Thermoperiodism in the Gulf killifish,Fundulus grandis

✍ Scribed by Weld, Madeline M. ;Meier, Albert H.

• Book ID: 102894746
• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 574 KB
• Volume: 226
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402260203

✦ Synopsis

Male Gulf killifish, Fundulus grandis, were held on various photoperiodic and thermoperiodic regimens for 2 to 4 weeks and examined with respect to body fat stores and testes weights. Groups of fish kept on a 24-hr (LD 12:12) photoperiodic regimen were provided a water temperature of 28°C except for a 4-hr daily interval of 20°C given a t one of six different times during the photocycle. Similarly, fish kept on a 48-hr (LD 12:36) photocycle and 28-30°C were provided 4-hr cryophases (20°C) once during each photocycle in various phase relations to the photoperiodic regimen. In addition, some groups were held a t 20°C and provided 4-hr thermophase (28-30"C) interruptions. Fat stores and gonad weights varied among the groups as a function of the time of day when the temperature interruptions occurred. The photoperiod appears to entrain a circadian rhythm of thermosensitivity, so that the coincidence of a temperature change with a thermosensitive phase alters metabolic and reproductive indices. The circadian mechanism in thermoperiodism appears similar to that involved in photoperiodism.