Declining wild salmon populations in relation to parasites from farm salmon     

Krkosek M  Ford JS  Morton A  Lele S  Myers RA  Lewis MA 《Science (New York, N.Y.)》2007,318(5857):1772-1775

Rather than benefiting wild fish, industrial aquaculture may contribute to declines in ocean fisheries and ecosystems. Farm salmon are commonly infected with salmon lice (Lepeophtheirus salmonis), which are native ectoparasitic copepods. We show that recurrent louse infestations of wild juvenile pink salmon (Oncorhynchus gorbuscha), all associated with salmon farms, have depressed wild pink salmon populations and placed them on a trajectory toward rapid local extinction. The louse-induced mortality of pink salmon is commonly over 80% and exceeds previous fishing mortality. If outbreaks continue, then local extinction is certain, and a 99% collapse in pink salmon population abundance is expected in four salmon generations. These results suggest that salmon farms can cause parasite outbreaks that erode the capacity of a coastal ecosystem to support wild salmon populations.  相似文献   

Radical reactions of c60     

Krusic PJ  Wasserman E  Keizer PN  Morton JR  Preston KF 《Science (New York, N.Y.)》1991,254(5035):1183-1185

Photochemically generated benzyl radicals react with C(60) producing radical and nonradical adducts Rn C(60) (R = C(6)H(5)CH(2)) with n = 1 to at least 15. The radical adducts with n = 3 and 5 are stable above 50 degrees C and have been identified by electron spin resonance (ESR) spectroscopy as the allylic R(3)C(60)(.) (3) and cyclopentadienyl R(5)C(60)(.) (5) radicals. The unpaired electrons are highly localized on the C(60) surface. The extraordinary stability of these radicals can be attributed to the steric protection of the surface radical sites by the surrounding benzyl substituents. Photochemically generated methyl radicals also add readily to C(60). Mass spectrometric analyses show the formation of (CH(3))nC(60) with n = 1 to at least 34.  相似文献