and "balls of phosphorescence" were noted by observers on board the SS 

 BEAVERGLEN in Jxine 1957 off Beachy Head, England. Off Lands End, Cornwall 

 very bright light has been noted in the late sxammer, when shoals of 

 luminescent jellyfishes are brought in by currents. 



Although many oceanographic and fisheries investigations have been 

 conducted in the North Sea, very little infonnation is available con- 

 cerning bioluminescence in this region. As might be expected in 

 temperate regions such as this, the greatest peak of biolumine scent 

 activity appears to take place from April through June and a smaller 

 peak from late August through November. Bioluminescence generally is 

 restricted to shallow coastal regions or to the waters over the Dogger 

 Bank, although some strong displays can occur some distance from the 

 coasts over deeper regions. 



The majority of the references are to spark-type biolinninescence. 

 Murina (l95^) observed very intense bioluminescence east of the Orkney 

 Islands in August 1953- The surface water appeared to be full of 

 "speirkling emerald dots." Further investigation showed that a luTni n- 

 escent copepod, Metridia lucens, was responsible for the light. 

 Various species of luminescent euphausiids also contribute to the spark- 

 type luminescence observed in late summer and early autumn. Euphausiids 

 may be present in large numbers in the momerous inlets and firths along 

 the Scottish coast, where they remain at depth during the day and migrate 

 to the surface layers at night, creating displays of some brilliance. 



Sheet-type luminescence occurs in the late spring and late summer. 

 The light given off usually is produced by large niimbers of luminous 

 dinoflagellates, most prominently Ceratium , Peridinium , and Hoctiluca . 

 The last organism causes bioluminescence in coastal regions in late 

 spring, and the other two organisms are responsible for late summer 

 displays. Noctiluca develops in such great numbers at times that it 

 constitutes up to 1/7 of the water voliome. 



Glowing-ball bioluminescence may be observed in such regions as the 

 Thames Estuary when influxes of luminous medusae occur. Farther to the 

 north great shoals of salps appear in late summer and early autumn at 

 the northern entrance to the Worth Sea and at times extend into the 

 central North Sea. Such large concentrations often create strong 

 glowing-ball displays. 



Ocean Waters West and North of the British Isles 



Although no specific reports are on file it is known that many 

 types of bioluminescent organisms cause displays in the ocean west of 

 the British Isles. Displays have been observed in coastal waters during 

 all seasons, although most of the bioluminescence appears during the 

 late spring, late summer, and early autiimn. Scott (l920) noted that 

 although Noctiluca reached a peak of abundance in the coastal waters of 

 the Irish Sea in late summer and eaxly autumn during mild winters as in 



U 



