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Paris was at the forefront of public bike-sharing schemes, and it now has electric car-sharing schemes and is something of a laboratory for mobility. As of today, motorists with cars built before 1997, and motorcycles built before 2000, will no longer be able to drive them in the city during daylight hours on weekdays.

Paris Mayor Anne Hidalgo says keeping old cars out of the city will help lower pollution levels. But not everyone is happy about it.

Marc Vernhet makes his living driving tourists around Paris in the classic French car known as the Deux Chevaux, or two-horse power. Peugeot Citroen no longer makes the model, but for collectors, it's a nostalgic symbol of the good old days. Vernhet says tourists from all over the world want to ride in them.

Engineers at Oregon State University have created a new computer modeling package that people anywhere in the world could use to assess the potential of a stream for small-scale, “run of river” hydropower, an option to produce electricity that’s of special importance in the developing world.

The system is easy to use; does not require data that is often unavailable in foreign countries or remote locations; and can consider hydropower potential not only now, but in the future as projected changes in climate and stream runoff occur.

Especies en todo el mundo van rápidamente extinguiéndose debido a la actividad humana, pero los humanos también están causando una rápida evolución y la aparición de nuevas especies. Un nuevo estudio publicado hoy, resume las causas de la especiación hecha por el hombre y se explica por qué las especies de reciente evolución simplemente no pueden sustituir a las especies silvestres extintas. El estudio fue dirigido por el Centro de Macroecología, Evolución y Clima de la Universidad de Copenhague.

Climate change is already affecting inland fish across North America -- including some fish that are popular with anglers. Scientists are seeing a variety of changes in how inland fish reproduce, grow and where they can live, according to four new studies published today in a special issue of Fisheries magazine.

Fish that have the most documented risk include those living in arid environments and coldwater species such as sockeye salmon, lake trout, walleye, and prey fish that larger species depend on for food.

Climate change can cause suboptimal habitat for some fish; warmer water, for example, can stress coldwater fish. When stressed, fish tend to eat less and grow less. For other fish, climate change is creating more suitable habitat; smallmouth bass populations, for example, are expanding.

Las tuberías que transportan petróleo crudo a puertos en Columbia Británica pueden significar malas noticias para el salmón, según un nuevo estudio liderado por la Universidad de Guelph. La exposición a un producto de arenas bituminosas (betún diluido) que deteriora la capacidad para nadar y cambia las estructuras del corazón de los salmones jóvenes. La investigación será publicada en la revista Environmental Toxicology and Chemistry, y está disponible en línea.