Risposte comportamentali dei mammiferi marini ai suoni prodotti da attività antropiche

A New Context-Based Approach to Assess Marine Mammal
Behavioral Responses to Anthropogenic Sounds

W.T. ELLISON, B.L. SOUTHALL, C.W. CLARK, AND A.S. FRANKEL
Conservation Biology, Volume **, No. *, 1–8
2011, Society for Conservation Biology
published online: DOI: 10.1111/j.1523-1739.2011.01803.x

The link to the full article is http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2011.01803.x/full
The link to the abstract is http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2011.01803.x/abstract
and the abstract text is given below:

Abstract: Acute effects of anthropogenic sounds on marine mammals, such as from military sonars, energy
development, and offshore construction, have received considerable international attention from scientists,
regulators, and industry. Moreover, there has been increasing recognition and concern about the potential
chronic effects of human activities (e.g., shipping). It has been demonstrated that increases in human activity
and background noise can alter habitats of marine animals and potentially mask communications for species
that rely on sound to mate, feed, avoid predators, and navigate. Without exception, regulatory agencies
required to assess and manage the effects of noise on marine mammals have addressed only the acute effects
of noise on hearing and behavior. Furthermore, they have relied on a single exposure metric to assess acute
effects: the absolute sound level received by the animal. There is compelling evidence that factors other than
received sound level, including the activity state of animals exposed to different sounds, the nature and
novelty of a sound, and spatial relations between sound source and receiving animals (i.e., the exposure
context) strongly affect the probability of a behavioral response. A more comprehensive assessment method
is needed that accounts for the fact that multiple contextual factors can affect how animals respond to both
acute and chronic noise. We propose a three-part approach. The first includes measurement and evaluation
of context-based behavioral responses of marine mammals exposed to various sounds. The second includes
new assessment metrics that emphasize relative sound levels (i.e., ratio of signal to background noise and
level above hearing threshold). The third considers the effects of chronic and acute noise exposure. All three
aspects of sound exposure (context, relative sound level, and chronic noise) mediate behavioral response, and
we suggest they be integrated into ecosystem-level management and the spatial planning of human offshore
activities.