Scientists use common economic theory to save endangered habitats

Puerto Rico’s coastal wetlands face mounting challenges, many of which threaten the delicate balance of these ecosystems and their resident species.

Among the most vulnerable is the coquí llanero, Puerto Rico’s smallest tree frog, which relies on the island’s dwindling freshwater wetlands. With its entire known population confined to three small marshes on the northern coast, the coquí llanero has become a symbol of the fragility of Puerto Rico’s natural resources.

Human activity has significantly altered Puerto Rico’s coastal wetlands since the 1500s. Agriculture and, more recently, urbanization have reshaped the landscape. These wetlands are largely sustained by aquifers from the adjacent karst region, which extend the hydroperiod, favoring marsh habitats over forested wetlands.

Vegetation here includes grasses, rushes, and intermittent stands of Pterocarpus officinalis. This vegetation supports species like the bulltongue arrowhead, a critical substrate for the reproduction of the coquí llanero.

Rising sea levels pose one of the most significant threats to these wetlands. Northern Puerto Rico has experienced a sixfold increase in sea-level rise rates, from 2.08 mm per year between 1962 and 2016 to 12.12 mm annually between 2010 and 2016.

Most coquí llanero habitats lie less than five meters above sea level, putting them at immediate risk. Development has restricted the inland migration of these wetlands, leaving only river valleys and undeveloped riparian zones as potential refuges.

Additional threats include recreational activities, habitat damage from flood control, landfill contamination, and invasive species. These pressures, combined with the looming impacts of climate change, led to the coquí llanero’s designation as endangered by the U.S. Fish and Wildlife Service in 2012.

Puerto Rico’s warming climate and drier rainy seasons exacerbate the vulnerability of amphibians like the coquí llanero. Changing temperatures and humidity levels can directly impact their survival. Additionally, increased disease transmission linked to these climatic shifts poses further risks. Conservation efforts must therefore not only protect existing habitats but also anticipate future environmental changes.

Securing habitat refugia is a key strategy for adapting to these changes. These refugia—areas expected to develop favorable conditions in the future—can allow species to migrate naturally or through assisted efforts like translocation. Identifying and protecting such sites now can mitigate risks.

For example, using climate models, researchers have pinpointed potential refugia that could be restored or preserved to support amphibian populations as current habitats become unsuitable.

Puerto Rico has already placed 16% of its land under conservation status. However, achieving long-term resource persistence requires innovative approaches to manage the risks associated with climate and habitat uncertainties.

Borrowed from the world of finance, modern portfolio theory offers a unique way to manage conservation risks. The theory suggests that diversification—investing in a mix of assets that respond differently to changing conditions—can stabilize outcomes. Applied to conservation, this means identifying a diverse range of habitats and strategies to ensure species survival.

Published in the journal, Frontiers, researchers have used this approach to model scenarios for the coquí llanero. These models account for current protected habitats, future sea-level rise, and climate projections, as well as various funding levels for conservation efforts.

Two portfolio strategies were tested: one maximizing conservation benefits within budget constraints, and another balancing benefits against risks.

The benefit-maximization strategy focused on relocating coquí populations to already protected areas, minimizing costs but increasing risks due to limited habitat diversity. In contrast, the risk-benefit tradeoff strategy prioritized acquiring new lands for conservation, which offered greater long-term stability but at higher costs.

These models revealed that relying solely on existing protected areas may not be sufficient to mitigate future climate risks. Investing in additional habitats, while costly, could significantly reduce extinction risks. Notably, potential habitats on Puerto Rico’s eastern coast emerged as promising options, expanding the geographic range for the coquí llanero.

The case of the coquí llanero underscores the importance of forward-thinking conservation strategies. Modern portfolio theory provides a framework to navigate the uncertainties of climate change and habitat loss. By diversifying conservation investments—from habitat restoration to species translocation—managers can maximize benefits while minimizing risks.

“Diversification of investments is kind of a magic bullet for stability under future market uncertainty,” says Mitch Eaton, lead author of the study and research ecologist at the Southeast Climate Adaptation Science Center. This approach helps managers allocate resources effectively, considering budget constraints and realistic environmental variables.

Amphibians are among the most sensitive vertebrates to environmental changes, making them important indicators of ecosystem health. Puerto Rico, home to a remarkable array of amphibian species, faces a biodiversity crisis as climate change alters habitats. The coquí llanero exemplifies the broader challenges amphibians face in adapting to rapid environmental shifts.

While the study focused on the coquí llanero, the principles of modern portfolio theory have broader applications. From amphibians to other species facing habitat loss, this strategy offers a scalable solution for managing conservation challenges. Researchers suggest that this approach could be tailored to address the needs of multiple species simultaneously, enhancing ecosystem resilience.

As ecosystems worldwide face unprecedented pressures, innovative tools like this can guide resource managers in safeguarding biodiversity. Incorporating economic principles into ecological planning represents a forward-thinking approach to conservation. “The idea is to pool resources in a way that manages risks while maximizing conservation benefits,” explains Eaton.

For the coquí llanero, these efforts represent a lifeline. Protecting its limited habitat, exploring new refugia, and employing adaptive strategies can help ensure the survival of this iconic species. By acting decisively and strategically, we can address the intertwined challenges of climate change and biodiversity loss, securing a future where species like the coquí llanero continue to thrive.

Continued research and collaborative efforts between scientists, conservationists, and policymakers are critical. Ensuring adequate funding and public support for these initiatives will also be essential. The coquí llanero’s plight reminds us of the delicate interplay between human activities and natural ecosystems.

By embracing innovative conservation strategies, we not only preserve species but also safeguard the ecological services upon which human well-being depends.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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