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Island invasives: scaling up to meet the challenge. Proceedings of the international conference on island invasives 2017

Biodiversity Conservation, BRB

Available Online

Godwin, J.

Heard, N.

Serr, M.

House mice are significant invasive pests, particularly on islands without native mammalian predators. As part of a multi-institutional project aimed at suppressing invasive mouse populations on islands, we aim to create heavily male-biased sex ratios with the goal of causing the populations to crash. Effective implementation of this approach will depend on engineered F1 wild-lab males being effective secondary invaders that can mate successfully. As a first step in assessing this possibility, we are characterising genetic and behavioural differences between Mus musculus strains in terms of mating and fecundity using wild house mice derived from an invasive population on the Farallon Islands (MmF), a laboratory strain C57BL/6/129 (tw2), and F1 wild-lab off spring. Mice with the t allele (tw2) have a naturally occurring gene drive system. To assess fertility in F1 wild-lab crosses, tw2 males were paired with wild-derived females from the Farallon Islands (MmF). Results of these matings indicate litter sizes are comparable but that weaned pup and adult wild-lab mice are heavier in mass. Next, we initiated tests of male competitiveness using larger (3 m2) enclosures with enrichment. We introduced both an MmF and a tw2-bearing male to two MmF females to assess mating outcomes. Preliminary results of these experiments show none of the off spring carried the t-allele. However, performing the same experiment with F1 wild-lab males instead of a full lab background resulted in 70% of off spring carrying the tw2 allele. This indicates that F1 wild-lab males may be able to successfully compete and secondarily invade. It will be important in subsequent experiments to determine what characteristics contribute to secondary invasion success. More generally, a better understanding of characteristics contributing to overall success in increasingly complex and naturalistic environments will be critical in determining the potential of a gene drive-based eradication approach for invasive mice on islands.

A potential new tool for the toolbox: assessing gene drives for eradicating invasive rodent populations

Biodiversity Conservation, BRB

Available Online

Brown, P.R.

Campbell, K.J.

Delborne, J.

Godwin, J.

Gould, F.

Howald, G.R.

Kanavy, D.M.

Kuiken, T.

Packard, H.

Piaggio, A.

Saah, J.R.

Serr, M.

Shiels, A.

Thomas, P.

Threadgill, D.

Tompkins, D.M.

Invasive rodents have significant negative impacts on island biodiversity. All but the smallest of rodent eradications currently rely on island-wide rodenticide applications. Although significant advances have been made in mitigating unintended impacts, rodent eradication on inhabited islands remains extremely challenging. Current tools restrict eradication efforts to fewer than 15% of islands with critically endangered or endangered species threatened by invasive rodents. The Genetic Biocontrol of Invasive Rodents partnership is an interdisciplinary collaboration to develop and evaluate gene drive technology for eradicating invasive rodent populations on islands. Technological approaches currently being investigated include the production of multiple strains of Mus musculus with a modified form of the native t-complex, or a CRISPR gene drive, carrying genes or mechanisms that determine sex. These systems have the potential to skew the sex ratio of off spring to approach 100% single-sex, which could result in population collapse. One goal proposed is to test the ability of constructs to spread and increase in frequency in M. musculus populations in biosecure, captive settings and undertake modelling to inform development and potential deployment of these systems. Structured ecologically-based risk assessments are proposed, along with social and cultural engagement to assess the acceptability of releasing a gene drive system. Work will be guided by an external ethics advisory board. Partners are from three countries with significant regulatory capacity (USA, Australia, New Zealand). Thus, we will seek data sharing agreements so that results from experiments may be used within all three countries and treat regulatory requirements as a minimum. Species-specific, scalable, and socially acceptable new eradication tools could produce substantial biodiversity benefits not possible with current technologies. Gene drive innovation may provide such a tool for invasive species management and be potentially transformative and worthy of exploring in an inclusive, responsible, and ethical manner.

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

Biodiversity Conservation, 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.

Échange de données sur les espèces envahissantes du Pacifique dans le cadre du Système mondial dinformation sur la biodiversité (GBIF).

Biodiversity Conservation, BRB

Available Online

Secretariat of the Pacific Regional Environment Programme

Nous formons un groupe diversifié dans la région du Pacifique, qui sétend sur environ un tiers de la surface de la Terre et englobe près de la moitié des mers de la planète

Seabird colonies as important global drivers in the nitrogen and phosphorus cycles

Available Online

Ferreira, Tiago Osorio.

Huerta-Diaz, Miguel Angel.

Otero, Xose Luis.

Pena-Lastra, Saul De La.

Perez-Alberti, Augusto.

Seabirds drastically transform the environmental conditions of the sites where they establish their breeding colonies via soil, sediment, and water eutrophication (hereafter termed ornitheutrophication). Here, we report worldwide amounts of total nitrogen (N) and total phosphorus (P) excreted by seabirds using an inventory of global seabird populations applied to a bioenergetics model. We estimate these fluxes to be 591 Gg N y?1 and 99 Gg P y?1, respectively, with the Antarctic and Southern coasts receiving the highest N and P inputs. We show that these inputs are of similar magnitude to others considered in global N and P cycles, with concentrations per unit of surface area in seabird colonies among the highest measured on the Earths surface. Finally, an important fraction of the total excreted N (72.5 Gg y?1) and P (21.8 Gg y?1) can be readily solubilized, increasing their short-term bioavailability in continental and coastal waters located near the seabird colonies.

Invasive rat eradication strongly impacts plant recruitment on a tropical atoll

Available Online

Croll, Donald A.

Dirzo, Rodolfo.

Holmes, Nick D.

Kropidlowski, Stefan.

McKown, Matthew.

Tershy, Bernie R.

Wegmann, Alexander S.

Wolf, Coral A.

Young, Hillary S.

Zilliacus, Kelly M.

Rat eradication has become a common conservation intervention in island ecosystems and its effectiveness in protecting native vertebrates is increasingly well documented. Yet, the impacts of rat eradication on plant communities remain poorly understood. Here we compare native and non-native tree and palm seedling abundance before and after eradication of invasive rats (Rattus Rattus) from Palmyra Atoll, Line Islands, Central Pacific Ocean. Overall, seedling recruitment increased for five of the six native trees species examined. While pre-eradication monitoring found no seedlings of Pisonia grandis, a dominant tree species that is important throughout the Pacific region, post-eradication monitoring documented a notable recruitment event immediately following eradication, with up to 688 individual P. grandis seedlings per 100m2 recorded one month post-eradication. Two other locally rare native trees with no observed recruitment in pre-eradication surveys had recruitment post-rat eradication. However, we also found, by five years post-eradication, a 13-fold increase in recruitment of the naturalized and range-expanding coconut palm Cocos nucifera. Our results emphasize the strong effects that a rat eradication can have on tree recruitment with expected long-term effects on canopy composition. Rat eradication released nonnative C. nucifera, likely with long-term implications for community composition, potentially necessitating future management interventions. Eradication, nevertheless, greatly benefited recruitment of native tree species. If this pattern persists over time, we expect long-term benefits for flora and fauna dependent on these native species.

Share Pacific invasive species data using the Global Biodiversity Information Facility (GBIF)

SPREP Publications, Biodiversity Conservation, BRB

Available Online

The Invasive Species Battler series has been developed to share what we have learned about common invasive species issues in the region. They are not intended to cover each issue in depth but to provide information and case-studies that can assist you to make a decision about what to do next or where to go for further information.

Will climate change impact the potential distribution of a native vine (Merremia peltata) which is behaving invasively in the Pacific region?

Available Online

Kumar, Lalit

Taylor, Subhashni

Merremia peltata is a species with uncertain status in the island nations of the Pacific region. It has been designated introduced and invasive in some countries whereas it is considered native in others. Recent increase in its abundance across some island landscapes have led to calls for its designation as an invasive species of environmental concern with biological control being suggested as a control strategy. Climate change will add to the complications of managing this species since changes in climate will influence its range limits. In this study, we develop a process-oriented niche model of M. peltata using CLIMEX to investigate the impacts of climate change on its potential distribution. Information on the climatic requirements of M. peltata and its current geographic distribution were used to calibrate the model. The results indicate that under current climate, 273,132 km2 of the land area in the region is climatically unsuitable or marginal for M. peltata whereas 664,524 km2 is suitable to highly suitable. Under current climate, areas of climatic suitability for M. peltata were identified on the archipelagos of Fiji, Papua New Guinea, Solomon Islands and Vanuatu. By the end of the century, some archipelagos like Fiji, Hawaii, New Caledonia and Vanuatu will probably become more suitable while PNG and Solomon Islands become less suitable for M. peltata. The results can be used to inform biosecurity planning, management and conservation strategies on islands.

Invasive species baseline surveys and feasibility studies, Huvalu Forest, Niue

Biodiversity Conservation, BRB

Available Online

Dr. Butler, David J.

This report was prepared as one of the outputs of the GEF PAS project Prevention, eradication and control of invasive alien species in the Pacific islands funded by the Global Environment Facility (GEF), implemented by the United Nations Environment Programme (UNEP) and executed by Secretariat of the Pacific Regional Environment Programme (SPREP) in partnership with the Department of Agriculture, Forestry and Fisheries of Niue (DAFF). It was designed to contribute to two activities in Niues programme within this project: 1. Develop and establish long term monitoring and GIS for areas with important native biodiversity that may be impacted by invasives. Huvalu Conservation Area, which is the subject of a project within the Regional Forestry and Protected Areas Management Project (FPAM), was identified as the key area for survey. 2. Conduct a pilot feasibility study for ten priority weed or vertebrate eradication targets.

Review of invasive alien species management in the Aleipata Islands, Samoa, GEF-PAS Invasive Alien Species project/Samoa

Available Online

Serra. G

Tipamaa. F.T.

The Aleipata islands are considered to be of great regional conservation significance because they are uninhabited (with the exception of Namua), relatively pristine as forest ecosystems, hosting many species threatened throughout the greater Samoa, and still not invaded by most invasive alien species (IAS) present within Upolu main island. Due to this reason they were included in the list of the 7 key biodiversity areas of Samoa (Conservation International et al. 2010).

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