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. 2023 Jul 25;13(7):e10353.
doi: 10.1002/ece3.10353. eCollection 2023 Jul.

Effects of a hydropower project on a high-value Asian elephant population

Kris Budd  1 , Daophone Suddychan  2 , Martin Tyson  3 , Camille N Z Coudrat  4 , Alex McWilliam  5 , Christopher D Hallam  6 , Arlyne Johnson  7   8 , Lori S Eggert  1
Affiliations

Effects of a hydropower project on a high-value Asian elephant population

Kris Budd et al. Ecol Evol. .

Erratum in

Abstract

Habitat loss and fragmentation are leading contributors to the endangered status of species. In 2006, the Nakai Plateau contained the largest known Asian elephant (Elephas maximus) population in the Lao People's Democratic Republic (Lao PDR), and the population was among those with the highest genetic diversity reported for Asian elephants. In 2008, completion of the Nam Theun 2 hydroelectric dam inundated much of the Plateau, resulting in the loss of 40% of elephant habitat. We studied elephant presence, movements, and the incidence of human-elephant conflict (HEC) on the Nakai Plateau and surrounding areas from 2004 to 2020, before and for 12 years after dam completion. To examine contemporary population dynamics in the Nakai elephants, we used genetic sampling to compare minimum population numbers, demography, and levels of genetic diversity from the wet and dry seasons in 2018/2019, 10 years after dam completion, with those reported in a pre-dam-completion genetic survey. After dam completion, we found a major increase in HEC locally and the creation of new, serious, and persistent HEC problems as far as 100 km away. While we were unable to compare estimated population sizes before and after dam completion, our data revealed a decrease in genetic diversity, a male-biased sex ratio, and evidence of dispersal from the Plateau by breeding-age females. Our results raise concerns about the long-term viability of this important population as well as that of other species in this region. Given that hydropower projects are of economic importance throughout Laos and elsewhere in southeast Asia, this study has important implications for understanding and mitigating their impact.

Keywords: elephants; habitat loss; human‐elephant conflict; hydroelectric dam; hydropower.

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Conflict of interest statement

The authors declare that they have no conflicts of interest with respect to this work.

Figures

FIGURE 1
FIGURE 1
The Nakai plateau and surrounding landscape. (a) Human–elephant conflict (HEC) incident locations on the Nakai Plateau and in the surrounding landscape (pre‐inundation, October 2004–March 2008); (b) HEC incidents April 2008–December 2010; (c) HEC incidents January 2011–December 2012; (d) HEC incidents January 2013–December 2014; (e) HEC incidents January 2015–14 August 2020. (Data from: Hedges et al., ; McWilliam et al., ; Tyson & Phakphothong, ; and NTPC unpub. data).
FIGURE 2
FIGURE 2
Population structure results from Structure 2.3.4 based on 9 nuclear microsatellite loci for K = 4 (∆K = 39.42) with cluster 1 in medium gray, cluster 2 in light gray, cluster 3 in white, and cluster 4 in dark gray (EV = Elephant Village).
FIGURE 3
FIGURE 3
Age distribution density plots for the Nakai 2006, 2018, and 2019 surveys using fecal bolus circumference as a proxy for age; age class thresholds defined by Tyson et al. (2002) are indicated and significant differences are shown by *.
See this image and copyright information in PMC

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