CYANOPHYTA. The Blue- green Algae. 



No attempt \)^aSi made to classify the dlverae kinds of hlue- 

 green algae, that were obtained during Mission 6-50, 

 principally Because current taxonomy is unsettled and 

 identification a specialists task. I did submit a sample 

 of a particularly abundant blue-green algae to Dr. Francis 

 R. Drouet for naming, however, because it formed a con- 

 spicuous ground cover among Udotea and Dictyota plants 

 in many areas close to the reef face, a region actively 

 grazed by numerous species of herbivorous fishes. I was 

 particularly curious because ciguatera, fish poisoning, 

 often is attributed to blue-greens and incidence is 

 common in the Virgin Islands CRandall, 1958). Dr. Drouet 

 kindly determined the species as Oscillatoria submembranacea 

 but said that to his knowledge, it had never been implicated 

 as a cause of ciguatera. It may be worthy of further study, 

 however, for among the blue-greens observed, this was the 

 most abundant and heavily grazed. It occurred in dark 

 sometimes reddish tufts lightly attached to calcareous sand 

 substrate and later forms dense mats and rolls that are 

 nosed and worked over daily by flocks of grazing fishes. 



VI-200 



