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Astaxanthin is ubiquitous in calanoid copepods in high latitude or altitude regions and is well studied. However, the dynamics of astaxanthin in calanoids at low latitudes are less studied. We collected samples during the ice-free season from Lake Mubanghai, an alpine lake located in a low-latitude and high-altitude region, and analyzed astaxanthin content changes among different developmental stages in Arctodiaptomus walterianus. The total astaxanthin content in A. walterianus varied from 1.66 to 4.49 μg/mg dry weight and was highest in October, the month with the lowest temperature among the three sampling dates. Both free astaxanthin and astaxanthin esters content per biomass and the ratio of free astaxanthin increased from the nauplius to adult stage, and astaxanthin esters dominated in total astaxanthin in all developmental stages. The concentrations of polyunsaturated fatty acids were low in seston but were the main fatty acids in the calanoid. The total fatty acid concentration was positively correlated with the concentrations of total astaxanthin, free astaxanthin and astaxanthin esters in the calanoid. These results suggested that astaxanthin may be beneficial to the accumulation of fatty acids. This strategy may benefit calanoids in adaptation to high mountain environments at low latitudes.

Diaptomid copepods belonging to the genus Arctodiaptomus Kiefer, 1932 were collected in two temporary water bodies in Malta. The morphological identification of the collected specimens proved that they belong to Arctodiaptomus wierzejskii (Richard, 1888) even if a morphological peculiarity pertaining to the morphology of the male right antennule of the Maltese populations was observed and here briefly discussed. This finding constitutes the first record of a calanoid copepod from the inland waters of the Maltese Islands.

Analiziran je sastav zooplanktona u geološki starom, tektonskom Ohridskom jezeru (Makedonija, jugoistočna Europa). Glavni cilj rada bio je utvrditi sezonske i prostorne značajke funkcionalnih hranidbenih skupina zooplanktona i njihovu povezanost s uvjetima okoliša. Najveća produkcija zooplanktona utvrđena je u metalimniju, u kojem su biomasa fitoplanktona i brojnost zooplanktona postigle najveće vrijednosti. Utvrđeno je 16 pelagičkih vrsta od kojih dvije endemične: Arctodiaptomus steindachneri (Richard, 1897) i Cyclops ochridanus (Kiefer, 1932). Zooplankton pelagijala bio je zastupljen s niskom brojnošću, 25 ± 22 ind. L-1, a najveći udio, 60 %, postigli su veslonošci. Unutar trofičke skupine mikrofaga, prevladavali su tijekom ljeta kolnjaci s vrstom Kellicottica longispina (Kellicott, 1879), a naupliji veslonožaca prevladavali su u proljeće Eudiaptomus gracilis (Sars, 1862) and C. achridanus i jesen C.achridanus. Ova trofička skupina hrani se suspenzijom bakterija i detritusa, te je tijekom istraživanog razdoblja zauzimala afotički hipolimnij. Predatori su uglavnom bili zastupljeni s kopepoditima i odraslim veslonošcima u metalimniju. Na njihove populacije su značajno i pozitivno utjecali: temperatura (r = 0.417, p = 0.001), otopljeni kisik (r = 0.463, p = 0.0001) te najizraženije biomasa fitoplanktona (r = 0.708, p < 0.00001). Ovo istraživanje među prvima razmatra zooplankton Ohridskog jezera kao važnu kariku unutar hranidbene mreže ovog oligotrofnog ekosustava., Zooplankton is studied in the ancient, tectonic, oligomictic and oligotrophic Lake Ohrid (Macedonia, South Eastern Europe). The main aim of this study was to assess the seasonal and spatial patterns of the zooplankton functional feeding guilds in relation to the environmental conditions. Metalimnion of the lake was detected as the most productive environment, where biomass of the phytoplankton and abundance of the zooplankton reached their maxima. Pelagial zooplankton of low abundance (25 ± 22 ind. L-1) consisted of 16 species including two endemic copepods, Arctodiaptomus steindachneri (Richard, 1897) and Cyclops ochridanus (Kiefer, 1932). Copepods obtained remarkable share (60%) in the zooplankton assemblage. Microphagous zooplankton was mainly comprised of the most abundant rotifer Kellicottia longispina (Kellicott, 1879) in summer, and copepod nauplii during the spring Eudiaptomus gracilis (Sars, 1862) and C.ochridanus, and autumn C.ochridanus. Due to their requirements for the bacterio-detritus suspension, this microphagous zooplankton occupied aphotic hypolimnion during the entire study period. Raptorials were typically represented by copepodites and adult copepods in the metalimnion, and were significantly and positively affected by temperature (r = 0.417, p = 0.001), dissolved oxygen (r = 0.463, p = 0.0001) and, particularly, phytoplankton biomass (r = 0.708, p < 0.00001). This is the first study in which the link between the lower and higher trophic levels is investigated in Lake Ohrid.

The composition and temporal abundance patterns of zooplankton community in Lake Prespa pelagic zone were studied throughout an annual cycle (October 2008–September 2009). Eighteen species (10 Rotifera, 5 Cladocera, 2 Copepoda, 1 Mollusca) were evidenced. It includes Arctodiaptomus steindachneri, an endemic calanoid of the Western Balkans. The zooplankton density varied during the investigated period and certain seasonal successions in temporal transpositions of their maximal development were noticed. The total zooplankton density was much higher in spring and summer period. The representatives of subclass Copepoda were dominant during the whole year. The dominant species was A. steindachneri. At the second place (with exception of the winter period) were the Cladocera representatives. The dominant species was Daphnia cucullata. At the third and fourth place were rotifers and larval form of Dreissena polymorpha, respectively. The quantitative presence of the Copepoda representatives was significantly lower in terms of the previous investigations. The Cladocera quantity reached high values during this period, particularly in summer. Such altering in the quantitative ratio between Copepoda and Cladocera in favor of the Cladocera, especially high quantitative presence of D. cucullata, typical for eutrophic lakes, imply of significant changes in zooplankton community and changes of the water quality in Lake Prespa pelagial.

The zooplankton structure of large lakes (Noyon-Khol’, Shuram-Khol’, Borzu-Khol’, Many-Khol’, Kadysh, and Todzha) of the Todzha Depression has been studied. A comparison of the species composition, abundance, and biomass of zooplankton in the lakes was made. Rotifers have the largest species diversity: from 10 to 16 species, with Conochilus sp., Collotheca sp., Kellicottia longispina (Kellicott), and Asplanchna priodonta Gosse being the most abundant. Copepods are represented mostly by Arctodiaptomus paulseni (Sars), Eudiaptomus graciloides (Lilljeborg), Cyclops scutifer Sars, and Mesocyclops leuckarti Claus. Daphnia galeata Sars and Bosmina longispina Leydig are the dominant cladoceran species. It is shown that the zooplankton communities of the lakes in the Todzha Depression are characterized by a high degree of species composition similarity. Factors forming the taxonomic structure of pelagic zooplankton in the system of these lakes are displayed.

Two pairs of neighboring subalpine lakes located in the Northern Calcareous Alps of Austria were investigated. Each pair comprised a deeper lake containing European minnows (Phoxinus phoxinus ), and a corresponding shallower lake harboring Alpine newts (Triturus alpestris ) as top predators. Plankton successions within fish and amphibian lakes differed markedly from each other. Throughout the year rotifers numerically dominated within the minnow lakes, while pigmented copepods (Genera Heterocope, Acanthodiaptomus , Arctodiaptomus , Mixodiaptomus ) and Daphnia were prominent in the amphibian lakes, at least early during the ice-free period. We argue that size-selective predation by minnows was the ultimate reason for this predominance of smaller zooplankton. While one of the minnow lakes was characterized by a succession of spatially and temporally segregated rotifer species, the other minnow lake permitted the development of populations of small-sized Bosmina and Ceriodaphnia during summer, probably due to the existence of a strong oxycline allowing zooplankton crustaceans to avoid predation from shore-based shoals of minnows. Once trout were introduced into this lake, minnows were visibly reduced in abundance. Bosmina and Ceriodaphnia disappeared and Daphnia together with a predacious copepod (Heterocope ) emerged either from egg banks or arrived from nearby source populations. We argue that the crustacean communities within the fishless lakes were adapted to the comparatively weak predation rates of Alpine newts. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The distributional patterns and diversity of the diaptomid calanoid copepods were analysed to assess the faunistic affinity of North and South America with respect to Mexico and Central America. In the Neotropical region, the most speciose genera of Diaptomidae are Leptodiaptomus and Mastigodiaptomus. The former genus is a Nearctic form, and Mastigodiaptomus is Neotropical. Based on the current distribution of their diversity, it is probable that these genera radiated into Mexico and Central America from North America and the insular Caribbean, respectively. Arctodiaptomus dorsalis is a primarily Palaearctic taxon, it is widely distributed between North and Central America. This species probably radiated in the Americas as a Tethyan derivate. Prionodiaptomus is the only member of the highly diverse South American diaptomid fauna that has expanded beyond the subcontinent. Despite the high diversity present in South America, its influence in Mexico and Central America appears to be weak; this is probably a consequence of the geologically recent union of the two main subcontinental landmasses. Mexico shares 33% of its species with NA, and no species are shared between NA and SA. For the Diaptomidae, the Nearctic influence is strongest in Mexico. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Aim To determine and analyse the distribution of the freshwater calanoid copepod (Diaptomidae and Pseudodiaptomidae) fauna of the Yucatan Peninsula (YP) and its relation to the geological history of this Neotropical karstic plain. Location The Yucatan Peninsula, Mexico. Methods Plotting of geo-referenced sites, analysis of local and regional geological history, analysis and comparison of regional and local records. Results The current composition and distribution of Diaptomidae and Pseudodiaptomidae in the YP mainly reflects recent, post-Pliocene colonization events. This invasion did not reach America, but only parts of Central America (CA). The presence of diaptomids in the continent since the pre-Cretaceous and the presumed post-Cretaceous (Palaeocene–Oligocene) radiation of Diaptomidae in Middle America suggest earlier colonizations of the YP. The marine transgressions kept most of the YP submerged in different geological periods, thus eliminating any original primary freshwater colonizers, such as the diaptomids. The periods of marine regression probably represented opportunities for new waves of diaptomid colonization of the YP. The latest dispersal of diaptomids in the YP during the Holocene (8000 yr bp) was probably an intermittent process because of the alternative dry and wet periods and interglacial transgressions. The presence of the Nearctic Leptodiaptomus and Arctodiaptomus in the YP and the current distribution of Mastigodiaptomus might represent remnants of earlier invasions of Diaptomidae in Middle America. The Neotropical Mastigodiaptomus probably originated in the Late Cretacic CA/proto-Antilles complex. Forms derived from a M. albuquerquensis type ancestor radiated into the YP leaving relatively isolated populations of three species in the northern half of the peninsula. The distribution of the brackish water Pseudodiaptomus marshi well inside the coastline might have resulted from stranding and subsequent adaptation of this species during a marine regression in the Bacalar formation; this agrees with the vision of this taxon as being in process of invasion of freshwater environments. Main conclusions It is not probable that the South American (SA) diaptomid fauna originated from an invasion of upper Neotropical/Nearctic forms. The current distribution of freshwater calanoid copepods reflects relatively recent, post-Pliocene biogeographical patterns, but probably older patterns are involved as well. The northern and eastern coasts of the Yucatan are the most recently colonized by diaptomids. Differing from other freshwater groups surveyed in the Yucatan that have marine relatives (i.e. fishes, amphipods, isopods, mysids, macrocrustaceans), there is no evidence of local vicariant events involving cave-dwelling forms or marine relicts in the diaptomid fauna of the YP.

The effect of treatment water containing chemicals released by Gammarus lacustris or crushed/injured Arctodiaptomus salinus induced changes in vertical distribution of Arctodiaptomus in laboratory conditions. With food concentration in the medium corresponding to the maximum of algae concentration in Shira lake, A. salinus in an experimental vessel was situated higher than in the control. Average population depth of A. salinus decreased as the inoculation density of G. lacustris increased.

A flow-through method was employed to study the algal part of the diet spectrum of the calanoid Arctodiaptomus salinus in the surface layer of the lake and in the phytoplankton biomass maximum zone (10 m deep). Daily consumption rates of this calanoid differed markedly in these layers, being 1 and 11 μg ind −1 d−1, respectively. The cyanobacterial taxa, Lyngbya contorta and Microcystis sp., accounted for more than a half of the ration. Nevertheless, the negative Ivlev electivity coefficient indicated that Arctodiaptomus prefers none of these two taxa. The low measured uptakes suggest that the energy expenditure is compensated by other resources, presumably microzooplankton and detritus.

In 1991 about twenty-five age 2+ specimens of the Arctic charr (Salvelinus alpinus (L.) (length between 100 and 130 mm) were introduced into the fishless small mountain lake Dvojno Jezero (= Twin Lake) (area 0.5+0.4 ha; max. depth 8 m, altitude 1670 m) in NW Slovenia. The first spawning of the Arctic charr was observed in autumn 1994 and regularly each year thereafter. Fish of different sizes were observed from 1995 onward each year but a fish census was never carried out. Autumn zooplankton samples, collected before the introduction of Arctic charr, contained adults (including ovigerous females) of two copepod species: Cyclops abyssorum tatricus and Arctodiaptomus alpinus. No planktonic Cladocera were found. Seven years after the introduction of fish standing crop of zooplankton declined 100-fold. The zooplankton contained only a few copepodites (IV and V) of C. a. tatricus. Simultaneously, water transparency declined and the concentration of chlorophyll a increased and filamentous green algae and picoplankton became abundant in the littoral zone of both lakes.

We surveyed the zooplankton community of Lake Mogan, which has been undergoing gradual eutrophication in recent decades. The zooplankton was dominated by Rotifera (91.1%), followed by Copepoda (7.7%) and Cladocera (1.2%). The dominant species were Filinia longiseta, Brachionus angularis, Synchaeta pectinata, Anureopsis fissa, Polyarthra vulgaris, Lecane clostrocerca, Arctodiaptomus acutilobatus, Hexarthra oxyuris, Polyarhtra dolichoptera and Arctodiaptomus bacillifer. The zooplankton composition of Lake Mogan has changed dramatically since the 1970s when rotifers did not dominate the community.

The natural diet of herbivorous zooplankton was analyzed for a better understanding of the trophic relationships in Lake Xolotlan (Managua). Gut content of the most common zooplankton species (Arctodiaptomus dorsalis, Moina micrura andDiaphanosoma fluviatile) were analyzed. The quality and the relative abundance of ingested algae was studied. The most consumed algae during the dry season (February) wereCyclotella, Oocystis andLyngbya, and during the rainy season (November)Cyclotella, Oocystis andChroococcus. The kind of food ingested byA. dorsalis andM. micrura was similar in both periods. There was no similarity with the diet ofD. fluviatile. During the dry season, when algal biomass in the lake was high,A. dorsalis andM. micrura ingested a higher proportion of diatoms. During the rainy season, when food was scarce, the diet was more diverse and bluegreen algae (Chroococcus) were ingested in a larger proportion.Diaphanosoma fluviatile ingested predominantly tiny particles (bacteria and detritus) and algal food consisted mainly of green algae (Oocystis) and probably (not studied) nanoplanktonic algae. The results were consistent with those obtained in other lakes, indicating the importance of diatoms and green algae for zooplankton nutrition.

Zooplankton from Lake Coatetelco, a shallow tropical reservoir in Morelos State, Mexico, was surveyed monthly through one year. The entire zooplankton community was represented by only five species, with the calanoid Arctodiaptomus dorsalis overwhelmingly dominant throughout the year. A cyclopoid copepod species, one cladoceran species, and two species of rotifers completed the zooplankton. Although some seasonal fluctuations were noted, zooplankton abundance did not appear related to simple physiocochemical parameters; however, there was a general inverse relationship between zooplankton and phytoplankton.

Contribution to the Knowledge of the Branchiopod and Copepod Fauna of Mongolia One species of Anostraca, 25 species of Cladocera and 19 species of Copepoda are reported, mainly from the eastern Khangai mountains, the Tola valley near Ulan-Bator, and the Khentei mountains. One subspecies, Arctodiaptomus rectispinosus mongolicus, is new to science. An important fraction of species in the present collection had not yet been recorded from Mongolia. The relations between Daphnia longispina O. F. MULLER, 1785 and Daphnia rosea SARS,1862,Simocephalus vetulus (O. F. MULLER, 1776) and Simocephalus vetuloides SARS, 1898 are discussed. Due to hydrochemical factors, to trophic and climatic conditions most of the sampled localities can be divided into two groups: those of the mountainous steppe zone with high contents of nutrients and electrolytes and those situated in the northern montainous forest steppe zone which are more or less acidic and poor in nutrients and electrolytes. This is also reflected by the fauna composition.

Between May 1970 and May 1972 the total standing crop of planktonic crustaceans was highest in summer (288–693 ind. x103·m-3), whilst winter values varied from 8 to 58 ind. x103·m-3. The dominant species are Arctodiaptomus spinosus Daday and Diaphanosoma brachyurum Lieven. For Arctodiaptomus 4–5 generations per year were found, resting stages were never present. Diaphanosoma starts its development from the resting eggs at the end of March or at the beginning of April; the first male individuals occur at the end of August or at the beginning of September. Production of resting eggs begins in the middle of September. The biomass of individuals at various stages was determined as dry weight. By multiplying these values with the numerical counts one arrives at a value for biomass in the lake. The daily production has been calculated from the turnover time; the annual mean for Arctodiaptomus was 10.3 mg dry weight·m-3·day-1 (1970) and 26.8 mg dry weight·m-3·day-1 (1971), and that for Diaphanosoma was 1.6 mg dry weight·m-3·day-1 (1970), and 21.7 mg dry weight·m-3·day-1 (1971).

In the present study the author continues the revision of several species of the genus Arctodiaptomus Kiefer. Based on a detailed morphological comparison of animals from 34 different localities the species Arctodiaptomus similis (Baird), A. dudichi Kiefer, A. stephanidesi (Pesta) and A. byzantinus Mann are redescribed. Arctodiaptomus osmanus is characterized as a new species. For A. similis a list of synonyms is given. The centre of distribution of this interesting diaptomid seems to be in Israel, Lebanon and Jordan. Some populations are known also from Iran, Anatolia and Bulgaria. A. byzantinus is found not only in SE-Europe but recently also in the peninsula of Krim. Finally, there are only two habitats known of A. osmanus, both situated in 2 000 m above sea-level in NW Turkey and in Armenia. Zusammenfassung Verfasser setzt in der vorliegenden Studie seine Revisionsarbeit an mehreren Arten der Gattung Arctodiaptomus Kiefer fort. Arctodiuptomus similis (Baird), A. dudichi Kiefer, A. stephanidesi (Pesta) und A. byzantinus Mann werden auf Grund neuer vergleichend-morphologischer Untersuchungen eingehend gekennzeichnet und A. osmanus als neue Spezies in die Wissenschaft eingefuhrt. Fur A. similis wird eine Liste von Synonymen rusammengestellt. Der Schwerpunkt der Verbreitung dieses interessanten Diaptomiden scheint in den Landern des ostlichen Mittelmeers zu liegen, namlich in Israel, Libanon und Jordanien. Einzelne Funde stammen auBerdem aus Iran, Zentral- und West-Anatolien sowie aus Bulgarien. A. byrantinus ist nicht nur in Siidosteuropa verbreitet, sondern konnte nunmehr auch fur die Halbinsel Krim nachgewiesen werden. A. osmanusschlieDlich ist vorerst nur aus zwei 2000 m hoch gelegenen Seen in Nordwest-Anatolien und in Armenien bekannt.