Wildlife trade is causing biological diversity around the world to plummet. And, while the rate at which international wildlife breeders and traders remove individual animals from natural habitats remains unquantified, largely due to illegal and unregulated instances of trade evading attempts to quantify it, the consequences of this unsustainable process may be far greater and more dire than we could even begin to estimate for entire ecosystems.
Wildlife Trade Often Targets Animals with Desired Characteristics
The process of continuously taking individual animals from the wild who have the same desirable qualities for different avenues of trade (i.e. size, unique features, abundance, rarity, or high fecundity) has long-term and detrimental effects on species extinction risk and selection processes in the wild, which then has broader consequences for other species and ecosystem processes. Therefore, to holistically maintain a sustainable level of wildlife trade, we must also consider the other species and environmental factors that that may simultaneously be harmed by the depletion of members from a singular species.
Wildlife Trade Has Dramatic Consequences for Ecosystems, Habitats, and Even Non-Targeted Species
A paper recently published in Biological Reviews, entitled “The ecological drivers and consequences of wildlife trade” (Hughes et al., 2022), defines these broader trade-induced ecosystem repercussions. These effects include altered seed dispersal networks, trophic cascades (an ecological phenomenon triggered by the addition or removal of top predators, which then enhances the survival of the next trophic level), long-term compositional changes in plant communities, altered forest carbon stocks, and the introduction of harmful invasive species.
- Marmots in Mongolia. For example, Mongolian marmots’ communal burrowing systems have been associated with increased abundance of several other species. However, exploitation of Mongolian marmot meat and skins has contributed to substantial population declines with unquantified consequences for other species.
- Leopards in Gabon. Additionally, where wildlife trade causes severe reductions in prey availability, predators are also likely to decline. In Gabon, where prey species are hunted heavily to supply the bushmeat trade, leopards occurred at reduced densities and shifted their diets towards smaller animals. Their populations were gone completely in the most heavily exploited sites, despite not being directly hunted.
- Primates in the Amazon. Alternatively, declines of large-bodied species caused by trade can increase the abundance of medium- and small-bodied species through reduced predation. For example, at moderate levels of hunting, medium-sized primate populations in the Amazon increased due to the absence of larger primate species with similar diets. Similarly, populations of meso-predators often increase after the eradication of large predators, which may increase the rate of bird nest predation.
- Invasive Species in Florida. Adding to these imbalances, the pet trade is notorious for increasing the prevalence of invasive species: 85% of 140 non-native reptiles and amphibians introduced to Florida arrived via the pet trade. Perceived charisma and attractiveness are major drivers in the pet trade. Interestingly, invasiveness is often preferred in the global pet trade, as traits associated with commercial success are often the same traits linked to invasion success.
- Impact on Plant Species. These domino effects hamper plant survivability, and thus the amount of carbon sequestered, too: approximately 75% of woody plant species in tropical forests are dispersed by animals. Overexploitation of animals targeted for the bushmeat trade has reduced populations of many large-bodied frugivores, which function as long-distance seed dispersers for many large-seeded tree species. Over 70% of individuals hunted by an average Central African village have a seed dispersal role.
Globally, over 100 million plants and animals are traded every year, including at least 24% of the world’s terrestrial vertebrates and thousands of plant and invertebrate species that receive substantially less research and policy attention. Further, around 800 million people in the rural tropics depend on wildlife for food and other long-term natural resources. With these numbers in mind, imagine the colossal impact that the decline of just one species has on larger ecosystem functionality. Therefore, considering a species’ larger impacts on a functional ecosystem is crucial in determining their CITES status, which acts as the regulating body for which global sustainable trade may be achieved.
The authors of the article suggest three main avenues for future research in wildlife trade: focus more on the impacts of often-overlooked species, including smaller invertebrates; analyze how trade impacts local communities’ resources; and scrutinize links between the spread of disease and trade.
The Future of the Natural World is Our Future, Too
Ecosystems will always attempt to achieve homeostasis, but with the added accelerated damage of the unsustainable wildlife trade in the mix with no real idea of its impacts, this balance seems impossible. All organisms, whether directly or indirectly, depend on the rich balance of these ecosystems to survive; including the humans reading this, far removed from the natural environment behind an electronic screen. We depend on each other. Every molecule of life is intertwined with and dependent on another. Keep wildlife in the wild, to ensure both their future and yours.
Keep Wildlife in the Wild,
Devan
