Agent-based modelling reveals a disproportionate exposure of females and calves to a local increase in shipping and associated noise in an endangered beluga population. (December 2021)

• Record Type: Journal Article
• Authors: Chion, Clément; Bonnell, Tyler R.; Lagrois, Dominic; Michaud, Robert; Lesage, Véronique; Dupuch, Angélique; McQuinn, Ian H.; Turgeon, Samuel
• Is Part Of: Marine pollution bulletin. Volume 173:Part A(2021)
• Publication Date: 2021-12
• Subjects: St. Lawrence Estuary Beluga Population -- Agent-based model -- Shipping noise -- Acoustic impact assessment -- Species at risk -- Behaviour; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2021.112977
• Languages: English
• ISSNs: 0025-326X

Abstract

Abstract: Vessel underwater noise (VUN) is one of the main threats to the recovery of the endangered St. Lawrence Estuary Beluga population (SLEB). The 1% yearly population decline indicates that the cumulative threats are already beyond sustainable limits for the SLEB. However, a potential threefold increase in shipping traffic is expected within its critical habitat in the coming years resulting from proposed port-industrial projects in the Saguenay River. Current data indicate that SLEB typically use multiple sectors within their summer range, likely leading to differential VUN exposure among individuals. The degree of displacement and spatial mixing among habitats are not yet well understood but can be simulated under different assumptions about movement patterns at the individual and population levels. Here, we propose using an agent-based model (ABM) to explore the biases introduced when estimating exposure to stressors such as VUN, where individual-centric movement patterns and habitat use are derived from different spatial behaviour assumptions. Simulations of the ABM revealed that alternative behavioural assumptions for individual belugas can significantly alter the estimation of instantaneous and cumulative exposure of SLEB to VUN. Our simulations also predicted that with the projected traffic increase in the Saguenay River, the characteristics making it a quiet zone for SLEB within its critical habitat would be nullified. Whereas spending more time in the Saguenay than in the Estuary allows belugas to be exposed to less noise under the current traffic regime, this relationship is reversed under the increased traffic scenario. Considering the importance of the Saguenay for SLEB females and calves, our results support the need to understand its role as a possible acoustic refuge for this endangered population. This underlines the need to understand and describe individual and collective beluga behaviours using the best available data to conduct a thorough acoustic impact assessment concerning future increased traffic. Highlights: Vessel-generated underwater noise is a major threat to the recovery of the St. Lawrence belugas. Agent-based modelling is used to estimate belugas exposure to noise in case of shipping increase. The Saguenay will no longer be a low-frequency noise refuge in case of a threefold shipping increase. Belugas' behaviour must be accounted for to complete a comprehensive noise impact assessment. Shipping increase in the Saguenay would disproportionately affect females and calves.