202 PROCEEDINGS OF THE ROYAL SOCIETY OP QUEENSLAND. 



In a report Mr. J. B. Henderson stated that toxic effects 

 Avere not produced by a sample of the water in which the 

 epidemic had occurred, when a fish was kept in it for 48 hours. 

 It should be pointed out, however, Ihat all species are not 

 equally suscej)tible, and that it was possible that gaseous 

 poisons, if such were the cause, may have escaped or have 

 become altsred. 



The possibility of some toxic substance being liberated as a 

 result of decomposition of myriads of dinoflag ellates has been 

 mentioned. It is laiown that certain phytoflagellates, especially 

 Peridinium, Gonyaulax, and allied forms, have caused very 

 serious epidemics amongst various organisms, the result being 

 brought about by the death of immense numbers of these 

 tiny organisms, the decomposition products destroying fish, 

 molluscs, etc., In fact, such water, which is generally coloured 

 reddish by these flagellates, is often spoken of as '" poison 

 water." The animals so killed, on decomposing, aggravate the 

 condition so that widespread mortality has been caused. 



In the " Sydney Morning Herald " of 27th December 1918, 

 attention was drawn to the " red weed pest " destroying fish 

 and oysters owing to its extraordinary abundance in Port 

 Macquarie, N.S.W. Mr. A. H. Lucas^^ described this dull-red 

 seaweed as Falkenbergia olens. He stated that it probably 

 lived on plants in deeper water, being brought inshore in great 

 masses at irregular intervals, sometimes collecting on oyster- 

 beds with disastrous results, oAving to its rapid decomposition 

 and putrefaction, a great deal of gas being evolved. 



Hedley (1915, p. 29) referred to two sudden and widespread 

 epidemics which occurred amongst sedentary intertidal organ- 

 isms in Port Jackson in 1866 and 1891. In regard to the latter 

 Whitelegge (1891) reported that immense numbers of the dino- 

 flagellate Glenodinimn rubrum caused the clogging of the 

 gills of various molluscs and led to their death and ultimately, 

 through their decomposition, to the destruction of great 

 numbers of other organisms. 



Other accounts of heavy mortality amongst marine fish, 

 caused by flagellates, have been published by Torrey, 1902 

 [Gonyaulax — Cahfomian Coast in 1901] ; Gilchrist, 1914 

 [Noctiluca, Peridinium — South Africa] ; Hornell, 1917 [Eugle- 



11 A. H. Lucas, Notes on Australian Marine AlgEP, P.L.S. N.S.W. 

 44, 1919 (pp. 175-6). 



