Macrophyte Community Dynamics in Lake Simcoe’s Fringe Wetlands: Potential use as Biological Indicators of Water Quality

Indices have been developed using macrophytes and water quality parameters to detect the impact of anthropogenic disturbance on coastal wetlands of the Great Lakes, but such an index does not currently exist for Lake Simcoe. As wetland macrophytes are influenced by water quality, any impairment in wetland quality should be reflected by taxonomic composition, biomass and dynamics of the macrophyte community. This study investigates the potential use of macrophytes as a tool for monitoring water quality by examining the dynamics (species richness, density, diversity, and above-ground biomass) in emergent macrophyte communities in fringe wetlands around Lake Simcoe exposed to contrasting degrees of disturbance. Macrophytes and limnologic data were collected from six wetlands over four seasons from 2013 – 2014. The macrophytes were identified to species and limnologic data was quantified to reflect the water quality, which was measured as a proxy for site disturbance. Wetlands in this study correspond to a wide range of environmental conditions, ranging from very clear and nutrient poor oligotrophic conditions (e.g., TP =11.25 µg/L, TN = 345.25 µg/L, CHL a =1.37 mg·m-3) to turbid and eutrophic wetlands (e.g., TP = 47.25 µg/L, TN = 2285 µg/L, CHL a = 3.26 mg·m-3. Overall, the limnologic parameters indicated that water quality reflected the degree of anthropogenic degradation influencing the wetland. Taxonomic composition and population dynamics reflected the water quality. The least disturbed site was dominated by native Scirpus acutus and Scirpus pungens, which are mostly intolerant of environmental degradation, as well as the cosmopolitan Sparganium eurycarpum, found in all sites and tolerant of many different conditions. The moderately disturbed sites were dominated by both intolerant and tolerant species, including Scirpus acutus, Leersia oryzoides, Eleocharis smallii, Typha x glauca, Typha angustifolia, and Sparganium eurycarpum. The highly disturbed sites were also dominated by Sparganium eurycarpum, and species that are considered to be invasive, aggressive, and/or very tolerant of degradation, including Typha x glauca, Typha angustifolia, Phragmites australis, and Calamagrostis canadensis. These species are indicator species of wetland integrity and their relationship with the limnologic parameters as determined by ordination demonstrated responses that were consistent with the literature. Thus this study validates that macrophytes could be used as an indicator of water quality changes in this study area

Biomineral electron backscatter diffraction for palaeontology

Electron backscatter diffraction (EBSD) originated in materials science and has transferred to biomineral research providing insight into fossil and modern biominerals. An electron microscopy technique, EBSD requires a fine polished sample surface where the electron beam diffracts in the first few lattice layers, identifying mineral, polymorph and crystallographic orientation. The technique is particularly well suited for the analysis of modern and fossil calcium carbonate biominerals, where it provides key insight into biological control of mineral formation such as in molluscs and brachiopods. EBSD readily identifies original and secondary mineralogy, which helps to inform our understanding of biomineral evolution such as the identification of original aragonite in Silurian trimerellid brachiopods. As a technique to identify and thus avoid the inclusion of secondary minerals in proxy organisms such as corals, EBSD can be used to ensure accuracy of palaeoproxy data. Even when fossil systems have no modern equivalents, EBSD can provide key data to determine functional mechanisms such as in the lenses of schizochroal eyes of phacopine trilobites. These few examples illustrate that EBSD is proving to be a valuable component of the palaeontology toolkit

Digestive and appendicular soft-parts, with behavioural implications, in a large Ordovician trilobite from the Fezouata Lagerstätte, Morocco

Trilobites were one of the most successful groups of marine arthropods during the Palaeozoic era, yet their soft-part anatomy is only known from a few exceptionally-preserved specimens found in a handful of localities from the Cambrian to the Devonian. This is because, even if the sclerotized appendages were not destroyed during early taphonomic stages, they are often overprinted by the three-dimensional, mineralised exoskeleton. Inferences about the ventral anatomy and behavioural activities of trilobites can also be derived from the ichnological record, which suggests that most Cruziana and Rusophycus trace fossils were possibly produced by the actions of trilobites. Three specimens of the asaphid trilobite Megistaspis (Ekeraspis) hammondi, have been discovered in the Lower Ordovician Fezouata Konservat-Lagerstätte of southern Morocco, preserving appendages and digestive tract. The digestive structures include a crop with digestive caeca, while the appendages display exopodal setae and slight heteropody (cephalic endopods larger and more spinose than thoracic and pygidial ones). The combination of these digestive structures and the heteropody has never been described together among trilobites, and the latter could assist in the understanding of the production of certain comb-like traces of the Cruziana rugosa group, which are extraordinarily abundant on the shallow marine shelves around Gondwana.This work has been supported by the Spanish Ministry of Economy and Competitiveness, project number CGL2012- 39471/BTE.Peer reviewe

Global Taxonomic Diversity of Anomodonts (Tetrapoda, Therapsida) and the Terrestrial Rock Record Across the Permian-Triassic Boundary

The end-Permian biotic crisis (∼252.5 Ma) represents the most severe extinction event in Earth's history. This paper investigates diversity patterns in Anomodontia, an extinct group of therapsid synapsids (‘mammal-like reptiles’), through time and in particular across this event. As herbivores and the dominant terrestrial tetrapods of their time, anomodonts play a central role in assessing the impact of the end-Permian extinction on terrestrial ecosystems. Taxonomic diversity analysis reveals that anomodonts experienced three distinct phases of diversification interrupted by the same number of extinctions, i.e. an end-Guadalupian, an end-Permian, and a mid-Triassic extinction. A positive correlation between the number of taxa and the number of formations per time interval shows that anomodont diversity is biased by the Permian-Triassic terrestrial rock record. Normalized diversity curves indicate that anomodont richness continuously declines from the Middle Permian to the Late Triassic, but also reveals all three extinction events. Taxonomic rates (origination and extinction) indicate that the end-Guadalupian and end-Permian extinctions were driven by increased rates of extinction as well as low origination rates. However, this pattern is not evident at the final decline of anomodont diversity during the Middle Triassic. Therefore, it remains unclear whether the Middle Triassic extinction represents a gradual or abrupt event that is unique to anomodonts or more common among terrestrial tetrapods. The end-Permian extinction represents the most distinct event in terms of decline in anomodont richness and turnover rates

Proposed use of the Plenary Powers to suppress the generic name Asaphus as published by Brongniart in Desmarest, 1817, and to designate a type species in harmony with general usage for the genus Asaphus Brongniart, 1822 (Class Trilobita)

Volume: 12Start Page: 90End Page: 9

Proposed use of the Plenary Powers to designate a type species in harmony with generally accepted usage for the genus Ptychopyge Angelin, 1854 (Class Trilobita)

Volume: 11Start Page: 359End Page: 36

Proposed use of the Plenary Powers to suppress the generic name Cryptonymus Eich-wald, 1825 (Class Trilobita) for purposes of the Law of Priority but not for those of the Law of Homonymy

Volume: 12Start Page: 60End Page: 6