PSEUDOSPHAERITA EUGLENAE, A FUNGAL PARASITE OF EUGLENA SPP IN THE MANGERE OXIDATION PONDS, AUCKLAND, NEW-ZEALAND

We report the first observation of the fungal parasite of unicellular algae, Pseudosphaerita euglenae, in New Zealand. The parasite infectio n was observed in the Mangere oxidation pond algae Euglena acus and Eu glena polymorpha and increased potential for pond odour problems, posi ng a threat to pond operations. E. acus was particularly susceptible t o parasitism and was identified as the putative primary host; this is the first record of P. euglenae infecting E. acus. Epidemic levels of P. euglenae were seasonal, lasting for 4-5 weeks from early November u ntil late December of 1992 and 1993. Physico-chemical parameters showi ng a significant relationship to E. acus infection levels were tempera ture, cell numbers of E. polymorpha and Chlorella. Parameters associat ed with E. polymorpha infection were temperature, cell numbers of E. p olymorpha and Chlorella, dissolved oxygen (a.m.), and negative redox p otential. The calculated critical temperature for P. euglenae infectio n of Euglena was 17 degrees C.