The lichen family Teloschistaceae from the Galapagos is revised. Most of the species belong to the Caloplacoideae, two to Teloschistoideae and a few to Xanthorioideae, three subfamilies not validly ...published, which is remedied here. Four different datasets were analyzed using Bayesian inference. For the bulk of the species, a combined dataset of nrITS, nrLSU and mrSSU was analyzed. Additionally, three analyses were performed using nrITS to further investigate phylogenetic relationships within and between species in each subfamily, and in the genera Xanthomendoza and Squamulea. Four new genera are described: Lacrima, Oceanoplaca, Phaeoplaca, Sucioplaca. Twenty-four species are reported, of which ten are new to science: Caloplaca nigra, Lacrima galapagoensis, Oceanoplaca chemoisidiosa, O. sideritoides, Phaeoplaca tortuca, Squamulea chelonia, S. humboldtiana, S. osseophila, S. oceanica, and Xanthomendoza leoncita. Several new combinations are proposed and three species of Xanthomendoza are reduced to synonymy. Several new combinations and species placed into synonymy do not occur in the Galapagos, but are treated as a consequence of our taxonomic revision. Morphology, anatomy, secondary chemistry, distribution and molecular phylogenetic affiliation are presented for each species and a key is provided. Eight different chemical patterns are quantitatively described based on HPLC analyses. The new genus Lacrima includes L. galapagoensis, a species without vegetative propagules, and two densely isidiate species, L. epiphora and L. aphanotripta that are morphologically similar to ‘Caloplaca’ wrightii. The only species of Galapagos Teloschistaceae that contains xanthones is placed into Huneckia. Oceanoplaca includes two species with the new anthraquinone isidiosin, O. isidiosa and O. chemoisidiosa, while a third species, O. sideritoides, does not contain this secondary metabolite. Phaeoplaca camptidia has previously been reported from Galapagos, but our phylogenetic analysis suggests that it is a new species, here named P. tortuca. An isolated position is occupied by ‘Caloplaca’ diplacia, which we place in it its own monotypic genus Sucioplaca. Some Galapagos Teloschistaceae can be considered a ‘residue’ of unresolved Caloplaca s.l., i.e. the corticolous C. floridana is possibly related to the saxicolous C. nigra, while C. cupulifera can currently not be placed. Squamulea remains particularly problematic and includes S. phyllidizans, that is nested among otherwise unresolved Squamulea species. Based on molecular data, S. phyllidizans is close to ‘Huriella’. ‘Huriella’ flakusii, described from Peru, is confirmed to occur in the Galapagos and the genus is reduced to synonymy with Squamulea. The Squamulea squamosa/subsoluta group remains largely unresolved, but the new species S. chelonia, S. humboldtiana, S. oceanica, and S. osseophila are phylogenetically distinct. Foliose Teloschistaceae are represented only by one species, described as Xanthomendoza leoncita, while the only fruticose species, Teloschistes chrysophthalmus and T. flavicans, are cosmopolitan.
The 2015 eruption of Wolf volcano was one of the largest eruptions in the Galápagos Islands since the onset of routine satellite‐based volcano monitoring. It therefore provides an excellent ...opportunity to combine geophysical and petrological data, to place detailed constraints on the architecture and dynamics of subvolcanic systems in the western archipelago. We present new geodetic models that show that pre‐eruptive inflation at Wolf was caused by magma accumulation in a shallow flat‐topped reservoir at ~1.1 km, whereas edifice‐scale deformation during the eruption was related to a deflationary source at 6.1–8.8 km. Petrological observations suggest that the erupted material was derived from both a subvolcanic mush and a liquid‐rich magma body. Using a combination of olivine‐plagioclase‐augite‐melt (OPAM) and clinopyroxene‐melt barometry, we show that the majority of magma equilibration, crystallization, and mush entrainment occurred at a depth equal to or greater than the deep geodetic source, with little petrological evidence of material sourced from shallower levels. Hence, our multidisciplinary study does not support a fully transcrustal magmatic system beneath Wolf volcano before the 2015 eruption but instead indicates two discrete storage regions, with a small magma lens at shallow levels and the major zone of magma storage in the lower crust, from which most of the erupted material was sourced. A predominance of lower crustal magma storage has previously been thought typical of subvolcanic systems in the eastern Galápagos Archipelago, but our new data suggest that this may also occur beneath the more active volcanoes of the western archipelago.
Key Points
Combined geophysical and petrological constraints provide a detailed picture of the subvolcanic architecture at Wolf volcano
Wolf is underlain by two discrete magma storage regions: one within the edifice, the other in the lower crust
Almost all the magma ejected during the 2015 eruption of Wolf was derived from the lower crust
The Galápagos and Hawai'i archipelagos are formed by mantle plumes originating at the large low shear velocity province (LLSVP) boundary. We report new high‐precision Pb, Sr, Nd, and Hf isotopic ...analyses on 83 Galápagos samples and compare them with those of Hawai'i. The data confirm that like Hawai'i, Galápagos is a bilaterally asymmetric plume whose compositional boundary trends NW‐SE. On their northeast sides, the plumes share a common source, Pacific lower mantle, whose intermediate isotopic signature may be common to many plumes. The Hawaiian and Galápagos plumes' southwestern sides are anchored in the Pacific LLSVP and are compositionally distinct; in Hawai'i, Loa trend lavas reflect contributions from the EM1 mantle end‐member, whereas in Galápagos, HIMU is dominant, suggesting that the Pacific LLSVP is compositionally heterogeneous and includes different types of recycled material. Furthermore, the surficial expression of a bilaterally asymmetric plume is strongly influenced by its tectonic setting: (a) Thick Hawaiian lithosphere supports a volcano evolution process, including rejuvenated volcanism, whereas the thin Galápagos lithosphere inhibits Hawai'i‐style rejuvenated‐stage eruptive activity, instead causing extended, widespread volcanism; (b) the proximity of the Galápagos to a mid‐ocean ridge causes entrainment of the depleted upper mantle, overwhelming depleted material intrinsic to the plume and affecting volcanoes' magmatic architecture; and (c) the geometric relationship between the LLSVP boundary and plate motion influences geochemical patterns at the surface. Thus, despite striking differences in surficial expression of the Galápagos and Hawai'i plumes, they share a common generation mechanism, supplied by the Pacific LLSVP and the lower mantle.
Plain Language Summary
The Galápagos and Hawaiian Islands are formed by mantle plumes, which provide an opportunity to document the compositional structure of the lower mantle. The Hawai'i plume ascends from the core–mantle boundary along the interface between two major mantle reservoirs, the Pacific large low shear velocity province (LLSVP), and the surrounding lower mantle. The LLSVP is a region at the core–mantle boundary that seismic velocities suggest is denser and hotter than the rest of the mantle. The Galápagos is also located along the LLSVP‐lower mantle interface, in the eastern Pacific. Prior to this study, the Galápagos plume was thought to be quite different from the one supplying Hawai'i, primarily because the distribution of geochemical compositions across the islands forms two parallel volcanic chains in Hawai'i, a pattern not observed in the Galápagos. Our new geochemical data from 83 lavas across the Galápagos indicate that the Galápagos plume also exhibits bilateral compositional asymmetry, but it is expressed as two broad zones that cross the archipelago instead of parallel chains. We propose that the Hawai'i and Galápagos plumes are generated by the same mechanism, consisting of parallel filaments of compositionally distinct material rising from the boundary of the LLSVP with the lower mantle.
Key Points
The Galápagos and Hawai'i plumes are bilaterally asymmetric in composition, sourced at the LLSVP‐lower mantle interface
The Galápagos and Hawai'i plumes share a common mantle source, the Pacific lower mantle
The Pacific large low shear velocity province is heterogeneous, with a variety of ancient recycled material (HIMU‐ and EM1‐type)
Dissolved Rare Earth Element (REE) fractionation mechanisms in freshwater environments have been parameterized by laboratory experiments and measured in major world rivers. To investigate the ...relationship between such observations and small-scale natural systems, we analyze REE contents in water samples from groundwater springs and streams on San Cristóbal Island, Galápagos. The island is comprised of a single lithology (Ocean Island Basalt) and exhibits a steep precipitation gradient on the windward slope over a short spatial extent, which results in a wide range of physicochemical properties and regolith weathering intensities. This allows us to investigate primary controls of REE fractionation without the influence from varying lithology. Samples show a wide range of measured pH, as well as concentrations of Mn and Fe. Local basalt-normalized REE patterns exhibit a wide range (Nd/Ybb = 0.19–1.21 and Ce/Ce*b = 0.65–2.22) for the small areal extent of the watersheds (~13 km2). Comparisons between data from 0.45 μm to 0.02 μm filtered samples demonstrate the importance of colloidal-sized (0.02–0.45 μm) metal species in aqueous solution. Our results suggest that two mechanisms are responsible for the observed REE fractionation in this catchment: pH-driven changes in aqueous complex stability by organic or anionic complexes and the preferential adsorption of heavy rare earth elements (HREE) onto Fe- and Mn- oxyhydroxides at low pH. This contrasts with moderate enrichment of light rare earth elements (LREE) observed at higher pH. These results suggest that several proposed REE fractionation mechanisms established previously in laboratory experiments can be observed in a natural watershed system, despite being obscured in larger world rivers. The homogenous lithology and strong climate gradient of San Cristóbal island allow for the observation of REE fractionation mechanisms which are usually obscured in larger world rivers despite being predicted in laboratory experiments, such as a positive Ce anomaly associated with HREE enrichment in low pH waters.
•Small watersheds in San Cristobal, Galapagos show a broad range of REE patterns.•Normalizing REE patterns to bedrock yields lithology-independent fractionation.•Diversity of Ce, La, and Y anomalies indicate varied control of metal oxides.•LREE vs. HREE abundance displays broad pH dependence despite the small spatial scale.
New rhenium–osmium data for high-MgO (>9 wt.%) basalts from the Galápagos Archipelago reveal a large variation in 187Os/188Os (0.1304 to 0.173), comparable with the range shown by primitive global ...ocean island basalts (OIBs). Basalts with the least radiogenic 187Os/188Os occur closest to the Galápagos plume stem: those in western Galápagos have low 187Os/188Os, moderate 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb and high 3He/4He whereas basalts in the south also have low 187Os/188Os but more radiogenic 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb and 3He/4He. Our new Os isotope data are consistent with the previously established spatial zonation of the common global isotopic mantle reservoir “C” and ancient recycled oceanic crust in the mantle plume beneath western and southern parts of Galápagos, respectively.
Galápagos basalts with the most radiogenic 187Os/188Os (up to 0.1875) typically have moderate MgO (7–9 wt.%) and low Os (<50 pg g−1) but have contrastingly unenriched Sr, Nd and Pb isotope signatures. We interpret this decoupling of chalcophile and lithophile isotopic systems as due to assimilation of young Pacific lower crust during crystal fractionation. Mixing models show the assimilated crust must have higher contents of Re and Os, and more radiogenic 187Os/188Os (0.32), than previously proposed for oceanic gabbros. We suggest the inferred, exceptionally-high radiogenic 187Os of the Pacific crust may be localised and due to sulfides precipitated from hydrothermal systems established at the Galápagos Spreading Centre.
High 187Os/188Os Galápagos basalts are found where plume material is being dispersed laterally away from the plume stem to the adjacent spreading centre (i.e. in central and NE parts of the archipelago). The extent to which crustal processing influences 187Os/188Os appears to be primarily controlled by melt flux: as distance from the stem of the Galápagos plume increases, the melt flux decreases and crustal assimilation becomes proportionally greater, accounting for co-variations in Os and 187Os/188Os. The Os concentration threshold below which the 187Os/188Os of Galápagos basalts are contaminated (100 pg g−1) is higher than the canonical value (<50 pg g−1) assumed for many other global OIBs (e.g. for Iceland, Grande Comore and Hawaii). This most likely reflects the low overall melt flux to the crust from the Galápagos plume, which has only a moderate excess temperature and buoyancy flux. Our findings have implications for the interpretation of 187Os/188Os ratios in other ocean island settings, especially those where large variations in 187Os/188Os have been linked to heterogeneity in mantle lithology or sulfide populations: the effect of crustal contamination on 187Os/188Os may be greater than previously recognised, particularly for basalts associated with weak, low melt flux mantle plumes, such as Tristan, Bouvet, Crozet and St Helena.
•High MgO Galápagos basalts exhibit a range of 187Os/188Os comparable to global OIB.•187Os/188Os of Galápagos basalts broadly correlates with distance from plume stem.•187Os/188Os of Galápagos basalts is influenced by melt flux to the crust.•Os threshold value for crustal contamination in OIB varies with setting.•Some regions of lower oceanic crust may have higher 187Os than previously found.
Philornis downsi (Dodge & Aitken), the avian vampire fly, is the main threat to land bird conservation in the Galapagos Islands. However, very little is known about the reproductive morphology, ...physiology, and behavior of P. downsi adults impeding progress on developing effective methods for its control. Here, we provide the first preliminary description of the female and male reproductive systems of a Philornis species and compare the activity of lab-reared and wild flies. In mature females, the accessory glands are connected from the common oviduct toward the ovaries, and there are 3 spermathecae (1 double and 1 singlet). For males, we found 2 peanut-shaped testes, one possible accessory gland, an apodeme, and an aedeagus. Both wild and lab-reared individuals had similar patterns of movement, although lab-reared adults were more mobile at dusk. We observed higher locomotion in the morning and dusk with a lull at midday, and increased activity as flies aged from 1 to 10 days. Females became more active during the morning at 10 days of age compared to males. Knowledge on the morphology of P. downsi's reproductive system will give us a better understanding of its reproductive physiology and will aid in efforts at establishing a self-reproducing colony. Mobility trials can be used as an easy and practical quality control method, as well as providing essential information on peak activity times, which may be related to foraging in the morning for females and sexual activity and host searching at dusk. Graphical abstract
The reef-fish fauna of the Tropical Eastern Pacific (TEP) includes 12 species of surgeonfishes (Acanthuridae), five of them in the genus
Acanthurus
. Recent recreational scuba diving at Isla Darwin ...in the Galapagos archipelago produced photographs of adults of an additional species of
Acanthurus
,
A. mata
(Cuvier, 1829), for which there are no previous records in the TEP. This species may have escaped previous notice due to its semi-pelagic habitat preference and its resemblance to
Acanthurus xanthopterus
Valenciennes, 1835, which occurs throughout much of the Galapagos.
Haemosporidian parasites in the genus Plasmodium were recently detected through molecular screening in the Galapagos Penguin (Spheniscus mendiculus). We summarized results of an archipelagowide ...screen of 3726 endemic birds representing 22 species for Plasmodium spp. through a combination of molecular and microscopy techniques. Three additional Plasmodium lineages were present in Galapagos. Lineage A-infected penguins, Yellow Warblers (Setophaga petechia aureola), and one Medium Ground Finch (Geospiza fortis) was detected at multiple sites in multiple years. The other 3 lineages were each detected at one site and at one time; apparently, they were transient infections of parasites not established on the archipelago. No gametocytes were found in blood smears of infected individuals; thus, endemic Galapagos birds may be dead-end hosts for these Plasmodium lineages. Determining when and how parasites and pathogens arrive in Galapagos is key to developing conservation strategies to prevent and mitigate the effects of introduced diseases. To assess the potential for Plasmodium parasites to arrive via migratory birds, we analyzed blood samples from 438 North American breeding Bobolinks (Dolichonyx oryzivorus), the only songbird that regularly migrates through Galapagos. Two of the ephemeral Plasmodium lineages (B and C) found in Galapagos birds matched parasite sequences from Bobolinks. Although this is not confirmation that Bobolinks are responsible for introducing these lineages, evidence points to higher potential arrival rates of avian pathogens than previously thought. Parásitos de la familia Haemosporidia, del género Plasmodium recientemente fueron detectados por medio de análisis moleculares en el pingüino de las Galápagos (Spheniscus mendiculus). Resumimos los resultados de un análisis, extendido a lo largo del archipiélago, de 3726 aves endémicas representando a 22 especies para Plasmodium spp. mediante la combinación de técnicas moleculares y de microscopía. Tres linajes adicionales de Plasmodium estuvieron presentes en las Galápagos. El linaje A infectó pingüinos, individuos Setophaga petechia aureola y a un individuo de Geospiza fortis en sitios múltiples y en varios años. Los otros 3 linajes fueron detectados cada uno en un sitio y en un tiempo específico; aparentemente, fueron infecciones transitorias de parásitos no establecidos en el archipiélago. No se encontraron gametocitos en los frotis de sangre de individuos infectados; por esto, las aves endémicas de las Galápagos pueden ser hospederos finales de estos linajes de Plasmodium. Determinar cuándo y cómo llegaron los parasitos y los patógenos a las Galápagos es clave para desarrollar estrategias de conservación para prevenir y mitigar los efectos de las enfermedades introducidas. Para evaluar el potencial de llegada de Plasmodium en aves migratorias, analizamos muestras de sangre de 438 Dolichonyx oryzivorus en época reproductiva. Esta ave es la única canora que migra regularmente a través de las Galápagos. Dos de los linajes efímeros de Plasmodium (B y C) que se hallaron en las aves de las Galápagos coincidieron con secuencias de parásitos del ave canora. Aunque esto no confirma que Dolichonyx oryzivorus sea responsable de introducer estos linajes, la evidencia apunta a un potencial más alto de tasas de llegada de patógenos aviares de lo que se pensaba previamente.
Although pesticides are frequently used for agriculture in the Galapagos Islands (Ecuador), there are, to date, no investigations of pesticide occurrences in its coastal waters. We examined the ...presence of pesticide residues in the coastal waters of urban areas in two islands of the Galapagos archipelago using a repeated sampling design. Quantification was performed by solid-phase extraction, followed by chemical analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-electron capture detector (GC-ECD). The diversity and concentration of pesticide residues in Santa Cruz island were higher compared to Isabela island. In total, sixteen pesticides were detected, including three persistent organic pollutants. Carbendazim (23.93 μg·L−1), cadusafos (4.74 μg·L−1), DDT (2.99 μg·L−1), diuron (1.61 μg·L−1) and aldrin (1.55 μg·L−1) were detected with the highest concentrations between samples. Repetitions in locations show that concentrations of pesticide residues varied considerably in space and time. Comparison with local products indicated agricultural activities on the islands as a possible source. Furthermore, evaluation through ecological risk quotients showed that the observed concentration levels of seven pesticides pose a relatively high risk for three biotic groups (i.e. algae, invertebrates and fishes). Taken together, this study provides insights into the need to regulate, monitor and assess the presence of pesticides in the islands. At a global scale, this study is moreover valuable for the many islands that are facing the same challenges.
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•Pesticides occurrence was evaluated in coastal urban areas of Galapagos archipelago.•Sixteen pesticides were detected including three persistent organic pollutants.•Source of pesticides was associated with agriculture production in the islands.•Pesticide residues concentration varied considerably in space and time.
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