The Ischia project was thought to perform my PhD study on the effects of underwater noise on fish behaviour. Ischia is a volcanic island in the Southern Mediterranean sea. It is located in front of the Naples harbour and next to the most famous Capri island in Italy.
The reason why I decided to move the field work to Ischia was that the underwater visibility is excellent here and it will allow me to film the behavioural reaction of fish to playback underwater noise. In addition to this, Ischia has natural CO2 vents that makes the seawater naturally acidified. What I would like to investigate is whether or not the behavioural response to playback noise will be different in condition of CO2 enriched seawater compared to the normal one.
The target species, Sarpa salpa (Teleostei: Sparidae), inhabits both areas, with acidified and normal seawater, grazing on the edge of Posidonia oceanica meadows, endemic of the Mediterranean Sea. Sarpa salpa, known commonly as the Salema porgy, is a species of bream, recognisable by the golden stripes that run down the length of its body. This species is ecologically significant in the Posidonia oceanica seagrass meadows as it accounts for up to 75% of the total herbivorous consumption and represents a significant part of the fish fauna.
I will use a video system made of an underwater camera connected to a HD digital recorder placed on a custom-built tripod, which will be employed from the rib, to video the behavioural response of groups of salema feeding on seagrass meadows. The target behavioural response will be therefore a biologically important one, which, if affected by noise exposure, might lead to important ecological consequences in terms of fitness of this species and the role that this species has as consumer of primary production.
The acoustic system includes 2 loudspeakers connected to an amplifier that will playback man-made noise at different levels. Attached to the tripod there will be also a calibrated hydrophone, which will be used during the initial survey to record the background level of noise to which this species is exposed and later on to record the playback noise levels of the playback signal. I intend to use both playback of sound from a ferry boat and a smaller vessel.
The first week of study will be used to survey the 2 areas and create the behavioural baseline. The following weeks will be dedicated to the playback experiments.
Wish me good luck!