Can climate warming save Daphnia from parasites? Reduced parasite prevalence in Daphnia populations from artificially heated lakes

Climate warming might modify infection outcomes and it has been proposed that temperature increase will result in a “sicker world.” We tested this hypothesis by comparing the prevalence of infection in a common freshwater host–parasite system (crustacean Daphnia infected with the ichthyosporean pathogen Caullerya mesnili) between five artificially heated lakes and four nearby non‐heated control lakes. The heated lakes, which receive warm water from two power plants, have experienced an elevation in water temperature of ca. 3–4°C for the last 60 yr. Analyses of 5 yr of field data revealed that Daphnia communities from heated lakes had lower parasite prevalence than communities from control sites. To disentangle a possible direct detrimental effect of elevated temperature on the parasite from differences in baseline levels of host resistance, we compared infection susceptibility between Daphnia clones isolated from heated and control lakes, under laboratory conditions at two different temperatures. Daphnia from heated lakes were less susceptible to infection than clones from control lakes, while experimental temperature did not affect infection outcome. The data did not confirm the “warmer hence sicker world” scenario. Instead, it seems that indirect effects of temperature elevation (via shifts in lake hydrology) may restrict its spread into heated lakes. Then, local adaptation to the host from control lakes further inhibits re‐establishment of the parasite from control to heated lakes. Our results underline the context‐dependency of the impact of temperature increase on host–parasite interactions

Czynniki ryzyka rozwoju migotania przedsionków, nie zawsze ciężkiej i nie zawsze izolowanej choroby serca

Dotychczas nie poznano dokładnych mechanizmów wpływających na powstanie migotania przedsionków (AF). Każdorazowo klinicysta musi sobie odpowiedzieć na pytanie, czy ma do czynienia z izolowanym AF czy wywołanym innymi zamaskowanymi zaburzeniami. Migotanie przedsionków ma bowiem silne związki epidemiologiczne z innymi chorobami sercowo-naczyniowymi, takimi jak niewydolność serca, choroba wieńcowa, wady zastawkowe, cukrzyca czy nadciśnienie tętnicze. W pracy omówiono tak zwane nowe czynniki ryzyka i mechanizmy, w wyniku których prowadzą one do powstania migotania przedsionków. Na podstawie najnowszych badań zaprezentowano obecny stan wiedzy o związku występowania AF z następującymi zaburzeniami: zespołem metabolicznym i jego składowymi, bezdechem sennym oraz procesem zapalnym. Opisano również niektóre aspekty wpływu stylu życia (spożycie alkoholu i aktywność fizyczna) na pojawianie się epizodów migotania przedsionków. (Folia Cardiologica Excerpta 2010; 5, 5: 285-291

Wpływ podwyższonej temperatury na cechy historii życia oraz na dynamikę populacji i strukturę zgrupowań Daphnia spp.

Wydział BiologiiMy PhD thesis focuses on the impact of temperature increase on body size and reproduction of Daphnia, as well as dynamics of their populations and structure of communities. I investigated communities of Daphnia longispina complex, inhabiting lakes heated by power plants, and I showed that Daphnia can adapt to elevated temperature by increase of constitutive body size and plastic change of size. Large body size maximizes their reproduction during mild winters, while plastic size reduction allows maintaining efficient reproduction under thermal extremes. Temperature elevation also induced Daphnia community reconstruction, with appearance of characteristic to Southern Europe D. galeata and reduced abundance of North-European D. longispina. I also found that Daphnia from heated lakes were reproducing equally well in the presence filamentous cyanobacteria and without them, while filaments reduced reproduction of Daphnia from non-heated lakes. The results obtained during my PhD program indicate that D. galeata is capable of evolutionary adaptation to temperature increase and frequent cyanobacterial blooms, and that makes it superior in climate change conditions. Body size adjustments and efficient resources allocation seem to be key traits determining the success of D. galeata in coping with climate warming.Moja praca doktorska skupia się na wpływie wzrostu temperatury na rozmiary ciała i rozmnażanie Daphnia, oraz dynamikę ich populacji i strukturę zbiorowisk. Badałem zbiorowiska kompleksu Daphnia longispina zasiedlające jeziora podgrzane przez elektrownie i wykazałem, że Daphnia są w stanie zaadaptować się do podwyższonej temperatury poprzez zwiększenie rozmiarów ciała oraz większą ich plastyczność. Większe rozmiary zwiększają płodność Daphnia podczas łagodnych zim, podczas gdy ich redukcja poprzez plastyczność fenotypową pozwala na wydajne rozmnażanie w wysokiej temperaturze. Wzrost temperatury spowodował również przebudowę zbiorowisk Daphnia, w których pojawiła się charakterystyczna dla jezior południa Europy D. galeata, a zmniejszyła się liczebność północnoeuropejskiego gatunku D. longispina. Odkryłem również, że Daphnia z jezior podgrzanych rozmnażały się równie dobrze w obecności sinic nitkowatych co w warunkach kontrolnych – bez sinic, podczas gdy filamenty sinic ograniczały płodność Daphnia z jezior niepodgrzanych. Uzyskane przeze mnie wyniki wskazują, że D. galeata jest zdolna do adaptacji do wzrostu temperatury i częstszych zakwitów sinic, co daje jej przewagę w warunkach zmian klimatycznych. Przystosowanie rozmiarów ciała i wydajna gospodarka zasobami wydają się być kluczowymi cechami determinującymi zdolność D. galeata do mierzenia się z ociepleniem klimatu

Can climate warming save Daphnia from parasites? Reduced parasite prevalence in Daphnia populations from artificially heated lakes

Climate warming might modify infection outcomes and it has been proposed that temperature increase will result in a “sicker world.” We tested this hypothesis by comparing the prevalence of infection in a common freshwater host–parasite system (crustacean Daphnia infected with the ichthyosporean pathogen Caullerya mesnili) between five artificially heated lakes and four nearby non-heated control lakes. The heated lakes, which receive warm water from two power plants, have experienced an elevation in water temperature of ca. 3–4°C for the last 60 yr. Analyses of 5 yr of field data revealed that Daphnia communities from heated lakes had lower parasite prevalence than communities from control sites. To disentangle a possible direct detrimental effect of elevated temperature on the parasite from differences in baseline levels of host resistance, we compared infection susceptibility between Daphnia clones isolated from heated and control lakes, under laboratory conditions at two different temperatures. Daphnia from heated lakes were less susceptible to infection than clones from control lakes, while experimental temperature did not affect infection outcome. The data did not confirm the “warmer hence sicker world” scenario. Instead, it seems that indirect effects of temperature elevation (via shifts in lake hydrology) may restrict its spread into heated lakes. Then, local adaptation to the host from control lakes further inhibits re-establishment of the parasite from control to heated lakes. Our results underline the context-dependency of the impact of temperature increase on host–parasite interactions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/175762/1/lno12257_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/175762/2/lno12257.pd

Can climate warming save Daphnia from parasites? Reduced parasite prevalence in Daphnia populations from artificially heated lakes

Climate warming might modify infection outcomes and it has been proposed that temperature increase will result in a “sicker world.” We tested this hypothesis by comparing the prevalence of infection in a common freshwater host–parasite system (crustacean Daphnia infected with the ichthyosporean pathogen Caullerya mesnili) between five artificially heated lakes and four nearby non‐heated control lakes. The heated lakes, which receive warm water from two power plants, have experienced an elevation in water temperature of ca. 3–4°C for the last 60 yr. Analyses of 5 yr of field data revealed that Daphnia communities from heated lakes had lower parasite prevalence than communities from control sites. To disentangle a possible direct detrimental effect of elevated temperature on the parasite from differences in baseline levels of host resistance, we compared infection susceptibility between Daphnia clones isolated from heated and control lakes, under laboratory conditions at two different temperatures. Daphnia from heated lakes were less susceptible to infection than clones from control lakes, while experimental temperature did not affect infection outcome. The data did not confirm the “warmer hence sicker world” scenario. Instead, it seems that indirect effects of temperature elevation (via shifts in lake hydrology) may restrict its spread into heated lakes. Then, local adaptation to the host from control lakes further inhibits re‐establishment of the parasite from control to heated lakes. Our results underline the context‐dependency of the impact of temperature increase on host–parasite interactions.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655Fundacja Uniwersytetu im. Adama Mickiewicza http://dx.doi.org/10.13039/100016906Ministerstwo Nauki i Szkolnictwa Wyższego http://dx.doi.org/10.13039/501100004569Narodowe Centrum Nauki http://dx.doi.org/10.13039/50110000428

Risk factors for atrial fibrillation: Not always severe heart disease, not always so ‘lonely’

The precise mechanisms that cause atrial fibrillation (AF) are not completely understood. Clinicians should ask themselves whether AF is truly ‘lone’ or is the effect of an underlying, ‘masked’ disorder. Atrial fibrillation shares strong epidemiological associations with other cardiovascular diseases such as heart failure, coronary artery disease, valvular heart disease, diabetes mellitus and hypertension. In this review, we discuss the ‘new risk factors’ and the mechanisms by which they lead to AF. Based on the most recent studies, we present the current knowledge about the relationship between AF occurrence and the following disorders: metabolic syndrome and its components, sleep apnea and inflammation. Moreover, some aspects of the influence of lifestyle (alcohol consumption and physical activity) on AF events are described. (Cardiol J 2010; 17, 5: 437-442

Plankton hitch-hikers on naturalists' instruments as silent intruders of aquatic ecosystems: current risks and possible prevention

Organism dispersal is nowadays highly driven by human vectors. This also refers to the aquatic organisms that can often silently spread in and invade new waters, especially when human vectors of dispersal act without brakes. Thus, it is mandatory to continuously identify human-mediated mechanisms of organism dispersal and implement proper biosecurity treatments. In this study, we demonstrate how the plankton net - one of the basic instruments in the equipment of every plankton sampling person is a good vector for plankton dispersal and invasions. We also demonstrate whether keeping the net in an ethanol solution after sampling is a proper biosecurity treatment, and what kind of treatments are implemented by people worldwide. The first simulation shows that bloom-forming cyanobacteria can easily infiltrate into the new environment thanks to the nets, and can prosper there. However, ethanol-based biosecurity treatment efficiently prevented their spread and proliferation in the new environment. The second simulation, based on wild plankton from an eutrophic lake, indicates that a plethora of phytoand zooplankton taxa can infiltrate into the new waterbody through the net and sustain themselves there if the net is only flushed in the waterbody and left to dry after sampling (an approach that is commonly used by naturalists). Here, we also show that native plankton residents strongly shape the fate of hitchhikers, but some of them like cyanobacteria can successfully compete with residents. Survey data alert us to the fact that the vast majority of biologists use either ineffective or questionable biosecurity treatments and only less than a tenth of samplers implement treatments based on disinfectant liquids. Our results emphasize that the lack of proper biosecurity methods implemented by the biologists facilitates the spread and invasions of plankton including also invasive species of a great nuisance to native ecosystems. Considering that naturalists usually use different instruments that might also be good vectors of plankton dispersal, it is necessary to develop proper uniform biosecurity treatments. No longer facilitating the plankton spread through hydrobiological instruments is the milestone that we, plankton samplers worldwide, should achieve together in the nearest future if we want to continue our desire to explore, understand, protect and save nature

Countergradient variation concealed adaptive responses to temperature increase in Daphnia from heated lakes

To test the general assumption that global warming will induce body size reduction in aquatic organisms, we used a system of lakes continually heated for six decades by warm water discharge from power plants. Their temperature elevation of 3–4°C corresponds with climate change forecasts for the end of the 21st century. We compared body size and reproduction of Daphnia longispina complex communities inhabiting heated and non‐heated (control) lakes nearby. No difference in body size was found, but Daphnia communities from heated lakes had a wider thermal breadth for reproduction. The two lake groups varied in the taxonomic composition of Daphnia communities. Thus, to disentangle inter‐ and intraspecific sources of variation, and to examine evolution vs. phenotypic plasticity of investigated traits, we performed two life history experiments: (1) a between‐species experiment compared D. galeata inhabiting heated lakes with D. longispina typical of nearby control lakes, under three temperature regimes; (2) a within‐species experiment compared D. galeata from heated lakes with conspecifics from high latitude (cold control) and low latitude (warm control) lakes, under two temperature regimes. The experiments revealed countergradient variation: environmental constraints on body size in situ concealed evolution of larger potential body size in Daphnia from heated lakes. In turn, evolution of increased body size plasticity resulted in an efficient resource allocation trade‐off: more effective reproduction at high temperature, at the cost of size reduction. We suggest that large size is adaptive during active overwintering, while plastic size reduction is a coping strategy for high temperatures.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655Ministerstwo Nauki i Szkolnictwa Wyższego http://dx.doi.org/10.13039/501100004569Narodowe Centrum Nauki http://dx.doi.org/10.13039/50110000428

Identification of Cyanometabolites and Toxicity Assessment of Cyanobacteria Isolates from Chosen Polish Eutrophic Waters and Polar Glaciers

Cyanobacteria have the ability to produce various types of bioactive compounds. Some of them can exert toxic effects on aquatic fauna, including daphnids, which are sensitive organisms that respond fast to toxins. Therefore, these crustaceans are useful for aquatic toxicity assessment. In this study, several dozen cyanobacterial strains isolated from different types of water bodies were analyzed for the presence of anabaenopeptins (APs), anatoxin-a (ATX-a), β-methylamino-L-alanine (BMAA), cylindrospermopsin (CYN), microcystins (MCs), nodularin (NOD), saxitoxin (STX) using immunoassay and chromatographic techniques. We also investigated the toxicity of extracts and filtrates from 40-days-old cyanobacterial cultures using biotests with D. magna and D. pulicaria. Analytical techniques revealed the presence of the cyanometabolites studied in isolates of Aphanizomenon (APs, BMAA, CYN, STX), Planktothrix (APs, MCs), Cuspidothrix (ATX-a, CYN) and Limnothrix (BMAA). Polar strains were free of examined compounds. Biotests revealed a reduction in Daphnia survival in response to some extracts and filtrates. It was also found in the case of one polar strain. However, there was no clear pattern indicating that extracts/filtrates from strains with identified toxic compounds reduced Daphnia survival more than other strains. This suggests that other yet unknown toxic compounds are at play. This study was financed by the Polish National Agency for Academic Exchange (project no. PPN/BEK/2020/1/00241), and partially by the National Science Centre in Poland (project no. UMO-2020/39/D/NZ8/02436)