Assessing the impacts of nonindigenous marine macroalgae: an update of current knowledge

Nonindigenous marine species continue to be one of the foremost threats to marine biodiversity. As an update to a 2007 review of the impacts of introduced macroalgae, we assessed 142 additional publications to describe species’ impacts as well as to appraise information on the mechanisms of impact. Only 10% of the currently known nonindigenous macroalgal species were subjects of ecological impact studies, with changed community composition as the most commonly reported effect. Economic impacts were rarely published. Recent research has focused on the impacts of introduced macroalgal assemblages: red algal introductions to the Hawaiian Islands and turf algae in the Mediterranean. Several general issues were apparent. First, many publications included nonsignificant results of statistical analyses but did not report associated power. As many of the studies also had low effect and sample size, the potential for type II errors is considerable. Second, there was no widely accepted framework to categorize and compare impacts between studies. Information in this updated review was still too sparse to identify general patterns and mechanisms of impact. This is a critical knowledge gap as rates of introductions and hence impacts of nonindigenous macroalgae are expected to accelerate with climate change and increasing global trade connectivity

Can U.S. oil production survive the 20th century?

The plunge in world oil prices has brought further difficulties to U.S. oil production, which has been declining in recent years. At the current low prices, most domestic oil wells are not profitable. This calls into question the long-run viability of oil production in the United States. Whether oil production remains a viable part of the U.S. economy in the next century will depend on how long oil prices remain at their current low levels.> Lamb and Wilkerson show how the recent low prices for oil on world markets reflect a combination of demand and supply effects, with both short-run and long-run forces at work. For example, sluggish demand growth reflects both milder weather in some parts of the world (a short-run phenomenon) and the impacts of the Asian financial crisis, which could persist for some time. Meanwhile, supply has mushroomed, in part due to the short-run effect of Iraq's return to higher levels of oil production. In the main, however, the increase in supply reflects sharp declines in the cost of discovering and extracting oil reserves. On balance, the current low prices appear to be mainly the result of longer run demand and supply forces, suggesting that prices are likely to remain low for some time to come. If world oil prices do remain low, U.S. oil is unlikely to be competitive in world markets. Therefore, the domestic oil sector is likely to continue to lose market share for the foreseeable future.Petroleum industry and trade ; Prices