Summary

Merremia peltata (M. peltata) is a woody vine found throughout warm, tropical regions of the Pacific Islands and its native/non-native status across the region is uncertain. In parts of the Pacific, it is considered a troublesome weed that can smother trees and reduce native biodiversity, and the Australia and Hawaiʻi Weed Risk Assessments classify it as “high risk.” In some locations, however, this species can play an important role in rainforest regeneration and it is known to support biodiversity when growing in the forest canopy. How this species distribution will be impacted by climate change is currently unknown.

To determine the current distribution as well as potential future distributions under climate change, Taylor and Kumar used species distribution modeling based on experimental observations of M. peltata growth response to temperature, soil moisture, current distribution, and seasonal phenology. They used occurrence data to assess the fit of the model to current distributions and considered two end-of-century global climate model projections for future distribution (a warmer/much drier projection and a much warmer/less dry projection).

Results

M. peltata is expected to both expand and contract its range in response to modeled climate shifts over time. Generally, range expansion is expected on Fiji, Hawaii, New Caledonia, and Vanuatu, and contractions are expected in Papua New Guinea and the Solomon Islands. Areas currently not suitable are expected to become suitable under a future climate. In addition, substantial range contraction under a future climate is expected in Papua New Guinea. Finally, the projected changes to future ranges were consistent between climate models for Fiji, Hawaiʻi, New Caledonia, and Vanuatu, but differed for the other countries and appeared to be strongly related to rainfall.

Management Considerations

• Consider strengthening quarantine regulations and enforcement as well as surveillance around ports and airports in order to prevent the introduction of species like Merremia peltata, especially in areas where climatic suitability is expected to expand the species range in the future.
• Where M. peltata is non-native, consider potential future climate change distributions when prioritizing areas for intervention, such as eradication or containment.
• Where M. peltata is native, consider potential future climate change distributions to inform conservation strategies; modeling may identify areas of potential range contraction or refuges where protection could be prioritized.
• Consider monitoring for impacts to agriculture, native plant communities, or culturally important plant species; factors such as disturbance (clearing, typhoons) or growth form (ground or tree vine) may influence its impact on the community.

Take Home Points

• Species distribution modelling of current and potential future ranges can play an important role in invasive plant management as ranges and habitat suitability shift with changing climatic conditions.
• Increased access to species occurrence records, as well as climate-informed distribution modelling is needed to support informed decision-making.
• Integrated assessments that investigate large-scale changes to ecosystems due to multiple interacting factors are needed. How species shift in the future will depend not just on the direct effects of climate change, but also on changes in land use and disturbance, new invasive species arrivals, nutrient pollution, and species interactions.

Summary

Island ecosystems in the Pacific are particularly vulnerable to the impacts of invasive species, and climate change is expected to intensify these impacts. We have little information, however, on how the distribution of most invasive species may shift under a future climate. Lantana (Lantana camara) has been ranked as one of the world’s 100 worst invasive species due to its impacts to agriculture, timber production, and natural ecosystems. It is also considered among the most invasive species found on the majority of the Islands in the Pacific Region and it is unclear how it will respond to climate change.

Taylor and Kumar (2014) used species distribution models (SDMs) to project the recent and future distributions of Lantana on the islands of Fiji. The researchers used phenological observations, geographical occurrence data (from both native and non-native ranges), and 5 environmental variables derived from temperature, precipitation, and relative humidity to estimate the potential distribution under historical climate (1950-2000). They then used a global climate model to project the plant’s future distribution in 2030 and 2070 under two climate scenarios.  The higher scenario (A2) corresponds to a global mean temperature increase of ~4 °C above pre-industrial by 2100, while under the midrange scenario (A1B) global average temperatures would be about 3.4 °C higher by century’s end.

Results

When using the historical data (1950-2000), the modeled distribution of Lantana was a good match to the known distribution of the plant at a regional level (Vanuatu, New Caledonia, and Solomon Islands). The model also indicated that large parts of Fiji are currently conducive to Lantana growth and spread. When the model was used to project the future distribution of Lantana, however, it indicated a contraction in the species’ range; all of Vanua Levu and western Viti Levu would remain climatically suitable for Lantana until 2030, but suitability would decrease in 2070 with only the west coast of Viti Levu and the island of Tavenui remaining at risk of Lantana invasion. This was due to projected increases in wet stress (one of the indicies modeled) due to a projected increase in soil moisture levels. These results did not depend on emission scenario (both scenarios showed similar results).

Management Considerations

• Not all species will respond the same to climate change; the distribution of some invasive species may contract in the future as shown by this example of Lantana in Fiji.
• Consider monitoring for shifts in the distribution of invasive weeds and adapt management as conditions change; an early detection and rapid response system for established invasives shifting distribution with climate change may increase effectiveness of control efforts.
• Climate change could affect how managers prioritize management; responses to declining invasive species abundance or distribution due to climate change could include 1) do nothing and monitor, 2) invest more resources in control, especially if eradication becomes possible, or 3) direct resources elsewhere, especially to control other invasive species that may be increasing due to climate change.

Take Home Points

• Species distribution models for invasive plants can be informative tools to understand invasive species distributions in the Pacific region, and projected distributions that use current and future climates may be useful to help prioritize management.
• Climate change may reduce the distribution of certain invasive weeds such as Lantana, where habitat quality for the species is expected to decline due to increases in soil moisture.
• More modeling studies of the potential future ranges of invasive plants are needed for Pacific Island jurisdictions to assist with prioritization efforts and long-term planning.

Summary

Platydemus manokwari is a large predatory flatworm that was originally discovered in New Guinea. It has been deliberately introduced as a biocontrol agent in some Pacific Islands in an attempt to control an invasion of the Giant East African Snail, and has accidentally been introduced to other Pacific countries potentially through the movement of live plant material or soil in potted plants or on machines. In the U.S. Pacific, this species has been found in the Federated States of Micronesia, Palau, Guam, and the Northern Mariana Islands. In Hawaiʻi the species was first reported on Oʻahu in 1992, and there are 30 observations on iNaturalist that have been posted since 2019.

Sugiura studied the effects of temperature and density on P. manokwari predatory activity and survival using field and lab experiments. The study took place in the western Pacific on the subtropical Chichijima island, the largest of the Ogasawara islands, which are a Japanese archipelago of over 30 islands located around 620 miles south of Tokyo. P. manokwari was introduced to this island in the 1990s, which is believed to have been accidental through the importation of contaminated soils. Since this introduction, there are areas of Chichijima in which local snail species have been extirpated by P. manokwari, yet the factors that influence flatworm predation pressure on land snails is unclear.

For the field study, Sugiura placed live snails of the introduced species Acusta despecta in nylon bags sized to exclude larger predators on the forest floor throughout the year (from November 2007 to September 2008), and then observed the level of P. manokwari predation by determining snail survival. This was coupled with lab experiments examining the impact of temperature and P. manokwari density on feeding activity. To examine temperature’s effect on P. manokwari, individual flatworms were housed in small containers and exposed to five different temperatures. Survival at each temperature was determined after a week, and then snails were added to the containers and snail survival was quantified. Sugiura also measured the predation rates on snails at three different densities of P. manokwari.

Results

The highest rates of snail mortality due to P. manokwari predation were observed in July, September, and November, while no predation was observed in February, the coldest month. Relative humidity and precipitation did not appear to impact predation rates. P. manokwari had high survival in all temperatures tested except for the 50 °F (10 °C) treatment, which was the coldest temperature tested, where only 23.3% survived. At 50 °F (10 °C) no snail predation was observed. In the ~57 °F (14 °C) treatment, however, half of the flatworms attacked snail prey, and for the other temperature treatments (64 °F/18 °C, 71 °F/22 °C, and 78 °F/25 °C), nearly all P. manokwari were observed hunting snails. Higher P. manokwari densities resulted in higher snail predation rates.

Take Home Points

• Introductions of P. manokwari are a serious concern because they can feed on any species of gastropod (i.e., slugs and snails) and they have caused local snail extinctions in areas they invade.
• Climate-change induced warming will likely expand the potential range of P. manokwari, and they may be active for longer periods throughout the year in a warmer climate.
• Rapid population growth of P. manokwari can be expected under warming conditions, and higher densities could also intensify their predation of native slugs and snails.
• Stringent quarantine procedures should be enacted for any imported materials that contain soil to prevent introduction; P. manokwari has been introduced via potted plants and other infected sources of soil in the past

Final Note: Except for upper elevations found in Hawai’i (e.g., see below), no place in the region has mean annual air temperatures below 57 °F (14 °C), so P. manokwari establishment is not likely to be limited by temperature anywhere except where the 57 °F (14 °C) isotherm occurs (i.e., on Maui and Hawai’i Island). These temperature isotherms are expected to shift due to climate change, which may lead to greater impacts of P. manokwari at higher elevations in the future.

This year, we featured the successful Pacific Ecological Security Conference, which Pacific RISA led last October in the Republic of Palau. Outcomes from the conference, which included Strategic Action Plans that highlight how the failure to adequately address invasive species in Pacific Island ecosystems weakens the resilience of communities and ecosystems to cope with the impacts of climate change, are already being used to drive legislative and policy outcomes, and are being referenced in regional and international calls for action and funding around invasive species.

“The Pacific is at the frontline of the climate crisis, and invasive species only further undermine the resilience of our ecosystems. Now more than ever, addressing invasive species should be at the forefront of our priorities and this meeting was a positive step forward to jointly ensure there is a strong regional coordinated approach to these critical threats.” ~ Gibson Susumu, Programme Lead for Sustainable Agriculture, The Pacific Community

The report covers some of Pacific RISA’s new research projects, including PI Dr. Kirsten Oleson’s ecosystem-based adaptation work on Kaua‘i that is forging connections with local community groups and the county Planning Department. Ongoing research related to climate early warning systems, peer-to-peer knowledge exchange, and hydrologic modeling for compound climate events is also included. The report concludes with an assessment of the team’s adaptation and policy impacts, and our sustained climate assessments work that has most recently produced the Pacific Islands Regional Climate Assessment report for the Federated States of Micronesia.

Learn more about Pacific RISA’s latest achievements and check out our report today!

Featured image: The Pacific RISA visited Ngkeklau in 2022 to look for remnants of the Beng, a traditional Palauan fishing weir.

At the 14th annual University of Guam Conference on Island Sustainability this April, it was all of the above and much, much more. Featuring hundreds of island sustainability scholars, practitioners, and students from across Micronesia and the world, this year’s conference shared innovations and strategies to collectively move toward a sustainable future under the theme of “Rediscover the Depths of Our Island Abundance“.

The University of Guam 14th Conference on Island Sustainability team, led by Associate Professor and Sea Grant program Director Austin Shelton. Photo credit: Laura Brewington

Conference attendees had the chance to learn more about Guam’s southern ecosystems from the Guam Restoration of Watersheds (GROW) Initiative, which is conducting essential conservation work to protect the island’s drinking water and coral reefs, and is in line with the Guam Green Growth Action Framework for sustainability. After planting over 100 trees in the Ugum Watershed to reduce erosion into the local water supply, participants toured the river below and the reef in Talo’fo’fo’ Bay.

Left: Participants planted over 100 seedlings of an acacia tree to stabilize the soil and reduce erosion in the Ugum watershed. Right: A boat trip down the Talo’fo’fo’ river provided an opportunity to see the importance of protecting southern Guam’s drinking water supplies. Photo credits: University of Guam; Laura Brewington

Farther inland at Chamorro Village, participants also visited the Circular Economy Makerspace and Innovation Hub – the first of its kind – which is supporting Guam’s emerging Green Economy by inviting craftspeople and community members to utilize the facility and training opportunities to create marketable products out of upcycled and recycled waste. Not only will the space help reduce Guam’s reliance on imported goods, it supports entrepreneurs who want to benefit the local economy in a regenerative, transformative way.

Left: Visitors learn about the Makerspace from University of Guam technicians. Right: The Precious Plastics workspace contains tools for creating new products from recycled plastics. Photo credit: Laura Brewington

“[The circular economy] concept is a win-win for our business, academia, our island’s environment, and all of Guam”

~Governor Lou Leon Guerrero

As part of the main conference events, Pacific RISA PI Laura Brewington joined three notable island experts in a panel to discuss sustainable alliances across oceans, moderated by Lieutenant Governor of Guam Josh Tenorio. Along with Kate Brown (Executive Director of the Global Island Partnership), Bob Underwood (former University of Guam President and Guam Congressional Delegate), and Kristin Wilson-Grimes (Research Assistant Professor of Watershed Ecology at the University of the Virgin Islands), PI Brewington shared examples of action being taken to build more resilient and sustainable island communities through Pacific RISA and the Pacific Regional Invasive Species and Climate Change (RISCC) management network.

PI Brewington and panelists discussing cross-ocean island alliances for sustainability. Photo credit: Trina Leberer

Didn’t have a chance to join in the celebration and exchange this year?

Save the dates for next year’s conference on April 8-12, 2024!

Meanwhile, learn more about the University of Guam Center for Island Sustainability.

Featured image: A member of the GROW Initiative looks over Ugum watershed in southern Guam. Credit: Laura Brewington

Conference organizer and Pacific RISA co-lead investigator Laura Brewington described the profound impacts of invasive species on the Pacific Islands region, while pointing to the need for regional collaboration to address the issue. “This first PESC has reminded us that invasive species impact every aspect of Pacific Island life and security. While we have many of the tools we need for their prevention, control, and eradication, we also recognize that no country can do it alone,” said Dr. Brewington.

Participants shared stories from across the region about the multi-faceted and devastating impacts of invasive species on climate resilience, food security, and ecosystem sustainability. Dr. Brewington, as a co-founder of the Pacific Regional Invasive Species and Climate Change management network, gave a keynote presentation focusing on three main interactions between climate change and invasive species in Pacific Islands:

• Climate change is expected to alter mechanisms for invasive species transport and introduction, by creating new tourism or shipping opportunities, or by increasing the frequency and intensity of extreme events like storms and flooding.
• Climate change will alter the distributions of invasive species that already exist on islands, allowing them to spread into new areas, especially under warmer conditions.
• Climate change will alter the effectiveness of our current methods of controlling invasive species, so much so that restoration may not even be possible under new climate regimes and conservation strategies will have to be dynamic.

High-level conference outcomes

• Participants at the PESC acknowledged the importance of invasive species work to building and maintaining the climate resilience and adaptability of Pacific Island ecosystems, as well as food security, biodiversity, sustainable livelihoods, and the protection of native traditions and cultural resources.
• Participants developed three Strategic Action Plans to address the issues of coconut rhinoceros beetles, invasive ants, and biocontrol needs. The Plans are living documents that are intended to be modified as milestones are achieved and new needs are identified.
• Statements, backed by conference, recommended that the Pacific Community (SPC) and the Secretariat of the Pacific Regional Environment Programme (SPREP) collaboratively take on the PESC outcomes, and the issue of invasive species itself, as a joint effort.
• A second PESC must be convened in two years to address other critical invasive species issues, such as biosecurity, invasive vertebrates, and marine invasive species, as well as to report on progress in implementing Plans from the first PESC.

Momentum initiated at the PESC has already been translated into concrete legislative outcomes: At the Association of Pacific Island Leaders (APIL) meeting in mid-October, Resolution 39-GA-15 was passed to endorse and support invasive species management, control, and eradication in Micronesia. For more information about the PESC, conference resources, and outcomes documents, please stay tuned to the Conference Website!

“Biodiversity and climate are two sides of the same coin.”

~ Christine Lagarde, President of the European Central Bank

Despite being postponed from 2020 to 2021 during the COVID-19 pandemic, the City of Marseille still hosted an impressive 4,000 global participants and hundreds of sessions, forums, and events centered around the Congress themes of climate change, freshwater, landscapes, governance, oceans, and more. The Pacific RISA team, represented in person by co-lead investigator Laura Brewington, and virtually by PI Zena Grecni, joined a large Delegation from Hawaiʻi that was led by the Hawaiʻi Conservation Alliance Foundation, the KUA movement, and the University of Hawaiʻi Environmental Law Program’s Our Drowning Voices team. The Hawaiʻi State Department of Land and Natural Resources Chair, Suzanne Case, served as head of the Delegation, and dozens of events and presentations were held at the Hawaiʻi-Oceania Pavilion during the first six days of the Forum.

Dr. Brewington was involved in three sessions, which featured updates and achievements toward the Honolulu Challenge that were made by Pacific partners at the 2016 Congress, the synergistic effects of climate change and invasive species and the new Pacific RISCC management network, and partnerships for Pacific Island resilience to climate change. During the session on partnerships, Hawaiʻi Green Growth shared a video highlighting their leading role in Hawaiʻi’s Aloha+ Challenge and the UN Local2030 Islands Network. This was followed by a virtual panel discussion, hosted by PI Grecni, with participants from Guam, American Sāmoa, and the Commonwealth of the Northern Mariana Islands as they discussed climate research innovations and science-based adaptation initiatives in their islands. In particular, the session spotlighted leadership in building resilience, and the role of governments, practitioners, and researchers in developing the recent series of PIRCA reports for Pacific Islands.

“I don’t think that anyone at this conference is unaware of the impacts of climate change on Pacific peoples, communities, ecosystems, and islands”

~ Laura Brewington, Co-Lead of the Pacific RISA program

During the session on climate change and invasive species, Brewington and collaborators from the Pacific Regional Invasive Species and Climate Change (RISCC) management network shared voices from around the region, describing the challenges and opportunities for research on these synergistic threats. The US Fish and Wildlife Service offered an introduction to disease that threatens the very survival of Hawaiʻi’s native forest birds, as temperatures rise and invasive mosquitoes reach higher grounds. Focusing in on the Big Island of Hawaiʻi, the Pacific Islands Climate Adaptation Science Center (PICASC) shared a manager’s perspective from the Puʻuwaʻaʻwaʻa experimental forest unit, where the challenges of managing under drought and wildfire are magnified by pressure from ungulates and other disturbances. From Guam to American Sāmoa and the Commonwealth of the Northern Mariana Islands, Pacific RISCC partners emphasized that dealing with the dual impacts of climate change and invasive species in islands is not a “one size fits all” approach, and requires greater collaboration and research to protect Pacific Island natural heritage into the future.

The Congress closed with call for a post-pandemic recovery based on nature, and the IUCN Members Assembly voted on numerous motions to propel countries and the international community toward urgent action on priority themes. Motion 003, to establish a seventh IUCN Commission focusing on the global climate emergency, passed with overwhelming support, thanks to the week’s concerted efforts by Hawaiʻi-Oceania Delegation members and supporters of Our Drowning Voices. Motion 003 will now become a component of IUCN’s general policy and influence the adoption of international environmental instruments, standards, agreements, and conservation best practices.

Watch

The Pacific RISA and partners share a panel on building resilience in Guam, American Samoa, and the Commonwealth of the Northern Mariana Islands

Learn about the Aloha+ Challenge and how to get involved with Hawaiʻi Green Growth and the UN Local2030 Islands Network

The US Fish and Wildlife Service shares the agency’s mission and describe the twin threats of climate change and invasive species facing native Hawaiian forest birds

The Pacific Islands Climate Adaptation Science Center and the Hawaiʻi Division of Forestry and Wildlife discuss the challenges facing Hawaiʻi’s rangeland managers under changing drought and wildfire conditions

The Commonwealth of the Northern Mariana Islands Division of Fish and Wildlife shares how accelerated habitat loss, combined with the introduction of invasive species, is threatening endemic birds and other native plants and animals found only on these small islands of Micronesia

The American Sāmoa Visitors Bureau describes how climate change is bringing heavy rains, erosion, and damage, from the island’s coral reefs to farmland and mountaintops, but policies to reduce human impacts in those areas are only as strong as the and agencies who people enforce them

The Guam Department of Agriculture shares how the small island of Guam in Micronesia is deeply connected to the Asia-Pacific region through international trade and shipping, while being buffeted by the impacts of a changing climate

The newly-formed Pacific Regional Invasive Species and Climate Change Management Network is among the regional, cooperative efforts underway to address the compound impacts of climate change and invasive species. Pacific RISCC gathers together scientists and natural resource managers to improve the ways that communities can anticipate and prepare for global warming and ecological change, said Brewington. Another regional initiative, the Pacific Invasives Partnership, has long worked on high-priority international invasive species issues, with members representing state and local institutions, non-governmental organizations and academia. The partners advocate for changes in the ways that governments approach compound threats and stressors to ecosystems, she said.

“Pacific RISCC gathers together scientists and natural resource managers to improve the ways that communities can anticipate and prepare for global warming and ecological change”

Other panelists included Austin Shelton, executive director of the University of Guamʻs Center for Island Sustainability and director of the universityʻs Sea Grant Program, who described Guam’s approach to sustainability in the face of change through the Local2030 Islands Network, an international partnership created by the United Nations to implement its sustainable development goals at the local level. The networkʻs diverse members include Hawai‘i, the Marshall Islands, and Ireland. Guamʻs watershed initiative is helping restore the islandʻs coral reefs, which are at risk because of the compound effects of pollutants in erosion runoff and other climate impacts. As part of this initiative, Guam is taking several steps to mitigate the erosion, restore vegetation, and slow runoff.

Masanori Kobayashi, senior fellow with the Sasakawa Peace Foundation’s Ocean Policy Research Institute, described the potential for changes in fish stock distributions along with with rising temperatures, typhoon activity and other signs of climate change in the Pacific Islands region. “There may be a shift of fish stock distribution from west to east,” Kobayashi said, with Micronesia projected to see fish catch declines and Polynesia to experience increases. Attention should be paid to possible correlations involving drought, climate change, and pressures on agriculture and fisheries.

Brewington noted that for the time being, economic recovery from COVID-19 will likely occupy the most global attention, with less emphasis on issues like biodiversity and climate change. She said states and nations need to prioritize biodiversity in their stimulus packages, just as the European Commission has done, by incorporating compound stressors and adaptation in their recovery plans.

Featured image from the Intergovernmental Panel on Biodiversity and Ecosystem Services Global Assessment Report 2019.

For years, Pacific Island leaders have declared that the greatest threat to security in the region is climate change, because it dramatically alters the ecosystems that Pacific peoples depend on economically, culturally, and socially. This non-traditional concept of security is not new, and must be integrated into future frameworks for adaptation and response, not only to climate change but to other threats to global sustainability. Furthermore, as the impacts of the pandemic have reached nearly every country and sector worldwide, it has become more clear how intertwined our health is with the global environment. The Planetary Health framework specifically focuses on how human-caused disruptions to ecosystems can have negative and unpredictable health effects.

To learn more about ecological security in the Pacific and the concept of Planetary Health, check out Pacific RISA’s Dr. Laura Brewington recent video interview with Doug Parsons, host of the Adaptation Channel at Cimpatico Studios, where they discussed the Covid-19 pandemic, Pacific RISA’s work throughout the region, and more. She has also published an East-West Center Wire on the topic. The Planetary Health Alliance contains numerous print, video, and audio resources for more information on the Planetary Health Framework.

Cover photo source: Upsplash.

On May 5, the working group coordinated an online workshop that was attended by over 100 managers and researchers who wanted to learn more about the survey results and help identify next steps for coordinated research and product development. Laura Brewington from the Pacific RISA presented the survey results, followed by an expert panel discussion with invasive species specialists who helped answer participants’ questions about the limitations and availability of existing climate information products for natural resource applications. Toni Lyn Morelli, a USGS research ecologist with the Northeast Climate Adaptation Science Center, then described their processes for establishing a Regional Invasive Species and Climate Change network, and the remainder of the discussion centered around next steps for creating such a network for invasive species managers and climate change researchers in Hawaii and the Pacific.

Attendees participating in the “Where Do We Go Next” discussion segment of the workshop demonstrated unanimous support for the development of a climate change and invasive species network. The top three hopes for what such a network could achieve were: 1) Improved communication between researchers/managers/landowners; 2) Better sharing of and access to resources in a centralized location; and 3) Better alignment of research with management goals. For next steps, the majority of participants suggested: 1) Collecting information and data resources into a centralized platform for access and communication; and 2) Prioritizing gaps and setting research priority areas. The working group will develop a formal listserv to share information, updates, and announcements, and establish a webinar series beginning this summer focused on the nexus between climate change and invasive species. We will continue to identify pathways to build this network and make it a success, based on the input from the workshop. Watch the recording of the workshop here.

Featured image credit: the Maui Forest Bird Recovery Project.