Applications - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 265

Unfortunately, natural cycles and trends of the biological and ecological systems
are rarely considered from the sonic perspective and few data are yet available on
the variation of sound amplitude, frequency, and typology at the long term. The
requested and recommended actions for sonic monitoring is not a short, intense, and
scientifically sound investigation but consists of a long-term evaluation of the
natural soundscape able to cover hours, days, and seasons over the years.
Krause ( 1993 ) reported that in old growth forest the repartition of frequencies
are quite continuous, and the concept of acoustic niche was strongly supported by
this author. In secondary forests, however, the gaps along this spectrographic
sequence indicate defaunation. The study of frequency distribution and of the
frequency gaps could help to better understand the effects on ecosystems and
communities of human intrusion.
Environmental monitoring using acoustic cues is an innovative and nonintrusive
methodology to collect biological and nonbiological information from the sonic
environment (Andr´ et al. 2011 ; Bassett et al. 2012 ). In this direction is oriented
the Perennial Acoustic Observatory in the Antarctic Ocean (PALAOA), also the
Hawaiian word for “whale,” constructed in austral summer 2005-2006 on the
Ekstr¨m ice shelf 15 km north of Germany's Neumayer Base. This system collects
acoustic information 365 days per year, 24 h per day, real-time data access with full
frequency and dynamic coverage (Boebel et al. 2006 ).
An acoustic environmental observatory (Mason et al. 2008 ) can represent an
important tool for monitoring changes at a broad range of temporal and spatial
scales and to realize an ecosystem-based management.
Acoustics coupled with other data can produce a very efficient tool to respond to
questions pertaining to the effects of global warming, the changes in land use, and
the effect of agriculture practices on natural systems.
Acoustic procedures can measure and recognize phenomena such as different
species and species density, species identification, species behavior, and localiza-
tion of individuals.
Ecosystem-based management (EBM) requires more information than single-
species management, and synthetic indices are necessary for efficient evaluation.
Acoustic methods seem to have a great potential to contribute to EBM, as recently
stressed by Trenkel et al. ( 2011 ).
For instance, recent recording methodologies coupled to ad hoc metrics have
allowed distinguishing individuals in populations of endangered species. In the
European eagle owl ( Bubo bubo ), an endangered species that suffers from human
presence, Grava et al. ( 2008 ) have identified a vocal signature for every individual
contacted in the field. This approach opens new perspectives to study population
composition, territorial fidelity, and definitively indicates the availability of envi-
ronmental resources for this owl.
Monitoring the sounds uttered by marine animals and in particular mammals
seems a further promising perspective because animal vocalizations are audible at a
long distance and represent a more efficient methodology to estimate abundance,
activity, and dynamics of such pelagic animals. For this are required robust methods