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Anticipating and mitigating the impacts of climate change on biodiversity requires a comprehensive understanding on key habitats utilized by species. Yet, such information for high mobile marine megafauna species remains limited. Here, we compile a global database comprising published satellite tracking data (n = 1035 individuals) to spatially delineate foraging grounds for seven sea turtle species and assess their thermal stability. We identified 133 foraging areas distributed around the globe, of which only 2% of the total surface is enclosed within an existing protected area. One-third of the total coverage of foraging hotspots is situated in high seas, where conservation focus is often neglected. Our analyses revealed that more than two-thirds of these vital marine habitats will experience new sea surface temperature (SST) conditions by 2100, exposing sea turtles to potential thermal risks. Our findings underline the importance of global ocean conservation efforts, which can meet climate challenges even in remote environments. A global study reveals 133 sea turtle foraging hotspots, with only 2% under current protection. One-third is situated in high seas and two-thirds will face new sea surface temperatures by 2100, stressing the need for comprehensive ocean conservation. [ABSTRACT FROM AUTHOR]

Extreme regional ocean warming events, like marine heatwaves (MHWs), could have severe and long-lasting impacts on species and ecosystems. Extreme and persistent warming of the ocean could directly threaten survival of marine species, as exceeding their thermal tolerance often leads to massive mortality events. Similarly, MHWs could further threaten species persistence indirectly, by altering food webs, leading to cascading effects that are expected to be more pronounced for species at a lower trophic position. Green turtles, a representative species of the charismatic marine megafauna, are largely herbivorous; thus, their food availability is tightly linked to environmental conditions. Here, we explored the degree to which foraging areas of green turtles along the Southeast Asian region could be subjected to MHWs in the future. For this, we applied a series of climatic niche models to spatially delineate important foraging habitats for adult green turtles, Chelonia mydas, across the marine region of Southeast Asia. Our analysis revealed that marine sites, which could host foraging grounds for adult green turtles, cover around 37% of the Southeast Asian region, with high probability of experiencing prolonged and intense MHWs for the vast majority of these sites. The annual number of days subjected to MHWs could increase by 16-fold from the very recent past period, leading to even a permanent MHW state. These results offer some alarming messages for scientists and conservation planners, highlighting the need to improve our knowledge on the potential response of species to MHWs and design climate adaptation strategies. [ABSTRACT FROM AUTHOR]

Sea level rise could result in the loss and shrinkage of coastal habitats, jeopardizing the persistence of a number of species that rely upon these highly dynamic and sensitive areas. With reproduction and population recruitment depending exclusively on low-lying sandy beaches, marine turtles are among the organisms for which sea level rise represents a major threat. Here, we provide an assessment of the potential impacts of sea level rise upon sandy beaches located at the Ionian Archipelagos, which host some of the main nesting sites of the Mediterranean population of the loggerhead marine turtle Caretta caretta. Our analyses focused on sandy beaches which host stable or sporadic nesting as well as on sites that could potentially serve as nesting grounds for the species. We demonstrated that more than 60% of the stable nesting sites (accounting for about half of the total nesting activity in the region) are likely to fail to act as nesting sites under moderate and worst case scenarios of projected sea level rise by 2100. We found that only about one fifth of the stable and the sporadic nesting beaches were characterized by high resilience to SLR, meaning that the effective zone for nesting can migrate landwards and fit in the remaining upper beach part. Potential nesting sites were subjected to even lower resilience to sea level rise, suggesting that even if marine turtles could shift to new, nearby nesting sites, the efficiency of such a response would be limited. These alarming findings call for the prioritization of conservation and restoration efforts towards sandy shores of moderate and high resilience to sea level rise which are currently used for stable or even sporadic nesting. [ABSTRACT FROM AUTHOR]

There is an intense interest in long-term trends of species abundance that may reflect, for example, climate change or conservation actions. Less well studied are patterns in the magnitude of inter-annual variability in abundance across large spatial scales. We collated abundance time-series for 133 nesting sites across the globe of the seven sea turtle species. Inter-annual variability in nest numbers was lowest in loggerhead turtles (Caretta caretta), Kemp's ridley (Lepidochelys kempii) and flatback turtle (Natator depressus) and highest in green turtles (Chelonia mydas), likely reflecting their lower trophic position compared to other species and hence tighter coupling of food availability to environmental conditions each year. The annual number of nests in green turtles could vary by 60-fold between successive years. We identified regional patterns in the magnitude of inter-annual variability in green turtle nest numbers, variability being highest for nesting beaches around Australia and lowest in the western Indian Ocean and equatorial Atlantic. These regional patterns are likely linked to corresponding patterns of environmental variability with, for example, areas subjected environmental extremes as part of the El Nino Southern Oscillation (ENSO) showing high inter-annual variability in nest numbers. [ABSTRACT FROM AUTHOR]

Delineating priority areas for highly mobile marine megafauna represents a major challenge for conservation biology. To manage such areas, one must understand both their spatial properties (i.e., location, number, extent), and the level of exposure to a number of given pressures. Here, we used a combination of ensemble distribution models, field-based validation methods and a cumulative effect assessment to illustrate key foraging sites and risk hotspots for adult loggerhead sea turtles, Caretta caretta, in the Mediterranean Sea. We found that foraging sites covered about 10% of the neritic zone of the Mediterranean basin. We identified sites which are well recognized by scientists, but also other areas for which our knowledge on the potential importance is limited. The patterns of the habitat use generated by field data validated the accuracy of the distribution model. About one fifth of the foraging areas hosted in the Mediterranean could be considered as hotspots of risk, characterized by high or very high exposure to cumulative pressures. Our results suggest that management and conservation efforts should continue to be held at key, well-known foraging grounds of adult sea turtles (e.g., Northern Adriatic Sea, Tunisian Plateau) but there are several more potential sites (e.g., parts of the Aegean Sea and the Western Mediterranean) which deserve our attention in order to ensure viable populations. [ABSTRACT FROM AUTHOR]

Context: Landscape connectivity quantification is essential to achieve effective conservation of wildlife. Graph theory is a common mathematical framework for representing habitat patch networks and evaluating their connectivity. Objectives: While several graph-related indices have been used for this purpose, there is still need to evaluate landscape connectivity from different perspectives. Methods: Based on classic network indices, we developed five novel landscape connectivity indices that incorporated attributes related to the quality of the patches, the connections among them, the dispersal probabilities and the overall habitat availability. To evaluate their performance, we applied them on three ecological networks developed for three species with different traits, at different scales, and compared them with widely used landscape connectivity indices. Results: The developed indices identified, in all the three networks, critical patches that were well-connected with others, and also aggregated valuable features which could affect network quality. Some critical patches and specific network connectivity properties could be overlooked if not considering the additional dimensions of information that these advanced indices incorporate. Conclusions: We showed that the developed indices exhibited flexibility and wide applicability, offering novel insights on the evaluation of node contribution to the overall network connectivity. By integrating spatial patterns and processes, the solutions provided by the new indices could serve as an effective tool towards supporting landscape conservation planning. [ABSTRACT FROM AUTHOR]

The magnitude and frequency of extreme warming events over the last decades pose threats to biodiversity. In the near future, heatwaves will become even more frequent and longer-lasting. As ectothermic species, sea turtles are particularly vulnerable to climate change, with their reproductive success and offspring sex ratios dependent on in-nest conditions, particularly temperature. Here, we used field observations and climate model outputs (1) to examine impacts of extreme conditions on reproductive output and (2) to project thermal conditions within nest environments through the year 2100. Data were collected from 225 green turtle nests over 5 years (2009–2013) at Akyatan beach, Turkey, one of the most important nesting sites for this species in the Mediterranean. Our results suggest that green turtle eggs may demonstrate some resilience to rising temperatures if periods of temperature extremes are short. Declines in hatching success were observed only after conditions exceed the 33 °C thermal threshold for two-fifths of the incubation period. Under a moderate climate scenario (RCP 4.5), the number of days above lethal thresholds (i.e., 35 °C) would increase from 1% at the year that the study was conducted to 19.3% in 2100. Although sea turtles have survived through past climate changes, these projections raise concerns about future recruitment success and the persistence of sea turtle populations. Regular monitoring and determination of tipping points at local scales are required to inform conservation and management under global warming. [ABSTRACT FROM AUTHOR]

Context: National borders remain an impediment to efficient preservation of biodiversity and ecosystems. For transboundary water resources, conservation planning becomes more challenging, as competitive interests make these sensitive and productive systems focal points of interstate conflicts. Objectives: This global study aims to explore the patterns of protection coverage for transnational lakes and their catchments, highlighting gaps and inconsistencies at the protection observed among countries sharing the same lake. Methods: Identifying 793 transnational lakes globally, we initially investigated protection coverage at their water bodies. Next, we explored protection coverage patterns across each lake's catchment, in which we also quantified human pressures' extent and intensity. Socio-economic and political parameters were examined as potential predictors of the observed patterns. Results: Only half of the world's transnational lakes are fully or partly covered by existing protected areas. Our analysis demonstrated that in only 37% of the protected transnational lakes, the extent of protection coverage was similar in the neighboring counties sharing the same lake. Protection patterns were not driven by the relative area of the transnational lakes found in the neighboring countries. Moreover, protection cover focuses mainly on lakes' water surface ignoring the terrestrial surroundings, while more than 75% of the catchments are subjected to intense human pressures. Conclusions: Providing the first overview of the protection gaps of transnational lakes globally, we highlight a failure of policy responses to cross-border conservation of sensitive freshwater ecosystems. Consequently, such limitations are likely to loom risks for human well‐being and for the initiation of intense conflicts. [ABSTRACT FROM AUTHOR]

Climate change is postulated to alter the distribution and abundance of species which serve as vectors for pathogens and is thus expected to affect the transmission of infectious, vector-borne diseases such as malaria. The ability to project and therefore, to mitigate the risk of potential expansion of infectious diseases requires an understanding of how vectors respond to environmental change. Here, we used an extensive dataset on the distribution of the mosquito Anopheles sacharovi, a vector of malaria parasites in Greece, southeast Europe, to build a modeling framework that allowed us to project the potential species range within the next decades. In order to account for model uncertainty, we employed a multi-model approach, combining an ensemble of diverse correlative niche models and a mechanistic model to project the potential expansion of species distribution and to delineate hotspots of potential malaria risk areas. The performance of the models was evaluated using official records on autochthonous malaria incidents. Our projections demonstrated a gradual increase in the potential range of the vector distribution and thus, in the malaria receptive areas over time. Linking the model outputs with human population inhabiting the study region, we found that population at risk increases, relative to the baseline period. The methodological framework proposed and applied here, offers a solid basis for a climate change impact assessment on malaria risk, facilitating informed decision making at national and regional scales. [ABSTRACT FROM AUTHOR]

Context: Artificial light at night (ALAN) represents a significant threat to biodiversity. Given that protected areas (PAs) are in relative darkness compared to the surrounding sites, they could be considered an effective tool towards eliminating the impacts of ALAN. However, the extent to which climate change-induced shifts would drive species out of PAs and thus, alter their exposure to ALAN remains an open question. Objectives: We assessed the extent and protection coverage of dark areas across the current and future distributions of 39 raptor species of European conservation interest. Methods: We initially developed a set of distribution models using current and projected climatic variables. Next, we used a satellite dataset of nighttime lights composite to determine the spread of ALAN within the raptors' ranges. Finally, we applied three indices of proportional changes in the expansion of suitable habitats and dark areas to quantify patterns in ALAN within the current and future raptors' ranges across Europe. Results: Our analyses revealed that potential future distribution shifts of raptors will lead to changes in the exposure of species to ALAN, with these patterns being rather unfavourable for most of them. Still, PAs in Europe were found to offer a relative high proportion of dark areas which overlap with the current and future raptors range. Conclusions: Our findings provided some first insights into the spatial conflict between species ranges and ALAN, considering potential distribution shifts driven by climate change. The proposed methodology offers the means to identify potential dark refugia towards prioritizing conservation actions. [ABSTRACT FROM AUTHOR]

Context: Identifying animals movement through the landscape and delineating key corridors is critical for effective management and conservation. Still, assessments of space-use patterns and landscape connectivity are subjected to many limitations, especially in large scales. Objectives: The main objective of this study was to assess functional connectivity for four focal mammal species with varying dispersal abilities and diets, across protected areas in a transnational region where only scarce information on movement patterns exists. Methods: We used models relying on circuit theory, multiple layers of spatial information and graph-theoretical analysis. We delineated potential pathways suitable for species movement and evaluated connectivity status of the protected areas network in the Balkan Peninsula, southeastern Europe. Models were parameterized by combining information from experts and scientific literature, or by applying allometric equations, while novel connectivity metrics were developed. Results: We identified four key, suitable corridors within the transnational study region. The largest one crossed three countries, highlighting the need for international conservation efforts. For species with higher dispersal abilities, the network of protected areas appeared to be well connected and robust while for others it consisted of numerous isolated sites, raising the need for species-specific management plans. Conclusions: Our study serves as an example of how to set monitoring and conservation priorities in data-poor regions. Our findings highlight the need to identify a number of ecological corridors that could facilitate movement of multiple species with different functional traits and habitat preferences. This information is proved to be critical for setting spatially explicit conservation plans at local, regional and transnational scales. [ABSTRACT FROM AUTHOR]

Phenological shifts are widely reported for different species as a response to climate change. Still, the efficiency of this mechanism is questioned because of the accelerated rate of change and the different change patterns of various climate parameters that may cause mismatches. Here, using loggerhead sea turtles (Caretta caretta) as model species, we examined whether phenological shifts could be an effective adaptive strategy over the critical period that determines reproductive output in the Mediterranean region. We compared the rate of temperature and precipitation change over the recent past (1971-2015) and future periods (2016-2060) along the 45 main nesting sites of the Mediterranean population, during the incubation period. Next, utilizing predictions of an earlier nesting season, we evaluated whether the timing of incubation will impact offspring survival on the Mediterranean population. To further assess species vulnerability, we investigated any potential relationship between hatching success and climate parameters at the largest Mediterranean nesting rookery (Zakynthos, Greece). We found that phenological changes would allow species to capture a thermal window similar to one they experience nowadays during the incubation period. Still, phenological shifts might be less adequate to follow precipitation changes, which however, were found to have a limited impact upon hatching success. Global adaptation management strategies should be directed towards (a) acquisition of long-term high-resolution temperature and precipitation series at nesting sites, (b) developing early warning systems to prevent negative impacts upon reproductive outputs, and (c) directly applying cooling of the nests when first altered climate signs are detected. [ABSTRACT FROM AUTHOR]

The conservation of biological diversity represents a major challenge for modern societies. Research offers the fundamental information to advance and integrate our knowledge on ecological systems, their processes and interactions. Yet, the transfer of scientific knowledge and results represents a critical step towards enhancing conservation efficiency. Here, we use sea turtle research, as an example to test the potential and dynamics of international scientific cooperation reflecting the advancement of knowledge. The selection of sea turtles as a case study was mainly based on two factors. First, they represent a highly mobile group of species with cosmopolitan distribution that cross geopolitical borders, policies and agreements. Second, encouraging evidence on global population recovery are increasingly presented. We used research publications on sea turtles (from 1967 since 2016) as the main product of scientific knowledge, to develop a series of co-authorship networks. Countries that were mentioned in authors’ affiliations were used as nodes, with two nodes being connected if authors of these countries had collaborated as co-authors in a publication. The properties of the co-authorship networks revealed that sea turtle scientific collaboration networks are ] getting larger and spreading constantly over different countries through time. Network metrics revealed a robust and coherent network supported by numerous countries. Our results showed a steady flow of scientific information among countries within sea turtle research communities, a factor that might have contributed to the encouraging evidence on sea turtle population trends observed globally. This analysis highlights the potential benefits generated by international collaborations reflecting the integration of skills, scientific backgrounds and knowledge. [ABSTRACT FROM AUTHOR]

AC was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the "First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant" (Project Number: 2340). ADM acknowledges the European Union's Horizon 2020 research and innovation programme under grant agreements No 869300 (FutureMARES)." Correction to: Biodiversity and Conservation https://doi.org/10.1007/s10531-021-02326-0 In the original publication of the article, the last sentence of the funding statement was inadvertently missed to be included. [Extracted from the article]

We investigated the potential associations of habitat type richness patterns with a series of environmental variables in 61 protected aquatic ecosystems of the Greek Natura 2000 network. Habitat type classification followed the Natura 2000 classification scheme. Habitat type richness was measured as the number of different habitat types in an area. To overcome a potential area effect in quantifying habitat type richness, we applied the 'moving window' technique. The environmental variables were selected to account for some of the major threats to biodiversity, such as fragmentation, habitat loss and climate change. We run GLMs to associate habitat type richness with different combinations of climatic, spatial and topographic variables. Habitat type richness seemed to significantly associate with climatic variables, more than spatial or topographic ones. In particular, for the climatic ones, the importance of precipitation surpassed that of temperature and especially the precipitation of the wettest and driest month had a limiting contribution to richness unlike average climate estimators. Moreover, the landscape's latitude and longitude and fragmentation were significantly associated to richness. Our findings are in accordance to those observed in recent literature at lower (i.e. species) levels of ecological organization, fact showing that large-scale phenomena (such as climate change) can also be observed at the habitat type level, at least in our case. Thus, following the context of the Habitats Directive (92/43/EEC), that habitat types and not solely species of community interest should be protected and restored, this study serves as a first step towards investigating habitat type richness patterns. [ABSTRACT FROM AUTHOR]

So far landscape analysis meant analysis of the spatial pattern of land cover or land use. However, biological organisms do not perceive the landscape only as land cover or land use, but they use all their senses, in order to become familiar with and react to their surroundings. We analyzed the acoustic environment as an additional layer of spatial information in landscape analysis, shortening the monopoly of visual patterns as landscape descriptors. We recorded sounds from a rural protected area into seven categories based on their origin, and examined their spatiotemporal variability and their correlation with landscape characteristics. The sounds were distinguished as Foreground or Background sounds. Foreground sounds correspond to sharp sounds originating near the observer and usually are understood as signals of urgent information, triggering reactions; while background sounds carry information over longer distances and may be used as landmarks to help individuals find their bearing even in the absence of visual signs. We found that the acoustic environment varies both temporally and spatially reflecting anthropogenic, geophysical and biological activities. The spatial pattern of the background sounds correlates, to an extent, with the visually perceived landscape features, but it does not correlate with the spatial pattern of the foreground sounds, which do not correlate strongly with the landscape pattern. This spatial pattern mismatch between acoustic environment and landscape, along with the highly dynamic nature of the acoustic environment compared to the relatively static nature of the land cover and land use spatial pattern highlight a limitation of the classical landscape analysis, and expands our understanding of the cognitive landscape. [ABSTRACT FROM AUTHOR]

Understanding how overall patterns of spatial variation in species richness are affected by distributional patterns of species has been an area of growing concern. In the present study, we investigated the relative importance of common and rare species as contributors in overall plant species richness. We further examined if the effects of common or rare species in richness patterns are affected by the size of the sampling units and if the observed patterns hold at different habitats. We used a dataset of 5,148 higher plant species distributed across 16,114 sampling plots located in 240 sites of the NATURA 2000 network of Greece. We ranked all species based on the number of sites they occupied and we developed a common to rare and a rare to common sequence. We correlated those sequences with cumulative species distributions. We performed this analysis in nine different sizes of sampling units and in three different datasets referring to (a) all habitat types together, (b) coniferous habitats only and (c) alpine habitats only. Our analysis showed that despite the proportionally higher numbers of restricted species, widespread species make a greater contribution to overall richness patterns and that this observed pattern does not depend on the size of the sampling units. Moreover, the observed pattern stands for different habitat types. Our findings support the generality of this pattern and highlight the importance of widespread species as adequate indicators of biodiversity patterns at various habitat types. [ABSTRACT FROM AUTHOR]