Beijing Wokshop, September 2002 Larval food (Artemia), larviculture and ecotoxicology group (UE partner 4) Members:Dr. Francisco Amat Dr. Francisco Hontoria Dr. Juan Carlos Navarro Dr. Inmaculada Varó Óscar Monroig Germán Medina Olga Ruiz Instituto de Acuicultura de Torre de la Sal Consejo Superior de Investigaciones Científicas Ribera de Cabanes (Castellón) SPAIN

 Distribution of A. persimilis and A. franciscana populations in Argentina  Presence of rare males in diploid parthenogenetic Artemia populations from the Old World  Updating of cyst bank and database

Distribution of A. persimilis and A. franciscana populations in Argentina (1) Presence of Artemia franciscana North of 36º S and A. persimilis South of 37º S. The population of A. franciscana from Las Tunas lagoon (33º 44´S) evidences a phenomenon of hybridisation or introgression: 50% males show n=22 chromosomes, and 50% n=21 chromosomes. Laboratory crossbreeding experiments show reproductive isolation between A. franciscana (Mar Chiquita, Las Tunas) and A. persimilis (Salinas Grandes de Hidalgo) Argentinean populations. Laboratory population from Las Tunas crossbreeds with Mar Chiquita (A. franciscana) population, and does not with Salinas Grandes de Hidalgo (A. persimilis) population.

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Distribution of A. persimilis and A. franciscana populations in Argentina (2) Laboratory populations from A. franciscana and A. persimilis in competition show different reproductive output in terms of oviparism/ovoviviparism. Under suboptimal conditions of food availability A. persimils shifts immediately to oviparism, while A. franciscana always keeps moderate levels of ovoviviparism (> 13 %) Under the same conditions (environmental, food availability) co- occurring populations from both species show different reproductive output. A. franciscana females show always higher fecundity than A. persimilis females. Former results explain a competitive development under which A. franciscana population outcompetes completely A. persimilis.

Presence of rare males in diploid parthenogenetic Artemia populations from the Old World (1) Rare males were found in 22 populations of Artemia parthenogenetica (diploid) from the Old World: 9 populations in the Iberian peninsula (Spain and Portugal), 2 populations from Africa (Namibia and Egypt), and 11 populations from Eurasia (Italy, Ukraine, West Altai, Kazakhstan, Mongolia, China, Iran and India). These rare males are morphologically different from those present in bisexual species or populations. This “atavism” is more frequent in parthenogenetic populations from Central Eurasia (Iran, Kazakhstan, Ukraine, Mongolia) and less frequent, or scarce, in peripheral Western (Iberian peninsula, Africa) and Eastern (China) populations.

Presence of rare males in diploid parthenogenetic Artemia populations from the Old World (2) Although rare males seem useless in reproductive strategies for parthenogenetic females, they are not sterile. They can mate and fertilize females from the bisexual strains or populations Artemia urmiana (lake Urmia, Iran) and Artemia sinica (lake Yuncheng, Shanxi, China), producing live offspring. It is suspected that this rare male atavism could help to explain the origin of parthenogenetic strains (monophyletic?, polyphyletic?) from lineages leading to present-day Asiatic Artemia or from hybridization between two of the Asiatic bisexual species (A. urmiana and A. sinica).

Quantification of rare males found in diploid parthenogenetic populations of Artemia N= number of individuals studied from laboratory populations male/1000:  ratio of males to 1000 individuals Origin Nmale/ 1000 SPAIN and PORTUGALEURASIA La Mata lagoon (Alicante)16,1972-3Marg. di Savoia salterns (Italy)12,103 1 Janubio salterns (Lanzarote)13,092 0Santa Gilla salterns (Italy) 4,647 1 Odiel salterns (Huelva)14,188 1Kujalnik lake, Ukraina12, Sanlucar salterns (Cádiz)12,202 1Maloje Jar. Lake, W.Altai 8, San Fernando salterns (Cádiz)12,504 1Bjurliu lake, Kazakhstan18, Calpe salterns (Alicante)12,000 1Urmia lake, Iran 4, Bonmatí salterns (Alicante) 7,2682-3Ka lake, Inner Mongolia10, Gerri salterns (Lleida)12,319 1Dong Fang Hong salterns, China 8, Aveiro salterns18,105 2Xiao Tan salterns, China16, Yingkou salterns, China 5, AFRICAMadras salterns, India 3, Walvis Bay, Namibia10,066 1 Wadi Natron, Egypt 4,947 1

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Updating of cyst bank and database (1) The present cyst collection held at the IATS-CSIC contains about 280 samples: 146 from Western Europe, 24 from Asia, 16 from Africa and 94 from the Americas. The updating of cyst bank is mainly focused now to the study of samples coming from countries neighbouring Spain, specially Portugal, France, Italy and North Africa countries. The biogeography and biodiversity of Artemia populations in Spain are well known (Amat et al., 1995), and changes about it were not expected, unless undue allochthonous species introduction. A similar situation was reported from Portugal and France since the early 80´s. Narciso (1989) and Thiery & Robert (1992) rendered preliminary information on the presence of A. franciscana populations in Portugal and France, respectively.

Updating of cyst bank and database (2) Cyst samples from Portugal, France, Spain and Morocco, present in the IATS-CSIC bank, and collected between 1991 and 2002, produced A. franciscana populations. Preliminary research on Italian cyst samples (Tarquinia, Carloforte) are showing, up today, autochthonous Artemia populations (A. salina and A. parthenogenetica). The suspected absolute presence of A. franciscana in Portugal and France is endangering the biodiversity of Spanish autochthonous populations in the South of Spain (Cadiz and Huelva) at short- medium (?) term, and of the Mediterranean Spanish autochthonous populations at medium-long (?) term. Amat, F., Barata, C., Hontoria, F., Navarro, J.C., Varó, I Int. J. Salt Lake Res., 3: Narciso, L EAS Special Publ., 10: Thiery, A. and Robert, F Int. J. Salt Lake Res.,1:

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