Soil Fertility Changes With Climate and Island Age in Galápagos: New Baseline Data for Sustainable Agricultural Management

While the extended absence of human influence has led to matchless natural conditions on the Galápagos archipelago, agricultural activities on the inhabited islands are increasingly affecting soil health and functioning. However, a systematic assessment of the agricultural soils on the Galápagos Islands is still absent. Plate tectonics and hotspot volcanism cause an eastward drift of the archipelago and result in a west-to-east soil age gradient from approx. 1 to 1,000 ka. In addition, precipitation regimes change from arid to humid with elevation on the higher-standing islands. The objective of this study was to investigate differences in soil fertility parameters and Mehlich (III)-extractable nutrient levels along these gradients in order to provide baseline information for sustainable agricultural management. Topsoil samples (0–20 cm) from 125 farms of the islands Isabela, Santa Cruz and San Cristóbal were analyzed. Gravel and sand content, pH, electrical conductivity, cation exchange capacity, base saturation, soil organic C and total N content tended to decrease with increasing island age, while clay content, soil macroaggregate stability, plant-available water and bulk density increased. Mehlich (III)-extractable base cations Ca, K, Mg and Na as well as P, Fe and Zn showed a decreasing tendency from the youngest to the oldest island, while Mn increased with island age. Mehlich (III)-extractable Cu and Na reached their highest levels on the most intensively farmed, intermediate-aged island Santa Cruz, likely related to anthropogenic inputs and irrigation with brackish water, respectively. Changes along the altitudinal climate gradient within the studied islands were most significant for soil pH, base saturation, and Mehlich (III)-extractable Ca and Mn. Our results highlight the importance of site-specific agricultural management to account for the strong heterogeneity in soil parameters among and within the Galápagos archipelago. The data provided herein shall serve as a baseline for targeted future management strategies to avoid soil degradation, restore and maintain soil functioning and, hence, sustain the soils’ provision of ecosystem services in this unique archipelago.

Nesting Success and Nesting Height in the Critically Endangered Medium Tree Finch (Camarhynchus pauper)

When different introduced species across trophic levels (parasite, predator) invade island systems, they may pose significant threats to nesting birds. In this study, we measure nesting height and infer causes of offspring mortality in the critically endangered Medium Tree Finch (Camarhynchus pauper), an island endemic restricted to Floreana Island on the Galápagos Archipelago. Considering all nests at which a male built a nest, sang and attempted to attract a female (n = 222 nests), only 10.4% of nests produced fledglings (5% of nests had total fledging success, 5.4% of nests had partial fledging success). Of the 123 nests chosen by a female, 18.7% produced fledglings and of 337 eggs laid, 13.4% produced fledglings. Pairing success was higher for older males, but male age did not predict nesting success. All nests with chicks were infested with avian vampire fly larvae (Philornis downsi). We attributed the cause of death to avian vampire fly if chicks were found dead in the nest with fly larvae or pupae (45%) present. We inferred avian (either Asio flammeus galapagoensis or Crotophaga ani) predation (24%) if the nest was empty but dishevelled; and black rat (Rattus rattus) predation (20%) if the nest was empty but undamaged. According to these criteria, the highest nests were depredated by avian predators, the lowest nests by rats, and intermediate nests failed because of avian vampire fly larvae. In conclusion, there is no safe nesting height on Floreana Island under current conditions of threats from two trophic levels (introduced parasitic dipteran, introduced mammalian/avian predators; with Galápagos Short-Eared Owls being the only native predator in the system).

Acanthurus mata (Cuvier, 1829), Elongate Surgeonfish (Acanthuridae), newly recorded in the Tropical Eastern Pacifi

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.

Temporal and spatial variation in sex-specific abundance of the avian vampire fly (Philornis downsi)

Understanding the range and behaviour of an invasive species is critical to identify key habitat areas to focus control efforts. Patterns of range use in parasites can differ temporally, across life stages and between sexes. The invasive avian vampire fly, Philornis downsi, spends the larval stage of its life within bird nests, feeding on developing nestlings and causing high levels of mortality and deformation. However, little is known of the ecology and behaviour of the non-parasitic adult fly life stage. Here, we document sex-specific temporal and spatial patterns of abundance of adult avian vampire flies during a single Darwin’s finch breeding season. We analyse fly trapping data collected across 7 weeks in the highlands (N = 405 flies) and lowlands (N = 12 flies) of Floreana Island (Galápagos). Lowland catches occurred later in the season, which supports the hypothesis that flies may migrate from the food-rich highlands to the food-poor lowlands once host breeding has commenced. Fly abundance was not correlated with host nesting density (oviposition site) but was correlated with distance to the agricultural zone (feeding site). We consistently caught more males closer to the agricultural zone and more females further away from the agricultural zone. These sex differences suggest that males may be defending or lekking at feeding sites in the agricultural zone for mating. This temporal and sex-specific habitat use of the avian vampire fly is relevant for developing targeted control methods and provides insight into the behavioural ecology of this introduced parasite on the Galápagos Archipelago.

Umzug einer Galapagos-Riesenschildkröte aus dem Zoologischen Garten in die Zoologische Sammlung

Galápagos-Riesenschildkröten sind ausschließlich auf dem Galápagos-Archipel im Pazifischen Ozean zu finden. Dort leben sie sowohl in regennassen Regionen als auch in Gebieten mit spärlicher Vegetation. Sie sind tagaktiv und wandern vom Hochland zu ihren Eiablageplätzen in wärmeren Küstengebieten. Sie können ein sehr hohes Alter erreichen, in der Regel werden sie 50–80 Jahre alt. Im Jahr 2020 verzeichnete das Europäische Zuchtbuch für Galápagos-Riesenschildkröten 108 Tiere in 23 Zoos und Einrichtungen. In Europa wird diese Art in 12 Zoos gezeigt, darunter in Rostock und Hoyerswerda. Im Jahr 2012 wurden im Rostocker Zoo fünf Tiere gehalten, die alle aus dem Zoo Zürich kamen. Im Juni 2019 wurde eine der fünf Schildkröten, Elvida, tot in ihrem Gehege aufgefunden. Elvida wurde zur Sektion an das Leibniz-Institut für Zoo- und Wildtierforschung in Berlin übergeben. Danach wurde sie im Museum für Naturkunde Berlin präpariert. Die Präparation erfolgte mit einem Imprägnierverfahren, bei dem das Wasser der Zellen durch Polyethylenglykol (PEG) ersetzt wird. Seit Dezember 2020 ist das Exponat der Galápagos-Riesenschildkröte Elvida Teil der Zoologischen Sammlung der Universität Rostock, wo es den Studierenden für Lehrzwecke zur Verfügung steht und Teil der Ausstellung ist. Relocation of a Galapagos giant tortoise from the Zoological Garden to the Zoological Collection Abstract: Galápagos giant tortoises are found exclusively on the Galápagos archipelago in the Pacific Ocean. There they live both in rain-wet regions and in areas with sparse vegetation. They are diurnal and migrate from the highlands to their egg-laying sites in warmer coastal areas. They can reach a very old age, usually they live 50–80 years. In 2020, the European Studbook for Galápagos giant tortoises listed 108 animals in 23 zoos and institutions. In Europe, this species is kept in 12 zoos, including Rostock and Hoyerswerda. Five individuals were kept at Rostock Zoo in 2012, all of which came from Zurich Zoo. In June 2019, one of the five tortoises, Elvida, was found dead in her enclosure. Elvida was handed over to the Leibniz Institute for Zoo and Wildlife Research in Berlin for dissection. After finishing the dissection, it was prepared at the Museum für Naturkunde Berlin. The preparation was carried out with an impregnation procedure in which the water of the cells is replaced by polyethylene glycol (PEG). Since December 2020, the exhibit of the Galápagos giant tortoise Elvida has been part of the Zoological Collection of the University of Rostock, where it is available to students for teaching purposes and is part of the exhibition.

Constraints on the behaviour and content of volatiles in Galápagos magmas from melt inclusions and nominally anhydrous minerals

Despite their relatively low concentration in most oceanic basalts, volatile species (e.g. H2O, CO2 and S) have a disproportionately large influence on a wide range of mantle and magmatic processes. However, constraining the concentration of H2O (and other volatiles) in basaltic magmas is not straightforward as submarine glass analyses are influenced by assimilation of hydrothermal brines, and the melt inclusion record is often reset by post-entrapment processes. Nevertheless, in this study we show that it is possible to reconstruct a detailed history of the volatile content of basaltic magmas through integration of multiple discreet volatile records and careful consideration of secondary processes. We present new analyses of volatiles in olivine-hosted melt inclusions, melt embayments and nominally anhydrous minerals (NAMS, clinopyroxene and orthopyroxene) found in basalts erupted on Floreana Island in the south-eastern Galápagos Archipelago. Our results indicate that the Floreana magmas, which are characterised by the most radiogenic Pb and Sr isotope signatures in the Galápagos Archipelago, contain H2O concentrations between 0.4 and 0.8 wt% (at a melt Mg# of 0.65, where Mg# = Mg/(Mg + Fe) molar). These are marginally greater than the H2O contents of magmas beneath Fernandina in the western Galápagos Archipelago (cf. 0.2–0.7 wt% H2O at Mg# = 0.65). While the volatile content of magmas from the western archipelago follow trends defined by concurrent mixing and crystallisation, NAMs from Floreana reveal the presence of rare, volatile-rich magmas (~2 wt% H2O) that form as a consequence of reactive porous flow in mush-dominated magmatic systems beneath the south-eastern Galápagos. Furthermore, the Floreana magmas have similar H2O/light Rare Earth Element ratios to basalts from the western Galápagos but contain F/Nd and Cl/K ratios that are ~2 – 3 times greater, indicating that the mantle source of the Floreana lavas might represent an important halogen reservoir in the Galápagos mantle plume.

Inter-island local adaptation in the Galápagos Archipelago: genomics of the Galápagos blue-banded goby, Lythrypnus gilberti

The Galápagos Archipelago is a place where terrestrial adaptive radiations of finches, mockingbirds, and tortoises have been studied extensively. In contrast, little is known about the potential for marine species to diverge among islands. The overall degradation of coral reefs in the Galápagos makes understanding the mechanisms and factors of speciation, the engine of biodiversity, important, and timely. While speciation in marine archipelagos has been described in the past, such as for cone snails in Cabo Verde Archipelago and limpets in Hawaii, adaptive radiations in the marine environment are still rare and poorly understood. In this study, we focused on the Galápagos blue-banded goby, Lythrypnus gilberti, a small endemic fish that is found in shallow subtidal rocky habitats. Using RAD sequencing, we analyzed 19,504 loci that were either neutral, or potentially under directional selection. As expected, considering the small geographic range, population structure based on neutral markers was weak. For loci under directional selection, however, marked differences between islands suggested potential for local adaptation. Our data suggest that for marine species, where dispersal barriers are less apparent, mechanisms of local adaptation may also be at play in the Galápagos Archipelago.

A new species of Helmutkunzia Wells & Rao, 1976 from an intertidal sandy beach in Xiamen, China and proposal of Pseudobalucopsylla gen. nov. (Copepoda, Harpacticoida, Miraciidae)

A new species of the genus Helmutkunzia Wells & Rao, 1976 (Miraciidae) is described from specimens collected from an intertidal sandy beach in Xiamen, Fujian Province, China. Helmutkunzia xiamenensis sp. nov. differs from its two congeners by the length/width ratio of the female P5 exopod, the number or length of the setae on the sexually dimorphic P2 endopod in the male and the relative length of the spines on the endopodal lobe of the male P5. The Chinese species is morphologically closest to H. variabilis Wells & Rao, 1987 from the Andaman and Nicobar island chain. Females of both species can readily be differentiated by the relative length of the P5 exopod while males can be differentiated by the length of the armature elements on P2 enp-2 and the endopodal lobe of P5. The genus Balucopsylla Rao, 1972 is reviewed, resulting in the proposal of Pseudobalucopsylla gen. nov. to accommodate the type species Balucopsylla triarticulata Wells & Rao, 1987 and three new Indo-Pacific species previously identified with it: P. obscura sp. nov. from the Andaman Islands, P. costaricensis sp. nov. from the Pacific coast of Costa Rica and P. mielkei sp. nov. from the Galápagos archipelago. A key to species of Pseudobalucopsylla sp. nov. is provided.