Consistent identification of diatoms is a prerequisite for studying their ecology, biogeography, and successful application as environmental indicators. However, taxonomic consistency among observers has been difficult to achieve because taxonomic information is scattered across numerous literature sources, presenting challenges to the diatomist. Firstly, literature is often inaccessible because of cost or its location in journals that are not widely circulated. Secondly, taxonomic revisions of diatoms are taking place faster than floras can be updated. Finally, taxonomic information is often contradictory across literature sources. These issues can be addressed by developing a content creation community dedicated to making taxonomic, ecological, and image-based data freely available for diatom researchers. Diatoms.org represents such a content curation community, providing open, online access to a vast amount of recent and historical information on North American diatom taxonomy and ecology. The content curation community aggregates existing taxonomic information, creates new content, and provides feedback in the form of corrections and notices of literature with nomenclatural changes. The website not only addresses the needs of experienced diatom scientists for consistent identification but is also designed to meet users at their level of expertise, including engaging the lay public in the importance of diatom science. The website now contains over 1000 species pages contributed by over 100 content contributors, from students to established scientists. The project began with the intent to provide accurate information on diatom identification, ecology, and distribution using an approach that incorporates engaging design, user feedback, and advanced data access technology. In retrospect, the project that began as an ‘extended electronic book’ has emerged not only as a means to support taxonomists, but for practitioners to communicate and collaborate, expanding the size of and benefits to the content curation community. In this paper, we outline the development of diatoms.org, document key elements of the project, examine ongoing challenges and consider the unexpected emergent properties, including the value of diatoms.org as a source of data. Ultimately, if the field of diatom taxonomy, ecology, and biodiversity is to be relevant, a new generation of taxonomists needs to be trained and employed using new tools. We propose that diatoms.org is in a key position to serve as a hub of training and continuity for the study of diatom biodiversity and aquatic conditions.

To determine the influence of water level drawdown on littoral areas, we compared the temporal and spatial changes in the water column and sediment in the littoral region of a drinking water reservoir and a natural lake. The reservoir (Sooke) experiences more than six meters of seasonal drawdown compared to a nearby, morphometrically and trophically similar lake (Shawnigan) that experiences less than one meter of drawdown. A greater drawdown in Sooke increased the littoral area and resulted in more littoral water column mixing, more solar warming, and higher PAR at a greater range of littoral depths than in Shawnigan. Based on sediment physical and chemical characteristics, sites farthest from shore were most similar, whereas sites in the drawdown exposure zone of Sooke and the upper littoral area of Shawnigan showed the largest differences. Low macrophyte abundance and loss of fine sediments, nutrients, and organic matter from the drawdown exposure zone in Sooke compared to the equivalent littoral area in Shawnigan suggest that drawdown enhances sediment erosion and focusing. Element and stable isotope ratios of sediment carbon and nitrogen suggest organic matter in the drawdown zone in Sooke is more allochthonous in origin and is coupled more strongly with deeper sites than in Shawnigan. Organic matter source and distribution also suggests that the littoral area extends out farther in Sooke than Shawnigan. This study demonstrates that drawdown has the potential to fundamentally change reservoir littoral sediment and biogeochemical characteristics. Understanding how littoral zones in reservoirs respond to drawdown compared to natural lakes may help water managers make more ecologically informed decisions regarding drawdown impacts on the ecology of littoral zones and water quality.

Littoral benthic macroinvertebrate communities in lake reservoirs often are exposed to repeated fluctuations in water level, but little is known of the effects of drawdown on benthic community composition. We compared the taxonomic composition and spatial patterns of benthic macroinvertebrate communities in sediments of littoral areas in a reservoir with >30 y of seasonal drawdowns (Sooke Lake Reservoir [SLR]) and a natural lake with little seasonal change in water levels (Shawnigan Lake [SHL]). Contrary to our predictions, macroinvertebrate density and biomass usually were greater in SLR than in SHL. In SLR, densities and biomasses of macroinvertebrates, especially chironomids, were higher below the drawdown exposure zone than in the upper littoral area. Chironomids with r-selected survival strategies (i.e., smaller size) or desiccant-resistant stages appeared well suited to the fluctuating environment of littoral zones in reservoirs. Orthocladiinae, Chironomini, Tanytarsini, and Tanypodinae domi...

Examination of algal assemblages from aerial environments around the globe, especially those from pseudoaerial habitats found on moistened rocks underneath waterfalls or around springs and seeps, reveals the presence of unique diatom floras. Yet, diatom assemblages from northern regions like Iceland remain understudied, especially those from the volcanic rock outcrops and boulders that create euaerial habitats where biota receive moisture from the atmosphere or the rock itself. During the summers of 2013 and 2015, we examined the biodiversity of mostly euaerial, but also pseudoaerial, diatom assemblages collected from volcanic rock outcrops or large boulders on the landscape from southwestern Iceland. We used light and scanning electron microscopy to document the biodiversity of common, smaller, new, or interesting specimens, such as Humidophila and Eunotia. We describe one new Humidophila species, H. eldfjallii sp. nov., with triundulate valve margins and include information on another unidentified taxon, Humidophila sp. 1, naviculoid in shape with tapering to rounded ends, continuous striae through the length of the valve, and a circular central area. We formally transfer Diadesmis contenta var. biceps to Humidophila biceps. To correct the nomenclature, we recognized Humidophila parallela at the species level. Relative abundance estimates of diatom populations provided further characterization of the assemblages on these habitats. Humidophila taxa, especially H. gallica dominated the diverse diatom flora. We discuss adaptations for survival with access to mostly atmospheric water. The diatom flora described here adds to the flora for this region, highlights the diversity of diatom assemblages that can inhabit euaerial environments, and provides evidence of adaptive success of diatoms in extreme habitats with limited moisture and nutrients.