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Collection Island and Ocean Ecosystems
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Persistence, accuracy and timeliness: finding, mapping and managing non-native plant species on the island of South Georgia (South Atlantic)

Island and Ocean Ecosystems, BRB

Available Online

Floyd, K.

Lee, J.

Myer, B.

Pass?eld, K.

Poncet, S.

The South Georgia ecosystem-based habitat restoration project is a major project that began with the eradication of invasive rats (Rattus norvegicus) and reindeer (Rangifer tarandus), 20112017. As part of this restoration programme a non-native plant management strategy was developed and implemented. With only 8% of the whole South Georgia landmass suitable for vascular plants (ca. 283 km²) due to permanent ice and bare rock, there have been 25 indigenous vascular plants and 41 non-native plants recorded from earlier surveys. Following removal of grazing pressure from introduced mammals, surveys were conducted to quantify the current status and distribution of non-native plant populations and enable a non-native plant control strategy to be developed for the island. Due to the vast scale of the island, multiple seasons were required to carry out rapid surveys of key indicators such as species, area of plant coverage in square metres and age class (mature or juvenile). Survey and control data were entered into a spatial database to enable analysis, allow data-informed management decisions and be used for long-term control-based monitoring of outcomes. During this series of surveys, 44 naturalised, non-native plant species were identi?ed and mapped. Of these, 34 species are now being managed at zero density with 56,851 m2 at 184 sites controlled to date; four are managed at speci?c sites with 22,443 m2 controlled to date, three require con?rmation of species and the remaining three species are widely established and receive limited control. Spatially quantifying the distribution and control of non-native plants has enabled the development and implementation of an e?ective management strategy which contributes to the restoration of South Georgias native biodiversity.

Criteria to help evaluate and guide attempts to eradicate terrestrial arthropod pests

Island and Ocean Ecosystems, BRB

Available Online

Broome, K.

Brown, K.

Green, C.

Phillips, C.B.

Walker, G.

Attempts to eradicate invasive terrestrial arthropods are often regarded as gambles. They o?er the possibility of long term freedom from a pest but are usually confronted with substantial uncertainty and come with a range of technical, economic, environmental, social and political risks. Few guidelines are available for evaluating eradication attempts against terrestrial arthropods. Here, we build on scienti?c literature, including six criteria previously developed to evaluate the feasibility of vertebrate eradications, and our own experiences to de?ne nine criteria that are intended to both assist experts to evaluate proposed arthropod eradication attempts and guide attempts that are underway. The criteria are straight forward and easily interpreted, though evaluating them for a particular programme relies on expert group assessment that will often benefit from rigorous supporting statistical and/or modelling analyses.

Eradication of invasive alien crayfish: past experiences and further possibilities

Island and Ocean Ecosystems, BRB

Available Online

Sandodden, R.

The EU regulation 1143/2014 On the prevention and management of the introduction and spread of invasive alien species entered into force on 1 January 2015. On 13 July 2016, the EU list of invasive alien species that require action was adopted. The list includes ?ve di?erent cray?sh species. Member states will be required to take measures for early detection and rapid eradication of these species. Except for some eradications performed in the United Kingdom and Norway, there has not been much e?ort put into eradication of invasive cray?sh species throughout Europe. The reasons for this are probably complex and di?er between member states. Are the main reasons legislative constraints, ability to eradicate or lack of knowledge and experience? Is eradication of alien cray?sh possible and desirable, and what is left to save in Europe? Focus could be put into identifying or creating island populations of special concern and preserve them for the future survival of European native cray?sh populations. Eradication measures should be considered as an option in this work. What are the experiences from completed eradication e?orts in Europe? Two cray?sh eradications have been performed in Norway, and both have been successful. The eradications were performed in locations with several ponds and small streams and performed using the synthetic pyrethroid-based pharmaceutical BETAMAX VET®. Both legislative and funding constraints seem less prominent as successful eradications have been con?rmed. Time will show if this trend will spread throughout Europe.

Modelling invasive plant alien species richness in Tenerife (Canary Islands) using Bayesian Generalised Linear Spatial Models

Island and Ocean Ecosystems, BRB

Available Online

Arévalo, J. R.

Bacaro, G.

Da Re, D.

Fernàndez-Palacios, J. M.

Negrín-Pérez, Z.

Otto, R.

Rocchini, D.

Tordoni, E.

Biological invasions are one of the major threats to biodiversity, especially on islands where the number of endemic species is the highest despite their small area. In the Canary Islands, the relationships among invasive alien species (hereafter IAS) and their environmental and anthropogenic determinants have been thoroughly described but robust provisional models integrating species spatial autocorrelation and patterns of IAS communities are still lacking. In this study, we developed a Generalised Linear Spatial Model for Invasive Alien Species Richness (IASR) under a Bayesian framework, using a methodological approach that encompass GIS and geostatistical analysis. In this study, we hypothesised that the inclusion of spatial autocorrelation can improve model performance thus obtaining more IASR-reliable predictions. In addition, this method provides uncertainty maps that prioritize areas where further sampling e?orts are needed. Our model showed that IASR in Tenerife is mainly driven by a combination of anthropogenic and natural processes, highlighting favourable conditions for IAS from the coastline to about 800 m a.s.l., especially on the windward humid aspect. Among anthropogenic factors, a clear positive relationship between road kernel density estimation and IASR was found. Indeed, road density has recently increased especially in low to mid altitudinal zones on the Canary Islands, strictly associated with urban expansion and it has been widely demonstrated to be one of the main IAS pathways. Hence, higher road density can be related to increased propagule pressure which is, together with source of disturbance, one of the most important factors explaining richness in alien species invasion success. Our main conclusions highlight the importance of considering spatial autocorrelation and researchers prior knowledge to increase the predictive power of statistical models. From a practical perspective, these models and their related uncertainty, will serve as important management tools highlighting those portions of territories that will be more prone to biological invasions and where monitoring e? orts should be directed.

Using expert Knowledge and Field Surveys to Guide Management of an Invasive Alien Palm in a Pacific Island Lowland Rainforest

Island and Ocean Ecosystems, BRB

Available Online

Boehmer, H.J.

Dyer, M.J.B.

Keppel, G.

Tuiwawa, M.

Vido, S.

Watling, D.

Invasive alien ornamental plants are a global problem, especially on oceanic islands, and can have severe impacts on native biodiversity. Pinanga coronata, is an ornamental palm tree that can form mono-dominant stands in its native habitat and is widely cultivated throughout the tropics. Here we investigate the introduction, spread, impact and management of this invasive palm in the Fiji Islands, using extensive discussions with local experts and ?eld surveys. Pinanga coronata was introduced in the 1970s to the Colo-i-Suva area, eastern Viti Levu island, Fiji´s principal island, and has since become invasive in mahogany plantations and lowland rainforest. It has also been introduced and is becoming invasive on the western side of that island. However, the distribution of P. coronata remains geographically limited to the immediate vicinity of introduction sites but it is rapidly spreading. In each location, the species has formed mono-dominant stands in the understorey and appears to be displacing native plant species, as suggested by a negative correlation of its abundance with that of native tree ferns. This highlights the need for rapid control of P. coronata in Fiji. Local experts state management should involve manual removal of seedlings and saplings, killing of adult palms by injection of herbicide, and education and legislation to prevent the further spread of the species. Based on these recommendations and ?eld data, management actions to control P. coronata are proposed and steps to develop these into a management plan are discussed. Given P. coronata threatens native biodiversity in Fiji and has the potential to invade other rainforest ecosystems in the tropics, proposed management approaches are urgent and relevant for other tropical countries.

Methods for monitoring invertebrate response to vertebrate eradication

Island and Ocean Ecosystems, BRB

Available Online

Houghton, M.

Shaw, J.

Terauds, A.

Once an island vertebrate eradication is deemed successful, it is typically assumed that ecosystem recovery will follow. To date, most post-eradication monitoring focuses on the recovery of key threatened or charismatic species, such as seabirds. Little attention has been given to monitoring and quantifying the response of invertebrate communities. Rabbits (Oryctolagus cuniculus), house mice (Mus musculus), and ship rats (Rattus rattus) impacted sub-Antarctic Macquarie Island for over 140 years, with wide ranging ecosystem impacts. In 2014, the eradication of rabbits and rodents was o?cially declared successful. To determine whether management objectives are being met, we are investigating the response of invertebrate communities to pest eradication, using both historic data and contemporary surveys to track changes over space and time. To achieve this, we have developed a survey strategy that is e?ective and e?cient. Here we report on the merits of utilising a variety of invertebrate trapping methodologies to establish current baselines for future invertebrate monitoring. We identify sampling techniques that are most e?ective for speci?c groups of taxa, particularly those of interest to post-eradication monitoring, and how the implementation of such methods can improve and facilitate e?ective post-eradication monitoring of invertebrates.

Introduction of biological control agents against the European earwig (Forficula auricularia) on the Falkland Islands

Island and Ocean Ecosystems, BRB

Available Online

González-Moreno, P.

Maczey, N.

Moore, D.

Rendell, N.

The Falkland Islands (FI), as with many island ecosystems, is vulnerable to invasive species, which can cause wide ranging social and environmental consequences. Control of invasive species is widely recognised as a priority, but there have never been attempts to use classical biological control (CBC) for this purpose in FI. The European earwig was recently introduced to the FI and has since become abundant in the Stanley area and some other settlements on the islands. Earwigs now cause considerable damage to garden crops and also pose a number of health hazards. There are also concerns that earwigs have started to spread into grasslands and irreversibly alter this important native ecosystem. After extensive stakeholder consultations it was decided to use the invasive earwigs as a case study for the introduction of CBC to the FI. Based on previous work on earwig control, supplemented by additional host range testing, two tachinid ?ies, Triarthria setipennis and Ocytata pallipes, were selected as the most suitable control agents for the Falkland Islands. Extensive awareness raising activities, focusing on the threat of invasive species, bene?ts and risks of CBC, secured the support of the wider public to go ahead with the release of both control agents during 2015 and 2016. Major challenges encountered during the release process were the need to install makeshift quarantine facilities and the switchover of the life-cycle of both control agents to southern hemisphere seasons.

Assessment of snail exposure to the anticoagulant rodenticide brodifacoum in the Galapagos Islands

Island and Ocean Ecosystems, BRB

Available Online

Alifano, A.

Campbell, K.J.

Fisher, P.

Jolley, W.

Parent, C.E.

Eradication of invasive rodents has become a powerful tool to protect native island biota. Use of brodifacoum, an anticoagulant rodenticide, has contributed to hundreds of successful invasive rodent eradication e?orts on islands. Application of bait containing brodifacoum for this purpose requires appropriate consideration of adverse e?ects on non-target wildlife. Thus, a priori identi?cation of non-target risks and, where needed, approaches to mitigate these to acceptable levels, is now an essential component of eradication planning and implementation. As part of the plan for eradicating invasive rats and mice from Floreana Island in the Galapagos, we experimentally tested the e?ect of brodifacoum on the Galapagos endemic land snail species Naesiotus unifasciatus. Importantly, the trials were designed to evaluate e?ects of particular components of the bait pellets, namely the active brodifacoum, the pyranine biomarker, and a blue dye. We found no evidence for increased snail mortality following exposure to any of these bait components. We review results of past toxicity studies on terrestrial molluscs and ?nd that, as for our own study, there is likely to be little impact of anticoagulant rodenticide on terrestrial mollusc survival as the result of application of brodifacoum bait. However, given the limited taxonomic representation in the toxicity tests performed on terrestrial molluscs so far, we recommend the continued used of captive toxicity trials to assess potential e?ect of any rodenticide applications on native malacological fauna on a case-by-case basis where large-scale eradication programmes are planned and undertaken.

Management of an invasive avian parasitic fly in the Galapagos Islands: is biological control a viable option?

Island and Ocean Ecosystems, BRB

Available Online

The bird-parasitic ?y, Philornis downsi, was ?rst recorded in the Galápagos Islands in 1964 where it likely invaded from mainland Ecuador. This muscid ?y is now the leading cause of recent declines in endemic landbird populations as its larvae feed on the nestlings of at least 19 bird species in the Galápagos, including many species of Darwins ?nches. As yet, no long-term control method has been implemented for P. downsi, but importation (also known as classical) biological control may be a viable option. Due to historically high-pro?le examples of biological control agents attacking non-target species, some consider biological control to be too risky to be compatible with conservation aims. However, since biosafety practices were implemented beginning in the 1990s, these risks have been drastically reduced, and biological control is now an important tool for suppressing invasive species that are di?cult to control using other means. We investigated the safety of a potential biological control agent, the parasitoid wasp, Conura annulifera, that attacks P. downsi in its native range. Here we summarise the results of a series of ?eld, laboratory and comparative studies on C. annulifera (methods and results are not reported here) and outline future directions. We used a ?eld experimental paradigm involving nest boxes baited with non-target hosts, and quarantine laboratory no-choice trials in which non-target hosts were exposed to C. annulifera. Our work to-date suggests that C. annulifera is restricted to attacking species within the genus Philornis. Furthermore, a phylogenetically controlled comparative study suggests that C. annulifera is evolutionarily constrained in its host range. These results lead us to conclude that C. annulifera demonstrates promise as an ecologically safe agent for the long-term biological control of P. downsi. Studies will now focus on an evaluation of risks to endemic and native species in the Galápagos.

Feasibility of eradicating the large white butterfly (Pieris brassicae) from New Zealand: data gathering to inform decisions about the feasibility of eradication

Island and Ocean Ecosystems, BRB

Available Online

Broome, K.

Brown, K.

Green, C.

Phillips, C.B.

Toft, R.

Walker, G.

Pieris brassicae, large white butter?y, was ?rst found in New Zealand in Nelson in May 2010. The Ministry for Primary Industries (MPI) responded with a monitoring programme until November 2012 when the Department of Conservation (DOC) commenced an eradication programme. DOC was highly motivated to eradicate P. brassicae by the risk it posed to New Zealand endemic cress species, some of which are already nearly extinct. DOC eliminated the butter?y from Nelson in less than four years at a cost of ca. NZ$5 million. This is the ?rst time globally that a butter?y has been purposefully eradicated. Variation in estimates of bene?ts, costs, the e?cacy of detection and control tools, and the probability of eradication success all contributed to uncertainty about the feasibility. Cost bene?t analyses can contribute to assessing feasibility but are prone to inaccurate assumptions when data are limited, and other feasibility questions are equally important in considering the best course of action. Uncertainty does not equate to risk and reducing uncertainty through data gathering can inform feasibility and decision making while increasing the probability of eradication success.

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