Context-dependent consumer control in New England tidal wetlands.

Alexandria Moore,Christopher W Mckindsey

doi:10.1371/journal.pone.0197170

Abstract

Recent studies in coastal wetlands have indicated that consumers may play an important role in regulating large-scale ecosystem processes. Predator removal experiments have shown significant differences in above-ground biomass production in the presence of higher level consumers, or predators. These results indicate that predators play an important role in regulating biomass production, but the extent to which this regulation impacts additional ecosystem functions, such as nutrient cycling and organic matter accumulation, is unclear. This study evaluated the impact that consumers have on large-scale ecosystem processes within southern New England tidal wetlands and contributes to the general understanding of trophic control in these systems. I established enclosure cages within three coastal wetlands and manipulated the presence of green crab predators to assess how trophic interactions affect ecosystem functions. Findings suggest that although these consumers may exert some top-down effects, other environmental factors, such as other consumers not studied here or bottom-up interactions, may variably play a larger role in the maintenance of ecosystem processes within the region. These results indicate that the loss of top-down control as an important mechanism influencing ecosystem functions may not hold for all wetlands along the full extent of the New England coastline.

Highlights

Research in a wide variety of ecosystems has shown that trophic structure and species interactions are important determinants of ecosystem function [1,2,3,4,5,6,7,8,9,10]
The loss of large apex predators within aquatic ecosystems, for instance, may impact phytoplankton density, affecting primary production, CO2 uptake rates, and the direction of carbon flux between lakes and the atmosphere [11,12]. These and other studies show that trophic interactions may be important mediators of large-scale ecosystem processes, but the strength and degree to which these interactions influence ecosystem functions is often dependent upon several variables, including habitat type, community structure, abiotic factors, and anthropogenic impacts [13,14,15]
The reigning ecological paradigm has historically focused on the importance of bottom-up control over top-down control in regulating key ecosystem functions and services [16,17,18,19]

Summary

Introduction

Research in a wide variety of ecosystems has shown that trophic structure and species interactions are important determinants of ecosystem function [1,2,3,4,5,6,7,8,9,10]. The loss of large apex predators within aquatic ecosystems, for instance, may impact phytoplankton density, affecting primary production, CO2 uptake rates, and the direction of carbon flux between lakes and the atmosphere [11,12]. These and other studies show that trophic interactions may be important mediators of large-scale ecosystem processes, but the strength and degree to which these interactions influence ecosystem functions is often dependent upon several variables, including habitat type, community structure, abiotic factors, and anthropogenic impacts [13,14,15]. Recent research in tidal salt marshes suggests that top-down factors,

Objectives

Methods

Results

Conclusion