DIEL VARIATIONS OF GUT FLUORESCENCE IN THE PONTELLID COPEPOD ANOMALOCERA-PATERSONI

Diel variations in the gut fluorescence of Anomalocera patersoni (Cope poda, Pontellidae) were studied on adult males and females collected i n the northwest Mediterranean at 1-2-hr intervals over a 24-hr cycle, Total pigment content (chlorophyll + phaeopigment) ranged from 5.1 to 19.5 ng ind.(-1) in males and from 7.1 to 21.3 ng ind.(-1) in females; it was higher at night than during the day in both sexes. As a result of the large dispersion of values, chlorophyll levels did not change significantly during the 24 hr cycle. Phaeopigment levels were highest at night between 19.45 and 23.45 GMT in both sexes. A smaller peak wa s noted around 12.30 GMT. Between these two peaks, lows were noted at 9.30 and 15.30 GMT, respectively. Thus, A. patersoni exhibits a diel b imodal rhythm in gut fluorescence. Individual phaeopigment levels were much lower than data reported for herbivorous species. These differen ces are certainly linked to the clearly carnivorous tendency of A. pat ersoni. In this species, the levels of phaeopigments seem to correspon d to pigments contained in ingested prey. Rhythmic variations probably reflect the daily rhythm of feeding activity.