Temperature selection and avoidance in the sand goby,Pomatoschistus minutus (Pallas), collected at different seasons

Abstract

SynopsisThe sand goby from the Oslofjord, Norway, is extremely eurythermal. In spring and autumn it avoids temperatures lower than about 4" C, in summer 6" C. Acclimation did not influence the lower avoidance temperature, but the critical thermal maximum, the upper avoidance temperature and the temperature where the whole fish darkened (the darkening temperature) varied with acclimation and season. The darkening temperature is suggested to be the upper temperature limit with the greatest ecological significance. The fish, collected at different seasons darkened at between 19.5 and 22" C. In the field the fish is not found at 20" C and higher.The preference temperature varied with season and with acclimation temperature, generally with low precision. In May, the preference temperature was 13.5" C, that is higher than the ambient temperature of 10" C. In summer, the temperature in sampling locality and preference temperature was the same, 17 and 16.5" C respectively. In October, temperature preference was 7.5" C as compared to 9" C in the field. The variation is explained as a behavioural thermoregulation to direct the fish towards optimal conditions at any time.The seasonal variation in preference temperature can not be ascribed only to seasonal variation in temperature, that is an acclimation phenomenon, but other factors are operative as well, factors which will modify the temperature tolerance in the fish.

Microhabitat utilisation by an assemblage of temperate Gobiidae (Pisces: Teleostei)

“…), where the algal mat may have afforded cover and/or food. No seasonal depth migrations were observed for P. n~inutus in this study, although many studies have shown P. minutus to perform depth migrations to deeper waters in winter months (Fonds 1971, 1973, Healey 1971, Hesthagen 1975, 1979.…”

Strategies of Pomatoschistus minutus and Pomatoschistus microps to cope with environmental instability

“…Several hypotheses may be causing the decrease: (a) mortality or migration to sea (Fonds and Veldhuis, 1973;Hesthagen, 1977Hesthagen, , 1979von Oertzen, 1984) as suggested by the complete disappearance of cohort 5 after the reproductive period; (b) behavioural differences; or (c) inter-annual variability in the recruitment's success, as suggested by Pampoulie et al (2000), Attrill and Power (2004) and Maes et al (2004). In fact, the scarcity of individuals in 2005 suggests a non-expressive recruitment, although the April recruitment seemed to occur in two periods (April and August 2005), which may also be an adaptation to the environment conditions.…”

Influence of acclimation temperature and season on acute temperature preference of adult mountain whitefish, Prosopium williamsoni

“…The influence of hormones involved in gonadal maturation on temperature preference before and during the spawning season must also be considered (Hesthagen 1979). In the walleye, Stizostedion vitreurn, gamete viability is affected by acclimation temperature of the adult fish (Hokanson 1977).…”

“…The influence of photoperiod and temperature on gonadal maturation is well known (Hoar 1969), as attested by the frequent manipulation of these factors to stimulate fish to spawn outside the normal spawning season. In turn, temperature preference during the spawning season may be influenced by hormones involved in gonadal maturation (Hesthagen 1979). Spawning adults would be expected to subordinate their own thermal preference to the needs of embryos.…”