► Leisure boating is the major source of anthropogenic noise in the sea. ► Leisure boating noise affects dolphin distribution in the study area. ► Dolphin displacements are reported during the season ...of highest boat presence. ► Highest sea ambient noise levels characterizes areas of the most intense boating. ► Reduced dolphin presence characterizes area of highest sea ambient noise.
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 2km 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.
The common bottlenose dolphin (Tursiops truncatus) population along the eastern Adriatic coast is believed to comprise discrete communities, yet many of them are unstudied. This study provides the ...first description of occurrence and demographic parameters for the community inhabiting waters of North Dalmatia. Dedicated boat‐based surveys conducted in summer months from 2013 to 2017 resulted in 13,896 km of research effort and 284 dolphin sightings from which 336 individuals were identified. Site‐fidelity analysis revealed that 52.1% of encountered marked adults occur in the area regularly or occasionally. No significant difference among years could be found for mean group sizes (5.73–7.46) and group encounter rates (1.159–1.942 groups/100 km). Pollock's Robust Design models estimated annually variable adult apparent survival (0.737–0.986) and constant temporary emigration rate of 0.172. The estimated abundance varied annually from 116 to 138 individuals and showed a negative slope, but a significant trend could not be confirmed. Age‐dependent models estimated first‐year calf survival at 0.875. These results provide a baseline for informed management of two Sites of Community Importance, and a benchmark for future monitoring in North Dalmatian waters, an area under significant anthropogenic pressure.
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.
•Cres-Lošinj Natura 2000 SCI is home to a resident bottlenose dolphin population.•Variations in home range patterns of dolphins are primarily related to gender.•Females use large areas and live in more fluid associations.•Males have smaller home ranges and form strong and territorial alliances.•Recreational and fishing boats have a significant effect on dolphin home ranges.
In the Adriatic Sea, a female common bottlenose dolphin named "Boa" was observed on 19 occasions between 2009 and 2019, inhaling via her mouth for every observed respiration. We provide some ...explanations for the potential cause of this behaviour using existing evidence. Boa appeared to be in good physical shape and displayed behaviour similar to other individuals. She mothered three calves, raising at least one to independence successfully. Because she lived a normal life, we believe she could vocalise and echolocate. Boa may have been forced to breathe through her mouth to deal with internal injuries, occlusion, or disease. Of the potential causes, an occlusion of the upper respiratory tract seems more likely than a perforation or permanent dislocation of the larynx. An occlusion could result from disease, a congenital disorder, and/or wrongly ingested or inhaled food items or foreign materials. To breathe via the mouth, Boa must have been able to circumvent the separation of the respiratory tract from the oral cavity. By relaxing the respiratory muscles, particularly the palatopharyngeus, she could have used the negative pressure of the lungs to pull in air from the oropharynx into the upper respiratory tract. The true cause of Boa's condition will probably never be discovered.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Accurate description of population structure and genetic connectivity is essential for efficient conservation efforts. Along the European coastline,
Tursiops truncatus
typically shows high site ...fidelity to relatively small areas, often semi-enclosed waters, but patterns of genetic connectivity among such areas are often poorly understood. In this study, we investigate the patterns of genetic structure and connectivity of
Tursiops truncatus
in the Adriatic Sea and contiguous Mediterranean, using multilocus microsatellite genotypes. We focus particularly on areas where photo-ID studies suggest the occurrence of local ‘resident communities’. Patterns of geographic structure were identified using multivariate methods, Bayesian assignment methods, and analyses of relatedness. Our results are consistent with the occurrence of communities with high site fidelity to the Gulf of Ambracia, Croatian island archipelagos, and the Gulf of Trieste. Dolphins in these regions do not fit a model of complete panmixia, but neither do they exhibit multiple discrete population units. Even for the community in the Gulf of Ambracia, which is well separated by several population genetic estimates, we can unambiguously identify individual dispersal to the most distant area in the Northern Adriatic Sea. We suggest that the population structure patterns in these animals might be best described as a stable metapopulation and discuss the implications of such a model for regional conservation efforts. The critically endangered Ambracian sub-population is particularly well differentiated, and is therefore at high risk of local extinction due to relatively small size, high degree of isolation and exposure to several anthropogenic pressures. The exact geographic boundaries of individual sub-populations cannot always be determined due to lack of sampling and low resolution of the methods used. Nevertheless, our results have important implications for effective conservation of local communities showing strong site fidelity.
Photo-identification is a commonly used non-invasive technique in cetacean research which can be utilized to identify individuals and, consequently, acquire a variety of life history and demographic ...information such as group composition, site fidelity, movement patterns, and abundance estimates. Many dolphin species acquire nicks and notches along the trailing edge of the dorsal tin as a result of interaction with conspecifics. Coupled with scars and other lesions on the dorsal fin and body (secondary marks) as well as natural body pigmentation, these marks make each individual uniquely identifiable. Tissue loss is permanent--that is, nicks and notches might change their shape or size due to additional injuries but regeneration of the tissue has never been recorded. Here, Miocic-Stosic et al look at the possible errors in the matching procedure stemming from images showing several individuals surfacing in tight formation, using the common bottlenose dolphin (Tursiops truncates) as an example.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Evidence-informed decision-making is in increasing demand given growing pressures on marine environments. A way to facilitate this is by knowledge exchange among marine scientists and ...decision-makers. While many barriers are reported in the literature, there are also examples whereby research has successfully informed marine decision-making (i.e., ‘bright-spots’). Here, we identify and analyze 25 bright-spots from a wide range of marine fields, contexts, and locations to provide insights into how to improve knowledge exchange at the interface of marine science and policy. Through qualitative surveys we investigate what initiated the bright-spots, their goals, and approaches to knowledge exchange. We also seek to identify what outcomes/impacts have been achieved, the enablers of success, and what lessons can be learnt to guide future knowledge exchange efforts. Results show that a diversity of approaches were used for knowledge exchange, from consultative engagement to genuine knowledge co-production. We show that diverse successes at the interface of marine science and policy are achievable and include impacts on policy, people, and governance. Such successes were enabled by factors related to the actors, processes, support, context, and timing. For example, the importance of involving diverse actors and managing positive relationships is a key lesson for success. However, enabling routine success will require: 1) transforming the ways in which we train scientists to include a greater focus on interpersonal skills, 2) institutionalizing and supporting knowledge exchange activities in organizational agendas, 3) conceptualizing and implementing broader research impact metrics, and 4) transforming funding mechanisms to focus on need-based interventions, impact planning, and an acknowledgement of the required time and effort that underpin knowledge exchange activities.
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•We analyzed 25 successful examples of marine science-policy knowledge exchange (KE).•A diversity of KE approaches was used, and a diversity of successes were achieved.•Successes were enabled by the right actors, processes, support, context, and timing.•Situational awareness, building relationships & engaging diverse actors/knowledge types is key.•Better training, institutionalization, broader impact metrics & flexible funding needed.
The ACCOBAMS Survey Initiative (ASI) is the first synoptic large-scale survey of the entire ACCOBAMS Area and as such it plays a key role in filling the current gaps in our biological and ecological ...knowledge of large vertebrate species occurring in the region. Data gathered during the ASI were analyzed in a distance sampling surface-modelling framework to assess the summer distribution, densities and patterns, as well as to investigate the correlates of these parameters, for large vertebrate species and taxa in the Mediterranean Basin. Static and dynamic explanatory variables, including water depth (m), distance to depth contours (km), distance to canyons and seabed slope (km), sea surface temperature (°C), mixed layer depth (m) and levels of chlorophyll-a (mg/l), were considered to predict density and compute its variance spatially at a resolution of 10x10 km. A strong longitudinal gradient from low densities in the east to high densities in the west is shared by most taxa. In addition, several taxa also showed a less marked latitudinal gradient varying in direction according to species, and finally, a few of them exhibited patchy distributions.
The Natura 2000 (N2k) network is an important site-based protection tool for the protection of biodiversity in Europe. However, for highly mobile and adaptable marine species, such a tool might not ...be the most effective way to achieve conservation objectives, unless this includes a broader consideration of the direct threats to these species throughout their range. Considering that the N2k network requires that a ‘significant proportion’ of 60% of the population be under protection, this creates a challenge for the conservation of these wide-ranging species. This paper reviews the efficacy of the N2k network as it is presently implemented within the Adriatic Sea for the conservation of two highly mobile marine species - the common bottlenose dolphin and the loggerhead turtle. In particular, it considers the appropriateness of the current Sites of Community Importance (SCIs) in the region and the relevance of the existing marine N2k network for the conservation of these species. It provides new insights on the approach used to evaluate SCI designations highlighting important weaknesses in the system, including threat identification after SCI designation, and the relevance of SCI size in relation to management commitments. Data from two basin-wide aerial surveys were used to define areas of relative high density of these species, in comparison to other areas in the basin. Given the ambitious 60% conservation target of the N2k network, analysis shows that site-based protection tools are unlikely to be sufficient to protect a ‘significant proportion’ of either species, unless very large areas are designated as SCIs. However, given that the main threats known to affect these species in this region (i.e. fishery bycatch and seismic surveys) are present throughout the basin, these large SCIs would still have limited conservation success without implementing other wide-scale mitigation measures. For these two species, the Member States and the European Union authorities should give higher priority to the implementation of another pillar of the Habitats Directive, mitigating accidental catches in fishing gear and other human-induced mortalities. This should take into consideration the full effects of these mortalities on the populations of these two species through regular transboundary monitoring programs.
Interactions between fishing and dolphins can be detrimental, since on one hand dolphins can be lethally entangled by nets and trawls, and on the other dolphins can predate fish caught by nets. For ...dolphins, this interaction can be dangerous as they can be wounded or accidentally killed; for fishers, the predation of their catch results in economic losses due to reduced quantity and/or quality of catches and damage to fishing gear. During July and November 2020, we surveyed the “dolphin–fisheries conflict” through compiling 209 fisher interviews from nine locations in Italy and Croatia. Fishers mentioned the common bottlenose dolphin (Tursiops truncatus) as the species primarily interacting with fishing, with the major issue being catch damage by predation. The interaction probability varied among gears and seasons, with some fishing activities (e.g., passive nets) more affected than others (e.g., bottom trawls), especially in terms of economic loss (1000–10,000 €/year on average). More than 70% of the fishers claimed that dolphin populations have increased over the last 10 years, in different degrees and based on different areas. Dolphin bycatch rates are generally low; however, 34.6% of respondents reported having captured at least one dolphin during their career. The fishers’ attitude towards acoustic deterrents (“pingers”) as a mitigation measure revealed that few of them were aware of these devices or were using them.
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