Observations On the Narcotization of Crustacean Zooplankton 1)

NOTES AND NEWS OBSERVATIONS ON THE NARCOTIZATION OF CRUSTACEAN ZOOPLANKTON 1) BY JOHN E. GANNON and SUSAN A. GANNON 2) Center for Great Lakes Studies, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, U.S.A. INTRODUCTION Crustacean zooplankton that is preserved with formalin undergoes an initial unfavorable reaction to this universal preservative. This reaction, termed here as "formalin frenzy", is expressed as violent locomotor activity prior to death that often causes rejection of gut contents, spilling of eggs from cladoceran brood pouches, and dropping of egg sacs by copepods. Elbourn (1966) suggested that a high percentage of empty guts in Cyclops strenuus stresauus