From molecular hypotheses to valid species: description of three endemic species of Baetis (Ephemeroptera: Baetidae) from the Canary Islands

Baetis (Rhodobaetis) canariensis s.l. was considered to be the most common species of mayfly (Ephemeroptera) in running waters of the Canary Islands. Recent studies using mitochondrial genetic markers suggested that what was considered a single species was in fact composed of four closely related, but distinct species. Here we present the results of comprehensive morphological analysis of specimens from Tenerife, Gran Canaria, La Palma, and La Gomera that confirms the validity of the four species based on small but consistent differences in some characters. Three of these are new species and are described herein at the larval stage. Each of the four species appears to be restricted to a single island. The loss of freshwater habitats on the islands has led to a drastically diminished distribution and these species are largely restricted to protected areas in national parks. All four species must be considered endangered and are very sensitive sentinels of the state of conservation of running waters

Histone H3.3 beyond cancer: Germline mutations in Histone 3 Family 3A and 3B cause a previously unidentified neurodegenerative disorder in 46 patients

Although somatic mutations in Histone 3.3 (H3.3) are well-studied drivers of oncogenesis, the role of germline mutations remains unreported. We analyze 46 patients bearing de novo germline mutations in histone 3 family 3A (H3F3A) or H3F3B with progressive neurologic dysfunction and congenital anomalies without malignancies. Molecular modeling of all 37 variants demonstrated clear disruptions in interactions with DNA, other histones, and histone chaperone proteins. Patient histone posttranslational modifications (PTMs) analysis revealed notably aberrant local PTM patterns distinct from the somatic lysine mutations that cause global PTM dysregulation. RNA sequencing on patient cells demonstrated up-regulated gene expression related to mitosis and cell division, and cellular assays confirmed an increased proliferative capacity. A zebrafish model showed craniofacial anomalies and a defect in Foxd3-derived glia. These data suggest that the mechanism of germline mutations are distinct from cancer-associated somatic histone mutations but may converge on control of cell proliferation

Endemism and diversification in freshwater insects of Madagascar revealed by coalescent and phylogenetic analysis of museum and field collections.

The biodiversity and endemism of Madagascar are among the most extraordinary and endangered in the world. This includes the island's freshwater biodiversity, although detailed knowledge of the diversity, endemism, and biogeographic origin of freshwater invertebrates is lacking. The aquatic immature stages of mayflies (Ephemeroptera) are widely used as bio-indicators and form an important component of Malagasy freshwater biodiversity. Many species are thought to be microendemics, restricted to single river basins in forested areas, making them particularly sensitive to habitat reduction and degradation. The Heptageniidae are a globally diverse family of mayflies (>500 species) but remain practically unknown in Madagascar except for two species described in 1996. The standard approach to understanding their diversity, endemism, and origin would require extensive field sampling on several continents and years of taxonomic work followed by phylogenetic analysis. Here we circumvent this using museum collections and freshly collected individuals in a combined approach of DNA taxonomy and phylogeny. The coalescent-based GMYC analysis of DNA barcode data (mitochondrial COI) revealed 14 putative species on Madagascar, 70% of which were microendemics. A phylogenetic analysis that included African and Asian species and data from two mitochondrial and four nuclear loci indicated the Malagasy Heptageniidae are monophyletic and sister to African species. The genus Compsoneuria is shown to be paraphyletic and the genus Notonurus is reinstalled for African and Malagasy species previously placed in Compsoneuria. A molecular clock excluded a Gondwanan vicariance origin and instead favoured a more recent overseas colonization of Madagascar. The observed monophyly and high microendemism highlight their conservation importance and suggest the DNA-based approach can rapidly provide information on the diversity, endemism, and origin of freshwater biodiversity. Our results underline the important role that museum collections can play in molecular studies, especially in critically endangered biodiversity hotspots like Madagascar where entire species or populations may go extinct very quickly

Effects of artificial light at night on benthic primary producers in freshwaters

In recent decades, the use of artificial nocturnal illumination has rapidly increased worldwide, leading to light pollution in many areas – an increase of nocturnal light above natural levels, and a disruption of natural light/dark cycles. This widespread alteration of the natural light regime by artificial light at night (ALAN) contributes to global environmental change and raises concerns about potentially adverse effects in illuminated ecosystems. Ecological studies on ALAN report effects on a range of organisms along the food chain, however they have largely focused on nocturnal animals and terrestrial ecosystems. Effects on aquatic ecosystems, and in particular on primary producers, remain relatively understudied. We conducted manipulative field experiments in two different freshwater systems: a flume system on a sub-alpine stream and a lowland agricultural drainage ditch. We mimicked light conditions of urban and suburban areas (approx. 20 lux at the water surface) using white LED or high-pressure sodium (HPS) lamps and compared biomass and community composition of periphyton exposed to ALAN to those of periphyton grown under natural night lights. Nocturnal LED illumination over three to six weeks decreased the biomass of phytobenthos in both aquatic systems. In stream phytobenthos, LED illumination also changed proportions of diatoms and cyanobacteria in contrasting patterns that depended on periphyton growth stage and season. We found no impact of the nocturnal HPS illumination on the periphyton. We also show that ALAN can significantly impact primary producers in reality, with yet unknown consequences for higher trophic levels and/or ecosystem functions

Does light pollution affect benthic primary producers in shallow streams?

The spread of the electrical artificial lighting worldwide continues to introduce artificial light at night into the environments that have not experienced nighttime illumination before, such as freshwater ecosystems adjacent to urban settlements. Light properties greatly influence photosynthesis and community structure and phenology of primary producers in aquatic systems, therefore changes in light quality, duration, intensity and natural light/dark patterns can potentially have numerous effects on these communities. We simulated night-time irradiance levels comparable with near shore street lighting in outdoor flume simulations to explore how artificial light at night may affect benthic primary producers. We measured biomass and community composition of autotrophs in biofilms at two different colonization stages in two seasons (spring and fall) and evaluated their susceptibility to altered light conditions. Biofilms at early colonization stages responded to nighttime illumination treatment with reduced biomass and increase in diatom content, compared to the biofilms grown under natural dark-light cycles. The responses were highly seasondependent. Contrastingly, pre-established communities were found to be resilient to the illumination treatment. Having in mind the important role of autotrophs in primary production and food webs, we conclude that aquatic systems dominated by biofilms in early colonization stages, such as shallow streams recovering after physical disturbances, may be particularly sensitive to light pollution

A pigment composition analysis reveals community changes in preestablished stream periphyton under low-level artificial light at night

Freshwaters are increasingly exposed to artificial light at night (ALAN), yet the consequences for aquatic primary producers remain largely unknown. We used stream-side flumes to expose three-week-old periphyton to LED light. Pigment composition was used to infer community changes in LED-lit and control periphyton before and after three weeks of treatment. The proportion of diatoms/chrysophytes decreased (14%) and cyanobacteria increased (17%) in lit periphyton in spring. This may reduce periphyton nutritional quality in artificially-lit waters

Artificial light at night affects biomass and community composition of freshwater primary producers

Artificial light at night is increasingly recognized as a contributor to environmental change at the global scale (Cinzano, Falchi & Elvidge, 2001) and a biodiversity threat (Hölker et al. 2010). Increasing research efforts have demonstrated numerous adverse effects on aquatic and terrestrial animals (e.g. Moore et al. 2000; Perkin et al. 2014), microorganisms (Poulin et al. 2013; Hölker et al. 2015) and plants (Bennie et al. 2015). Aquatic primary producers, however, have rarely been studied, and our understanding of ecological effects on benthic autotrophs remains limited. Diatoms, green algae and cyanobacteria grow attached to underwater surfaces and form the basis of the food web in many streams and clear, shallow waters (Stevenson 1996). They use light both as a source of energy for photosynthesis and growth, and as an information cue for the regulation of physiological processes, especially those that display a circadian rhythm (Kianianmomeni & Hallmann 2014). Further, the major autotroph groups differ in their preferences for light conditions (Richardson et al. 1983), therefore the alteration of light regimes may cause changes in community composition. We conducted experiments in two different freshwater systems: an outdoor flume system mimicking a sub-alpine stream (Bruno et al. 2016; Fig.1) and a lowland agricultural drainage ditch, the Westhavelland experimental site (Holzhauer et al. 2015; Fig.2). We simulated the night-time light conditions of a waterbody in a light-polluted area (approx. 20 and 58 lux), and compared the biomass and community composition of benthic autotrophs with those grown under natural nights. The experiments were performed in different seasons in both ecosystems in order to account for seasonal differences in community composition. Two light sources, white LEDs and high-pressure sodium (HPS) lamps, were used in the experiments in the Westhavelland site while only white LEDs were used in the sub-alpine stream. The LED-based nighttime illumination resulted in a decrease of autotroph biomass in both aquatic systems. Community composition was affected by both LED and HPS illumination but the effect varied between the systems, seasons, and developmental stage of the community. Primary producers responded less strongly to HPS than LED-based illumination, likely a result of different spectral composition. Our results show that artificial light can have profound effects on the primary producers of aquatic ecosystems. By negatively affecting the establishment of benthic autotrophs artificial light at night may impact the resilience of aquatic ecosystems. This effect is likely to increase with the current shift from sodium lights to white LED

Effects of artificial light at night (ALAN) on alpine stream periphyton: a flume simulation

Artificial light at night (ALAN) is one of the most widespread human-induced alterations of the landscape, it is increasingly recognized as a contributor to environmental change and a threat to biodiversity at the global scale. Increasing research efforts have demonstrated numerous adverse effects on aquatic and terrestrial animals, microorganisms and plants. Aquatic primary producers, however, have rarely been studied, and our understanding of ecological effects on benthic autotrophs remains limited. Benthic autotrophs, such as diatoms, green algae and cyanobacteria, grow attached to underwater surfaces within complex periphyton communities and form the basis of the food web in many streams and clear, shallow waters. They use light both as a source of energy as well as a source of information for the regulation of physiological processes according to light/dark cycles. The main autotroph groups differ in their preferences for light conditions, therefore the alteration of light regimes may cause changes in periphyton growth and community composition. We conducted experiments in an outdoor flume system mimicking a sub-alpine stream (Trentino, NE Italy). We simulated the night-time light conditions of a waterbody in a light-polluted area (approx. 20 lux), and compared the biomass and community composition of benthic autotrophs in periphyton grown under ALAN with those grown under natural nights. The experiments were performed in two seasons in order to account for seasonal differences in community composition. The LED-based nighttime illumination resulted in a decrease of autotroph biomass and an increase in the proportion of diatoms. The effects depended on the season and the growth stage of the periphyton, indicating higher sensitivity to ALAN exposure in early growth stages (one to three weeks) compared to the later ones (four to seven weeks). Our results show that artificial light can have profound effects on the primary producers of aquatic ecosystems. By negatively affecting the biomass and altering community composition, artificial light at night may hinder primary production, which is a vital ecosystem function. Streams with frequent flooding events, droughts, sediment transport or physical perturbations that all reset the development of periphyton are expected to be more affected by ALAN than those with stable conditions. ALAN may therefore negatively impact the resilience of aquatic ecosystems

Artificial light at night decreases biomass and alters community composition of benthic primary producers in a sub-alpine stream

Artificial light at night (ALAN) is recognized as a contributor to environmental change and a biodiversity threat on a global scale. Despite its widespread use and numerous potential ecological effects, few studies have investigated the impacts on aquatic ecosystems and primary producers. Light is a source of energy and information for benthic autotrophs that form the basis of food webs in clear, shallow waters. Artificial night-time illumination may thus affect biomass and community composition of primary producers. We experimentally mimicked the light conditions of a light-polluted area (approximately 20 lux, white LED) in streamside flumes on a sub-alpine stream. We compared the biomass and community composition of periphyton grown under ALAN with periphyton grown under a natural light regime in two seasons using communities in early (up to 3 weeks) and later (4–6 weeks) developmental stages. In early periphyton, ALAN decreased the biomass of autotrophs in both spring (57% at 3 weeks) and autumn (43% at 2 weeks), decreased the proportion of cyanobacteria in spring (54%), and altered the proportion of diatoms in autumn (11% decrease at 2 weeks and 5% increase at 3 weeks). No effects of ALAN were observed for later periphyton. Further work is needed to test whether streams with frequent physical disturbances that reset the successional development of periphyton are more affected by ALAN than streams with more stable conditions. As periphyton is a fundamental component of stream ecosystems, the impact of ALAN might propagate to higher trophic levels and/or affect critical ecosystem functions