My Project 

Intensifying wildfires, deadly floods, and damaging hurricanes are becoming increasingly common as climate change pushes weather to new extremes, placing strain on wildlife and ecosystems. These changes are in addition to already existing stressors, including habitat loss, pollution, and invasive species. One promising conservation strategy to cope with these changes is conservation translocations, a process of intentionally moving plants, animals, and genetic material for conservation. During my time as a CASC intern, I helped compile a database of past research on conservation translocations. The database includes studies on western swamp turtles, corals, salmon, and guppies to provide examples of various techniques to support these aquatic and coastal species under the broader framework of conservation translocations. 

Assisted Migration 

Assisted migration, which involves moving a species to an area different from their historical location, is one common conservation translocation technique. A study involving western swamp turtles (Pseudemydura umbrina) is a great example using this strategy. The historical area for the western swamp turtle is in Perth, Australia, where rainfall has significantly decreased over the last five decades and habitat has been lost due to “agriculture, mining, industrial and housing developments” (Schmölz, Pinder, Kuchling, & Gollmann, 2021). Beginning in August 2016, a total of 35 captive-bred juveniles were marked with Trovan microchips and released into three sites. The first site, Moore River Nature Reserve, was selected because it previously served as a successful translocation site. The other two sites were farther south, where the climate is cooler and wetter: the Meerup Wetland in the D’Entrecasteaux National Park, and a wetland in East Augusta adjacent to the Scott River National Park. After translocation, researchers measured invertebrate biomass, diversity in the wetlands, and the turtles’ diet. Results from the trials concluded that Moore River and East Augusta contain “enough biomass and variety of food for P. umbrina to grow normally and not to starve” (Schmölz, Pinder, Kuchling, & Gollmann, 2021).  
 

Assisted Gene Flow 

Another type of conservation translocation is assisted gene flow. This technique involves moving individuals or their genetic material from one population to another to increase adaptive potential. An example in our database includes reef-building corals in the Red Sea. Coral reefs are vital to marine ecosystems, providing “food, coastal protection, and tourism” to many countries and millions of people every year (Barreto, Schmidt-Roach, Zhong, & Aranda, 2023). Climate change is threatening coral reefs by warming ocean temperatures, leading to coral bleaching. This experiment aimed to test the success of the assisted gene flow technique by extracting coral colonies from the Red Sea to see if their heat-resistant genes could help threatened colder populations in a common garden experiment (Barreto, Schmidt-Roach, Zhong, & Aranda, 2023). Three sites were sourced in the Red Sea including Duba, Jazan, and Thuwal. The results showed significant bleaching in the months of July and August, with 75% of the fragments from the colder, northern Duba colonies experiencing bleaching. Less bleaching was observed in the fragments from the southern sites of Jazan and Thuwal, which suggests that southern coral reefs have thermally resistant alleles to protect against warming temperatures caused by climate change. Survival and growth rates varied among site sources, not necessarily reflecting thermal tolerance.  This variation may be attributed to environmental factors other than temperature.  
 

Genetic Rescue 

A similar conservation translocation technique that is aimed at reducing the risk of outbreeding depression is called genetic rescue: the process of introducing healthy individuals into a small, isolated population of the same species. An example of this technique in our database is a controlled reciprocal transplant experiment using Atlantic salmon from three neighboring populations. Only one of the three Atlantic salmon populations showed evidence of outbreeding depression, which “exhibited survival rates supportive of the hypotheses of local adaptation and the loss of local adaptation in outbred cross types” (Houde et al., 2011). Minimizing distances for integration proved successful in this experiment as the Atlantic salmon populations were mixed from smaller spatial distances, around 34–50 km geographic range. The authors emphasize the importance of evaluating on a case-by-case basis as every situation yields different needs in order to avoid “inbreeding and outbreeding in the conservation and management of endangered species” (Houde et al., 2011).  
 

Assisted Range Expansion 

One final study in the database, which examined guppies, provides an example of assisted range expansion. This specific type of assisted migration aims to extend a species’ suitable habitat by translocating populations just outside their current range. Researchers extended the natural range of the guppy's habitat in Trinidad to a guppy-free stream where a “barrier waterfall historically excluded it from these upper reaches” (Leduc et al., 2021). As a result of guppy introduction, researchers found that the ecosystem experienced higher levels of organic energy production and community respiration. The study showed how even introductions of species such as guppies into their natural range can reshape ecosystems and their functions when colonizing new habitats.  

Research has shown that using conservation translocation as a management technique requires careful planning and assessment of potential risks. A key risk of conservation translocations is the potential disruption of local ecosystems and the possibility that translocated species may become invasive. While the risk is small, the impact can be large. Along with the threat of invasiveness, issues such as disease and outbreeding depression have made this management strategy a controversial topic. Because of these challenges, research and monitoring throughout the translocation process are critical. 
 

What I Learned 

I feel incredibly lucky to be a part of creating this database over the course of my internship. With the goal of helping to consolidate success stories that strategically use conservation translocations to help species and genetic material continue to thrive, I feel like I am making a positive impact both within USGS and the world as a whole. Throughout this year, I have developed many skills such as analyzing complex science, sorting through thousands of research papers, and consolidating information so that it can be understood by the public. As I continue in this role, I look forward to mapping out these success stories and sorting them into easy-to-digest data on how we may look to this management strategy to support species in the face of a warming world.  
 

Citations 

Barreto, M. M., Schmidt-Roach, S., Zhong, H., & Aranda, M. (2023). Assessing the feasibility of assisted migration of corals in the Red Sea. Frontiers in Marine Science, 10, 1181456. https://doi.org/10.3389/fmars.2023.1181456 
 

Leduc, A. O. H. C., Thomas, S. A., Bassar, R. D., López-Sepulcre, A., MacNeill, K., El-Sabaawi, R., Reznick, D. N., Flecker, A. S., & Travis, J. (2021). The experimental range extension of guppies (Poecilia reticulata) influences the metabolic activity of tropical streams. Oecologia, 195, 1053–1069. https://doi.org/10.1007/s00442-021-04884-0 
 

Houde, A. L. S., Fraser, D. J., O’Reilly, P., & Hutchings, J. A. (2011). Relative risks of inbreeding and outbreeding depression in the wild in endangered salmon. Evolutionary Applications, 4(4), 634–647. https://doi.org/10.1111/j.1752-4571.2011.00186.x 
 

Schmölz, K., Pinder, A., Kuchling, G., & Gollmann, G. (2021). Evaluating candidate wetlands for the assisted colonization of the western swamp turtle Pseudemydura umbrina in a changing climate: Macro-invertebrate food resources and turtle diet. Aquatic Conservation: Marine and Freshwater Ecosystems, 31(6), 1407–1419. https://doi.org/10.1002/aqc.3543