Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 80. (Budapest 1988)
Forró, L.: The occurence of Moina salina Daday, 1888 (Cladocera) in a sodic pan in Hungary
48 L. FORRÓ In Hungary I have found M. salina in several samples collected from a highly sodic pan, Szappanosszék. In addition, I also recorded this species in samples from this pan which were collected by Professor J. MEGYERI in 1972-1974, however, he identified only M. brachiata in these samples (MEGYERI 1975). In this paper a short description of the species is given and its occurrence in an alkaline water is discussed. The size of the females varies between 0.85-1.36 mm, which is in good agreement with the measurements made by NEGREA (1984) on Romanian specimens from the type locality. The eye is small, there is a supraocular depression on the head (Fig. 1). The shell is broadly rounded, without hairs on the surface, in many specimens reticulation may be seen. There are 25-36 setae on the ventral rim of the shell. The first antennae are short, thick, the second antennae are long, well-developed. The first leg lacks the anterior seta on the penultimate segment (Fig. 2) and is similar to that described by NEGREA (1984). The postabdomen has eight to ten feathered teeth on the distal conical part (Fig. 3), and there is a relatively small bident tooth, its arms are of nearly equal length. The postabdominal claw is rather short and has fine hairs on the dorsal side. On the ventral side, at the base of the claw there is a "Basaldorn" which consists of three to four fine teeth (Fig. 4). The ephippium contains one egg, the surface has a polygonal pattern. The males are smaller than the females, in their morphology they are similar to those described in the literature. A more detailed description of both females and males will be given elsewhere. Moina salina occurs only in saline waters, as the above mentioned most recent papers also confirmed it. NEGREA (1984) considered it as a halobiont species. The salinity range of the species is very wide, Romanian localities (from Transylvania and the Romanian lowland) showed variation between 3.5-104.7%,, salinity. In the Kiziltash estuary SUKHANOVA (1971) first found it at salinities between 40.7-63.8%o- She observed the greatest abundance between 45.2-70.2% 0 , and reproduction occurred even at 97.14% 0- The species did not occur there at lower salinities. Previously it was very abundant in the Aral Sea, however, with increasing salinity (it altered from 8-10 to 16-18% 0 ) M. salina disappeared, thereafter only marine cladocerans remained in the plankton (ALADIN & ANDREEV 1984). DUMONT (1981) found it in a large hypersaline crater-lake in Anatolia, where pH was slightly alkaline (8.0-8.3) and salinity was high (chloride concentration reached over 50 g/1). GAUTHIER (1954) reported its occurrence in various salt-water bodies in North Africa. In these waters salinity was different, the species was found also in temporary salt marshes where the pH was 8.0-8.2. ALONSO (1983) found M. salina in small waters where chloride content was high (10.8-40.0 g/1), but the alkalinity values were not maximal in these localities. In ponds with less chloride content, but in some cases with greater alkalinity, M. brachiata occurred. ALONSO & COMELLES (1984) grouped the small epicontinental waters in Spain and concluded that M. salina is characteristic for temporary athalassohaline saline waters. To summarize, this species inhabits various saline waters, permanent and temporary ones, thalassohaline and athalassohaline, but was not known from alkaline water. To these data is added the Hungarian record, which is well within the range of its geographical distribution, nevertheless, it is very significant from ecological and physiological points of view. Szappanosszék is one of the most sodic pans in Hungary. It is a shallow (the depth mostly less than 0.5 m), temporary pan, it often dries out. During the period of my studies the pH varied between 9.3-10.3, and the conductivity was between 15000-80000 microsiemens. MEGYERI (1975) gave similar pH variation, and the total dissolved solid values between 9520-68500 mg/1. He recorded three rotifers and two microcrustaceans (Arctodiaptomus spinosus and Moina brachiata) here. A revision of his samples revealed that he actually collected M. salina, and only this species of Moina was present in the samples. In 1979 I carried out bimonthly sampling here from March onwards. Moina salina occurred in early May and was found during summer until the pan dried out. Ephippial females and males occurred already in late May. In April M. brachiata was found in the pan, this latter species disappeared in May. During the whole study period Arctodiaptomus spinosus inhabited the pan. Later on, in 1980, and in 1986-1987, I collected several samples from Szappanosszék, and only M. brachiata and A. spinosus were found. Hatching experiments (made on dried mud samples) gave similar results. Conductivity measurements in the last years show a sharp decrease, in the summer of 1987, in very shallow water only 10000 microsiemens was recorded.
