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Editor-in-Chief Published under auspices of Dan Mires The Society of Israeli Aquaculture and Marine Biotechnology (SIAMB), Editorial Board University of Hawaii at Manoa Library Sheenan Harpaz Agricultural Research Organization and Beit Dagan, Israel University of Hawaii Aquaculture Zvi Yaron Dept. of Zoology Program in association with Tel Aviv University AquacultureHub Tel Aviv, Israel http://www.aquaculturehub.org Angelo Colorni National Center for Mariculture, IOLR Eilat, Israel Rina Chakrabarti Aqua Research Lab Dept. of Zoology University of Delhi Ingrid Lupatsch Swansea University Singleton Park, Swansea, UK Jaap van Rijn The Hebrew University Faculty of Agriculture Israel Spencer Malecha Dept. of Human Nutrition, Food and Animal Sciences University of Hawaii Daniel Golani The Hebrew University of Jerusalem Jerusalem, Israel Emilio Tibaldi Udine University Udine, Italy ISSN 0792 - 156X Israeli Journal of Aquaculture - BAMIGDEH. Copy Editor Ellen Rosenberg PUBLISHER: Israeli Journal of Aquaculture - BAMIGDEH - Kibbutz Ein Hamifratz, Mobile Post 25210, ISRAEL Phone: + 972 52 3965809 http://siamb.org.il The Israeli Journal of Aquaculture – Bamidgeh 57(2), 2005, 105-114. 105 EFFECT OF TEMPERATURE ON EMBRYONIC DEVELOPMENT IN SHARPSNOUT SEABREAM (DIPLODUS PUNTAZZO) EGGS Kursat Firat*, Sahin Saka and Osman Ozden Department of Aquaculture, Faculty of Fisheries, Ege University, 351000 Bornova, Izmir, Turkey (Received 10.9.04, Accepted 25.1.05) Key words: Diplodus puntazzo, egg, embryonic development, sharpsnout seabream, temperature Abstract Embryonic development of sharpsnout seabream (Diplodus puntazzo) was studied at eleven water temperatures (two degree intervals from 12 to 32°C). Embryos successfully developed at temperatures of 16-28°C. Cells did not divide at the temperature extremes of 12 and 32°C. Total mortality was observed by the 128 cleavage stage at 14°C and all eggs were dead by the time the embryos extended 2/3 of the internal circumference of the egg at 30°C. There was an inverse relationship between incubation temperature and the rate of embryonic development. Introduction The commercially important sharpsnout sea- Hernandez et al., 2003), larvae rearing and bream (Diplodus puntazzo) lives on rocky bot- skeletal anomalies (Divanach and Kentouri, toms of the Mediterranean and Black Seas and 1982; Frenicevic, 1989; Marangos, 1995; the Atlantic Ocean, spawning in September and Favaloro et al., 2002; Boglione et al., 2003a), October (Tortonese, 1970). Its increasing morphology (Sara et al., 1999; Loy et al., 2000; importance as a new aquaculture species in the Favaloro and Mazzola, 2000, 2003; Palma and Mediterranean has interested many scientists Andrade, 2002), and nutrition and growth in its reproduction and physiology (Georgiou (Gatland, 1995; Katavic et al., 2000; Hernandez and Stephanou, 1995; Micale, et al., 1996; et al., 2001; Atienza et al., 2004). However, lit- * Corresponding author. Tel: +90-232-3434000/5221, fax: + 90-232-4636050, e-mail: [email protected] 106 Firat et al. erature about its early life history is scarce or x 40 x 25 cm aquaria filled with water that was limited to embryonic and larvae development in electrically heated or cooled by adding water captivity (Kentouri, 1983; Faranda, 1985; from a cooling system. The water in the Boglione et al., 2003b). aquaria circulated by aeration supplied at 35 Water temperature during spawning and ml/min. Temperatures in the glass beakers egg incubation is particularly important in were measured hourly with a calibrated ther- determining egg quality. Temperature can mometer to ±0.05°C. The water flow was affect the metabolism, activity, and structure adjusted to exchange 15% of the total water of developing embryos (Kinne and Kinne, volume every hour. Dead eggs were removed 1961). The relationship between incubation immediately. temperature and embryonic development of At least 15 eggs were removed for exami- sharpsnout seabream has yet to be nation from each beaker every 15 min during described. The aim of this study was to pro- the first 13 hours, and every hour thereafter vide information about the effects of tempera- (as in Jennings and Pawson, 1991), resulting ture on the length of the incubation period and in examination of 45 eggs from each temper- morphogenesis of sharpsnout seabream ature treatment at each sampling. Egg devel- eggs. opment was described prior to fixation in 4% distilled water formaldehyde buffered to pH 7 Materials and Methods with sodium acetate. Eggs incubated at 24°C Twenty male (0.9±0.1 kg mean wt) and 20 were photographed at one-hour intervals female (1.2±0.2 kg mean body wt) sharpsnout throughout development. The experiment ter- seabream broodstock were selected from wild minated when 50% of the viable eggs at each breeders and stocked in a 10-m3 tank with a temperature had hatched, or when all eggs seawater flow of 1.5 m3 per h. The fish were were dead. hand-fed once a day to satiation at noon with Development was divided into stages approximately equal amounts (by weight) of a using descriptions of fresh eggs, examinations moist pelleted broodfish diet, cuttlefish (Sepia of preserved eggs, and the photographic officinalis), and shrimp (Palaemon elegans). record (Nikon coolpix 5 Mb). Criteria for deter- The experiment began after observing the mining stages was according to Jennings and first batch of eggs. Eggs laid in the broodstock Pawson (1991): (a) stage descriptions must be tank flowed into a recouper via a guiding based on unambiguously defined and clearly panel in the tank. A sufficient amount of eggs identifiable embryonic events; (b) stages must was collected in about half an hour. The eggs begin and end concurrently in fresh and pre- were immediately taken out of the recouper, served eggs of the same age; (c) stages must and floating dead eggs were separated from be sufficiently different to allow precise identi- live eggs. The diameters of 100 eggs were fication of ageing; (d) transition between measured to the nearest 0.025 mm using an stages must be shorter than stage durations. ocular micrometer. The water temperature at We selected seven stages to describe sharp- spawning was 24°C. snout seabream egg development from fertil- Approximately 2000 fertilized eggs were ization to hatching (Table 1; Fig. 1). The first placed in each incubator (1.5-l glass beakers). stage was subdivided into six substages Thirty-three incubators were used for tripli- (Table 2) based on the number of cells, as cates of each temperature treatment (12, 14, suggested by Simpson (1971), Nichols (1989) 16, 18, 20, 22, 24, 26, 28, 30 and 32°C). The for plaice (Pleuronectes platessa), and eggs were allowed to gradually adapted to the Jennings and Pawson (1991) for sea bass test temperature in 15 min. The adaptation (Dicentrarchus labrax). The time required to period was limited to 15 min to be able to reach the midpoint of each stage was calculat- observe egg development at the test temper- ed at each temperature as the mean egg age ature from the very first cleavage. To control during the transitional periods before and after temperature, glass beakers were placed in 75 each stage. When consecutive samples con- Effect of temperature on seabream embryonic development 107 Table 1. Development stages of sharp- bation temperature was carried out for each snout seabream eggs (see Fig. 1). group. As samples were counted and all stage changes were determined in all samples, Stage Description there was no need for statistical analysis. 1 From fertilization until 7th division into Results 128 cells (in fresh material) or until Temperatures were maintained within 0.5°C individual cells can no longer be distin- of the mean for each treatment. Oxygen satu- guished within the blastodisc (in pre- ration was over 85%, salinity was 37.5‰, and served material). pH around 7.8. Ammonia and nitrite were always <0.01 mg/l. 2 Begins with completion of the 7th divi- The sharpsnout seabream eggs were sion (fresh material) or when individual buoyant, transparent, and typical of sparid cells can no longer be distinguished eggs. They ranged in diameter from 0.807 to within the blastodisc (in preserved 0.832 mm with a mean of 0.816±0.008 mm material). Ends when blastodisc mar- and contained a single unpigmented oil glob- gin begins to thicken and germ ule (0.250±0.001 mm diameter). (‘signet’) ring appears. Embryonic development was completed in 3 From first appearance of germ ring treatments ranging 16-28°C but cells did not until half the yolk mass is enveloped. divide at 12 and 32°C (Table 3). Total mortal- ity was observed at stage 2 at 14°C, and eggs 4 Begins with germ ring enveloping half at 30°C died in stage 6. Rate of development yolk mass; ends with blastopore clo- was inversely related to temperature (Figs. sure. 2,3). 5 From blastopore closure until embryo The relationship between temperature and extends around 2/3 of the internal cir- development stage was expressed by the cumference of the egg. relationship lnage = a + b (temperature), where a and b are coefficients calculated by linear 6 Begins with embryo extending around regression analysis (Table 4).