Integrating subsistence practice and species distribution modeling: assessing invasive elodea's potential impact on Native Alaskan subsistence of Chinook salmon and whitefish

The use of multiple evidence base methods to enrich climate change research and knowledge in the Arctic

Indigenous and local knowledge (ILK) is increasingly used along with scientific knowledge (SK) to understand climate change. The multi evidence base (MEB) offers ways of combining knowledge systems together. Nonetheless, there is little guidance on how to use MEB approaches in research. Our aim is to systematically evaluate empirical cases using MEB approaches in Arctic climate change research; and explore ILK inclusion in research stages. The mapping followed the ROSES protocol, which provides a checklist of details to be included in the review. The literature search identified 1483 records referring to MEB approaches. We identified seven papers applying the cross-fertilization and nine applying the coproduction approach to combine ILK with SK. The theory of change framework was used to evaluate participation, revealing a distinct difference between the approaches in participant involvement in the research stages. Regardless of MEB approach, the output and outcome of the cases were less clear.

Model-based management of macrophytes in shallow lakes under warming

Macrophytes are a critical component of freshwater ecosystems, harboring significant biodiversity and providing essential resources and services. However, their habitat faces multifaceted challenges from climate change, local anthropogenic disturbance, and biological invasions. Here, we aim to provide local management suggestions under both current and future higher temperature regimes. Using joint species distribution modeling (JSDM), we integrate comprehensive presence-absence data with environmental variables and ecological traits to predict the distributions and diversity of 44 vascular aquatic plant and charophyte species in three shallow lakes (435 sites in total) in southwestern France. The environmental variables considered included physical properties (including current surface temperature and a 2 °C warming scenario), anthropogenic disturbance, shoreline curvature, underwater topography, and the occurrence rate (temporary or permanent) of water and wetness. Subsequently, we use percentile-threshold-based spatial prioritization to identify conservation management hotspots. Our results show that macrophyte habitat suitability is largely influenced by land-use and human accessibility. Moreover, macrophyte habitat suitability and native species diversity generally decrease across lakes under warming. However, the decrease in habitat suitability is greater for native isoetid species than for invasive species-suggesting a potential forthcoming cascade of changing community composition, higher lacustrine trophic states, and impaired provisioning of ecosystem services. Therefore, we suggest immediately adopting adaptive management principles at the identified conservation management hotspots, including the control of and targeted monitoring for invasives as well as conservation and restoration measures for native species, in particular isoetids.

Elodea mediates juvenile salmon growth by altering physical structure in freshwater habitats

Invasive species introductions in high latitudes are accelerating and elevating the need to address questions of their effects on Subarctic and Arctic ecosystems. As a driver of ecosystem function, submerged aquatic vegetation is one of the most deleterious biological invasions to aquatic food webs. The aquatic plant Elodea spp. has potential to be a widespread invader to Arctic and Subarctic ecosystems and is already established in 19 waterbodies in Alaska, USA. Elodea spp. has been found to alter ecosystem processes through multiple pathways; yet little is known about the impact of Elodea spp. on fish life history. A primary concern is the effect of Elodea spp. on juvenile Pacific salmon (Oncorhynchus spp.), because this invading plant can form dense stands in littoral zones, potentially impacting important freshwater rearing habitats used by juvenile fish for foraging and refuge from predators. We used a field experiment to test the effect of Elodea spp. on juvenile coho salmon (O. kisutch) growth in an infested lake near Cordova, Alaska, USA. We found that Elodea spp. stands result in reduced growth and a lower trophic position for juvenile coho salmon over the summer compared to habitats dominated by a native assemblage of aquatic plants. While infested sites were not associated with significant changes in water condition or primary productivity compared to sites dominated by native vegetation, zooplankton densities were reduced, and Elodea spp. height and vegetation richness increased macroinvertebrate densities. Combined, these results indicate that Elodea spp. may alter the flow of energy to juvenile salmon by restructuring space and affecting prey resources for rearing fish. Furthermore, these results suggest that widespread establishment of Elodea spp. may alter the quality of habitat for juvenile salmon and, by affecting juvenile fish growth, could lead to population-level impacts on salmon returns.

Flight plan for the future: floatplane pilots and researchers team up to predict invasive species dispersal in Alaska

Aircraft can transport aquatic invasive species (AIS) from urban sources to remote waterbodies, yet little is known about this long-distance pathway. In North America and especially Alaska, aircraft with landing gear for water called floatplanes are used for recreation access to remote, often road-less wilderness destinations. Human-mediated dispersal of AIS is particularly concerning for the conservation of pristine wildlands, yet resource managers are often challenged by limited monitoring and response capacity given the vast areas they manage. We collected pathway data through a survey with floatplane pilots and used a Bayesian hierarchical model to inform early detection in a data-limited situation. The study was motivated by Alaska’s first known AIS, Elodea spp. (Elodea) and its floatplane-related dispersal. For 682 identified floatplane destinations, a Bayesian hierarchical model predicts the chance of flights originating from AIS source locations in freshwater and estimates the expected number of flights from these sources. Model predictions show the potential for broad spread across remote regions currently not known to have Elodea and informed monitoring and early detection efforts. Our result underlines the small window of opportunity for Arctic conservation strategies targeting an AIS free Arctic. We recommend management that focuses on long-distance connectivity, keeping urban sources free of AIS. We discuss applicability of the approach for other data-limited situations supporting data-informed AIS management responses.