Programa de Doctorado en Medicina de La Conservación, Facultad de Cs de La Vida, Universidad Andres Bello, República 440, Santiago, Chile.
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; ONG Ranita de Darwin, Santiago & Valdivia, Chile; Centro de Investigación para La Sustentabilidad, Facultad de Ciencias de La Vida, Universidad Andres Bello, República 440, Santiago, Chile.
Environ Pollut. 2021 Jun 15;279:116881. doi: 10.1016/j.envpol.2021.116881. Epub 2021 Mar 11.
Entanglement of pinnipeds with plastic debris is an emerging conservation and animal welfare issue worldwide. However, the origins and long-term population level consequences of these entanglements are usually unknown. Plastic entanglement could produce a combination of wounds, asphyxiation, or inability to feed that results in the death of a certain percentage of individuals from the total population. In this research, we report on the consequent effect of plastic entanglement on population growth demographics in a South American fur seal (Arctocephalus australis australis) colony on Guafo Island, southern Chile. Using a stochastic matrix population model structured according to age and sex, and assuming an otherwise stable population, we explored population growth rates under five scenarios with differing rates of entanglement: A) a zero rate of plastic entanglement, B) entanglement rates (number of entangled individuals as a proportion of the total number of individuals) as observed in our study population (overall entanglement ratio of 1.2 × 10); and for the other scenarios, entanglement ratios as reported in the literature for other pinniped colonies around the world: C) 3.04 × 10, D) 4.42 × 10, and E) 8.39 × 10. Over the 30 years forecasting period and starting with a population size of ∼2950 individuals, the population growth rate was lower under all scenarios with rates of entanglement greater than zero (scenarios B-E). In comparison with scenario A, at the end of the 30-year period forecasted, we calculated a projected decrease in population size of between 20.34% (scenario B) and 91.38% (scenario E). These results suggest that even the lowest levels of entanglement in pinnipeds as reported in the literature might have significant effects over time on population-level dynamics. Our research offers potential insight when devising policy for the management and limitation of plastic pollution in the oceans, and indeed for the conservation and management policy of affected marine species. Furthermore, whilst there are some limitations to our methodology, it offers a straightforward and potentially useful approach for the standardized prediction of impacts at a population level of different rates of plastic pollution and entanglement and could be applied in distinct populations of the same species around the world.
海洋中的塑料污染对生物多样性构成了严重威胁，而海洋哺乳动物尤其容易受到塑料污染的影响。本研究通过构建基于年龄和性别的随机矩阵种群模型，假设种群处于稳定状态，探讨了 5 种不同缠绕率情景下的种群增长率：A）零缠绕率；B）本研究中观察到的种群缠绕率（缠绕个体数与总个体数的比例）；以及其他 4 种在世界范围内其他鳍足类动物种群中报道的缠绕率：C）3.04×10-2；D）4.42×10-2；E）8.39×10-2。在 30 年的预测期内，从约 2950 只个体的种群大小开始，所有缠绕率大于零的情景（情景 B-E）下的种群增长率都较低。与情景 A 相比，在 30 年预测期结束时，我们计算出的种群规模预计减少 20.34%（情景 B）至 91.38%（情景 E）。这些结果表明，即使是文献中报道的最低水平的鳍足类动物缠绕率，也可能会对种群水平动态产生重大影响。本研究为制定海洋塑料污染管理和限制政策以及受影响海洋物种的保护和管理政策提供了潜在的参考。此外，尽管我们的方法存在一些局限性，但它提供了一种简单而有用的方法，可以在不同的塑料污染和缠绕率水平下，对种群水平的影响进行标准化预测，并可应用于全球范围内同一物种的不同种群。
