Evolution and ecology of influenza A viruses.

If stretched end to end, the estimated 1030viruses in the oceans would span farther than the nearest 60 galaxies. This reservoir of genetic and biological diversity continues to yield exciting discoveries and, in this Review, Curtis A. Suttle highlights the areas that are likely to be of greatest interest in the next few years. Viruses are by far the most abundant 'lifeforms' in the oceans and are the reservoir of most of the genetic diversity in the sea. The estimated 1030 viruses in the ocean, if stretched end to end, would span farther than the nearest 60 galaxies. Every second, approximately 1023 viral infections occur in the ocean. These infections are a major source of mortality, and cause disease in a range of organisms, from shrimp to whales. As a result, viruses influence the composition of marine communities and are a major force behind biogeochemical cycles. Each infection has the potential to introduce new genetic information into an organism or progeny virus, thereby driving the evolution of both host and viral assemblages. Probing this vast reservoir of genetic and biological diversity continues to yield exciting discoveries.

Marine viruses — major players in the global ecosystem

1. NEILSON A.H. & LEWIN R.A. 1974. The uptake and uti­ lization of organic carbon by algae: an essay in compar­ ative biochemistry (including the addenda by N.J. Antia). Phycologia 13: 227-264. 2. PROCfOR V.W. 1975. The nature of charophyte species. Phycologia 14: 97-113. 3. HOEK C. VAN DEN 1975. Phytogeographic provinces along the coasts of the northern Atlantic Ocean. Phycologia 14: 317-330. 4. JO HANSEN H. W. 1976. Current status of generic concepts in coralline algae (Rhodophyta). Phycologia 15: 221-244. 5. W YNNE M.J. & LoISEAUX S. 1976. Recent advances in life history studies of the Phaeophyta. Phycologia 15: 435452. 6. STARKS T.L., SHUBERT L.E. & T RAINOR F.R. 1981. Ecol­ ogy of soil algae: a review. Phycologia 20: 65-80. 7. MOESTRUP 0. 1982. Flagellar structure in algae. A review with observations particularly on the Chrysophyceae, Phaeophyceae (Fucophyceae), Euglenophyceae and Reck­ ertia. Phycologia 21: 427-528. 8. WOELKERLING WM J. 1983. The Audouinella (Acrochae­ tium-Rhodochorton) complex (Rhodophyta): present per­ spectives. Phycologia 22: 59-92. 9. STEIN J.R. & BORDEN c.A. 1984. Causative and beneficial algae in human disease conditions: a review. Phycologia 23: 485-50 1. 10. HOSHAW R. W. & MCCOURT R.M. 1988. The Zygnema­ taceae (Chlorophyta): a twenty-year update of research. Phycologia 27: 511-548. II. ANTIA N.J., H ARRI SON P.J. & OLIVEIRA L. 1991. The role of dissolved organic nitrogen in phytoplankton nutrition, cell biology and ecology. Phycologia 30: 1-89. 12. KAPRAUN D.F. 1993. Karyology of marine green algae. Phycologia 32: 1-21.

A review of harmful algal blooms and their apparent global increase

Mass mortalities due to disease outbreaks have recently affected major taxa in the oceans. For closely monitored groups like corals and marine mammals, reports of the frequency of epidemics and the number of new diseases have increased recently. A dramatic global increase in the severity of coral bleaching in 1997—98 is coincident with high El Nino temperatures. Such climate-mediated, physiological stresses may compromise host resistance and increase frequency of opportunistic diseases. Where documented, new diseases typically have emerged through host or range shifts of known pathogens. Both climate and human activities may have also accelerated global transport of species, bringing together pathogens and previously unexposed host populations. T he oceans harbor enormous biodiver- sity by terrestrial terms (1), much of which is still poorly described taxo- nomically. Even less well known are the dy- namics of intermittent, ephemeral, threshold phenomena such as disease outbreaks. De- spite decades of intense study of the biolog- ical agents structuring natural communities, the ecological and evolutionary impact of diseases in the ocean remains unknown, even when these diseases affect economically and ecologically important species. The paucity of baseline and epidemiological information on normal disease levels in the ocean chal- lenges our ability to assess the novelty of a recent spate of disease outbreaks and to de- termine the relative importance of increased pathogen transmission versus decreased host resistance in facilitating the outbreaks. Our objectives here are to review the prevalence of diseases of marine taxa to evaluate wheth- er it can be concluded that there has been a recent increase. We also assess the contribut- ing roles of human activity and global cli- mate, and evaluate the role of the oceans as incubators and conveyors of human disease agents. Is There an Increase in Diseases in the Ocean?

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Emerging Marine Diseases--Climate Links and Anthropogenic Factors

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment.

During a 5–wk period beginning in late November, 1987, 14 humpback whales, Megaptera novaeangliae, died in Cape Cod Bay after eating Atlantic mackerel, Scomber scombrus, containing saxitoxin (STX),...

Humpback Whales (Megaptera novaeangliae) Fatally Poisoned by Dinoflagellate Toxin

More than 400 harbor seals, most of them immature, died along the New England coast between December 1979 and October 1980 of acute pneumonia associated with influenza virus, A/Seal/Mass/1/180 (H7N7). The virus has avian characteristics, replicates principally in mammals, and causes mild respiratory disease in experimentally infected seals. Concurrent infection with a previously undescribed mycoplasma or adverse environmental conditions may have triggered the epizootic. The similarities between this epizootic and other seal mortalities in the past suggest that these events may be linked by common biological and environmental factors.

http://science.sciencemag.org/content/sci/215/4536/1129.full.pdf

Mass mortality of harbor seals: pneumonia associated with influenza A virus

Influenza A viruses of the H13N2 and H13N9 subtypes were isolated from the lung and hilar node of a pilot whale Serological, molecular, and biological analyses indicate that the whale isolates are closely related to the H13 influenza viruses from gulls

Characterization of two influenza A viruses from a pilot whale.

Influenza A virus isolates of the H4N5 subtype (which has previously been detected only in birds) were recovered from harbor seals dying of viral pneumonia on the New England coast from June 1982 through March 1983. When these isolates were compared with other mammalian and avian viruses in serological assays and RNA-RNA competitive hybridization, it was found that the seal viruses were most closely related antigenically and genetically to recent avian virus strains and were readily distinguishable from mammalian viruses, including H7N7 isolates recovered from seals in 1980. Unlike any previous isolates from mammals, these recent seal viruses replicate in the intestinal tracts of ducks, a characteristic of avian viruses. The association of avian viruses with influenza outbreaks in seals suggests that transmission of avian viruses to seals is occurring in nature. Potentially, this may be an example of the adaptation of avian viruses to mammals, which would represent an intermediate step in the evolution of new mammalian strains.

Are seals frequently infected with avian influenza viruses

The concentrations of a number of polychlorinated biphenyls and chlorinated pesticides in brain tissues of marine mammals of different age and regional origin were determined by using high-resolution capillary gas chromatography and electron capture detection. Brain tissues of two neonatal and three stillborn northern fur seals (Callorhinus ursinus) collected in the Bering Sea, Pacific Ocean, were examined. In addition, cerebrum, cerebellum, and hypothalamus of one adult female common dolphin (Delphinus delphis) stranded on the coast of Massachusetts, Atlantic Ocean, were examined. It showed clearly that α-HCH was dominant in all brain tissues (90–203 ng/g extractable lipids) compared with other tissues like liver or blubber (45–61 ng/g extractable lipids). This excess of α-HCH in brain tissue was due to only one enantiomer, (+)-α-HCH, whereas in other tissues both enantiomers contributed to the α-HCH concentration. Comparing the overall general xenobiotic burden, the HCH isomers (99–216 ng/g extractable lipids) resemble the PCB (17–105 ng/g extractable lipids) and DDT (111–171 ng/g extractable lipids) levels in brain tissues. The latter two groups exceed the HCHs in liver tissue and in blubber. On a single compound basis, the highest levels are found in brain for α-HCH (fur seal pups: 90–203 ng/g extractable lipids, adult dolphin: 221–305 ng/g extractable lipids), 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153) (fur seal pups: 4–25 ng/g extractable lipids, adult dolphin: 260–377 ng/g extractable lipids) and 4,4′-DDE (fur seal pups: 104–164 ng/g extractable lipids, adult dolphin: 364–625 ng/g extractable lipids). The levels of α-HCH and 4,4′-DDE are comparable. No significant difference concerning the xenobiotic burden between neonatal and stillborn northern fur seals could be seen in contrast to the higher concentrations of the adult common dolphin. The patterns of some xenobiotics in the samples were compared with each other by using statistical methods like the similarity index and the principal component analysis (PCA).

G. Early

Papers

Humpback Whales (Megaptera novaeangliae) Fatally Poisoned by Dinoflagellate Toxin

Mass mortality of harbor seals: pneumonia associated with influenza A virus

Characterization of two influenza A viruses from a pilot whale.

Are seals frequently infected with avian influenza viruses

Determination of HCHs, PCBs, and DDTs in brain tissues of marine mammals off different age