Institute for Polar Ecology

Kiel, Germany

Institute for Polar Ecology

Kiel, Germany
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Dolnik O.V.,Institute for Polar Ecology | Metzger B.J.,Institute of Avian Research Vogelwarte Helgoland | Loonen M.J.J.E.,University of Groningen
Parasitology | Year: 2011

For Isospora (Protozoa: Eimeriidae) parasites of passerine birds, diurnal periodicity of oocyst output is a well-described phenomenon. From the temporal zone to the tropics, oocyst production is correlated with the light-dark cycle, peaking in the afternoon hours. However, nothing is known about the existence of diurnal periodicity of these parasites in the birds of High Arctic environments, under permanent light during summer. We sampled free-ranging Snow Bunting (Aves: Passeriformes), on Svalbard in summer and tested oocysts output of Isospora plectrophenaxia. Here we show that under the permanent light conditions of Arctic summer in the wild, Isospora plectrophenaxia, a parasite of the Snow Bunting, still keeps the 24-h rhythm of oocyst output with the peak in the post-meridiem hours, despite the absence of diurnal periodicity in host's activity. Our findings prove the ability of avian Isospora to invoke alternative cues for synchronizing the circadian rhythms. Possible cues and adaptive significance of diurnal periodicity of parasite output in High Arctic are discussed. The maintenance of synchronization and timing of the parasite life-cycle stages is under positive selection pressure even in permanent daylight in the Arctic. © 2011 Cambridge University Press.

Dolnik O.V.,Institute for Polar Ecology | Dolnik O.V.,Institute of Avian Research Vogelwarte Helgoland | Dolnik V.R.,Russian Academy of Sciences | Bairlein F.,Institute of Avian Research Vogelwarte Helgoland
Ardea | Year: 2010

The prevalence and intensity of infection with isosporan Coccidia parasites in wild passerine birds varies greatly between bird species. Faeces of infected hosts contain oocysts that are a source of new infections when ingested. As a consequence, we expect that the main route of cocctdiosis transmission in the wild is related to the foraging behaviour of the hosts, and that bird species are exposed to infective oocysts, depending upon the way of foraging. We studied how prevalence and intensity of isosporan infection in wild birds are related to foraging stratum, gregariousness, and diet. Our data reveal that a bird's feeding habits play a significant role in the extent and severity of infection by isosporan Coccidia in the wild.

Kiko R.,Institute for Polar Ecology | Kiko R.,Alfred Wegener Institute for Polar and Marine Research | Kiko R.,Leibniz Institute of Marine Science
Polar Biology | Year: 2010

Sea ice is permeated by small brine channels, which are characterised by sub-zero temperatures and varying salinities. Despite sometimes extreme conditions a diverse fauna and flora thrives within the brine channels. The dominant calanoid copepods of Antarctic sea ice are Stephos longipes and Paralabidocera antarctica. Here, I report for the first time thermal hysteresis (TH) in the haemolymph of a crustacean, S. longipes, whereas P. antarctica has no such activity. TH, the non-colligative prevention of ice growth, seems to enable S. longipes to exploit all available microhabitats within sea ice, especially the surface layer, in which strong temperature fluctuations can occur. In contrast, P. antarctica only thrives within the lowermost centimetres of sea ice, where temperature fluctuations are moderate. S. longipes possesses two isoforms of a protein with TH activity. A high homology to a group of (putative) antifreeze proteins from diatoms, bacteria and a snow mold and, in contrast, no homologs in any metazoan lineage suggest that this protein was obtained through horizontal gene transfer (HGT). Further analysis of available sequence data from sea-ice organisms indicates that these antifreeze proteins were probably transferred horizontally several times. Temperature and salinity fluctuations within the brine channel system are proposed to provide "natural transformation" conditions enabling HGT and thus making this habitat a potential "hot spot" for HGT. © 2009 Springer-Verlag.

Schulz M.,Leibniz Institute for Baltic Sea Research | Bergmann M.,Alfred Wegener Institute for Polar and Marine Research | von Juterzenka K.,Institute for Polar Ecology | Soltwedel T.,Alfred Wegener Institute for Polar and Marine Research
Polar Biology | Year: 2010

The colonisation of hard substrata (HS) by epibenthic megafauna was studied by photographic surveys along the Ardencaple Canyon in the deep western Greenland Sea in 2000. Seven transects at 2,700-3,200 m water depth showed generally low densities of dropstones, sunken wood, and other substrata including anthropogenic material (range: 2-11 HS km-1). Overall, 30 different taxa and morphotypes were found on or associated with HS. While the sea anemone Bathyphellia margaritacea and the pantopod Ascorhynchus abyssi dominated the fauna on the substrate surfaces, a ball-shaped morphotype of uncertain taxonomic origin characterised assemblages marginally associated with HS. Community analysis revealed differences in faunal patterns near the continental rise and towards the deep sea, but diversity and evenness did not differ significantly between the various regions. However, we conclude that dropstones and other hard substrata at the seafloor serve as colonisation islands and thereby generally increase small-scale habitat diversity in polar deep-sea environments. © 2010 The Author(s).

Holzinger A.,Institute of Botany | di Piazza L.,Institute of Botany | Lutz C.,Institute of Botany | Roleda M.Y.,Institute for Polar Ecology | Roleda M.Y.,University of Otago
Phycological Research | Year: 2011

Fertile Saccharina latissima sporophytes, collected in the Kongsfjorden, Ny-Ålesund, Spitsbergen, Norway (78°56.87' N, 11°51.64' E) were investigated in relation to its sensitivity to experimentally enhanced ultraviolet radiation:photosynthetically active radiation (UVR:PAR) ratios. Irradiance of UVR were 4.30W m -2 of UV-A (320-400nm) and 0.40W m -2 of UV-B (280-320nm), and PAR (400-700nm) was ~4.30W m -2 (=20μmol photons m -2s -1). Excised soral (sporogenic) and non-soral (vegetative) tissues were separately irradiated for 16h at 7°C. Transmission electron microscopy showed abundant occurrence of physodes, electron dense particles (~300-600nm) in the sorus. Paraphysis cells, with partly crystalline content, large mitochondria and abundant golgi bodies were towering over the sporangia. In soral tissue, cells were not visibly altered by the PAR+UVR irradiation. The chloroplasts, flagella and nucleus of unreleased meiospores inside the sporangial parent cells were visibly intact. Severe changes in the chloroplast structure of vegetative tissue occurred after PAR+UVR irradiation. These changes included wrinkling and dilatation of the thylakoid membranes, and appearance of electron translucent areas inside the chloroplasts. In vegetative cells exposed to PAR+UVR, the total amount of physodes, was slightly higher as in cells exposed to PAR only. Initial values of optimum quantum yield of photosystem II (F v/F m) were 0.743±0.04 in non-soral and 0.633±0.04 in soral tissue. Vegetative tissue was observed to be more sensitive to radiant exposure of PAR and PAR+UVR compared to reproductive tissue. Under PAR, a 20% reduction in Fv/Fm was observed in non-soral compared to no reduction in soral tissue, whereas under PAR+UVR, 60% and 33% reduction in Fv/Fm was observed in non-soral and soral tissues, respectively. This can be attributed to the corresponding three times higher antiradical power (ARP) capacity in soral compared to non-soral tissue. © 2011 Japanese Society of Phycology.

Dolnik O.V.,Institute for Polar Ecology | Dolnik O.V.,Austrian Academy of Sciences | Hoi H.,Institute for Polar Ecology
Biological Journal of the Linnean Society | Year: 2010

Parasitic infections may change the equilibrium between the costs and benefits of an animal for maintaining its status in a social group. Consequently, parasites may influence the social status of an animal in a group. The present study investigated whether acute infection with Isospora spp. has any effect on the social relationships (e.g. dominance hierarchy) of male house sparrows and how the infection influences their behaviour, immune status, and body condition. Furthermore, the study allowed us to examine how important the 'badge of dominance' is with respect to maintaining social status even when the actual condition is changing as a result of infection. The results obtained showed that an acute infection leads to changes in the dominance hierarchy of a social group and that body mass losses of birds depend on the achieved hierarchy status. A positive correlation between the badge size and male aggressiveness was only found during acute infection. In addition, we also found a relationship between cell-mediated immune response and male aggressiveness during acute infection. This suggests that male badge size is not sufficient to maintain a given dominance position. On the other hand, badge size, a signal developed during the moult, appears to remain an informative and 'honest' signal several months later, reflecting the energy reserves of a bird faced with a demanding stressful situation such as acute infection. © 2010 The Linnean Society of London.

Marquardt M.,Institute for Polar Ecology | Kramer M.,Institute for Polar Ecology | Carnat G.,University of Manitoba | Werner I.,Institute for Polar Ecology
Polar Biology | Year: 2011

This is the first study to determine vertical distribution patterns of sympagic meiofauna, including metazoans, protozoans and eggs <20 μm, in the Amundsen Gulf (southeastern Beaufort Sea, Arctic). Full sea-ice cores were sampled from mid of March to end of May 2008 (Circumpolar Flaw Lead system study). Investigations were performed on first-year ice from three pack- and three fast-ice stations. Additionally, 5-cm bottom-ice sections were sampled at 13 pack-ice and 5 fast-ice stations. The metazoan community was composed of nematodes, rotifers, copepods, copepod nauplii, platyhelminthes and a few rare taxa such as mollusks, cnidarians and nemerteans. High numbers of eggs, between 50 and 2,188 eggs L -1, particularly of nematodes and copepods, were present in the ice. Investigations revealed also eggs of the pelagic species Calanus hyperboreus and Sagitta spp. within the ice, so that further research is needed to clarify whether more organisms than expected might use this habitat as a reproduction ground. Many different morphotypes of protozoans were observed in the samples, especially ciliates of the order Euplotida. The highest abundance was always found in the lowermost 5 cm of the ice cores, nevertheless sympagic meiofauna was not restricted to that part of the ice. Integrated meiofauna abundance ranged between 41 and 4,738 × 10 2 Ind. m -2 and was highest in the fast ice in early May. Differences between pack and fast ice in terms of integrated meiofauna communities and vertical distribution were not significant, while the analysis of the bottom-ice sections indicated both a temporal development and ice-type-specific differences. © 2011 Springer-Verlag.

Palinauskas V.,Vilnius University | Dolnik O.V.,Vilnius University | Dolnik O.V.,Institute for Polar Ecology | Valkiunas G.,Vilnius University | And 2 more authors.
Journal of Parasitology | Year: 2010

Avian malaria parasites (Plasmodium spp.) and related species of Haemoproteus constitute a remarkably diverse and species rich group of blood parasites. Analyses of the mitochondrial cytochrome b gene of these hemosporidians have demonstrated unexpected patterns of host distribution, host shifts, and host sharing. However, deeper insights into these patterns require access to multiple genetic markers and genetic analyses of single parasite cells. In the present study, we demonstrate the potential of laser microdissection microscopy (Olympus/MMI CellCut microdissection system) for solving these 2 problems. This technique was used for isolation of single blood stages and ookinetes of avian Haemoproteus and Plasmodium spp., which were then successfully used for DNA isolation, amplification, and sequencing. The methods of single cell dissection of hemosporidian parasites and PCR-based analyses with dissected single cells are described. These methods can be used to isolate substantial quantities of pure hemosporidian parasite DNA for large-scale sequencing, essential information when designing primers for developing multiple nuclear genetic markers. Such markers can then be applied to isolated single parasite cells for identification of parasites in mixed infections and deciphering mechanisms behind apparent reproductive isolation between parasite lineages. This method can be used in the molecular investigation of blood parasites of birds, reptiles, and fish because it enables removing the parasite DNA from the overpowering host DNA, which is present in red blood cells. © 2010 American Society of Parasitologists.

A primitive linear model is applied to quantify potential salt rejection and theoretical salinity increase in the standardized water column of 46 individual circum-Arctic flaw leads/polynyas based on intermediate salinities, seasonal ice production rates, and flaw lead/polynya size. Analysis shows that open water with low initial salinity may not reject enough salt to produce enhanced salinities despite high ice formation rates. Conversely, flaw leads/polynyas with higher initial salinities in combination with moderate to high ice formation rates produce sufficient salt to increase flaw lead/polynya salinities. Flaw leads/polynyas with maximum potential for theoretical salinity increase and dense brine formation are located along the Beaufort Sea coast, where both initial salinities and ice formation rates are high. Salinity increase is generally moderate to high in Chukchi Sea flaw leads/polynyas, and widely moderate in the East Siberian, Kara, and Barents Seas. Southern central and southeastern Laptev Sea flaw leads/polynyas show weak potentials for salt rejection, theoretical salinity increase and dense brine formation due to extremely low salinities and ice formation rates. Though the formation of dense brines on Arctic shelves is a complex process in nature, the simplified model provides a suitable and quick (graphic) tool for Arctic marine geologists and biologists or cold region engineers to compare individual flaw lead/polynya sections in terms of freeze-related potential salt rejection and theoretical salinity increase. © 2010 Elsevier B.V.

Dethleff D.,Institute for Polar Ecology
Journal of Geophysical Research: Oceans | Year: 2010

Two primitive equation-based models are used to estimate the formation of total volumes either of Arctic cold halocline water (CHW), intermediate water (IMW), or deep water (DW) through freeze-related salt rejection in the Siberian Laptev Sea flaw lead system. Model A assumes that the rejected salt remixes with surface mixed water (SMW) beyond the leads until salinities allow for contribution to the midlayers of either the CHW, the IMW, or the DW. Model B simulates direct salt rejection to the upper layer of the cold halocline, and, after remixing here, further contribution to the midlayers of CHW, IMW, or DW. Averaging both model estimates, Laptev leads contribute either 0.161 Sv of CHW, 0.075 Sv of IMW, or 0.065 Sv of DW, which represents as much as ∼23%, ∼16%, or ∼30% of Arctic-wide lead derived dense water contribution to the appropriate layer, respectively. Northwestern Laptev leads produce the greatest amount of dense water. These lead sections show very short buoyancy equilibrium timescales (∼6 to ∼13 days), and local dense water production may potentially be amplified by lateral brine injection into the cold halocline through bottom eddies. Central-southern and southeastern leads generally produce little salt due to low surface water salinities. As definite separation mechanisms and proportion distributions of rejected lead brines into CHW, IWM, and DW are still unidentified in nature, a combination of lead salt rejection and remixing (model A) and direct downward expulsion of brine packages (model B) is assumed to steer Laptev lead dense water production. Copyright 2010 by the American Geophysical Union.

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