Abstract

AbstractCoastal ecosystems face severe environmental change and anthropogenic pressures that affect both the structure and functioning of communities. Understanding the response and resilience of communities that face multiple simultaneous disturbances and stresses becomes essential. We observed the recovery of a rocky intertidal subarctic macrobenthic community dominated by a macroalgal canopy (Fucus spp.), a habitat‐forming species, over a period of 14 months. Using 0.25‐m2 plots, we ran an in situ one‐pulse experiment (removal of all materials to bare rock and then burning of the surface) followed by a full orthogonal factorial design of three press‐type disturbances or stresses: grazer reduction, canopy removal, and nutrient enrichment. We evaluated the single and interactive effects of the three disturbances and stresses on species diversity and abundance structure. Of all the main effects, canopy removal has the most severe impact, resulting in decreased biomass, richness, and diversity, as well as an altered community structure. Canopy‐removed plots had fewer invertebrates and more ephemeral algae; beyond this, however, there was minimal effect from grazer reduction and nutrient enrichment acting individually. We categorized the interaction types of all significant interaction effects: Canopy removal had a dominant effect over grazer reduction on richness, and it also dominated over nutrient enrichment on diversity and evenness. Nutrient enrichment and canopy removal had a negative synergistic interaction effect on richness at the end of the experiment. Without stressors, 11 months were required to achieve full recovery. The three stressors affected recovery time differently, depending on the identity and the number of stressors. Three stressors generally increased the time of recovery or even prevented recovery from being fully attained. Moreover, community structure and composition of plots subjected to the triple‐stressor treatment had not fully recovered by the end of the study. Our results suggest that multiple stressors may interact on community indices and structure and that their interaction cannot be predicted from the outcome of single stressor studies. The inclusion of multiple disturbances and stresses in field experiments provides a better understanding of the mechanisms that shape community structure and their functioning following various forms of disturbance.

Highlights

  • Coastal ecosystems are subjected to both natural and anthropogenic disturbances and stresses, for example, eutrophication, sedimentation, and habitat loss (Airoldi and Beck 2007, Halpern et al 2008)

  • We considered that each treatment was recovered for a given variable when no significant difference between that treatment and reference plots was observed until the end of the experiment

  • Effects of single and multiple stresses Abundance and diversity indices.—Our experimental treatments affected the associated community abundance and diversity profile, and some of their effects varied in time

Read more

Summary

Introduction

Coastal ecosystems are subjected to both natural and anthropogenic disturbances and stresses, for example, eutrophication, sedimentation, and habitat loss (Airoldi and Beck 2007, Halpern et al 2008). These various changes can have drastic negative effects on ecosystems, such as biodiversity loss, that impact community functioning and stability Resilience (or engineering resilience) is an essential ecosystem function that helps maintain biodiversity and functioning. It is defined as the ability of a system to mitigate an impact and recover following a disturbance. The rapid recovery of communities (within 1–5 yr) following a disturbance may be due to the open nature of this system that provides high numbers of propagules and larvae from unaffected shores (Hawkins et al 1999, Crowe et al 2000)

Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call