LIMNOFISH-Journal of Limnology and Freshwater Fisheries Research 5(1): 1-5 (2019) Thermal Tolerance of Turkish Crayfish (Astacus leptodactylus) Acclimated to Three Different Temperatures Abdullatif ÖLÇÜLÜ 1* , Metin KUMLU 2 , H. Asuman YILMAZ 2 , O. Tufan EROLDOĞAN 2 1Fisheries Faculty, Munzur University, Tunceli, Turkey 2Fisheries Faculty, Çukurova University, Adana, Turkey ABSTRACT ARTICLE INFO Critical thermal maxima (CTMax) and minima (CTMin) were determined for RESEARCH ARTICLE Turkish crayfish (Astacus leptodactylus) acclimated to 15, 20 and 25°C. CTMin and CTMax were 1.3, 1.1 and 2.0°C, and 37.4, 37.5 and 38.7°C, respectively. Received : 11.05.2018 Thermal tolerance tests showed that acclimation temperatures (15, 20 and 25C) Revised : 05.10.2018 had significant effects on CTMin values of A. leptodactylus (P≤0.05). The area of Accepted : 04.11.2018 thermal tolerance assessed using the CTMin and CTMax boundaries were 2 calculated as 364°C . The overall ARR values were calculated as 0.07 for CTMin Published : 25.04.2019 and 0.13 for CTMax values between 15 and 25 C acclimation tempera-tures. All DOI:10.17216/LimnoFish.422903 the crayfish crumpled at 0.5°C and showed overall spasm at 32.0 – 33.0°C. Farming A. leptodactylus in the southeastern part of the Mediterranean region may be practiced in terms of temperature tolerance. * CORRESPONDING AUTHOR Keywords: A. leptodactylus, CTMin, CTMax, thermal polygon, the acclimation [email protected] Phone : +90 428 213 17 94 response ratio Üç Farklı Sıcaklığa Alıştırılan Türk Kereviti (Astacus leptodactylus)’nin Sıcaklık Toleransı Öz: 15, 20 ve 25 °C’ye alıştırılan Türk kereviti için kritik termal maksima (CTMax) ve minima (CTMin) değerleri belirlenmiştir. CTMin ve CTMax değerleri sırasıyla 1,3, 1,1 ve 2,0 ile 37,4, 37,5 ve 38,7 °C’dir. Sıcaklık tolerans testleri alıştırma sıcaklıklarının (15, 20 ve 25 °C) A. leptodactylus CTMin değerlerine önemli etkilerde bulunduklarını göstermiştir (P≤0,05). Sıcaklık tolerans alanı CTMin ve CTMax sınırları ile değerlendirilerek 364°C2 olarak hesaplanmıştır. Genel olarak 15 ile 25 C arası alıştırma sıcaklıklarında, alıştırma tepki oranı (ARR) 0,07 ile 0,13 olarak hesaplananmıştır. Kerevitlerin tamamı 0,5 °C’de kıvrılma ve geneli 32,0- 33,0°C’de kasılma göstermiştir. Akdeniz bölgesinin güneydoğu kesiminde A. leptodactylus yetiştiriciliği sıcaklık toleransı açısından uygun olabilir. Anahtar kelimeler: A. leptodactylus, CTMin, CTMax, termal poligon, alıştırma tepki oranı How to Cite Ölçülü A, Kumlu M, Yılmaz HA, Eroldoğan OT, 2019. Thermal Tolerance of Turkish Crayfish (Astacus leptodactylus) Acclimated to Three Different Temperatures. LimnoFish. 5(1): 1-5. doi: 10.17216/LimnoFish.422903 Introduction are adaptive in determining the geographical Survival, reproduction, and growth of distribution of a species (Simčič et al. 2014). poikilothermal aquatic organisms are intimately One of the approaches to quantify lower and influenced by temperature fluctuations in their upper-temperature tolerance of aquatic animals in the environments. Ectothermic animals use a combina- laboratory is known as the critical thermal tion of behavioral and physiological mechanisms to methodology (CTM) (Cowles and Bogert, 1944). maintain their body temperatures within a narrow Thermal tolerance is quantified through the range, even under varied environmental conditions determination of the critical thermal maxima (Salas et al. 2014). The thermal preference of a (CTMax) where the temperature is increased species, therefore, corresponds closely with gradually until a critical point (lost of equilibrium) is temperatures that maximize growth and other reached (Kumlu et al. 2010a; González et al. 2010). physiological processes (Huey and Stevenson 1979; The acclimation response ratio (ARR) is an index of Diaz et al. 2011; Tepler et al. 2011). The thermal the magnitude of the thermal acclimation of an limits tolerated by an organism are set genetically and organism (Claussen 1977; Herrera et al. 1998; Díaz 2 Ölçülü et al. 2019 - LimnoFish 5(1): 1-5 et al. 2002; Pérez et al. 2003; Díaz et al. 2004; Re et was then acclimated to 15, 20 and 25°C in al. 2005). It is suggested that crustacean species that thermostatically controlled tanks at a rate of 1°C inhabit cold and temperate regions have low values increase or decrease per day. The animals were of ARR, in contrast to those from subtropical and cultured at the respective temperatures for a period of tropical regions, which present high ARR values; this 35 days prior to the onset of the experiment in round indicates that the ARR values are dependent on the fibreglass tanks (300-L) in order to stabilize their geographic gradient where the organisms are physiology and allow metabolic compensation in distributed. Attributes of thermal tolerance polygons flow through rearing systems. Each tank was fitted provide important insights into fish ecology and with 25 plastic pipes (5 cm in diameter and 10 cm distribution and have been used to identify length), which serves as hiding places for the temperature-related survival tactics (Bennett and animals. Crayfish (20-25 g) were fed twice a day Beitinger 1997). The usefulness of thermal tolerance (09.00, 17.00) by 2% of their biomass with artificial polygons lies inheritability to impart markedly more pelleted feed containing 35% protein. Water information than tolerance endpoints alone. Overall temperature was regularly checked twice a day with polygon area (reported as °C2) provides a convenient a thermometer. The food remainder, feces and moults and useful comparative index of eurythermicity were extracted daily from the reservoirs by between species (Eme and Bennett 2009). siphoning. The oxygen content and pH of rearing Turkish crayfish (A. leptodactylus) is accepted as tank was measured by an oxygen meter (OxiGuard®, a cold-water species with high economic value Birkerød, Denmark) and a WTW pH-meter (Holdich 1993; Wickins and O’C Lee 2003; (Germany). Each temperature group was then Harlioǧlu 2004). The knowledge of the critical divided into two groups to determine the CTMin and thermal minima and maxima provides a relevant CTMax in separate trials. CTMin and CTMax trials ecological index since the Turkish crayfish in nature were conducted in rectangular plastic containers (0.8 can find such spatial temperatures temporarily, as m x 0.35 m x 0.5 m) containing thermostatically acute fluctuations outside of their limit of tolerance. controlled water baths. Three containers were The CTM provides a relevant and ecological index allocated for each acclimation group and 5 crayfish when it is applied to Turkish crayfish (A. were randomly allocated to each container (n=15). leptodactylus) in its habitat. Paladino et al. (1980) During the experiment, the crayfish were not fed. mentioned that, in aquaculture, it is highly important Continuous aeration was provided for all containers to know CTMax and CTM values as they are to maintain dissolved oxygen above 5 ppm using an indicators of the thermal resistance of organisms. air blower. The photoperiod was maintained in 12 h Firkins (1993) reported thermal tolerance values for light/12 h dark. The trials were separately conducted the A. leptodactylus originating from England; at cooling or heating rates of 0.3 °C min-1. CTMin or however, basic CTM studies are necessary to CTMax was determined as the sub lethal thermal implement at different acclimation temperatures for point at which locomotory movements became A. leptodactylus originating from Turkey. Therefore, disorganized and crayfish lost the ability to escape to detect geographic influences on thermal tolerance from conditions, which ultimately lead to death. The values in crayfish, research is needed that allows for CTMin and CTMax values were calculated as the direct comparison. arithmetic mean of the collective endpoint of The aim of this study was to determine the critical individuals of a random sample of crayfish. The ARR thermal maximum and minimum, acclimation was calculated by dividing the tolerance change by response ratio (ARR) and the zone of thermal the total change in acclimation temperature according preference of Turkish crayfish acclimated to three to Claussen (1977). temperatures in order to evaluate the possibility of Statistical Analysis culturing the species in the south eastern region of the Following determination of the normality and Mediterranean of Turkey. homoscedasticity of the data, a one-way ANOVA was used to compare CTM tolerance of the species Materials and Methods (SPSS 20.1). Duncan’s multiple range test (DMRT) Critical Thermal Tolerance was carried out for post hoc mean comparisons. Sub-adult crayfish were caught in the Keban Dam Regression analysis was also carried out to evaluate Lake and transported in styrofoam boxes with wet the relationship between acclimation temperature and towels to the laboratory of Çukurova University, CTMin and CTMax (p≤0.05). Faculty of Fisheries (Adana – Turkey). The organisms were placed in a 1000-L tank, provided Results with a biological filter at 20°C for 1-week for Water quality parameters in the rearing tanks at adaptation to indoor culture conditions. Each group three acclimation temperatures were maintained at Ölçülü et al. 2019 - LimnoFish 5(1): 1-5 3 levels appropriate for the species (Table 1). Thermal 3.0–5.0 °C, and all the crayfish crumpled at 0.5°C. In tolerance tests showed that acclimation temperatures the CTMax trials, the crayfish started to show overall (15, 20 and 25C) had significant effects on CTMin spasms at 32.0 – 33.0 °C secreting mucus like fluids values of A. leptodactylus (P≤0.05). At the at between 33.0 and 37.0 °C. The thermal tolerance heating/cooling rate of 0.3C min-1 the CTMin values polygon area was calculated as 364°C2 between 15 ranged between 1.1 and 2.0C, while CTMax values and 25°C acclimation temperatures used in the ranged between 37.4 and 38.7C (Table 2). During experiments (Figure 1). The overall ARR values were the CTMin trials, the crayfish, regardless of the calculated as 0.07 for CTMin and 0.13 for CTMax acclimation temperatures, started to lose their values between 15 and 25 C acclimation balance and laid down laterally at temperatures of temperatures (Table 3).