Peter D. Roopnarine

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Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a(More)
1. The effects of added phosphorus (P) on the growth, P and RNA : DNA contents, and survivorship of snails grazing on laminated microbial mats (living ‘stromatolites’) were examined in the Rio Mesquites at Cuatro Ciénegas, Mexico (total P, c. 0.60 lmol L) to test the hypothesis that strong P-limitation of microautotroph growth produces a stoichiometric(More)
Studies of the end-Permian mass extinction have emphasized potential abiotic causes and their direct biotic effects. Less attention has been devoted to secondary extinctions resulting from ecological crises and the effect of community structure on such extinctions. Here we use a trophic network model that combines topological and dynamic approaches to(More)
We describe a new method for the calculation of river flow that uses the oxygen isotope composition of bivalve mollusk shells that grew in the river-water/seawater mixing zone of the Colorado River estuary. Sclerochronological techniques are used to identify tidally-induced, fortnight-scale bundles of daily growth increments within shell cross-sections.(More)
The fossil record presents palaeoecological patterns of rise and fall on multiple scales of time and biological organization. Here, we argue that the rise and fall of species can result from a tragedy of the commons, wherein the pursuit of self-interests by individual agents in a larger interactive system is detrimental to the overall performance or(More)
The sudden environmental catastrophe in the wake of the end-Cretaceous asteroid impact had drastic effects that rippled through animal communities. To explore how these effects may have been exacerbated by prior ecological changes, we used a food-web model to simulate the effects of primary productivity disruptions, such as those predicted to result from an(More)
J BRET BENNINGTON,1* WILLIAM A. DIMICHELE,2 CATHERINE BADGLEY,3 RICHARD K. BAMBACH,2 PAUL M. BARRETT,4 ANNA K. BEHRENSMEYER,2 RENÉ BOBE,5 ROBYN J. BURNHAM,3 EDWARD B. DAESCHLER,6 JAN VAN DAM,7 JUSSI T. ERONEN,8 DOUGLAS H. ERWIN,2 SETH FINNEGAN,9 STEVEN M. HOLLAND,5 GENE HUNT,2 DAVID JABLONSKI,10 STEPHEN T. JACKSON,11 BONNIE F. JACOBS,12 SUSAN M. KIDWELL,10(More)
Anthropogenic climate change is predicted to decrease oceanic oxygen (O2) concentrations, with potentially significant effects on marine ecosystems. Geologically recent episodes of abrupt climatic warming provide opportunities to assess the effects of changing oxygenation on marine communities. Thus far, this knowledge has been largely restricted to(More)
The fossil record contains exemplars of extreme biodiversity crises. Here, we examined the stability of terrestrial paleocommunities from South Africa during Earth's most severe mass extinction, the Permian-Triassic. We show that stability depended critically on functional diversity and patterns of guild interaction, regardless of species richness.(More)