this indicates that primary producers and availability of vascular plant detritus structure consumer trophic interactions and the flow of carbon. Functionally different consumers, subsurface-feeding detritivores (Oligochaeta) and surface grazers (Hydrobia sp.), showed distinct but converging trajectories of isotopic change over time, indicating that successional development may be asymmetric between brown' (detrital) guilds and green' (grazing) guilds in the food web.Synthesis and applications. Created marsh food webs converged into a natural state over about a decade, with successional shifts seen in both consumer community composition and stable isotope space. Strong spatial effects were noted, highlighting the utility of stable isotopes to evaluate functional equivalence in spatially heterogeneous systems. Understanding the recovery of functional properties such as food web support, and their inherent spatial variability, is key to planning and managing successful habitat restoration. Created marsh food webs converged into a natural state over about a decade, with successional shifts seen in both consumer community composition and stable isotope space. Strong spatial effects were noted, highlighting the utility of stable isotopes to evaluate functional equivalence in spatially heterogeneous systems. Understanding the recovery of functional properties such as food web support, and their inherent spatial variability, is key to planning and managing successful habitat restoration.

DOI10.1111/1365-2664.12473
Short TitleJ. Appl. Ecol.
Student Publication: 
No
Research Topics: 
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