In the winter of 2022–2023, hundreds of the Atlantic puffins (Fratercula arctica) appeared dead in the coast of the Canary Islands, a rare event considering their cold-living habits, normally occupying the North Atlantic Ocean. In this work, investigation about the parasites present in the Atlantic puffins found in the biggest islands of the Archipelago was carried out from a population portion. Necropsies of 39 birds were made and, during the examination of the urinary tracts, helminths were found. Morphoanatomical analysis under microscope allowed to identify them into Renicola genus with high similarity to Renicola sloanei. After that, DNA was extracted and NADH dehydrogenase subunit 1 gene were amplificated by a polymerase chain reaction method followed by sequencing and phylogenetic analysis. The molecular results demonstrated that in fact R. sloanei was the helminth parasite present in the urinary tracts of the Atlantic puffins found in the Canary Islands.

Archaeologists in the Canary Islands have gathered substantial quantitative data from radiocarbon measurements and aDNA analyses. While undeniably helpful and necessary for apprehending past human activity, their interpretation, based on theories underpinning models developed for island chains, has lagged, leaving a gap in our understanding of processes of occupation and social network systems. The decontextualized nature of the archaeological landscape of the Canaries and a lack of consensus about proper radiocarbon methodologies are some of the factors contributing to heated scholarly debate. Here, for the Canary Islands, the author reviews the current literature on aDNA and discusses settlement theories, the chronological evidence used for occupation models, and how such perspectives align with current thinking on island colonization.

How is the white researcher perceived by the border apparatus? What does this interaction say about the border itself? Ethnographic research has framed such questions as a debate on ‘insiders’ and ‘outsiders’ in fieldwork. This is problematic, as it assumes that a researcher can really be ‘external’ to the social worlds they investigate, as if the field site existed in isolation from transnational processes of racialised extraction. This paper challenges such an assumption by arguing that the white researcher cannot be an ‘outsider’ to the North African border: they approach it as the beneficiaries of a system of colonial and capital extractivism that feeds itself through migration control. I build on Ahmed's work on white phenomenology to analyse how various border workers perceived, made sense of and reacted to my presence as a white European woman at three different sites on the Spanish–Moroccan border. I argue that the white researcher is an expected presence at the border, as the accumulated history of (post)colonial encounters leads them where others have been before. Although whiteness opens doors, only a certain kind of performed whiteness remains welcome in the borderscape. The white researcher who appears not to be aligning with or supporting the premises of migration control is perceived by border workers as a potentially disruptive presence, and contained in different ways.

Invasive species pose a threat not only to biodiversity because they displace or compete with native fauna, but also because of the pathogens they can host. The Canary Islands are an Atlantic biodiversity hotspot threatened by increasing numbers of invasive species, including the California kingsnake Lampropeltis californiae, which was recently introduced to Gran Canaria. Seventy-seven snakes were examined for gastrointestinal parasites in 2019–2020. Sporocysts of Sarcocystis sp. were detected in 10 of them; detection of gamogonia stages in histological sections of 3 snakes confirmed the snake as a definitive host. Partial ssrDNA was amplified using SarcoFext/SarcoRext primers; an additional sequence of Sarcocystis was obtained from the tail muscle of the endemic Gran Canaria giant lizard Gallotia stehlini for a comparison. Identical ssrDNA sequences of unknown Sarcocystis sp. were obtained from 5 different snakes. Phylogenetic analysis showed that Sarcocystis sp. isolated from invasive California kingsnakes is unrelated to Sarcocystis provisionally considered S. stehlini from the endemic lizard. The dixenous coccidia are rarely reported to invade new predator–prey systems. However, the present data suggest that previously unknown Sarcocystis sp. is circulating among invasive snakes and as yet unknown vertebrate intermediate hosts, with undetermined consequences for the Gran Canaria ecosystem.

Bats are one of the most abundant and important mammals in ecosystems. However, their fossil record is scarce and fragile, making them difficult to find. Accordingly, there is no record of this group in the volcanic islands of the mid-Atlantic Ocean apart from the Canary Islands. This paper studies the first bat fossil record of the Canary Islands (Spain). The material studied is found within two Quaternary lava tubes, Cueva de los Verdes on Lanzarote and Cueva Roja on the island of El Hierro. The dental and humeral morphology and biometry are analysed and compared with current specimens. Among our results we highlight the first fossil data of two species endemic to the islands of the mid-Atlantic Ocean, Plecotus teneriffae and Pipistrellus maderensis, the former from the Canary Islands and the latter from the Azores, Madeira and the Canary Islands. We also confirm the presence of Pipistrellus kuhlii in the fossil record of the island of Lanzarote. No differences are observed between the dental morphology of the current and the fossil populations of P. maderensis and Pl. teneriffae. In the case of P. kuhlii, the populations of the Canary Islands and the Iberian Peninsula show differences in the paraconule with respect to the populations from central Europe. Palaeoecological studies of these taxa suggest that these islands presented a similar habitat when the sites were formed to the present-day habitat.

The appearances of palaeosurfaces intercalated into palaeo-dune fields on Fuerteventura are multifaceted. Although reddened layers in these dune sediments might suggest that strong soil-formation processes have taken place, the combination of aridity and parent material, namely biogenic carbonate sand of shelf origin, reveals that strong soil formation seems unlikely. These sediments rather represent de- and recalcification processes only. Solely in the case of admixed material of volcanic origin and dust deposits further soil-forming processes seem to be possible. Hematite-rich Saharan dust contributes to reddish colouration of the palaeosurfaces. In addition, CaCO3-coated iron particles appear to be ingredients of dust being leached after deposition and transformed to hematite. Overall, we propose much weaker soil-forming processes during the Pleistocene than previously postulated. Our findings support the relevance of local environments. Carbonate sands of shelf origin hinder strong soil formation and the reddish layers separating dune generations are palaeosurfaces, which mainly consist of Saharan dust. After deposition of allochthonous material, these layers are overprinted by weak soil-forming processes. The formation of palaeosurfaces primarily depends on morphodynamically stable periods during limited sand supply. Our data suggest a cyclicity of processes in the following order: (1) sand accumulation, (2) dust accumulation and weak soil formation, and (3) water-induced erosion. For the Canary Islands, we support the assumption of glacial maxima being periods of increased levels of moisture. In combination with rising sea level, we propose that favorable conditions of surface stability occur immediately after glacial maxima during periods of starting transgression, whereas regression periods immediately after sea-level high stands seem to yield the highest sand supply for the study area.

The island of Gran Canaria is regularly affected by dust falls due to its proximity to the Saharan desert. Climatic oscillations may affect the Saharan dust input to the island. Geochemical, mineralogical, and textural analysis was performed on a well-developed and representative early Pleistocene paleosol to examine Saharan dust contribution to Gran Canaria. Significant and variable Saharan dust content was identified in addition to weathering products such as iron oxides and clay minerals. Variations in quartz and iron oxide concentrations in the paleosol likely reflect different Saharan dust input in more/less-contrasted rhexistasic/biostatic climatic conditions. Linking the quartz content in Canarian soils, the Ingenio paleosol, and two Canarian loess-like deposits to different ages from the Quaternary, we hypothesized that the dust input should be lower (about 33–38%) throughout the early to middle Pleistocene than during the late Quaternary. The Saharan dust input to the Gran Canaria profile in the Pleistocene persisted in spite of climatic variations.

Three voluminous Quaternary phonolitic pumice fall deposits erupted from the compositionally-zoned Tenerife magma chamber exhibit variability in Sr and Pb isotope ratios. It has been previously argued that the Sr isotope variations are due to syn-eruptive interaction between magma and hydrothermal fluids (Palacz and Wolff, 1989). Pb compositions are not correlated with Sr, and are believed to reflect magmatic values. Pb isotope ratios exhibit regular variation with degree of fractionation, and one zoned deposit is heterogeneous in Pb. The highest values seem to characterize the most fractionated upper parts of the zoned system. This is unlikely to be a consequence of magmatic recharge. Isotopic and trace element behaviour is instead consistent with combined assimilation and fractional crystalliza- tion, involving the recycling of material containing relatively radiogenic Pb, from within the volcanic edifice. Assimilation of sediment intercalated within the submarine portion of the pile is ruled out by the isotopic data. The most probable contaminant is a felsic igneous rock. Early trachytes reported by Sun (1980) have the required Pb isotope compositions and may approximately represent the assimilant.

Despite efforts to combat invasive species, further measures are still required to prevent their arrival and translocation, especially into biodiverse island ecosystems. Although many governments worldwide have already established protocols to control alien species, the European outermost regions have yet to implement fully effective prevention or rapid response procedures. The numerous translocations of the invasive Barbary ground squirrel Atlantoxerus getulus within the Canary Islands illustrate this problem. From 1996 to 2016 at least 2.1 individuals per year have been moved from Fuerteventura to other islands. If movements of these medium-sized vertebrates are taking place regularly, the number of smaller species transported within the archipelago could potentially be greater. We argue that it is essential to implement stricter strategies for invasive species control in these remote biodiversity-rich islands, including early detection and rapid response, to minimize impacts on native biodiversity.

Intrathalline phycobiont diversity was investigated in a rosette-forming lichen, Parmotrema pseudotinctorum, using a combination of Sanger sequencing, 454-pyrosequencing, conventional light and confocal microscopy, and transmission electron microscopy. A total of 39 thalli sampled in five Canary Island populations were investigated. Three novel lineages of lichen phycobionts were detected, all being inferred within the Trebouxia clade G. The most abundant phycobiont lineage, occurring in all lichen populations investigated, is described here as Trebouxia crespoana sp. nov. This species produces spherical to pyriform cells possessing a crenulate chloroplast with lobes elongated at their ends, and one corticola-type pyrenoid with very thin, unbranched tubules of curved profile. Trebouxia crespoana is clearly distinguished from all other Trebouxia species by a characteristic cap-like cell wall thickening produced on one side of vegetative cells, and the larger size of vegetative cells that reach 21(–26) µm in diameter.

The isotopic composition of land snail shells was analyzed to investigate environmental changes in the eastern Canary Islands (28–29°N) over the last ~ 50 ka. Shell δ13C values range from −8.9‰ to 3.8‰. At various times during the glacial interval (~ 15 to ~ 50 ka), moving average shell δ13C values were 3‰ higher than today, suggesting a larger proportion of C4 plants at those periods. Shell δ18O values range from −1.9‰ to 4.5‰, with moving average δ18O values exhibiting a noisy but long-term increase from 0.1‰ at ~ 50 ka to 1.6–1.8‰ during the LGM (~ 15–22 ka). Subsequently, the moving average δ18O values range from 0.0‰ at ~ 12 ka to 0.9‰ at present. Calculations using a published snail flux balance model for δ18O, constrained by regional temperatures and ocean δ18O values, suggest that relative humidity at the times of snail activity fluctuated but exhibited a long-term decline over the last ~ 50 ka, eventually resulting in the current semiarid conditions of the eastern Canary Islands (consistent with the aridification process in the nearby Sahara). Thus, low-latitude oceanic island land snail shells may be isotopic archives of glacial to interglacial and tropical/subtropical environmental change.

La Cueva del Llano is a volcanic tube of Pleistocene age on Fuerteventura Island, in the Canary Islands. Part of it is infilled with sediments of external origin. These deposits are exceptional in stratigraphic complexity and thickness compared with other known tube infillings, and they comprise nine stratigraphic units deposited in five phases. In Phase I, which has not been dated, sedimentation of cinder from a nearby cone occurred. Phase II began ca. 16,830 ± 900 14C yr B.P., whereas phase IV dates to 9280 ± 370 14C yr B.P. The interpretation of sedimentary features shows that phases III and V correspond to a dry climate, similar to the present one, whereas the climate was much wetter during phases II and IV. This paleoclimatic sequence agrees with those suggested by the study of deposits formed in other sedimentary environments, not only in Fuerteventura but on other islands of the Canary group and the Sud-Maroc region.

Land snail shell δ13C value is often used as a paleovegetation proxy assuming that snails ingest all plants in relation to their abundance, and that plants are the only source of carbon. However, carbonate ingestion and variable metabolic rates complicate these relationships. We evaluate if live-collected snails from Lanzarote (Canary Islands) reflect the abundance of C3 and CAM plants. Snails were collected on either CAM or C3 plants for isotope analysis of shell and body, and shell size. Respective shell and body δ13C values of snails collected on CAM plants averaged − 8.5 ± 1.7‰ and − 22.8 ± 1.6‰, whereas specimens from C3 plants averaged − 10.1 ± 0.7‰ and − 24.9 ± 1.1‰. A flux balance model suggests snails experienced comparable metabolic rates. A two-source mass balance equation implies that snails consumed ~ 10% of CAM, which agrees with their abundance in the landscape. Snails collected on CAM plant were smaller than those on C3 plants. Conclusively: 1) snails consume CAM plants when they are available; 2) migration of snails among C3 and CAM plants is a common phenomenon; and 3) C3 plants may be a more energetic food for growth than CAM plants. This study shows that shell δ13C values offer approximate estimates of plants in C3–CAM mixed environments.

Molluscs are subjected to intense harvesting in many areas around the world. Conservation measures have been developed to preserve populations of an overexploited gastropod species, the abalone Haliotis tuberculata coccinea. This species was surveyed in subtidal localities throughout coastal Tenerife, Canary Islands over the last two decades (1994–2014). A clear indicator of non-recovery was observed in the decrease of mean size throughout the last two decades, even after the inclusion of this species in the Regional Catalogue of Endangered Species. The mean size of abalones decreased from 33.5 mm (1994) to 28–29 mm (2002 and 2014), corresponding to sub-adult individuals. The structure of size classes was typical of an overexploited species, with reduced occurrence of large individuals (>50 mm). Several factors might explain this pattern such as illegal harvesting, proliferation of featureless benthos and a decrease of suitable habitats for colonization and settlement. Complementary conservation actions are urgently needed to preserve this species in the area studied.

In the present work, we carried out a comparative molecular study of Stenoponia tripectinata tripectinata isolated from Mus musculus from the Canary Islands, Spain. The Internal Transcribed Spacers 1 and 2 (ITS1, ITS2) and 18S ribosomal RNA partial gene and cytochrome c-oxidase 1 (cox1) mitochondrial DNA partial gene sequences of this subspecies were determined to clarify the taxonomic status of this subspecies and to assess inter-population variation and inter-specific sequence differences. In addition, we have carried out a comparative phylogenetic study with other species of fleas using Bayesian, Maximum Parsimony, Maximum Likelihood and Neighbor-Joining analysis. A geographical signal was detected between the cox1 partial gene sequences of S. t. tripectinata isolated from M. musculus from different islands and those isolated from Apodemus sylvaticus from the Iberian Peninsula. Our results assess the monophyletic origin of Stenoponiinae and a different genetic lineage from Ctenophthalmidae. Thus, the elevation of subfamily Stenoponiinae to family level (Stenoponiidae) is suggested.

Sea-cage fish farms impact the seabed within their immediate vicinity, potentially affecting recipient communities. We assessed whether proximity to three sea-cage fish farms at the Canary Islands altered patterns in the abundance, assemblage structure and richness of soft-bottom macrofauna. We related among-farm variability in dissimilarities in macrofaunal assemblage structure between seabeds beneath cages and controls to differences in hydrodynamics, production and seabed topography. Contrasting patterns of species abundances with varying proximity to fish farms were observed: some species decreased while other species increased their abundances with increasing distance at some farms. Although faunal assemblages at 0 m (i.e. beneath the cages) were different, in terms of assemblage structure, from those found at controls, pairwise differences in assemblage structure among distances away varied among the studied fish farms. Species richness showed inconsistent patterns with proximity to cages among fish farms. In summary, inconsistent patterns of macrofaunal assemblages with varying proximity to aquaculture facilities preclude confident predictions on the way offshore aquaculture alters macrofauna in the study region.

The sea urchin Diadema africanum is considered a key herbivore in sublittoral ecosystems of the Canary Islands. Spatial and temporal variability in population structure was carried out at Gran Canaria. We performed a morphometric and population density analysis during 2005, 2006 and 2007 at four sites in zones of Gran Canaria. The study considered a vertical gradient (5, 10 and 20 m depth) during both seasons, the cold season (February and March) and the warm season (October and November). The sea urchin D. africanum in Gran Canaria exhibited an overall density of 7.59 ± 2.92 urchin m−2. A two-way ANOVA evidenced spatial differences in mean abundance of the species, while seasonality was not relevant. The vertical analysis of the abundance of D. africanum showed differences, the smaller sizes appeared at greater depths. The Aristotle's lantern width decreased in a vertical gradient, being remarkable between 10 and 20 m. Findings of uniformity in size over time, a stable range of high densities and the lack of a relationship between the size of the sea urchins and the season reveals that the density–size strategy displayed by D. africanum which explains in turns the high stability of the urchin barrens, which, once developed, remain as areas of permanent desertification in subtidal depths throughout the Canary Archipelago.

Three specimens of Platyscelus armatus (Crustacea: Amphipoda: Hyperiidea: Platyscelidae) are reported from coastal waters of the Canary Islands, Spain; these are the first records from these waters. The specimens were collected south-west of Tenerife and El Hierro Islands during the ‘CETOBAPH 2012' (April 2012) oceanographic cruise. Morphological and morphometric measurements of the specimens, geographical and bathymetric distribution of this species and a key to species of the genus reported in the Canary Islands are provided.