Temperature modulates spatio-temporal variability of the functional reproductive maturation of Octopus maya (Cephalopoda) on the shelf of the Yucatan Peninsula, Mexico

Abstract

Laboratory studies have demonstrated that high temperatures inhibit spawning of Octopus maya; therefore, in oceanic warming scenarios the population dynamics may be affected. The aim of the present study was to go beyond laboratory studies under controlled temperatures to examine the possible relationship between large-scale thermal patterns and reproductive season (represented by functional maturation) of O. maya in the wild on the continental shelf of the Yucatan Peninsula, where it is endemic. The macroscopic maturity index (MaMI) was obtained in females, and reproductive complex index (RCI) and number of spermatophores in males. Associations Associations between these indices and environmental temperature regime were inferred by sampling octopuses in an upwelling zone (Z-I), a transition zone (Z-II) and a nonupwelling zone (Z-III). The reproductive condition of O. maya differed between Z-I and Z-III. In all zones, the pro- portion of adults showing functional maturity was highest in both females (MaMI 36-71% of values ≤0.2) and males (RCI 12–40% of values ≥0.9; 41–49 spermatophores per octopus) during the season of winter storms (‘nortes’ season, November–February), when the sea-surface temperature oscillates around 25 °C. In Z-I, some individuals were functionally mature throughout the year, likely due to low temperatures maintained by summer upwelling. Zone-I had the greatest proportion of functionally mature males (up to 40% of adults in ‘nortes’ season) and the greatest number of spermatophores (mean 43–49 spermatophores per octopus in all seasons). Females in Z-III (without upwelling) were functionally mature mainly in the ‘nortes’ season when water temperature decreased, with only a small proportion mature in the rest of the year when water temperatures reached 31 °C. As predicted by laboratory studies, water temperature below 27 °C appears to be favourable for the functional reproductive maturation of wild O. maya.