Silvio Nuti’s research while affiliated with Centro di Ricerche Nutriterapiche and other places

The common bottlenose dolphin is a cosmopolitan species that can be found worldwide in all oceans except polar and sub-polar waters. This wide distribution is associated with a certain level of morphological variation, which seems consistent with the presence of a globally distributed pelagic/offshore ecotype and several coastal/inshore ecotypes distributed along the continental shelf. In the Mediterranean Sea, the common bottlenose dolphin is a regularly occurring species and the second most sighted cetacean after the striped dolphin. According to some studies, the Mediterranean bottlenose dolphin is more closely related to the Atlantic coastal ecotype, while others suggest a closer link with the pelagic ecotype. This apparent contradiction could stem from the coexistence of two ecotypes also within the Mediterranean Sea, as suggested by genetic analyses. We analysed data collected from 2004 to 2019 by 43 different research groups, distributed in different areas of the basin, and shared on the web-based GIS platform Intercet. We analysed the distribution and movements of 4919 bottlenose dolphins, individually identified through their natural dorsal fin markings, in relation to bathymetry and in particular to the 200-meter isobath that marks the edge of the continental shelf. In addition, we reconstructed the associations between individuals within connectivity networks, to identify possible segregations between ecotypes. Our results show that most bottlenose dolphin geographical units find their habitat over the continental shelf, while the analysed data do not support the coexistence of different ecotypes (pelagic vs. coastal) living in parapatry, as described in the adjacent waters of the eastern Atlantic Ocean.

We investigated the presence and diversity of cetaceans in the Mediterranean Sea, analysing the data collected by 32 different research units, over a period of 15 years (2004–2018), and shared on the common web-GIS platform named Intercet. We used the encounter rate, the species prevalence, and the Shannon diversity index as parameters for data analysis. The results show that cetacean diversity, in the context of the Mediterranean basin, is generally quite low when compared with the eastern Atlantic, as few species, namely the striped dolphin, the bottlenose dolphin, the fin whale, and the sperm whale, dominate over all the others. However, some areas, such as the Alboran Sea or the north-western Mediterranean Sea, which includes the Pelagos Sanctuary (the Specially Protected Area of Mediterranean Interest located in the northern portion of the western basin), show higher levels of diversity and should be considered hotspots to be preserved. Primary production and seabed profile seem to be the two main drivers influencing the presence and distribution of cetaceans, with the highest levels of diversity observed in areas characterized by high levels of primary production and high bathymetric variability and gradient. This collective work underlines the importance of data sharing to deepen our knowledge on marine fauna at the scale of the whole Mediterranean Sea and encourages greater efforts in the networking process, also to accomplish the requirements of the Marine Strategy Framework Directive, with particular reference to Descriptor 1: biological diversity is maintained.

The common bottlenose dolphin (Tursiops truncatus) is a cosmopolitan delphinid, regularly present in the Mediterranean Sea. According to previous studies, this dolphin tends to form resident geographical units scattered on the continental shelf. We investigated how the physiographic characteristics of the area of residence, with special reference to the size and shape of the continental shelf, affect the home range and the group size of the local units. We analysed and compared data collected between 2004–2016 by 15 research groups operating in different study areas of the Mediterranean Sea: the Alboran Sea, in the South-Western Mediterranean, the Gulf of Lion and the Pelagos Sanctuary for the marine mammals, in the North-Western Mediterranean, and the Gulf of Ambracia, in the North-Central Mediterranean Sea. We have found that in areas characterised by a wide continental platform, dolphins have wider home ranges and aggregate into larger groups. In areas characterized by a narrow continental platform, dolphins show much smaller home ranges and aggregate into smaller groups. The results obtained from this collective research effort highlight the importance of data sharing to improve our scientific knowledge in the field of cetaceans and beyond.

• Geospatial models are used to predict the distribution of terrestrial and marine species, according to their ecological and ethological habits. The bottlenose dolphin is a cosmopolitan marine top predator, inhabiting most of the ocean, with the exception of polar and subpolar waters. This wide distribution is associated with a remarkable plasticity in ecological and behavioural habits, which makes it difficult to model and predict its distribution. • This study proposes a ‘multi‐type approach’ to predict the presence and distribution of the bottlenose dolphin in the Pelagos Sanctuary, a Specially Protected Area of Mediterranean Importance located in the north‐west Mediterranean Sea. A multi‐type model based on random forest regression was developed, analysing the distribution habits of two geographical units living in the Pelagos area. • When compared with a classical single‐type model, the multi‐type model performed much better in a prediction test (true skill statistics, TSS = 85% vs. 52%), confirming the value of this experimental approach. This work suggests that wild species should not be considered as one single‐type entity, as local specialization may change and shape their distribution habits.

The reproductive histories of 41 adult bottlenose dolphin females were analysed using photo-identification data collected between 2006 and 2014 in four sub-areas of the eastern Ligurian Sea (northwest Mediterranean). The Rapallo sub-area revealed the highest (highly significant) frequency of encounters (per unit effort) of reproductive females in association with young individuals, therefore emerging as a candidate nursery area in the region. The estimated fertility rate of adult females ranged between 290 and 407 births per 1000 individuals per year, higher than that of other known bottlenose dolphin populations, with a calving interval between 2.45 and 3.5 years. These results will be useful for projecting future trends of this (sub)population.

CONISMA, CNR and CIRCE, involved Italian research units (RUs) working on cetaceans to join a National Network answering the Marine Strategy Framework Directive (MSFD) requirements by sharing monitoring data. Data obtained during the 2016 monitoring campaigns by 13 RUs are presented here.

Habitat modeling is an important tool to investigate the quality of the habitat for a species within a certain area, to predict species distribution and to understand the ecological processes behind it. Many species have been investigated by means of habitat modeling techniques mainly to address effective management and protection policies and cetaceans play an important role in this context. The bottlenose dolphin (Tursiops truncatus) has been investigated with habitat modeling techniques since 1997. The aim of this study was to develop a predictive model of bottlenose dolphin distribution and habitat preference in the whole area of Pelagos Sanctuary. We focused on the application of machine learning techniques (Random Forest).

Pooled data on the endangered short-beaked common dolphin Delphinus delphis collected in the central Mediterranean Sea over 2000-2014 period by different research groups in Italy were analysed. A total of 266 encounters with 4675 common dolphins was attained. The species was mainly recorded in the central and southern Tyrrhenian Sea (around Ischia island and Strait of Messina), in both pelagic and neritic habitats. Mixed groups of common dolphin with other cetacean species were observed in 78 occasions. Group size ranged from 1 to >100 individuals, with differences between study areas. The presence of calves was consistently documented around Ischia only.

The Pelagos Sanctuary is the largest marine protected area of the Mediterranean Sea (87 500 km2), and is located in the north-west part of the basin. The presence of the bottlenose dolphin in this area is well documented but its distribution and abundance are not well known.The present study collected and analysed data from 10 different research groups operating in the Pelagos Sanctuary from 1994 to 2007. Photo-identification data were used to analyse the displacement behaviour of the dolphins and to estimate their abundance through mark–recapture modelling.Results show that the distribution of bottlenose dolphin is confined to the continental shelf within the 200 m isobath, with a preference for shallow waters of less than 100 m depth.Bottlenose dolphins seem to be more densely present in the eastern part of the sanctuary and along the north-west coast of Corsica.Bottlenose dolphins show a residential attitude with excursions usually within a distance of 80 km (50 km on average). A few dolphins exhibit more wide-ranging journeys, travelling up to 427 km between sub-areas.The displacement analysis identified two (sub)populations of bottlenose dolphins, one centred on the eastern part of the sanctuary and the other one around the west coast of Corsica.In 2006, the eastern (sub)population was estimated to comprise 510–552 individuals, while 368–429 individuals were estimated in the Corsican (sub)population. It was estimated that in total, 884–1023 bottlenose dolphins were living in the Pelagos Sanctuary MPA in the same year.The designation of a number of Special Areas of Conservation (SACs) under the Habitats Directive is discussed as a possible tool to protect the bottlenose dolphin in the Pelagos Sanctuary and in the whole of the Mediterranean Sea. Copyright © 2011 John Wiley & Sons, Ltd.