Long Term Interactions of Native and Invasive Species in a Marine Protected Area Suggest Complex Cascading Effects Challenging Conservation Outcomes

Charalampos Dimitriadis,Ivoni Fournari-Konstantinidou,Drosos Koutsoubas,Stelios Katsanevakis,Laurent Sourbès

doi:10.3390/d13020071

Charalampos Dimitriadis, Ivoni Fournari-Konstantinidou + Show 3 more

Open Access

https://doi.org/10.3390/d13020071

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Journal: Diversity	Publication Date: Feb 9, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: University of the Aegean

Abstract

Understanding the interactions among invasive species, native species and marine protected areas (MPAs), and the long-term regime shifts in MPAs is receiving increased attention, since biological invasions can alter the structure and functioning of the protected ecosystems and challenge conservation efforts. Here we found evidence of marked modifications in the rocky reef associated biota in a Mediterranean MPA from 2009 to 2019 through visual census surveys, due to the presence of invasive species altering the structure of the ecosystem and triggering complex cascading effects on the long term. Low levels of the populations of native high-level predators were accompanied by the population increase and high performance of both native and invasive fish herbivores. Subsequently the overgrazing and habitat degradation resulted in cascading effects towards the diminishing of the native and invasive invertebrate grazers and omnivorous benthic species. Our study represents a good showcase of how invasive species can coexist or exclude native biota and at the same time regulate or out-compete other established invaders and native species.

Highlights

Biological invasions are largely recognized as a major threat to the marine realm worldwide that can induce the decline of native biodiversity and negative impacts on ecosystem functioning [1,2,3]
The Mediterranean Sea is considered to be a hotspot of marine biological invasions, their effects are overlooked in marine conservation planning [5,6] and have not received proper attention in the European network of marine protected areas [7]
The “biotic resistance hypothesis” [14] predicts that the high native species richness in marine protected areas (MPAs) could prevent the establishment of alien species or, if established, substantially reduce their ecological impacts

Summary

Introduction

Biological invasions are largely recognized as a major threat to the marine realm worldwide that can induce the decline of native biodiversity and negative impacts on ecosystem functioning [1,2,3]. We provide empirical evidence on community shifts in a Mediterranean MPA (National Marine Park of Zakynthos, Greece) impacted by biological invasions, by estimating occupancy (probability of presence) changes of both alien and native species belonging to different taxa (fish, macroalgae and invertebrates) and different trophic levels. To this end, we analyzed data, collected through occupancy surveys of alien and native species, in 2009 and 2019, in an effort to detect: (a) the long term changes in ecosystem structure of rocky reefs in the MPA, (b) the possible presence of trophic cascades, and (c) the interaction within and between invasive and native species. We discuss our findings in the perspective of management of biological invasions in MPAs

Study Area

Sampling Design

Data Analysis

Results

Discussion