Science Notes & News by Eric Borneman & Ronald L. Shimek, Ph. D.

Eric Borneman

Editor's Note:

For many years, little was known of viruses in marine systems. Recently, the technology has become available to begin probing ocean waters for viruses. It is now known they are highly abundant and represent a major source of mortality to phytoplankton. Also recently published is the finding of viruses in bleached corals.

Seymour JR, Patten N, Bourne DG, Mitchell JG. 2005. Spatial dynamics of virus-like particles and heterotrophic bacteria within a shallow coral reef system. Mar Ecol Prog Ser 288: 1-8.


Variations in the abundance and community characteristics of virus-like particles (VLP) and heterotrophic bacteria within a shallow, near-shore coral reef were determined using flow cytometric analysis. Mean concentrations of 6.5 × 105 and 1.3 × 105 ml-1 were observed for VLP and bacterioplankton, respectively, although concentrations of both populations varied significantly (p < 0.05) between 4 distinct reef water types. Significant (p < 0.05) variability in the percentage of high DNA (HDNA) bacteria, applied here as an estimate of the proportion of active bacterial cells, and the virus:bacteria ratio (VBR) was also observed between different reef water types. Microscale profiles were taken in the 12 cm layer of water directly above the surface of coral colonies to determine the small-scale spatial relationships between coral colonies and planktonic microbial communities. Across these profiles, mean changes of 2- and 3.5-fold were observed for bacterioplankton and VLP communities, respectively, with VLP abundance positively correlated to bacteria in 75% of profiles. Bacterial and VLP abundance, percentage of HDNA bacteria, and VBR all generally exhibited increasing trends with proximity to the coral surface. VLP abundance was significantly higher (p < 0.05) in the 4 cm closest to the coral surface, and the VBR was higher at the coral surface than in any other zone. The patterns observed here indicate that VLP represent an abundant and dynamic community within coral reefs, are apparently coupled to the spatial dynamics of the bacterioplankton community, and may consequently significantly influence nutrient cycling rates and food-web structure within coral reef ecosystems.

Wilson WH, Dale AL, Davy JE, Davy SK. 2005. An enemy within? Observations of virus-like particles in reef corals. Coral Reefs 24: 145-148.

No abstract.

Wilson WH, Francis I, Ryan K, Davy SK. 2001. Temperature induction of viruses in symbiotic dinoflagellates. Aquat Microb Ecol 25: 99-102.


Bleaching manifests itself as a loss of symbiotic dinoflagellates (zooxanthellae) and/or chlorophyll from a variety of symbiotic hosts, including corals and sea anemones. Bleaching is known to result from a range of environmental stresses, the most significant of which is elevated temperature; how these stresses elicit a bleaching response is currently the focus of intense research. One consequence of environmental stress that has yet to be considered is viral attack. Here, we have isolated a transferable infectious agent believed to be a virus, from zooxanthellae of the temperate sea anemone Anemonia viridis. The infectious agent is induced by elevated temperature. Once induced, the filterable agent can be further propagated without heat induction, thus fulfilling Koch's postulates. We propose that zooxanthellae harbor a latent viral infection that is induced by exposure to elevated temperatures. If such a mechanism also operates in the zooxanthellae harbored by reef corals, and these viruses kill the symbionts, then this could contribute to temperature-induced bleaching.

Breitbart M, Salamon P, Andresen B, Mahaffy JM, Segall AM, Mead D, Azam F, and Rohwer F. 2002, Proc Natl Acad Sci USA 99: 14250-14255.


Genomic analysis of uncultured marine viral communities. Viruses are the most common biological entities in the oceans by an order of magnitude. However, very little is known about their diversity. Here, we report a genomic analysis of two uncultured marine viral communities. Over 65% of the sequences were not significantly similar to previously reported sequences, suggesting that much of the diversity is previously uncharacterized. The most common significant hits among the known sequences were to viruses. The viral hits included sequences from all of the major families of dsDNA tailed phages, as well as some algal viruses. Several independent mathematical models based on the observed number of contigs predicted that the most abundant viral genome comprised 2-3% of the total population in both communities, which was estimated to contain between 374 and 7,114 viral types. Overall, diversity of the viral communities was extremely high. The results also showed that it would be possible to sequence the entire genome of an uncultured marine viral community.

Ronald L. Shimek, Ph. D.

Editor's Note:

If you ever wanted conclusive proof that the reef aquarium hobby can have a deleterious effect on natural populations, see these two articles. The first article showed that the natural population of Banggai cardinalfish is very small and localized.

The second article documented that as a minimum, 118,000 fish per month or 1,416,000 fish per year, were being collected for the aquarium trade from these limited populations. The authors conclude that this harvesting rate has already reduced the populations throughout the region and the fish remaining are now smaller than they had been previously.

It appears that the long-term effects of continued unregulated harvesting will mean at least local population extinction and may mean extinction of the species, probably in the not too distant future unless action is taken to regulate the fishery.

Bernardi G and A. Vagelli. 2004. Population structure in Banggai cardinalfish, Pterapogon kauderni, a coral reef species lacking a pelagic larval phase. Marine Biology (2004) 145: 803-810.


Previous studies on two reef fish lacking a pelagic larval phase (Acanthochromis polyacanthus and Embiotoca jacksoni) revealed features that may be characteristic of their lifestyle: (1) low levels of gene flow, (2) frequent population bottlenecks, and (3) strong phylogeographic breaks, all within their over 1,000 km coastal geographic ranges. The present study tested the predictive nature of these three characteristics in another species lacking a pelagic larval stage, but with a very restricted distribution (<10,000 km2). The Banggai cardinalfish, Pterapogon kauderni (Koumans, 1933), is a mouthbrooding species occurring in the Banggai Archipelago (eastern Indonesia). Fish were captured in January and February (2001, 2002). The mitochondrial control region of 122 individuals from 22 locations was sequenced. Pterapogon kauderni individuals clustered in two reciprocally monophyletic clades corresponding to a southwestern population (restricted to the southwest of Bangkulu Island) and all northern and eastern populations, which included all the remaining samples. Data were compatible with reduced gene flow and the presence of severe bottlenecks; however, small sample sizes and limited genetic variability in P. kauderni prevented a definitive conclusion. Further studies using larger samples and more rapidly evolving molecular markers may provide enough power to conclusively test our hypothesis.

Lunn, K. E. and M.-A. Moreau. 2004. Unmonitored trade in marine ornamental fishes: the case of Indonesia's Banggai cardinalfish (Pterapogon kauderni). Coral Reefs (2004) 23: 344-351.


Millions of coral reef fishes are collected each year for sale on the international aquarium market. Several marine ornamental species, including the Banggai cardinalfish, are biologically unsuitable for large scale exploitation, yet their trade continues largely unmonitored. With little known about the Banggai cardinalfish or its trade, we interviewed trade participants from north and central Sulawesi, Indonesia, and documented the organization, scale, and price structure of the species' local collection and sale. Interviews revealed a large and growing commerce in Banggai cardinalfish, with at least 118,000 fish per month being sold in the Banggai region during the study period. Given the nature of the trade, the species' restricted geographic range, its natural susceptibility to exploitation, we propose long-term monitoring is needed to safeguard Banggai cardinalfish populations and to serve as a much-needed example for monitoring and managing other marine ornamental fishes at risk of over-exploitation.

If you have any questions about this article or suggestions for future topics, please visit the respective author's forum on Reef Central (Eric Borneman's or Ronald L. Shimek's).

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Science Notes & News by Eric Borneman & Ronald L. Shimek, Ph. D.-