Search

The New Zealand mud snail, Potamopyrgus antipodarum, is a widely distributed non-native species of management concern on four continents. In a southern California stream, P. antipodarum abundance, which ranged from ca.

Mediterranean climate ecosystems are among the most fire-prone in the world; however, little is known about the effects of fire on mediterranean streams (med-streams). Fire impacts on med-streams are associated with increased runoff and erosion from severely burned landscapes during storms, particularly the first intense rains. Increased inputs of water, solutes, nutrients, sediment, organic matter, and ash to streams after fires are usually observed for months to up to 4 years. Return to pre-fire conditions is associated with vegetation recovery. Benthic algae, invertebrates, and fish are reduced to low levels by scouring floods after wildfire. If riparian zones are burned, benthic algae increase, and invertebrate communities become dominated by r-strategist species. Fishes are eradicated from reaches affected by intense wildfire and often do not re-colonize quickly because of downstream barriers. In general, med-stream communities appear to be more resilient to fire compared to streams in other ecosystems because of the rapid recovery of mediterranean upland and riparian vegetation and geomorphological conditions (1-4 years in med-streams vs 5-10 years in non-med streams). However, drought or mass sediment movements after fire can prolong fire effects. Studies of the long-term effects of fire and the consequences of fire management practices are still needed. © 2013 Springer Science+Business Media Dordrecht.

Nature News was a newsletter publication about activities at the Cheadle Center for Biodiveristy and Ecological Restoration.

In streams where algivorous fishes abound, striking variation of attached algae often develops along depth gradients, with bands of high standing crops in shallow water (20 cm) water, algae were rapidly consumed by grazing catfish. Catfish were removed from three stream pools and left in place in three control pools. Ten days after catfish removal, algal standing crops in deep and shallow areas of removal pools were similar, while algal standing crops were higher in shallow than in deep areas of control pools. Catfish were exposed to fishing birds in open-topped enclosures. In one of three series of these pens, most catfish in shallow pens (10 and 20 cm) disappeared after 14 days, while catfish in deeper pens (30 and 50 cm) did not. Other groups of catfish which were caged 8 days showed differences in behavior depending on whether they had been fed or starved. After their release into their home pool, starved catfish spent more time feeding than did fed catfish. Despite their apparently increased hunger levels, starved catfish did not venture into shallow water to obtain algae. These results support the view that predator induced avoidance by grazers of certain areas can produce spatial pattern in the flora of flowing water communities. © 1989 Kluwer Academic Publishers.