Catharina Vendl

Per‐ and polyfluoroalkyl substances (PFAS) are a large group of synthetic chemicals that have been in use for over 70 years. Their ubiquitous distribution and harmful effects pose a threat to wildlife worldwide. To provide a comprehensive synopsis and show the gaps and gluts of existing research on PFAS exposure in wildlife, we created a systematic map and bibliographic analysis of the literature. We followed our protocol to conduct a systematic literature search on Scopus, Web of Science and five other databases. In two steps (title/abstract/keywords and full‐text), we screened peer‐reviewed empirical articles, preprints and theses in English that studied the concentration of at least one of 34 PFAS compounds in free‐ranging wildlife or their parts/products. Following the protocol, we extracted data and performed a critical appraisal. We included 581 publications. From the first and only paper in 2001, there was a linear annual increase to 54 papers in 2021. While PFOS (97% of studies), PFOA (91%) and long‐chain PFAS in general were the most measured, few studies investigated new‐generation PFAS (e.g. GenX and ADONA). Across the studied 1042 species from 26 taxonomic classes, the most frequent were the common carp (Cyprinus carpio, 8%), polar bear (Ursus maritimus, 6%) and European perch (Perca fluviatilis, 5%). Most sampling took place in the United States (17%), Norway (13%), Canada (12%) and China (10%), which were also the main publishing countries. Polar regions attracted significant research interest from countries all around the globe. Aquatic habitats (marine: 31%, freshwater: 28%) of temperate zones were the most common locations for sample collection. We encourage researchers to work towards closing the following gaps: investigating new‐generation PFAS, assessing PFAS in mid‐ and low‐income countries and performing more long‐term studies, especially on invertebrates. We note the recent rise in studies on the physiological consequences of PFAS exposure and encourage further work on this crucial topic. Furthermore, we recommend that the statement of potential and actual conflicts of interest, and the provision of raw data and analysis code should be made compulsory by all journals and routinely enforced. This practice will mitigate conflict of interest and ensure reproducibility.

Per‐ and polyfluoroalkyl substances (PFAS) are a large group of manufactured chemicals. Since the beginning of their commercial production in the 1950s, PFAS have not only found their way into numerous industrial and commercial applications, but also into the bloodstream of much of the human population, the natural environment and wildlife. Exposure to high levels of PFAS poses a health risk for humans and animals, and may exacerbate the effects of other anthropogenic impacts faced by wildlife species. To gain a comprehensive overview of the abundance and distribution of PFAS research on wildlife species, and to better understand the drivers of this research, we will collate the available literature into a systematic evidence map and perform bibliometric analyses. The systematic mapping will present the distribution of research evidence that exists on PFAS in wildlife. The bibliometric analysis will provide an insight into the historical trends, interdisciplinarity, connectedness and the impact of the individual papers. We will conduct a systematic literature search on Scopus, Web of Science and 10 other databases using predefined search strings. We will screen title, abstract and keywords first. We will then screen full‐text papers. Two reviewers will be involved in the screening process. We will only consider publications in English, peer‐reviewed articles, preprints and theses. We will include papers reporting concentrations of any of 34 main PFAS types (based on a previous study) in wild animals. We will assess all publications included in the systematic map for predetermined indicators of quality and potential study‐level biases. In addition, we will use bibliometric records from Scopus to perform impact and network analyses. We will present the results using a narrative summary, tables and colour‐coded maps, bar and network plots. Results and associated database will be available on a dedicated freely accessible website. This study will provide critical insight into the gaps and clusters of the literature with regard to the PFAS concentrations in wildlife. Our study will inform and direct future research efforts to fill the gaps revealed.

Background: Per- and polyfluoroalkyl substances (PFAS) are a large group of manufactured chemicals. Since the beginning of their commercial manufacturing in the 1950s, PFAS haven’t only found their way into numerous industrial and commercial applications, but also into the bloodstream of the majority of the human population, the natural environment and its wildlife. Exposure to high levels of PFAS can create health risks for humans and animals which may exacerbate the effects of other anthropogenic impacts faced by wildlife species. To gain a comprehensive overview of the abundance and distribution of PFAS in wildlife species, and to better understand the risk of PFAS exposure on threatened species and PFAS transfer into human food chains, we will collate the available literature into a systematic evidence map and bibliometric analysis.Methods: We will conduct a comprehensive systematic literature search on Scopus, Web of Science and the ‘grey literature’. For screening purposes, we will use decision trees, scanning title, abstract and keywords first. The next step includes full-text screening performed by two reviewers. We will only consider publications in English, peer-reviewed articles, pre-prints and theses. We will limit our search to 31 PFAS types (based on a previous study). A pilot search on Scopus resulted in ~250 potentially relevant publications. We will scan all publications included in the systematic map for predetermined indicators of quality and potential study-level biases. In addition, we will extract bibliometric records from Scopus and perform network analysis. We will present the results using a narrative summary, tables (database), bar plots and colour-coded maps. Results will be available on a dedicated freely accessible website. Discussion: This study will provide critical insight into the gaps and clusters of the literature with regards to the PFAS concentration in wildlife. Therefore, our study will inform and direct future research efforts to fill the gaps revealed.Systematic review registration: osf.io osf.io/gnt2y

Background: The analysis of blow microbiota has been proposed as a biomarker for respiratory health analysis in cetaceans. Yet, we lack crucial knowledge on the long-term stability of the blow microbiota and its potential changes during disease. Research in humans and mice have provided evidence that respiratory disease is accompanied by a shift in microbial communities of the airways. We investigate here the stability of the community composition of the blow microbiota for 13 captive bottlenose dolphins over eight months including both sick and healthy individuals. We used barcoded tag sequencing of the bacterial 16S rRNA gene. Four of the dolphins experienced distinct medical conditions and received systemic antimicrobial treatment during the study.Results: We showed that each dolphin harboured a unique community of zero-radius operational taxonomic units (zOTUs) that was present throughout the entire sampling period (‘intra-core’). Although for most dolphins there was significant variation over time, overall the intra-core accounted for an average of 73% of relative abundance of the blow microbiota. In addition, the dolphins shared between 8 and 66 zOTUs on any of the sampling occasions (‘inter-core’), accounting for a relative abundance between 17 and 41% of any dolphin’s airway microbiota. The majority of the intra-core and all of the inter-core zOTUs in this study are commonly found in captive and free-ranging dolphins and have previously been reported from several different body sites. While we did not find a clear effect of microbial treatment on blow microbiota, age and sex of the dolphins did have such an effect.Conclusions: The airways of dolphins were colonized by an individual intra-core ‘signature’ that varied in abundance relative to more temporary bacteria. We speculate that the intra-core bacteria interact with the immune response of the respiratory tract and support its function. This study provides the first evidence of individual-specific airway microbiota in cetaceans that is stable over eight months.

Humpback whales endure several months of fasting while undertaking one of the longest annual migrations of any mammal, which depletes the whales’ energy stores and likely compromises their physiological state. Airway microbiota are linked to respiratory health in mammals. To illuminate the dynamics of airway microbiota in a physiologically challenged mammal, we investigated the bacterial communities in the blow of East Australian humpback whales at two stages of their migration: at the beginning (n = 20) and several months into their migration (n = 20), using barcoded tag sequencing of the bacterial 16S rRNA gene. We show that early in the fasting the whale blow samples had a higher diversity and richness combined with a larger number of core taxa and a different bacterial composition than later in the fasting. This study provides some evidence that the rich blow microbiota at the beginning of their fasting might reflect the whales’ uncompromised physiology and that changes in the microbiota occur during the whales’ migration.

Background: The analysis of blow microbiota has been proposed as a biomarker for respiratory health analysis in cetaceans. Yet, we lack crucial knowledge on the long-term stability of the blow microbiota and its potential changes during disease. Research in humans and mice have provided evidence that respiratory disease is accompanied by a shift in microbial communities of the airways. We investigate here the stability of the community composition of the blow microbiota for 13 captive bottlenose dolphins over eight months including both sick and healthy individuals. We used barcoded tag sequencing of the bacterial 16S rRNA gene. Four of the dolphins experienced distinct medical conditions and received systemic antimicrobial treatment during the study. Results: We show that each dolphin harboured a unique community of zero-radius operational taxonomic units (zOTUs) that was present throughout the entire sampling period (‘intra-core’). Although for most dolphins there was significant variation over time, overall the intra-core accounted for an average of 65% of relative abundance of the blow microbiota. In addition, the dolphins shared between 4 and 52 zOTUs on any of the sampling occasions (‘inter-core’), accounting for a relative abundance between 7 and 33% of any dolphin’s airway microbiota. The majority of the intra-core and all of the inter-core zOTUs in this study are commonly found in captive and free-ranging dolphins and have previously been reported from several different body sites. The blow microbiota of sick dolphins differed significantly from that of healthy dolphins, although we did not find evidence for a common impact of antimicrobial treatment. Conclusions: The airways of dolphins were colonized by an individual intra-core ‘signature’ that varied in abundance relative to more temporary bacteria. We speculate that the intra-core bacteria interact with the immune response of the respiratory tract and support its function. This study provides the first evidence of individual-specific airway microbiota in cetaceans that is stable over eight months.

Summary: The number of social contacts of mammals is positively correlated with the diversity of their gut microbes. There is some evidence that sociality also affects microbes in the respiratory tract. We tested whether the airway microbiota of cetacean species differ depending on the whales' level of sociality. We sampled the blow of blue ( Balaenoptera musculus ), grey ( Eschrichtius robustus ), humpback ( Megaptera novaeangliae ) and long‐finned pilot whales (PWs) ( Globicephala melas ) and analysed the blow microbiota by barcode tag sequencing targeting the V4 region of the bacterial 16S rRNA gene. Humpback whales (HWs) show higher levels of sociality than blue (BW) and grey (GW), while PWs are the most gregarious among the four species. The blow samples of the HWs showed the highest richness and diversity. HWs were also the only species with a species‐specific clustering of their microbial community composition and a relatively large number of core taxa. Therefore, we conclude that it cannot be sociality alone shaping the diversity and composition of airway microbiota. We suggest the whale species' lung volume and size of the plume of exhaled air as an additional factor impacting the transmission potential of blow microbiota from one individual whale to another.