Caterina Lanfredi

The comparability of methods applied to environmental DNA (eDNA) samples across laboratories remains a significant challenge for biodiversity monitoring on a global scale. Performance differences between protocols can jeopardize effective conservation strategies across regions and focal species. To address potential discrepancies amongst four international partners within a collaborative eDNA initiative, an inter-laboratory comparison (i.e., ring test) was conducted to compare efficiencies of established DNA extraction methodologies based on 39 eDNA samples. Each laboratory contributed eight to eleven samples collected throughout the North-East Atlantic and the Mediterranean Sea near sperm whales, porbeagle sharks, basking sharks, bottlenose dolphins and common dolphins. After lysis, aliquots were exchanged between laboratories before subsequent DNA extraction using each facility’s preferred method. Extracts were returned to the lysates’ respective laboratories of origin for measurements of total DNA concentration, as well as quantitative PCR using three novel species-specific assays for marine megafauna. Our findings revealed similar concentrations of total DNA, yet a significant reduction in extraction performance for targeted qPCR reactions by one laboratory, who has therefore modified their extraction method to be used for the remainder of this project. Overall, detection success differed based on the target taxa with sharks being less often detected (and at lower concentrations) than marine mammals. Significant interaction effects were found between combinations of laboratories and species, suggesting a link between extraction protocols and variable environmental conditions. Our study serves as a foundational step towards establishing reproducible practices that are crucial for the success of multinational eDNA projects to enable comparable results.

The comparability of methods applied to environmental DNA (eDNA) samples across laboratories remains a significant challenge for international biodiversity monitoring projects. Inconsistently performing practices can jeopardize the reliability of data that is essential for effective conservation strategies across geographic regions and focal species. To address potential discrepancies among four international partner laboratories who are part of a collaborative eDNA initiative, a ring test was conducted to compare extraction efficiencies based on 39 eDNA samples. Each laboratory contributed eight to eleven eDNA samples collected from five locations throughout the North-East Atlantic and Mediterranean Sea near marine megafauna (whales, dolphins, and sharks). After lysis, aliquots were exchanged between laboratories then independently extracted using each facility’s preferred method. Extracts were then returned to their respective laboratories of origin for measurements of total DNA concentration as well as quantitative PCRs using species-specific assays designed for each associated target species. Our findings revealed similar concentrations of total DNA, yet a significant deviation in extraction performance for targeted qPCR reactions by one laboratory. Overall, detection success differed based on the target taxa with sharks being less often detected (and at lower concentrations) than whales and dolphins. Significant interaction effects were found between combinations of laboratories and species, suggesting that particular extraction protocols may be most efficient for specific environmental conditions. Our study serves as a foundational step towards establishing rigorous, reproducible eDNA practices that are crucial for the success of multinational environmental monitoring projects to enable the direct comparison of results.

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.

Sperm whale trumpets are sounds only occasionally documented, with a well recognisable and stereotyped acoustic arrangement. This study investigated the acoustic features of the trumpets and the context in which these sounds were recorded, using acoustic data collected over 22 years, in the Pelagos Sanctuary area (North-Western Mediterranean Sea). Analysed trumpets (n = 230), recorded at the beginning of a dive after the whale fluke-up, comprised a series of acoustic units organized in short sequences. Acoustic parameters were derived for the entire trumpet and for each distinguishable unit in a trumpet. Overall, trumpet durations and their initial frequencies were higher in recordings collected when multiple whales were visually or acoustically detected in the observation area. The identity of 68 whales was assessed through photo-identification, with 29 individuals producing trumpets within and between years. The variability of the acoustic parameters appeared to be higher within the same individuals rather than between different individuals, suggesting an individual plasticity in composing and arranging units in a trumpet. Different click patterns were observed before and after the trumpets, with more complex sequences when (1) other whales were visually/acoustically detected, and (2) individuals were in suitable foraging sites (i.e., canyon areas). Trumpets were commonly followed or preceded by click patterns suited for communication, such as codas and/or slow clicks. Significant relations between the trumpet emission and the male-only long-range communication click pattern (i.e. slow clicks) emerged, supporting the hypothesis that a trumpet is a sound emitted by maturing/mature males in feeding grounds. This study provides the first evidence that trumpets were conserved in the sperm whale acoustic repertoire at the decadal timescale, persisting across years and individuals in the same area. This persistence may be functionally specific to foraging activities performed by males in a well-established feeding area.

Whale sharks are known to aggregate in coastal areas. In the South Ari Marine Protected Area (Maldives) a aggregation, mostly represented by young males with a high level of residency, has been described in the literature. Despite the worldwide interest in the natural resources of the Maldives, this population is increasingly subjected to anthropogenic pressure and major concern regards the flourishing tourist industry. In this study, data collected by the Maldives Whale Shark Research Programme between 2014 and 2017 have been used to detect both temporal and spatial patterns of occurrence. Favourable environmental conditions to visually detect whale sharks have been defined for the studied area. Accordingly, a total of 1077 shark encounters have been analysed in this study. Environmental conditions (i.e. sea surface temperature, monsoon occurrence) have been used to detect possible factors affecting the spatial and temporal variability of Rhincodon typus aggregations. A two-way ANOVA has been performed to detect temporal trends in animal occurrence, sea surface temperature pattern and to investigate the sea bottom depth variability during encounters. Significant differences in the monthly occurrence of whale sharks within the same year and among different years have been detected. Similar patterns have been observed for environmental parameters such as sea surface temperature and depth. A different spatial distribution has also been detected as a function of the Indian Monsoon reversal (north-eastern and south-western) affecting the area. During the northeast monsoon period, whale sharks appeared to concentrate in a smaller longitudinal range closer to the western-central part of the MPA, where deeper water conditions occur due to the proximity of a deep depression (submarine canyon). Results from this study provide new pieces of information for the implementation of dedicated management actions to protect the whale sharks population inhabiting the South Ari Marine Protected Area.

With the approaching end of the productive lives of offshore oil and gas platforms, the issue about decommissioning and what to do with existing structures arises. In this regard, this study aims to test solutions, at a preliminary level, for the eco-sustainable reuse of platforms at the end of their extraction phase. In particular, mineral accretion technology is applied by low-voltage electrolysis of seawater due to the precipitation of calcium carbonate on a cathode material in order to assess the protection capacity of the platforms against corrosion. This approach allows the extension of a platform’s “life” under a more sustainable purpose. The results, derived from laboratory and field experiments, will allow us to reduce uncertainties and define the best operating conditions to increase the efficiency of the mineral accretion technology in the marine ecosystem. The data collection on the main parameters that influence the process (i.e., temperature, salinity, and applied current) and the quantitative analysis of the collected material allowed us to acquire a better knowledge about mineral composition and deposition rate.

Marine mammals are under growing pressure as anthropogenic use of the ocean increases. Ship strikes of large whales and loud underwater sound sources including air guns for marine geophysical prospecting and naval midfrequency sonar are criticized for their possible negative effects on marine mammals. Competent authorities regularly require the implementation of mitigation measures, including vessel speed reductions or shutdown of acoustic sources if marine mammals are sighted in sensitive areas or in predefined exclusion zones around a vessel. To ensure successful mitigation, reliable at-sea detection of animals is crucial. To date, ship-based marine mammal observers are the most commonly implemented detection method; however, thermal (IR) imaging–based automatic detection systems have been used in recent years. This study evaluates thermal imaging–based automatic whale detection technology for its use across different oceans. The performance of this technology is characterized with respect to environmental conditions, and an automatic detection algorithm for whale blows is presented. The technology can detect whales in polar, temperate, and subtropical ocean regimes over distances of up to several kilometers and outperforms marine mammal observers in the number of whales detected. These results show that thermal imaging technology can be used to assist in providing protection for marine mammals against ship strike and acoustic impact across the world’s oceans.

The opportunity to co-locate wind and wave energy exploitation is analyzed in the Italian seas grounding on the rationale that benefits are greater when un-correlated resources are combined. The study shows that, although waves and winds are generally strongly correlated, in some conditions their correlation is lower and the combined energy harvesting more interesting. As spatial conflicts of sea use and demand for maritime space are increasing, the development of the marine renewable energy sector needs to be evaluated in the perspective of the cumulative pressures deriving from present activities or expected from future developments. The evaluation of areas of potential conflicts among human activities, environmental vulnerabilities and marine renewable developments may facilitate the early development of mitigation actions and negotiations between stakeholders. In this study the opportunity of co-locating offshore wind turbines and wave energy converters is analyzed through a spatial planning approach. Both the potential for combining different renewable technologies, and the impact associated to such development was considered in the context of the existing pressures (e.g., naval traffic; mariculture activities; submarine cables routes; dredge spoils dumping; offshore activities; windfarms and ocean energy projects) and vulnerabilities (Marine Protected Areas, Key habitat presence) through quantitative indicators. The portion of Tyrrhenian coast south of Elba island, the northern-western Sardinian coast, and the southern Adriatic and Ionian coastal waters appear to be the most suitable sites. Moreover, the study presents a spatial quantitative methodology to identify sites of potential interest for the development of the marine renewable energy sector in the perspective of cost-effectiveness and environmental impact minimization.