Modeling The Energetics And Population Dynamics Of Harbor Porpoises In The North Sea In Response To Anthropogenic Disturbance

Project: Research

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The population dynamics of food limited species are intertwined with the energetics of their individual constituents. As the energetics of individuals influence their fecundity and mortality, a shift in energy intake at the individual level can affect the population numbers as a whole [1]. A reduction in foraging success has been shown to impact breeding success, juvenile survival, and starvation rates in several marine mammal species [2, 3, 4]. However, for many marine species the data are lacking to adequately understand and predict the onset or severity of these effects. In the North Sea and inner Danish waters, harbor porpoises (Phocoena phocoena) can serve as an ideal focal species in energetic and population level modelling as they are a protected species (Annex II and IV of the Habitats Directive of 1992) with an abundance of data existing on their physiology and behavior in the region. As a species that depends on sound to navigate, forage, and communicate, porpoises are thought to be particularly vulnerable to disturbance by anthropogenic noise in their environment [5, 6, 7]. Disturbances, like anthropogenic noise, can influence foraging effort and movement patterns of marine mammals, which could significantly alter their energetics [8, 9]. To understand the effects of anthropogenic noise sources on marine mammals more studies are needed that focus on estimating disturbance induced shifts in population dynamics of sensitive species, such as the harbor porpoise.
For my study, I will model the energetics and population dynamics of harbor porpoises in the North Sea and inner Danish waters and assess how they are influenced by selected kinds of anthropogenic noise. By evaluating the kinematics and hydrodynamics of harbor porpoises, I will estimate the force that porpoises use to propel themselves through water. These estimates will then be employed, along with harbor porpoise movement, morphological, and reproductive data, to develop a velocity and water temperature dependent energy budget for porpoises. This energy budget will then be integrated into the existing DEPONS framework to test for the population level effects of spatial heterogeneity of porpoise prey patches (prey patchiness and distribution) in the North Sea. Once in the DEPONS framework, additional sources of anthropogenic noise and their individual level effects on porpoises will be added to the model to include the potential for compounding effects in the presence of multiple disturbances. The result will be a model more representative of the North Sea population of harbor porpoises and their environment as they experience it.
[1] Sibly, R.M. et al. 2005. On the regulation of populations of mammals, birds, fish, and insects. Science. 309:607-610
[2] Forcada, J., Trathan, P. N., Reid, K., and Murphy, E. J. 2005. The effects of global climate variability in pup production of Antarctic fur seals. Ecology. 86: 2408–2417.
[3] Greene, C. H., and Pershing, A. J. 2004. Climate and the conservation biology of North Atlantic right whales: the right whale at the wrong time? Frontiers in Ecology and the Environment. 2: 29–34.
[4] Simmonds, M. P., & Isaac, S. J. (2007). The impacts of climate change on marine mammals: early signs of significant problems. Oryx, 41(1), 19-26.
[5] Tougaard, J. et al. 2012. Behavioral reactions of harbor porpoise to pile-driving noise. The effects of noise on aquatic life. pp. 277-280.
[6] Nabe-Nielsen, J. et al. 2011. Effects of wind farms on harbour porpoise behavior and population dynamics. Scientific Report from Danish Centre for Environment and Energy no. 1. 48 pp.
[7] Bailey, H. et al. 2010. Assessing underwater noise levels during pile-driving at an offshore windfarm and its potential effects on marine mammals. Mar Pollut Bull. 60:888–897.
[8] Williams, R. et al. 2006. Estimating relative energetic costs of human disturbance to killer whales (Orcinus orca). Biological Conservation. 133(3): 301-311.
[9] Friedlaender, A. S. et al. 2016. Prey‐mediated behavioral responses of feeding blue whales in controlled sound exposure experiments. Ecological Applications. 26(4):1075-1085.
Effective start/end date01/12/201730/11/2020

    Research areas

  • Agent-based model, Metabolism, Cetacean, Marine mammal, Foraging, Bioenergetics

ID: 129076181