Common deficiencies of actions for managing invasive alien species: a decision-support checklist

Elías D Dana,Juan García-De-Lomas,Montserrat Vilà,Filip Verloove

doi:10.3897/neobiota.48.35118

Abstract

Despite the increasing number of invasive species, protocols devoted to assess the feasibility (i.e., probability of success or failure) of management actions in the field are scarce, yet success depends on a broad scope of issues beyond the biology of species and the ecosystem to be managed. In this paper we make a retrospective analysis of 90 actions and management proposals developed in Andalusia (southern Spain) in 2004 to 2018. Actions included 59 terrestrial and aquatic taxa. We identified items that in case of deficiency were responsible for either the rejection of action proposals (n = 44) or failure of implemented actions for which the goal was not achieved (n = 22). The most frequent deficiencies included the absence of funding during the necessary time to achieve the goals, the risk of reinvasion and an insufficient removal rate to achieve the specific objective. Based on the deficiencies found, we built a comprehensive, broad-scope compliance checklist to assist decision-makers to identify deficiencies before action. In addition, implemented actions for which the goal was achieved (n = 24) were used for validating the checklist. The checklist contains 40 items related to IAS features, administrative features, methodology effectiveness, efficiency and impacts of the action, and invaded ecosystem features. The checklist is valid across all taxa and habitats. The use of this checklist will help reduce the degree of arbitrariness and subjectivity of actions aimed at managing IAS, and a more efficient use of resources.

Highlights

The large number of invasive alien species (IAS) in natural areas contrasts with the scarce resources available for their management (Andreu et al 2009)
All the nonimplemented proposals shared deficiencies in 12 items which were nearly absent in implemented successful and unsuccessful actions (Fig. 2). These 12 deficiencies were related to basic aspects of the action and were considered as pre-requisites. These prerequisites include whether the target species is alien and invasive, the type of main conservation goal and IAS management specific objective, the absence of any effective methodology, legality, impacts on native ecosystem caused by the action implementation, incoherence between the methodology application, and the specific objective, risks for humans or workers
The most common deficient prerequisite in not-implemented proposals was the absence of an effective methodology to be applied at the full scale, because the invaded area was very large. Examples of such proposals are the control of the brown algae Rugulopteryx okamurae in the Strait of Gibraltar, the eradication of the zebra mussel (Dreissena polymorpha) and European catfish (Silurus glanis) in a reservoir of 2,500 ha, the eradication of Caulerpa cylindracea in the sea bed of Almería, and the control of the cord grass (Spartina densiflora) in Huelva salt marshes (Suppl. material 1: Table S1)

Summary

Introduction

The large number of invasive alien species (IAS) in natural areas contrasts with the scarce resources available for their management (Andreu et al 2009). When no evidence-based and standardised protocol is used to guide decision-making, decisions may be taken on arbitrary or biased judgements or guesstimates of stakeholders, planners or the general public rather than on comprehensive scientific and technical evidence (Bardsley and Edwards-Jones 2006; Sharp et al 2011) These deficiencies may cause a series of ‘cascade effects’ resulting in: (i) a poor definition of main objectives, actions and resource constraints (Game et al 2013), (ii) the application of different and erratic strategies between neighbour countries, regions and even municipalities (Keller et al 2011; Monceau et al 2014); (iii) shortlasting actions that have a high probability of failure (Blossey 1999); (iv) an inefficient use of resources, both monetary and non-monetary, something that is especially relevant given the paucity of available funds (Pluess et al 2012); (v) overlooking certain introduction pathways and the dynamics of propagule pressure (Simberloff 2006; Brasier 2008); (vi) disregarding action side effects such as the enhancement of other potentially invasive species or major ecosystem disturbances (Águas et al 2014; Buckley and Han 2014)

Methods

Results

Conclusion