Draško Holcer

Leisure boating noise as a trigger for the displacement of the bottlenose dolphins of the Cres–Lošinj archipelago (northern Adriatic Sea, Croatia)

The waters of the Cres-Lošinj archipelago are subject to intense boat traffic related to the high number of leisure boats frequenting this area during the summer tourist season. Boat noise dominates the acoustic environment of the local bottlenose dolphin (Tursiops truncatus) population. This study investigates the spatial and temporal change in the underwater noise levels due to intense boating, and its effect on the distribution of the bottlenose dolphins. In the period 2007-2009 sea ambient noise (SAN) was sampled across ten acoustic stations. During data collection the presence of leisure boats was recorded if they were within 2 km of the sampling station. Bottlenose dolphin spatial distribution was monitored in the same period. Results showed a strong positive correlation between high SAN levels and boat presence, particularly in the tourist season. Dolphin distribution indicated significant seasonal displacements from noisy areas characterized by the intense leisure boating.

Drivers of Population Structure of the Bottlenose Dolphin ( Tursiops truncatus ) in the Eastern Mediterranean Sea

The drivers of population differentiation in oceanic high dispersal organisms, have been crucial for research in evolutionary biology. Adaptation to different environments is commonly invoked as a driver of differentiation in the oceans, in alternative to geographic isolation. In this study, we investigate the population structure and phylogeography of the bottlenose dolphin (Tursiops truncatus) in the Mediterranean Sea, using microsatellite loci and the entire mtDNA control region. By further comparing the Mediterranean populations with the well described Atlantic populations, we addressed the following hypotheses: (1) bottlenose dolphins show population structure within the environmentally complex Eastern Mediterranean Sea; (2) population structure was gained locally or otherwise results from chance distribution of pre-existing genetic structure; (3) strong demographic variations within the Mediterranean basin have affected genetic variation sufficiently to bias detected patterns of population structure. Our results suggest that bottlenose dolphin exhibits population structures that correspond well to the main Mediterranean oceanographic basins. Furthermore, we found evidence for fine scale population division within the Adriatic and the Levantine seas. We further describe for the first time, a distinction between populations inhabiting pelagic and coastal regions within the Mediterranean. Phylogeographic analysis suggests that current genetic structure, results mostly from stochastic distribution of Atlantic genetic variation, during a recent post-glacial expansion. Comparison with Atlantic mtDNA haplotypes, further suggest the existence of a metapopulation across North Atlantic/Mediterranean, with pelagic regions acting as source for coastal environments.

Occurrence of Cuvier's beaked whales in the southern Adriatic Sea: evidence of an important Mediterranean habitat

The intent of this work is to summarize the available knowledge on the appearance, identification and distribution of Cuvier’s beaked whales (Ziphius cavirostris) in the Adriatic Sea through a review of historical data, inspection of natural history collections and collection of original data. In total, eleven occurrences are documented of Cuvier’s beaked whale along the Adriatic coast with all records originating from the deep southern Adriatic basin. The number of recorded stranded Cuvier’s beaked whales in the southern Adriatic represents about 3% of the recorded specimens in the entire Mediterranean. This percentage increases up to about 5% when considering only data collected after the first recorded stranding of the recent era in 1975. Comparing these percentages to the extent of the area relative to the Mediterranean, the proportion of occurrence of the total stranded Cuvier’s beaked whales in the southern Adriatic ranged between the same to double of that of the entire Mediterranean Sea. Therefore, the southern Adriatic Sea should be considered as a potentially relevant habitat of the Cuvier’s beaked whale. This hypothesis has clear conservation implications particularly in view of the adverse impact of sonar experiments, carried out by navies from several countries, on this species and should be further investigated. Finally, there is no evidence of the northern bottlenose whale (Hyperoodon ampullatus) ever having occurred in this part of the Mediterranean region.

Marine Conservation and Accession: The Future for the Croatian Adriatic

The European Union (EU) is the world’s largest trading bloc and the most influential supra-national organisation in the region. The EU has been the goal for many eastern European States, for Croatia accession remains a priority and underpins many of its national policies. However, entry into the EU requires certain commitments and concessions. In October 2003 the Croatian parliament declared an ecological and fisheries protection zone in the Adriatic. Under pressure the zone was suspended, finally entering into force in March 2008 exempting EU States. There are other marine conflicts between Croatia and the EU, particularly the contested maritime border with Slovenia, and the development of the Croatian fishing fleet in opposition to the Common Fisheries Policy. Conversely, attempts to harmonise Croatian Nature Protection with the EU Habitats Directive, facilitated by pre-accession funding, has galvanised conservation policy. Since 2005 two marine protected areas have been declared, significantly increasing the marine ecosystem under protection. Finally, the development of the Marine Strategy Framework Directive is the latest EU attempt to integrate environmental policy in the maritime realm. This will have an effect not only on member States but neighbouring countries. For marine nature protection to be effective in the region the Adriatic Sea needs to be viewed as a mutually important shared and limited resource not a bargaining chip. Negotiations of the EU and Croatia have been watched closely by the other Balkan States and precedents set in this case have the potential to affect EU expansion to the East.

Long-Term Monitoring of Anthropogenic Noise and Its Relationship to Bottlenose Dolphin (Tursiops truncatus) Distribution in the Cres–Lošinj Archipelago, Northern Adriatic, Croatia

The Cres-Losinj archipelago represents an important nursing and feeding ground for the resident Tursiops truncatus (bottlenose dolphin) population. Scientific research on Tursiops truncatus in this area has been conducted since 1987, and the population abundance is currently estimated to be 113 individuals (95% CI = 107–121; SE = 6.967), showing a significant decline of 39% between 1995 and 2003 (Fortuna 2006). Being top predators, dolphins represent the symbol of a healthy environment; hence a reduction in their abundance is considered an indication of the endangered status of this population. The low Tursiops truncatus density in the region may be related to the habitat degradation of the northern Adriatic waters, particularly to the scarce availability of food resources in an environment subject to high anthropogenic pressure (Bearzi et al. 2004).

Are the 1/3-Octave Band 63- and 125-Hz Noise Levels Predictive of Vessel Activity? The Case in the Cres–Lošinj Archipelago (Northern Adriatic Sea, Croatia)

A 3-years sea ambient-noise (SAN) monitoring was carried out in the Cres-Lošinj Archipelago (Croatia), where a bottlenose dolphin population is threatened by unregulated nautical tourism. A total of 540 5-min SAN samples were collected and analyzed in an Indicator 11.2.1 (Marine Strategy Framework Directive) perspective. The 1/3-octave band center frequencies of 63 and 125 Hz (re 1 μPa.rms) proved to be predictive of local predominant ship type over time. However, the noisiest band level was centered on 200 Hz. We therefore suggest measuring a wider frequency band than those requested in Indicator 11.2.1.

New data on the occurrence of the critically endangered common angelshark, Squatina squatina, in the Croatian Adriatic Sea

1Department of Zoology, Croatian Natural History Museum, Demetrova 1, HR-10000 Zagreb, Croatia 2Blue World Institute of Marine Research and Conservation, Kaštel 24, HR-51551 Veli Lošinj, Croatia 3Department of Biodiversity, Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, SI-6000 Koper, Slovenia 4Marine Sciences Program, Juraj Dobrila University of Pula, Zagrebačka 30, HR-52100 Pula, Croatia

Factor associated variations in the home range of a resident Adriatic common bottlenose dolphin population

This study investigates the influence of the most dominant factors (association patterns, gender, natal philopatry and anthropogenic pressure) on the home range size of the 44 most resident common bottlenose dolphins (Tursiops truncatus) inhabiting the waters of the Cres-Lošinj archipelago (north Adriatic Sea, Croatia), a recently declared NATURA 2000 SCI. Results show that variations in home range patterns (MCP, 95% KDE and 50% KDE home range size) among the individual resident dolphins are primarily related to differences in gender and reflect the way in which different genders respond to external stressors. In addition, results confirm the seasonal influence of nautical tourism on both female and male dolphins through changes in their home range sizes. The overall results improve current knowledge of the main anthropogenic threats that should be taken into consideration when developing conservation measures to be applied to this Cres and Lošinj SCI.

Cetaceans in the Boka Kotorska Bay

The Boka Kotorska Bay, as a unique geographical area, with specific ecological conditions, was always inhabited by cetaceans. There is very little recorded data on their presence in the bay. This article presents an overview of cetacean species inhabiting the southern Adriatic Sea, with a particular focus on bottlenose dolphin and fin whale, species whose presence has been documented in the Boka Kotorska Bay. A detailed review on the presence of one of the most famous dolphins in the bay, the dolphin Joca, who was a favourite with swimmers and bathers and was awarded a special protection status by the local government of the city of Kotor has been carried out. A history of unfortunate events – accidental and intentional dolphin deaths in the last 20 years – is provided, as recorded by the society for protection of animals ‘Fifi’ from Kotor. This society of volunteers was involved in the protection of the Boka Kotorska Bay environment since its founding in 1997, and the protection of marine mammals was among its activities. An overview of the first survey of marine mammal populations in the Boka Kotorska Bay area within the frame of the EU IPA NETCET project is also provided. The results of the survey represent the first scientifically collected data on cetaceans in the area. Preservation of these species in the area of the bay requires constant involvement, education of the local population and children on the importance of preservation of cetaceans and careful development of all forms of tourism, including the nautical tourism, which is one of the gravest threats to marine mammals in the Boka Kotorska Bay area.