Fatty acid composition and biometry of five Greek Artemia populations suitable for aquaculture purposes Maria Moraiti-Ioannidou 1 , Jeanne Castritsi-Catharios 1 , Hellen Miliou 2 & Yannis P Kotzamanis 3 1 Department of Biology, Sector of Zoology ^ Marine Biology, National and Kapodistrian University of Athens, Greece 2 Laboratory of Applied Hydrobiology, Department of Animal Production, Agricultural University of Athens, Greece 3 Hellenic Centre for Marine Research, Institute of Aquaculture, Athens, Greece Correspondence: J Castritsi-Catharios, Department of Biology, Sector of Zoology ^ Marine Biology, National and Kapodistrian University of Athens, University Campus, Athens15784, Greece. E-mail: cathario@biol.uoa.gr Abstract Evaluation of a new-to-science Artemia population and comparison with four other existing populations were carried out. Five parthenogenetic Artemia po- pulations from the following Greek saltworks were studied: Alyki (a new population), Kalloni, Milos, Polychnitos and Messolongi. The diameters of non- decapsulated and decapsulated cysts as well as the lengths of nauplii instar stages I, II and III were mea- sured. In addition, the fatty acid composition of dec- apsulated cysts was estimated. The cyst size of the Alyki population was the smallest, with the largest chorion found in Greece so far. The Messolongi popu- lation had the largest cysts, with the smallest chorion of all ¢ve populations. The diameter of the non-dec- apsulated cysts was highly related ( Po0.01) to the length of the nauplii instar I, II and III. The diameter of decapsulated cysts was found to be the most stable and reliable biometric characteristic. The study of their fatty acids pro¢les revealed that the Polychnitos and Messolongi populations are suitable as live food for freshwater species, while the Alyki, Milos and Kal- loni populations are suitable for marine species, hav- ing high levels (8.9%,11.2% and12.5% respectively) of eicosapentaenoic acid and detectable amounts (0.3%, 0.1% and 0.2% respectively) of docosahexaenoic acid. Keywords: Artemia, parthenogenetic populations, fatty acids, biometry, saltworks Introduction The brine shrimp Artemia is of considerable econom- ic importance in ¢sh and shrimp larviculture (Bengt- son, Leger & Sorgeloos 1991). Approximately 2000 tons of Artemia sp. are harvested annually through- out the world, while the shortage of cysts in the Great Salt Lake (Utah, USA) in 1994 prompted Sorgeloos (1995) to conduct research into the exploitation and development of alternative sources of cysts (Trianta- phyllidis, Abatzopoulos, Miasa & Sorgeloos 1996). Populations of Artemia are distributed all over the world except in Antarctica (Browne & MacDonald 1982). Nowadays, new populations of Artemia are being exploited, while others are extinct. This is be- cause the salt lakes and saltworks where brine shrimp were found have been destroyed or aban- doned, such as in Germany and Great Britain (Per- soone & Sorgeloos1980). The discovery of new populations can be of great importance for both fundamental and applied re- search. The biometrical characteristics of cysts and nauplii can be used as a preliminary tool for di¡eren- tiating various Artemia populations (Vanhaecke & Sorgeloos 1980; Abatzopoulos 1988; Triantaphyllidis, Abatzopoulos, Sandaltzopoulos, Stamou & Castritsis 1993; Triantaphyllidis et al .1996). Small variations in the diameter of non-encapsulated cysts are caused by salinity or temperature changes (Vanhaecke & Sorge- loos 1980; Sanggontanahit 1993), but it is still not clear whether these are due to the reduced chorion thickness or reduced size of the embryo. The nauplii of Artemia sp. are still widely used as live food for shrimp and ¢sh larvae (Cahu & Zambo- nino-Infante 2001), for example the sea bass Dicen- trarchus labrax (Cahu, Zambonino-Infante, Pe¤ res, Quazuguel & Le Gall 1998) and the gilthead sea bream Sparus aurata L. (Morais, Torten, Nixon, Lutzky, Conceicao, Dinis, Tandler & Koven 2006) Aquaculture Research, 2007, 38, 1664^1672 doi: 10.1111/j.1365-2109.2007.01835.x r 2007 The Authors 1664 Journal Compilation r 2007 Blackwell Publishing Ltd