Prime Directive, Reconsidered

Global climate change will soon be changing ecosystems around the world to such an extent that many species will no longer have proper habitats to survive and reproduce in. Over the past several years, the scientific community has been discussing the possibility of moving such species to new ranges in order to conserve biodiversity and reduce potential for extinction. This controversial process, known as assisted colonization or managed relocation, might be able to save some species from their current state of risk, but it may also prove dangerous for the natives of whatever area the “colonizers” are moved to. By diligently evaluating the perils and uncertainties of relocation and carefully considering the repercussions of leaving species to their shrinking habitats, The Nature Conservancy (TNC), given its mission and vision statements, should determine that in most cases, the costs of assisted colonization outweigh the benefits.

Patagonian mountains

By assisting the colonization of species with limited ability to adapt or relocate, the annual number of species gone extinct might be lowered in the coming decades. There are, however, disagreements as to whether or not humans should meddle with species movement. In their discussion of species introduction for conservation purposes, Philip Seddon states, “the deliberate moving of species is neither new nor controversial” (2009). Although the former claim certainly cannot be countered—species have been intentionally introduced before, such as Nile perch in Lake Victoria—there is no question that moving species has been controversial for some time: the simple fact that a heated debate over assisted colonization exists reflects as much. Part of the problem with relocation, as the Nile perch example shows, is that the adverse effects of the introduction of a species, even if they are partly predicted, cannot be fully known until the action takes place. Although some would point out that the majority of unintended introductions do not result in established or invasive populations, the few introductions that do become invasive can be extremely costly (monetarily, socially, and ecologically, in the case of the fire ant), and the concentrated aid from humans in assisted colonization (i.e. intended introduction) might lead to different, and perhaps seriously detrimental effects. For example, the colonizing species may hybridize with natives, leading to homogenized gene pools and thereby reducing global biodiversity should the distinct native and colonist species disappear.

But are the consequences of inaction severe enough to warrant managed relocation of some species, however risky it may be? Ronald Sandler (2009) claims that the value of a species is only great enough to justify assisted colonization when there is “strong evidence that translocation of the species is likely to be ecologically beneficial, not just benign, to the recipient system,” given that the ecological and instrumental value (i.e. the value of a species to the integrity of its ecosystem or to humans, respectively) of a species is generally overestimated by proponents of managed relocation. Although Sandler’s view might be taken as radical, it is clear that the risks of relocation will never be zero, and therefore rigorous research (e.g. experimentation and modeling) must always be carried out to ensure proper care is taken before moving species. Some species might present low enough risks and high enough benefits to justify assisting their colonization of a new or closely related range. For example, staghorn corals with heat-adapted genotypes could be moved to lower-latitude ocean areas, and two U.K. species of butterfly have already been successfully relocated, albeit not very far, for several years.

TNC’s mission is to “preserve the plants, animals and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive,” and the end-goal, or vision, is to leave a “sustainable world for future generations.” While biodiversity conservation is a key element of TNC’s purpose, transplanting species is not a necessary measure for TNC to preserve their target communities; protecting those targets by controlling land-use and human behavior in “the lands and waters they [the targets] need to survive” (e.g. by purchasing land, partnering with local communities, lobbying governments, etc.) is. TNC would do best by continuing to promote responsible and sustainable development, advocate conservation of ecosystems at risk, and restore natural areas degraded by climate change, all of which are key components of TNC’s current action plan. In fact, restoring natural areas is a strategy proposed, at least in passing, by most of those who discuss assisted colonization at all, since it is less risky, and sometimes less costly, than relocation.

Introducing a species that becomes detrimentally invasive or homogenizes gene pools has potential costs—both on an ecosystem and on TNC’s reputation as a leading conservation organization—high enough that only the lowest-risk endangered species (perhaps those identified as such by using the decision tree provided in Hoegh-Guldberg et al. 2008) should be considered as viable, since one of TNC’s goals is the preservation of local biotic communities. Although there are strong arguments for assisted colonization, and taking into account the fact that pressure from climate change is only increasing as deliberation continues, it is in TNC’s best interest to remain in their current operational niche and forego expansion into what is clearly risky territory in environmental health and positive public relations.

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Further Reading:

Kreyling, Juergen, Torsten Bittner, Anja Jaeschke, Anke Jentsch, Manuel Jonas Steinbauer, Daniel Thiel, and Carl Beierkuhnlein. 2011. Assisted colonization: a question of focal units and recipient localities. Restoration Ecology 19.

Ricciardi, A., and D. Simberloff. 2009. Assisted colonization is not a viable conservation strategy. Trends in Ecology and Evolution 24:248–253.

One thought on “Prime Directive, Reconsidered

  1. Pingback: When Rhinos Fly… « Raxa Collective

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