Climate simulation of the latest Permian: Implications for mass extinction

This report presents the results of climate modeling research which indicates that elevated levels of carbon dioxide in the atmosphere at the end of the Permian period led to climatic conditions inhospitable to both marine and terrestrial life. The Permian-Triassic boundary (about 251 million years ago) was the time of the largest known mass extinction in Earth's history, when greater than ninety percent of all marine species, and approximately seventy percent of all terrestrial species, died out. The model, which used paleogeography and paleotopography correct for the time period, indicated that warm high-latitude surface air temperatures and elevated carbon dioxide levels may have resulted in slowed circulation and stagnant, anoxic conditions in Earth's oceans. The report also suggests that the excess carbon dioxide (and sulfur dioxide) may have originated from volcanic activity associated with eruption of the Siberian Trap flood basalts, which took place at the same time. Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

Evaluation of three telemetry transmitter attachment methods for female silver-phase American eels ( Anguilla rostrata Lesueur)

Northern Lake Tanganyika is characterized by an almost permanently stratified water column which causes severe nutrient depletion in surface waters. Any external N source to surface waters, therefore, is of importance in sustaining primary production. This study attempted to quantify riverine input of dissolved inorganic nitrogen (DIN) to the extreme northern end of Lake Tanganyika (surface - 900 km2) as well as the DIN uptake by surface phytoplankton. Results showed that riverine DIN inputs (1,930 tons of N/year) were of similar importance to atmospheric deposition (1,520 to 1,720 tons of N/year) and were maximal during the dry season. Moreover, seasonal DIN variations in river and lake waters showed maximum concentrations during part of the dry season (May to July 1999) probably due to high atmospheric inputs. Phytoplanktonic nitrate and ammonium uptake rates were measured during nine cruises and varied from 0.01 to 19.3 nM/h. These values suggest that uptake by phytoplankton in the surface waters could represent a DIN sink of about 14,400 tons of N/year, thereby utilizing all available DIN coming in from external sources. External DIN sources represent approximately 25% of the annual phytoplankton N requirements, showing the major importance of unquantified N sources in sustaining primary production in the northern basin of Lake Tanganyika. These sources could include organic N present in the external sources, and internal N supply.SCOPUS: ar.jinfo:eu-repo/semantics/publishe