Miguel Alonso

Anostraca, Cladocera and Copepoda of Spanish saline lakes

A study of 102 samples from almost all salt water bodies in Spain has allowed the preparation of a comprehensive list of anostracans, cladocerans and copepods living in such extreme environments. Among the 26 species recorded, 9 are halobionts, but 17 can exist in less saline waters. Of the halobionts, several are widely distributed throughout arid areas around the Mediterranean (Arctodiaptomus salinus, Cletocamptus retrogressus, Branchinectella media, Branchinella spinosa, Daphnia mediterranea, Moina salina); Branchinecta orientalis ( = B. cervantesi) only appears in Guadiana watershed and toward the east of Hungary, and the Alona belonging to the A. elegans complex is a Spanish endemic. In the second group are many typically freshwater species which also appear occasionally in saline waters, and colonizers of wetlands in steppes, characteristically adapted to a wide range of salinity; one of the formers, Diaphanosoma cf. mongolianum, deserves closer study. The Spanish halobiontic fauna seems to be very old judging by the existence of some isolated species, e.g. B. orientalis may be a Tertiary relic. Persistence through time could have resulted from the continuous aridity of some Iberian localities during the Pleistocene and the ecological constancy of wetlands maintained by regional groundwater discharges.

Spanish salt lakes: Their chemistry and biota

A large number of small saline lakes are distributed throughout Spain. Four main lake districts occur from sea level to 1000 m.a.s.l. Most lakes are temporary because of the arid conditions in the Spanish endorheic areas. Many lakes are situated in Tertiary depressions in NE. and S. Spain. Lake basins were formed in karstic areas by hydrologic and aeolian erosion. Saline lakes in NE. Spain occupy areas isolated between river basins. The major ions encountered in these lakes are usually sodium-chloride and magnesium-sulphate; sodium carbonate or sodium-sulphate rich waters also occur.

Limnology of Gallocanta Lake, Aragon, northeastern Spain

A limnological study was sustained from September 1980 to October 1981 to show the evolution of Gallocanta Lake (N.E. Spain) under very dry climatic conditions. It is the physical terminus within an endorheic basin of 500 km2 situated 1 000 m over the sea level. In 1977 its maximum depth was 2.5 m but it decreased to 60 cm in 1981 as a consequence of the last very dry years. It is actually 6 km long and 2.5 km wide, and its area is approximately 12 km2. Salt concentration was quite constant (32–43 g l-1) since September 1980 until June 1981. The equivalent ratio Cl-:SOinf4sup2-varied between 2.2 and 2.8. From June through October 1981 salinity increased up to 105 g l-1 and Cl-:SOinf4sup2-equivalent ratio varied between 2.5 and 3.4. The relative concentrations of ions were retained all year ordinated as follows: Cl- > SOinf4sup2-> HCOinf3sup->. COinf3sup2-; Na+ > Mg2+ ≫ Ca2+ > K+.Total reactive phosphorus was less than 1.5 µg-at l-1 from September 1980 to January 1981. During the rest of the studied period it varied between 2 and 8 µg-at l-1 (the maximum, in February 1981). Nitrogen oxidized forms were relatively high in winter (4–8 µg-at N-NOinf3sup-l-1; 0.5–2.5 µg-at N-NOinf2sup-l-1), and early May 1981 (25 µg-at N-NOinf3sup-l-1; 1 µg-at N-NOinf2sup-l-1). Neither reached 1 µg-at l-1 from September through December 1980, or from June through October 1981.Planktonic algae increased in density during the period of the study from 103 to 5 105 cells ml-1. Chromulina sp. was the main species during autumn and winter (>50% in number of cells ml-1) while the copepod Arctodiaptomus salinus decreased its population. Lobocystis dichotoma increased its density from December 1980 to May 1981 and was dominant in spring (>90%), when a typical reproductive activity was observed in the Arctodiaptomus population. This species disappeared in late spring. In June 1981 Brachionus plicatilis reached up to near 2 000 individuals ml-1. This species was not observed after August 1981. Then the ciliate Fabrea salina was the only zooplankter staying in the free waters of the lake and Nannochloris sp. the dominant alga (>90%). Dense macrophytic beds constituted of Lamprothamnium papulosum and Chara galioides covered the bottom of the lake in September 1980 and before that date since the observations began in 1977. They decreased in covered area since October 1980 and disappeared during summer 1981.Gallocanta Lake is in a very stressed situation produced by prolonged drought. The increased salt concentration together with the extremely cold and hot temperatures, and the lack of nitrogen relative to phosphorus are the main environmental factors that controlled the biological populations during the period of the present study.

Daphnia (Ctenodaphnia) Mediterranea: A new species of hyperhaline waters, long confused with D. (C.) Dolichocephala Sars, 1895.

A very particular form of Daphnia (Ctenodaphnia), adapted to life in epicontinental hyperhaline waters of Mediterranean arid regions had long been confused with Daphnia (Ctenodaphnia) dolichocephala Sars, 1895. In this paper the morphological and ecological differences between the two taxa are pointed out and comparison is made with another closely related Rumanian form (Daphnia cf. mediterranea) and with the related Spanish species (D. atkinsoni and D. chevreuxi). The Daphnia of saline environments is described here as Daphnia (Ctenodaphnia) mediterranea. The most important differential characters of this new species are: 1) the short and widely rounded rostrum; 2) dorsal ridge of the female extends to the anteriormost part of the head; 3) elliptical ephippium with a ride anterior margin; convex shape and separate from the dorsal ridge; 4) males possessing a very long antennule base that reaches the distal limit of the head.

Morphological Differentiation of two new Ephemeroporus species (Cladocera, Chydoridae) belonging to the barroisi complex: E. margalefi and E. epiaphantoii, in Spain

The Ephemeroporus barroisi complex is of cosmopolitan distribution. To this day, very little is known of the component species, and their study is especially interesting in the Mediterranean region because of its proximity to Syria from which Richard made the original description. In Spain two taxa belonging to the complex occur, which in this paper are described as the new species E. margalefi and E. epiaphantoii. The taxonomic study has been carried out optical and scanning electronic microscopes on individuals of both sexes belonging to different populations. Their inclusion in the barroisi group is clearly justified. In both taxa the anterior margin of the labrum is toothed, and one or several denticules are present on the inferoposterior angle of the valves. The most consistent differential characters concern the shape of the body, the valve ornamentation, the postabdomen structure of both males and females, and the labrum structure. E. epiaphantoii is notably similar to the (very partial) description of Richard and to a population from Iran examined during this study. Due to the biogeographic relationship that characterizes the Mediterranean countries, it is pertinent to suggest that perhaps E. epiaphantoii may release E. barroisi from the nomen dubium status.

Daphnia (Ctenodaphnia) hispanica sp. nov., a new daphnid (Cladocera) from Spain

Daphnia (C.) hispanica n. sp. has thoracic limbs of A ‘D. (C.) atkinsoni type’ and is very similar toD. chevreuxi Richard, 1896. With this speciesD. (C.) hispanica shares the presence of a soft accessory seta on the outer side of the trunk of the first thoracic limb, apparently unique among the genusDaphnia. Although other morphological characteristics are very similar in this two species, a detailed comparison reveals that they can easily be separated as different species. The most useful features in differentiating both species are:D. (C.) hispanica has a dorsal crest in the head, its rostrum is longer, its accesory seta of the first thoracic limb is more developed, the juveniles are not helmeted and its male postabdomen lacks individual denticles on the anal and preanal margin.The new species is, up to now, restricted to Spain and inhabits the temporary and low mineralized waters of the steppe regions.

Abundance and morphometry changes across the high‐mountain lake‐size gradient in the tropical Andes of Southern Ecuador

The number, size, and shape of lakes are key determinants of the ecological functionality of a lake district. The lake area scaling relationships with lake number and volume enable upscaling biogeochemical processes and spatially considering organisms’ metapopulation dynamics. These relationships vary regionally depending on the geomorphological context, particularly in the range of lake area <1 km2 and mountainous regions. The Cajas Massif (Southern Ecuador) holds a tropical mountain lake district with 5955 water bodies. The number of lakes deviates from a power law relationship with the lake area at both ends of the size range; similarly to the distributions found in temperate mountain ranges. The deviation of each distribution tail does not respond to the same cause. The marked relief limits the size of the largest lakes at high altitudes, whereas ponds are prompt to a complete infilling. A bathymetry survey of 202 lakes, selected across the full-size range, revealed a volume-area scaling coefficient larger than those found for other lake areas of glacial origin but softer relief. Water renewal time is not consistently proportional to the lake area due to the volume-area variation in midsize lakes. The 85% of the water surface is in lakes >104 m2 and 50% of the water resources are held in a few ones ( 10) deeper than 18 m. Therefore, midlakes and large lakes are by far more biogeochemically relevant than ponds and shallow lakes in this tropical mountain lake district.

Branchipus cortesi n. sp.: a new anostracan from western Spain (Crustacea, Branchiopoda)

Branchipus cortesi, n. sp. (Anostraca, Branchipodidae) is characterized by the broadly enlarged distal segments of male antenna 2, and a combination of morphological features concerning thoracic limbs, abdominal segments and egg morphology. The species occurs in temporary fresh water bodies in flatlands with temperate Mediterranean climate; it is distributed in the south-western part of Spain. Our study includes a morphological analysis using optical and scanning electronic microscopes. Questions about ecology and distribution of the new species are also discussed.

Molecular and morphological data suggest weak phylogeographic structure in the fairy shrimp Streptocephalus torvicornis (Branchiopoda, Anostraca)

Inland aquatic organisms almost ubiquitously display a pattern of marked provincialism characterized by substantial population differentiation and genealogical discontinuities. This is the result of strong priority effects and local adaptation following dispersal and colonization of new habitats. We present a case that defies this biogeographic paradigm. We have investigated the phylogeography of the fairy shrimp Streptocephalus torvicornis across its circum-Mediterranean and Eurasian distribution. Based on three independent datasets, namely sequence variation at 12S and 16S rRNA, cyst morphology and male second antenna characters, we discern a pattern of extensive genetic and morphological homogeneity pointing to unhindered gene flow and widespread connectivity among populations. These intriguing findings may provisionally be explained by (i) a high dispersal frequency overwhelming the ability of a population to maintain resource monopolization, (ii) an outbreeding vigour opportunity offered to secondary immigrants, (iii) an ecological equivalence of genotypes generating long-term immigration–extinction equilibria and buffering genetic diversity over spatial scales, (iv) enhanced bird-mediated dispersal in open habitats as opposed to ponds surrounded by forests or shrub, or (v) a shallow population history with little time for substantial genetic differentiation.

The genus Mixodiaptomus Kiefer, 1932 (Copepoda, Diaptomidae) in Spain

The distribution of the Calanoid genus Mixodiaptomus was studied in a large number of pools and small lakes scattered over Spain. Four species occur: M. incrassatus, M. kupelwieseri, M. ortizi and M. laciniatus, the latter in 2 subspecies (M. laciniatus laciniatus and M. laciniatus atlantis). M. ortizi is described as a new species. M. laciniatus lives in mountains, while all other species occur in the plains. M. incrassatus is found all over the country, M. kupelwieseri only in the eastern part of Catalonia, M. laciniatus atlantis in Andalucia and M. ortizi in the central lands called Mesetas. All live in little mineralized waters and only M. incrassatus and M. laciniatus atlantis occur in clayey waters.