The sensory environment plays a critical role for a variety of aquatic species as sound is used for a variety of functions. These include communication, reproduction, intra (within) and inter (between) species interactions as well as predator-prey interactions (Sluijs et al. 2010). In water, sound travels five times faster and weakens less over the same distance in air. This means long-distance communication is possible underwater. However, noise can have a long-distance impact on aquatic animals (Slabbekoorn et al. 2010).

Man-made noise produced by boats/ships, sonar, construction, and exploitation of offshore platforms (Slabbekoorn et al. 2010) has the potential to impact the behaviour and physiology of individual animals. The frequency range of this man-made noise can overlap with the vocalisation and hearing range of aquatic organisms (Popper and Hastings 2009, Slabbekoorn et al. 2010). Impacting the communication ability between species should negatively influence species diversity. Marine noise will impact species in a different way.

Invertebrates can be affected by noise pollution. Bivalves and crustaceans can retract or hide due to this noise and this would decrease their ability to feed effectively and negatively impact the food available to their predators (Sabet et al. 2016).

Fish primarily produce sound with their swimbladder. There are special muscles (sonic muscles) that vibrate on the swim bladder which produce the sound (Laditch and Fine 2006). The sounds produced are typically in the low frequency range (<1000 Hz). The physiology of sonic muscles and the acoustic properties of the swimbladder differs in each species and this allows for different sounds to be produced (Amorim 2006). Fishes have sensitive auditory organs and use sound for communication during territorial defence, aggression, mating and as a way of indicating alarm (Popper and Hastings 2009, Sebastianutto et al. 2011).

Fish can be impacted in a variety of ways by noise pollution. The type, frequency, duration of exposure, degree of overlap of sound frequency spectrum and distance to noise source impacts species (Popper and Hasting 2009, Slabbekoorn et al. 2010, Sluijs et al. 2010). Different species will react differently to noise pollution. Short-term exposure elicits a stress response in certain fish species, long-term exposure could potentially affect egg survival and growth rates. Stress has been recorded in Gilthead seabream due to exposure to vessel noise (Celi et al. 2006).

Different engine types can affect species in different ways (McCorck et al. 2019). It has been shown that 2-stroke engines affect the ability of the settlement-stage fish to learn to identify predators. This leads to a 70% decrease in survival over a 72 hour period (Ferrari et al. 2009).

Noise has also been shown to affect the ability of the larvae of reef-associated fish. It can potentially impact the ability of these species to settle on their reef habitat (Holles et al. 2013). At the end of the larval phase when reef fish are particularly vulnerable to predation, noise could effect the ability of fish to assess risks and make choices regarding anti-predator behaviour (Almany et al. 2006), Simpson et al. 2016).

This underwater noise has also shown to affect some species in their foraging efficiency and were shown to attack prey less effectively (Sabet et al. 2016).

Man-made noise from fishing vessels has been shown to affect the distribution of fish, with horizontal and vertical movements of Atlantic herring (Vabǿ et al. 2002) and Atlantic Cod (Handegard et al. 2003) away from vessels being recorded. Blue-fin tuna schools broke down in the presence of boat noise (Sara et al. 2009).

Potential impacts include masking courtship sounds over long-distance during mate attraction (Smott et al. 2018). Even short -term exposure could negatively affect species in the breeding season. Pomacentrids (damselfish and clownfish family) use sounds at close range during courtship with females preferring a lower frequency as this indicates a larger body size (Myrberg et al. 1978) and masking of these sounds could have dire consequences for the breeding season.

Different engine types can affect species in different way. It has been shown that 2-stroke engines affect the ability of the settlement-stage fish to learn to identify predators. This leads to a 70% decrease in survival over 72h (Ferrari et al. 2009).

Brown meagre (Same family as Dusky Kob) in the Venice lagoon, use vocalisations for reproductive calls, which results in spawning aggregations and noise levels seen in this lagoon can mask this communication. This would affect the reproductive success of this species (Bolgan et al. 2016).