The effect of toxic Microcystis aeruginosa on four different populations of Daphnia

Cyanobacteria reduce the fitness of many Daphnia species, and blooms in eutrophic lakes may place strong selective pressure upon these primary consumers. This study examines the ability of daphnids to resist the deleterious effects of toxic Microcystis and determine if this resistance is related to the trophic conditions of their native lakes. Three populations of Daphnia pulex/pulicaria were examined; D. pulicaria from eutrophic Klamath Lake in Oregon, D. pulex from eutrophic Old Durham Reservoir in New Hampshire, and D. pulicaria from oligotrophic Russell Pond in New Hampshire. D. carinata from meso-oligotrophic Lake Rotoaira in New Zealand was used as a known cyanobacteria-sensitive species. Ten-day old 5th-6th instar animals were exposed to a mixture of Microcystis aeruginosa and Chlorella vulgaris (25% and 100% M. aeruginosa). Body length, lipid index, reproductive index and clearance rate were assessed for each population after 120 hours of treatment. A feeding bioassay response quantifying the energetic (feeding rate) cost of post abdominal rejections was also determined for a gradient of M. aeruginosa concentrations from 0% to 100%. The four populations of Daphnia exhibited different rates of decline in overall fitness when exposed to Microcystis. Populations exposed to Microcystis exhibited reduced thoracic beat rate, lower lipid and reproductive indexes, and higher cost of post abdominal rejections in comparison to daphnids in the control Chlorella. Length was not a sensitive indicator of fitness level. D. pulex from eutrophic Klamath Lake had a mean clearance rate in 100% Microcystis that was three to four times higher than D. pulicaria from oligotrophic Russell Pond. In general, daphnids from oligotrophic lakes exhibited a more drastic decline in fitness than daphnids from eutrophic lakes. This suggests that taxonomically related populations of Daphnia have evolved a suite of adaptations to Microcystis depending upon their history of exposure

Bindings as bounded natural functors

We present a general framework for specifying and reasoning about syntax with bindings. Abstract binder types are modeled using a universe of functors on sets, subject to a number of operations that can be used to construct complex binding patterns and binding-aware datatypes, including non-well-founded and infinitely branching types, in a modular fashion. Despite not committing to any syntactic format, the framework is “concrete” enough to provide definitions of the fundamental operators on terms (free variables, alpha-equivalence, and capture-avoiding substitution) and reasoning and definition principles. This work is compatible with classical higher-order logic and has been formalized in the proof assistant Isabelle/HOL

Are we approaching pit lake closure from the wrong perspective?

Pit lakes are similar to natural lakes formed by faulting, glacial action, volcanic action and asteroid collisions. These natural lakes have, after thousands of years, developed into environmentally significant ecosystems. As artificial constructs, pit lakes can be modified prior to filling to enhance lake attributes, such as modification of catchment size, creation of littoral zones and addition of organic matter. Significant advances could be made in successful closure and relinquishment of pit lakes, by 1) choosing appropriate model lakes, 2) understanding successional processes, 3) designing pit lakes to enhance ecological values, and 4) recognizing that it will take time to develop desired characteristics

Pit lakes are a global legacy of mining: an integrated approach to achieving sustainable ecosystems and value for communities

The impact of large-scale mining on the landscape is a permanent legacy of industrialisation and unique to the Anthropocene. Thousands of lakes created from the flooding of abandoned open-cut mines occur across every inhabited continent and many of these lakes are toxic, posing risks to adjacent communities and ecosystems. Sustainable plans to improve water quality and biodiversity in ‘pit lakes’ do not exist due to: (1) confusion as to the ultimate use of these lakes, (2) involvement of ecologists only after the lake is filled and (3) pit lake ecology struggling to reach the primary literature. An integrated approach to pit lake management engages ecologists in pit lake design, prioritising ecological progress and passive treatment in mine closure planning, ultimately empowering communities with post-mining options

Closing pit lakes as aquatic ecosystems: Risk, reality, and future uses

Mine pit lakes are formed when open-cut pits flood with water, and these lakes occur by the thousands on every inhabited continent. The remediation and closure of pit lakes is a pressing issue for sustainable development and provision of freshwater ecosystem services. While pit lakes can be spectacular examples of recreation and renewal, pit lakes may be better known for their poor water qualities and risks to communities and the environment. Often the public wants to simply “fill the pits in” to restore a terrestrial landscape, but this is not always possible. Therefore, planning for remediation and future uses is likely to provide the best outcome. Poor water quality is not necessarily a barrier to future use, although it may limit the number of uses. Short-term future uses tend to require commercial viability, active infrastructure investment, and maintenance, and should transition to complementary long-term uses that promote biodiversity. Long-term future uses require relatively less ongoing maintenance beyond the initial investment and adhere to the principles that pit lakes should be safe, sustainable, and non-polluting in perpetuity. Pit lakes will eventually develop “ecosystem values,” and the time to do so depends on the nature of the intervention and the values ascribed by the community. Where possible, closing pit lakes as sustainable ecosystems is the most realistic goal that permits a variety of future uses that is likely to see pit lakes valued by future generations. This article is categorized under: Engineering Water \u3e Planning Water Human Water \u3e Value of Water Human Water \u3e Water as Imagined and Represente

Aquatic ecosystems of the anthropocene: Limnology and microbial ecology of mine pit lakes

Mine pit lakes (‘pit lakes’) are new aquatic ecosystems of the Anthropocene. Potentially hundreds of meters deep, these lakes are prominent in the landscape and in the public consciousness. However, the ecology of pit lakes is underrepresented in the literature. The broad goal of this research was to determine the environmental drivers of pelagic microbe assemblages in Australian coal pit lakes. The overall experimental design was four lakes sampled three times, top and bottom, in 2019. Instrument chains were installed in lakes and measurements of in situ water quality and water samples for metals, metalloids, nutrients and microbe assemblage were collected. Lakes were monomictic and the timing of mixing was influenced by high rainfall events. Water quality and microbial assemblages varied significantly across space and time, and most taxa were rare. Lakes were moderately saline and circumneutral; Archeans were not prevalent. Richness also varied by catchment. Microbial assemblages correlated to environmental variables, and no one variable was consistently significant, spatially or temporally. Study lakes were dominated by ‘core’ taxa exhibiting temporal turnover likely driven by geography, water quality and interspecific competition, and the presence of water chemistry associated with an artificial aquifer likely influenced microbial community composition. Pit lakes are deceptively complex aquatic ecosystems that host equally complex pelagic microbial communities. This research established links between microbial assemblages and environmental variables in pit lakes and determined core communities; the first steps towards developing a monitoring program using microbes

Interactive Simplifier Tracing and Debugging in Isabelle

The Isabelle proof assistant comes equipped with a very powerful tactic for term simplification. While tremendously useful, the results of simplifying a term do not always match the user's expectation: sometimes, the resulting term is not in the form the user expected, or the simplifier fails to apply a rule. We describe a new, interactive tracing facility which offers insight into the hierarchical structure of the simplification with user-defined filtering, memoization and search. The new simplifier trace is integrated into the Isabelle/jEdit Prover IDE.Comment: Conferences on Intelligent Computer Mathematics, 201

Concrete Semantics with Coq and CoqHammer

The "Concrete Semantics" book gives an introduction to imperative programming languages accompanied by an Isabelle/HOL formalization. In this paper we discuss a re-formalization of the book using the Coq proof assistant. In order to achieve a similar brevity of the formal text we extensively use CoqHammer, as well as Coq Ltac-level automation. We compare the formalization efficiency, compactness, and the readability of the proof scripts originating from a Coq re-formalization of two chapters from the book

ENIGMA: Efficient Learning-based Inference Guiding Machine

ENIGMA is a learning-based method for guiding given clause selection in saturation-based theorem provers. Clauses from many proof searches are classified as positive and negative based on their participation in the proofs. An efficient classification model is trained on this data, using fast feature-based characterization of the clauses . The learned model is then tightly linked with the core prover and used as a basis of a new parameterized evaluation heuristic that provides fast ranking of all generated clauses. The approach is evaluated on the E prover and the CASC 2016 AIM benchmark, showing a large increase of E's performance.Comment: Submitted to LPAR 201