Crater Lake Research Articles

Variations of phytoplankton productivity and community evidenced by sterol records in Lake Tuofengling, a crater lake in northeast China, during the last 25,000 years

Volcanism, volcanic ash, and its role in forest ecology and management Mark Kimsey, the Director of the Intermountain Forestry Cooperative, discusses volcanism, volcanic ash, and their roles in forest ecology and management. Plate tectonics, the Ring of Fire, and volcanism have shaped and continue to shape Earth’s landscapes, particularly along the Pacific Rim. Volcanism has shaped the skylines and landscapes of the North American Pacific Coast; depositing during eruptive events, volcanic tephra ranging in centimeters to tens of meters in depth. One particular eruptive event that dramatically changed Northwest U.S. ecological history was the repeat and final circular ring fissure eruption of Mount Mazama (known currently as Crater Lake) in southwestern Oregon State approximately 7,700 years ago (Fig. 1).

Magma fragmentation and tephra deposition from a small-volume phreatomagmatic eruption: Blue Lake crater, Oregon, USA

Abstract Series of hydrothermal events and a large phreatomagmatic which shortly followed by an effusive eruption has changed the morphology of Anak Krakatau between 2019 and 2020. The large phreatomagmatic and effusive events that occurred on April, 10th 2020, produced tephra and lava flow deposit that enlarged the west flank area. Here, we investigated the morphological changes of Anak Krakatau between August 2019 and May 2020 using UAV SfM photogrammetry, Sentinel and Pleiades satellite imageries, and fieldworks photographs data. Our UAV orthomosaic image captured the morphology of Anak Krakatau in August 2019, while temporal Sentinel 2 and High-resolution Pleiades satellite images observed the morphology of Anak Krakatau between September 2019 and May 2020. We manually digitized the edifice of Anak Krakatau from UAV, sentinel 2, and Pleiades images to investigate morphological changes of Anak Krakatau. The high-resolution Pleiades satellite image was processed using supervised classification to automatically delineate the deposit of lava flow, altered rocks and tephra. Result shows volcaniclastic deposit due to the hydrothermal and/or phreatomagmatic eruptions that covered 0.08 km2 around an active crater lake at Anak Krakatau between January and February 2020. The large phreatomagmatic and effusive eruptions produced tephra that covered 0.815 km2 at the north–north west flanks of Anak Krakatau and lava flow that emplaced 0.2 km2 and elongated around 742 m from the pre-existing crater lake to the west shoreline of Anak Krakatau. The lava flow has blocky surface and highly fractured that possibly formed due to compression—extension stresses during lava flow emplacement and has widened the Anak Krakatau volcanic island from 2.99 km2 to 3.027 km2. We infer that Anak Krakatau is currently on reconstruction phase after the destructive flank collapse on December 22th, 2018.

Free-living amoebae population in a caldera lake after a phreatomagmatic eruption.

Extreme environments, such as hypersaline habitats, hot springs, deep-sea hydrothermal vents, glaciers, and permafrost, provide diverse ecological niches for studying microbial evolution. However, knowledge of microbial communities in extreme environments at high southern latitudes remains limited, aside from Antarctica. Laguna Timone is a hypersaline crater lake located in a Pleistocene maar of the Pali Aike Volcanic Field, southern Patagonia; the lake was formed during basaltic eruptions in a periglacial setting. Here, we report the first integrative characterization of microbial communities from biofilms and microbial mats in this lake using high-throughput 16S rRNA and ITS gene sequencing, along with mineralogical and hydrochemical analyses of water, sediments, and carbonates. Bacterial communities were dominated by the genera Enterobacterales ASV1, Pseudomonas, Oscillatoria, Nodularia, and Belliella, with site-specific assemblages. Fungal communities included Laetinaevia, Ilyonectria, Thelebolus, Plectosphaerella, and Acrostalagmus, each showing distinct distribution patterns. These baseline data contribute to understanding microbial dynamics in hypersaline maar environments and support future investigations. This integrative approach highlights key microbe-mineral relationships and underscores the potential of Laguna Timone as a natural laboratory for exploring biosignature formation and microbial adaptation in chemically extreme environments, both on early Earth and potentially beyond.

Sensory adaptation is widely hypothesized to drive ecological speciation, yet empirical evidence from natural populations undergoing early stage divergence remains limited. In Lake Masoko, a young crater lake in East Africa, the haplochromine cichlid Astatotilapia calliptera is undergoing early stage sympatric speciation into shallow-water littoral and deep-water benthic ecotypes that experience contrasting light environments. Here, we integrate retinal transcriptomics, phenotypic analyses, and visual modeling to uncover rapid sensory divergence associated with this ecological transition. We find striking shifts in cone opsin expression, with the benthic ecotype exhibiting a switch from short-wavelength sensitive SWS2B to SWS2A and an overall narrowing of cone sensitivity toward the center of the light spectrum, consistent with changes in deep-water light environment. In contrast, coding sequence variation in opsin genes was limited and no significant differences in allele frequencies were detected across nine polymorphic sites, pointing to expression regulation as the primary axis of early divergence in visual systems. In parallel, we observed divergence in male signaling traits, with benthic males displaying deeper red egg-spots, aligning with predictions from visual modeling of signal efficiency in different light environments. These results demonstrate rapid transcriptomic and phenotypic divergence in associated signaling traits—within ∼1,000 years—supporting a potential role for regulatory evolution in sensory adaptation during early ecological speciation.

During the early and mid Holocene deep lakes existed in the Tibesti volcanic complex, the highest mountain in the Sahara, but it is still unclear why they formed. Here, we combine sedimentary data analyses, high-resolution climate modelling and water balance modelling to provide a quantitative and differentiated estimate of the mid-Holocene water balance of the Trou au Natron (Doon Orei) and Era Kohor crater lakes and to discuss the underlying atmospheric circulation. During the mid-Holocene, the Tibesti received at least an order of magnitude more precipitation than the surrounding plains due to strong orographic uplift of moist air masses, which were surprisingly brought in by north-easterly winds from the Mediterranean, not by the stronger West African monsoon from the south. This may explain differences in the water levels between the Trou au Natron in the north-western part of the Tibesti and the Era Kohor in the south-eastern, leeward part. Our analysis demonstrates the importance of orographic precipitation for evaluating the hydroclimate of the central part of the Sahara - a factor grossly underestimated in the global climate models commonly used for palaeo and future climate simulations.

Abstract A key process in active magmatic systems is the “recharge” of deep-sourced mafic magma into cooler, more evolved, and crystal-rich shallow reservoirs; recharge may be the cause of, or response to, eruptive activity. Although compositional evidence for recharge has been extensively documented, physical models of recharge are limited, particularly processes that separate exsolving volatiles and melts from rapidly growing crystals. To improve constraints on phase separation behaviors, we re-examine andesitic enclaves in silicic andesite lava flows of Mt. Mazama (Crater Lake), USA, that provided early evidence of gas-driven filter pressing (Bacon, 1986). 2D and 3D imaging shows that enclaves have a sample-spanning crystal framework that is disrupted by melt patches, indicating that initially deformable crystal networks were subject to early phase reorganization. Small enclaves are poorly vesicular and require early gas loss. Large enclaves have porous cores with angular (diktytaxitic) voids that are well-connected in 3D and denser rinds with isolated pores. Large enclave rinds have similar bulk compositions to small enclaves but their less evolved cores require ~ 20% melt removal. In the large enclave, diktytaxitic core textures and gas fingering structures at the core–rind boundary suggest relatively slow late-stage outward gas migration. Both scaling arguments and evidence of outward gas/melt migration require a resistant rind. Rind formation is best explained by differential cooling and demonstrates the importance of thermal gradients for gas-driven filter pressing. A corollary is a limited time scale of recharge, enclave formation, and vesiculation to produce diktytaxitic textures, suggesting that recharge was (near) synchronous with eruption.

This paper analyses two volumes by American poet Louis Glück: The Wild Iris and Averno. Averno deals with the theme of trauma. The crater lake Averno is the setting, which is the gateway to Hades. The poetry collection shows our vulnerability and how we face loss. Averno presents a fragmented world, conveyed through Glück’s formal fragmentation and sombre imagery. In contrast, The Wild Iris presents a reconstruction of the world, set in a mystical garden where different flowers tell their own narratives. The book explores themes of life and death, rebirth, cyclicality, and the quest for transcendence. The third part of this essay compares the confessional poetry of Louis Glück and Sylvia Plath, based on shared poetic themes. Both Sylvia Plath and Louise Glück can be considered confessional poets, but the degree of self-discovery and the approach to existential themes differ. While Glück uses a distanced, mythological framework, Plath’s poetry is more direct and personal. Plath’s work immerses the reader in psychological turmoil, providing a deep and moving experience, while Glück’s poetry is more abstract. Most of the poems by the two poets explore themes of mortality, the fragility of life, trauma, pain, and time. Glück encourages the reader to reflect on their own existence.

ABSTRACTSympatric speciation is defined as the formation of new species in the absence of geographic barriers, but the genomic and life history strategy mechanisms underpinning sympatric speciation are still far from clear. It has recently been discovered that the cichlid fish Astatotilapia calliptera from crater Lake Masoko in Tanzania have diverged sympatrically into littoral (shallow water) and benthic (deep water) ecotypes, which differ in head and pharyngeal jaw morphology. Carbon stable isotope analysis has also broadly indicated trophic differentiation between ecotypes. Here, we explore trophic niche divergence on a finer scale, using metabarcoding of stomach contents. A combination of the mitochondrial COI region and 18S V4 region from the eukaryotic nuclear small subunit ribosomal DNA was used to target macroinvertebrate and broader eukaryotic taxonomic diversity, respectively, revealing dietary divergence between the ecotypes. Large proportions of Arthropoda (dipterans and copepod) were found in both ecotypes, indicating some food sources common to both microhabitats. However, gut contents of benthic A. calliptera individuals were characterized by an abundance of annelids and diatoms, while Lepidoptera, mayflies, fungi, freshwater mussels, and bivalves were common in littoral ecotypes. The variation observed in the dietary contents of the ecotypes indicates the presence of resource partitioning, facilitating adaptation to unique feeding strategies.

ABSTRACTThis manuscript presents a comprehensive presentation of ground temperature data collected at 16 nodes of the 121 of the Crater Lake Circumpolar Active Layer Monitoring (CALM) site on Deception Island, Antarctica, from 2008 to early 2022. Each one of the 16 shallow boreholes has been equipped with miniature temperature loggers, providing valuable insights into the thermal regime of the ground at a depth of 50 cm, which corresponds to the mean depth of the top of the permafrost table as observed by annual mechanical probing in the CALM site. Despite a 9‐month long gap in data collection during 2017 due to persistent snow cover, the time series remains largely intact, with annual measurements taken every 3 h. The manuscript details the methodologies employed for data collection, including the use of iButton loggers, and outlines the challenges faced in retrieving and processing the data in the harsh Antarctic environment. The cleaned dataset, which consolidates data from various nodes while removing erroneous records, is made freely accessible to the scientific community without any additional processing of the data such as offset corrections or gaps interpolation. This resource is expected to facilitate further research into the thermal dynamics of the active layer and permafrost and its implications for climate change since both are influenced by external factors such as snow cover, air temperature and others. Overall, the presented dataset contributes to the limited body of knowledge regarding Antarctic permafrost and provides a foundation for future investigations into the effects of climate change on frozen ground dynamics. The dataset serves as a vital tool for researchers aiming to model ground thermal behaviour and assess the impacts of environmental changes in polar regions.

Abstract Assessing Radiative Power (RP) output is essential for monitoring and understanding volcanic systems. While Mid‐Infrared channels are used to assess thermal outputs at volcanoes exhibiting effusive activity, Thermal‐InfraRed (TIR) bands are better suited for measuring moderate‐to‐low‐temperature (≲600 K) features, such as those associated with hydrothermal activity. However, failure to meet key assumptions in TIR‐based calculations results in up to a ∼90% RP underestimation of ≲600 K sources. We thus introduce the TIR‐based Volcanic Radiative Power () method to accurately retrieve RP from single‐band TIR (10.5–12 μm) spectral radiance at systems dominated by surface temperatures of ≲600 K, that is, crater lakes and fumarole fields, achieving an uncertainty of ±35%. Comparison with ground truth for Ruapehu, El Chichón, Taal, Vulcano, Puracé, Poás, and White Island demonstrates the accuracy of in quantifying thermal output and detecting subtle variations in volcanic activity. This exportable method will facilitate compilation of global RP inventories for moderate‐to‐low‐temperature volcanic systems.

Phenotypic plasticity enables organisms to adjust their traits in response to environmental changes, potentially enhancing survival under fluctuating conditions. While plastic capacity—the range of phenotypic change—has been extensively studied, the rate of plastic responses remains unexplored. The rate of plasticity is crucial, as prolonged mismatches between phenotype and environment reduce fitness. Nonetheless, evolutionary models typically do not investigate rates of plasticity. Here, we measure opsin gene expression to estimate the temporal changes in predicted visual sensitivity of Nicaraguan convict cichlids (Amatitlania siquia) from populations exposed to changes in light conditions. We show that rates of plasticity in single cone predicted sensitivity vary significantly among populations, developmental stages, and experimental light treatments, demonstrating that rates of plastic change are shaped by both genetic and context-dependent factors. Notably, great lake cichlids—native to predominantly turbid environments—responded more rapidly to red-shifted photic conditions than crater lake fish, but more slowly when returned to clear conditions. Additionally, younger individuals exhibited faster changes in opsin gene expression than older ones, highlighting the role of developmental stage in modulating plasticity. These findings challenge the assumption of constants rates of plasticity and suggest that selection could act not only on plastic capacity but also on the rate of plastic responses. Our results demonstrate that rates of plasticity are themselves evolvable traits. Incorporating this temporal dimension into models of plasticity will improve our understanding of how organisms respond to environmental heterogeneity, with broad implications for evolutionary biology and ecology.

Mid- to Late-Holocene branched GDGT-based air temperatures from a crater lake in Cameroon (Central Africa)

Land use is a major driver of biodiversity loss, but how it impacts parasite communities is scarcely documented. Crater lakes and their catchments in rural western Uganda greatly vary in their intensity of anthropogenic disturbance, thus providing an opportunity to assess the effects of land use on snail-borne parasitic trematodes. We applied state-of-the-art molecular biomonitoring to 2385 Bulinus tropicus snails from 34 lakes to detect and genotype trematode infections. The 45 trematode taxa recovered infect a wide range of final vertebrate hosts, and some can cause health burdens of significant public importance. Using constrained ordinations and generalized additive models, we found that B. tropicus reaches peak abundance in lakes with catchments partly under agriculture, whereas trematode infections increase with B. tropicus abundance and peak at intermediate aquatic productivity. Trematode diversity also increases with aquatic productivity, levelling off only in the most productive lakes. These relationships likely reflect the higher abundance and variety of final hosts sustained by more productive lakes. Finally, we found that land use affects trematode community composition, with more livestock parasites and less bird parasites occurring in agricultural catchments. Our results indicate that both land use and lake eutrophication affect the distribution of hotspots for parasitic disease transmission.

Toxic natural pollution at Ijen crater volcano: Environmental characteristics and health risk assessment.

Abstract Poás Volcano is a complex stratovolcano in Costa Rica’s Central Mountain Range and hosts acidic volcanic lakes. This study uses Unmanned Aerial Vehicles (UAV) to monitor the physicochemical characteristics of the hyperacid crater lake. Sampling was conducted in January and May of 2024, using a DJI Matrice 600 Pro equipped with a water collection system. The results showed extremely low pH values (as low as −1.04), high temperatures (up to 64 °C), and high concentrations of sulfate (134 877 ppm) and chloride (88 434 ppm), highlighting the influence of volcanic activity on the chemical composition of the hyperacid lake water. Sampling was marked by a decrease in rainfall patterns during the dry season and a reduction in the lake’s water volume, indicating a high evaporation rate and the release of gases and ash. The SO4 2−/Cl− ratio was relatively constant, with no increase in activity and that meant that it was safe for tourism, based on the physicochemical characteristics of the hyperacid crater lake.

This study aimed to identify, via questionnaire, the landscape preferences of 336 pre-service teachers—219 from a metropolitan area in Portugal and 117 from a rural area in Spain. Eight natural landscapes were assessed, each characterised by geodiversity, biodiversity, and cultural features. Overall, Portuguese students showed stronger preferences, possibly due to Spanish students’ familiarity with natural surroundings. Landscapes featuring geodiversity with water bodies (such as cascades and caldera lakes) were most favoured, while biodiversity-rich landscapes were preferred over those with only geodiversity. Both groups expressed a stronger commitment to landscape preservation than to their preferences, showing a moderate to weak correlation between these factors. Animals significantly attracted interest, and when various natural elements were present, geodiversity features tended to be less noticed. Positive emotions were generally associated with the landscapes, though some geological features and educational values were underappreciated. Suggestions for integrating these insights into teacher training are included.

Seasonal control on phreatic activity of the crater lake of Copahue volcano during the 2018–2022 eruptive cycle