Impacts of anthropogenic noise on reproduction and survival

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Noise-generating human activities, such as urbanisation, transportation and the exploitation of resources, have increased since the Industrial Revolution and have changed the acoustic landscape of terrestrial and aquatic ecosystems. Anthropogenic (man-made) noise is now recognised as a major component of environmental change and a pollutant of international concern; for example, it is included in the European Commission Marine Strategy Framework Directive (MSFD) and the US National Environment Policy Act, and as a permanent item on the environmental agenda of the International Maritime Organization.Fish can use natural sounds for communication, orientation and habitat selection, but we know that anthropogenic noise can raise their stress levels and affect communication, foraging and movement. However, it is difficult to predict what this might mean for individual fitness (survival and reproduction), and thus for populations and communities. Our recent work has shown that short-term exposure to motorboat noise can affect fish anti-predator behaviour, causing a doubling in mortality when encountering natural predators, but as yet we don't know how longer-term noise exposure affects other key life-history processes.The aim of this project is to use an established field-based study system (coral reef fish) to assess the impacts of a major source of anthropogenic noise (motorboats) on key life-history processes (reproduction, embryonic and larval survival) that have direct fitness and ecological implications. Driving boats around nests of the spiny chromis Acanthochromis polyacanthus and the Ambon damselfish Pomacentrus amboinensis, we will assess the impacts of the generated noise on reproduction and early-life survival. Subsequent experiments with captive-breeding populations will allow us to separate the relative effects of noise exposure on parents, embryos and larvae for offspring growth and mortality. Use of uniquely identifiable transponders, detailed field observations and experimental manipulations of egg predators will enable us to determine how boat noise affects the performance of parents tending eggs and guarding nests, and the consequences for reproductive output.Focussing on coral reef fish is especially important in the 21st Century as the reefs upon which they depend are among the most globally threatened marine ecosystems, yet they provide habitat for 25% of all fish species, and support fisheries that feed 0.5 billion people and the livelihoods of 100s millions, often in the world's poorest countries. We will test impacts of noise generated by motorboats for two main reasons. First, because coastal regions are experiencing unprecedented human population growth, with a significant rise in coastal recreation and tourism, including boating (e.g. 12.5 million registered powerboats in the USA, 0.5 million boats predicted for the Great Barrier Reef by 2040). Second, because it is feasible to drive boats near to natural and manipulated habitats on coral reefs, we can conduct carefully controlled experiments that are logistically far more challenging with other sources of marine anthropogenic noise (e.g. pile-driving and shipping).We will work in partnership with marine managers, boat-engine manufacturers, tourism and fishing operators, and conservation agencies to test whether modern four-stroke boat engines have less impact than traditional two-stroke engines, and determine the zone of impact for each engine type. Our research will directly inform future boat-engine design, and provide much-needed evidence for developing management plans for noise on the Great Barrier Reef and in European and US waters.