Aspects of the thermal ecology of the rusty crayfish Orconectes rusticus (Girard)

Abstract

Orconectes rusticus currently is undergoing an explosive range expansion in the midwestern U.S.A., but information on the potentially important effects of water temperature on the species' biology is lacking. The thermal ecology of O. rusticus in southwestern Ohio, U.S.A., was examined by determining 1) the effects of four water temperatures (16, 20, 25, and 29°C) on survival and growth of juveniles, 2) the responses of juveniles and adults to a thermal gradient (7-27° C), and 3) the thermal tolerances (critical thermal maximum, CTMax, and critical thermal minimum, CTMin) of free-living, field-acclimatized juveniles and adults on a biweekly basis throughout the summer. Month-long growth experiments predicted maximum growth rates of juveniles at water temperatures between 26 and 28°C, but greatest survival between 20 and 22° C. Laboratory-acclimated (22° C) adults and field-acclimatized (2.5° C) juveniles both had an acute preferred temperature of 22° C. CTMaxs and CTMins of juveniles were 0.5-2.6° C higher than those of adults throughout the summer, suggesting that juveniles were exposed to water temperatures 1.5-6.8° C warmer than those of adults. Juvenile and adult O. rusticus prefer habitats where water temperatures favor maximum survival, but they usually are not found together in the same habitat; adults apparently displace the juveniles into warmer habitats. Warmer temperatures can decrease survival of juveniles but improve their growth rates, leading to enhanced fecundity and competitive ability. The past and future success of O. rusticus in expanding its range may depend, in part, on the species ability to adjust to new thermal environments occupied by other species of crayfish.

Thermal tolerance of the crab Pachygrapsus marmoratus: intraspecific differences at a physiological (CTMax) and molecular level (Hsp70)

“…Results for different sized individuals showed that juveniles have a higher CTMax value and higher Hsp70 induction than adults, which is in accordance with other studies performed on ectotherms (e.g., Mundahl and Benton 1990;Winne and Keck 2005). One can argue that Hsp70 differences between juveniles and adults might be due to different growth rates.…”

Shelter use of the Red-Swamp Crayfish (Procambarus clarkii) in dry-season stream pools

“…This is in accordance with the hypothesis that the success of invading species depends on their ability to adjust to the new thermal environments occupied (Mundahl & Benton 1990). However, further studies will be required to examine the thermal tolerance of P. clarkii and its relation to crayfish behaviour.…”

Assessing the importance of food for improving noble crayfish culture conditions

“…Food consumption of crayfish in these feeding trials was expected to correlate positively with rising temperature (Mundahl, 1990;Croll and Watts, 2004). This was based on research verifying the assumption of a direct correlation between temperature increase and food intake (Jones andMomot, 1983, Söderbäck et al, 1987).…”

“…Our findings support the assumption of a direct correlation between food intake and increasing temperature for a water temperature exceeding 8 • C, but not for temperatures between 5 • C−8 • C. The increased food consumption at peak temperatures coincides with the approaching moulting-season. Previous research suggests the highest food intake for crayfish to occur at temperatures near maximum temperature tolerance (Mundahl, 1990). However, the experiments referred to had been carried out under laboratory conditions at constant temperature.…”