Climate Change and the Potential Spreading of Marine Mucilage and Microbial Pathogens in the Mediterranean Sea

Background: Marine snow (small amorphous aggregates with colloidal properties) is present in all oceans of the world. Surface water warming and the consequent increase of water column stability can favour the coalescence of marine snow into marine mucilage, large marine aggregates representing an ephemeral and extreme habitat. Marine mucilage characterize aquatic systems with altered environmental conditions. Methodology/Principal Findings: We investigated, by means of molecular techniques, viruses and prokaryotes within the mucilage and in surrounding seawater to examine the potential of mucilage to host new microbial diversity and/or spread marine diseases. We found that marine mucilage contained a large and unexpectedly exclusive microbial biodiversity and hosted pathogenic species that were absent in surrounding seawater. We also investigated the relationship between climate change and the frequency of mucilage in the Mediterranean Sea over the last 200 years and found that the number of mucilage outbreaks increased almost exponentially in the last 20 years. The increasing frequency of mucilage outbreaks is closely associated with the temperature anomalies. Conclusions/Significance: We conclude that the spreading of mucilage in the Mediterranean Sea is linked to climate-driven sea surface warming. The mucilage can act as a controlling factor of microbial diversity across wide oceanic regions and could have the potential to act as a carrier of specific microorganisms, thereby increasing the spread of pathogenic bacteria

Inducible defence against a ciliate grazer Pseudomicrothorax dubius, in two strains of Phormidium (cyanobacteria)

Experiments were done with two strain of filamentous, mat-forming Phormidium and their ciliate grazer Pseudomicrothorax dubius, to explain why the ciliates remain hungry in an apparent surplus of food, except for the first 24 hours after feeding. Under grazing pressure, both strains of cyanobacteria showed statistically significant increases in the number of filaments terminating in an empty sheath, compared to the control. Direct observations revealed that the mechanism behind this effect was active withdrawal of the trichomes inside the sheaths when disturbed by grazers. As P. dubius is unable to ingest trichomes with such endings, we conclude that cyanobacteria are not limited to chemical means of defence against grazers but can also defend themselves by means of movement and changes in filament morphology. This is apparently the first report on behavioural defence observed in cyanobacteria

Effects of polyaluminum chloride (PAX-18) on the relationship between predatory fungi and Lecane rotifers

PAX-18 (polyaluminum chloride) is frequently used in WWTPs (wastewater treatment plants) to overcome sludge bulking. An alternative biological method is the usage of Lecane rotifers, which can be endangered by predacious fungi. We investigated the influence of different PAX-18 concentrations on the relationship between Lecane inermis and predacious fungi (Zoophagus and Lecophagus) differing in feeding mode. High PAX concentration (6 mg Al3+ L−1) strongly limited the number of the rotifers, which in low concentration (1.2 mg Al3+ L−1), after an initial decline, increased, but significantly slower than in control. Under the simultaneous influence of Lecophagus and PAX, rotifers were driven almost extinct at the high concentration, but survived at the lower concentration and increased in the control. When treated with Zoophagus, only one or two rotifers survived in treatments and control. High concentrations of PAX significantly restricted the growth of fungi, whereas in low concentrations and control conditions, their length increased, with Zoophagus growing much quicker than Lecophagus. Zoophagus was significantly more efficient in trapping rotifers regardless of PAX concentration. The trapping ability of mycelium following extended exposure to PAX was strongly limited at high concentrations, in comparison to control. Conidia of Zoophagus turned out to be considerably more resistant to PAX-18 and starvation than Lecophagus conidia

Toksyczność soli glinu dla wrotków Lecane inermis : czy chemiczne i biologiczne metody zwalczania puchnięcia osadu czynnego wykluczają się wzajemnie?

The aim of this study was to assess the effects of two flocculants that are often used to overcome activated sludge bulking problems - aluminium chloride, AlCl3, and aluminium sulphate, Al2(SO4)3 - on Lecaneinermis (Rotifera, Monogononta) at three different temperatures: 8, 15 and 20°C. The mean EC50 value (effective concentration, mg dm-3) calculated for the 24 h mortality test was 0.012 mg Al3+dm-3. Next, the effects of low concentrations of the Al-salts on the population development from single individuals (parthenogenetic females) were tested in a 21-day experiment. At concentrations as low as EC4.8 and EC0.48, both Al-salts affected rotifer population negatively. However, temperature was the most pronounced factor that modified the toxicity of the Al-salts to the rotifers. On the 12th day of the experiment, there were significant interactions between temperature and the Al-salts, indicating that the chemicals were more toxic to the rotifers at 20°C than at lower temperatures. The weaker rotifers sensitivity to Al-salts (especially to AlCl3) in temperatures below 15°C, when the biggest problems associated with sludge bulking occurs,may means use both rotifers and chemicals reasonable and effective.Sole glinu są powszechnie stosowanym fl okulantem, służącym zwalczaniu puchnięcia osadu czynnego w biologicznych oczyszczalniach ścieków. Nowa idea biologicznego zwalczania tego niekorzystnego dla prawidłowej pracy oczyszczalni zjawiska polega na zastosowaniu wrotków z gatunku z Lecaneinermis. Wrotki te naturalnie występują w osadzie czynnym i są w stanie zjadać bakterie nitkowate, jak Microthrixparvicella, sprawiające najwięcej problemów w eksploatacji oczyszczalni podczas miesięcy zimowych. Celem badań było porównanie toksyczności chlorku glinu AlCl3 oraz siarczanu glinu Al2(SO4)3 dla wrotków Lecaneinermis w trzech temperaturach: 8, 15 and 20°C. Średnią wartość EC50 (stężenie powodujące 50% efekt, mg dm-3) dla śmiertelności wrotków na podstawie 24-godzinnego testu ustalono na poziomie 0.012 mg Al3+ dm-3. Następnie, badano wpływ niskich stężeń soli glinu na tempo wzrostu populacji z pojedynczego osobnika (partenogenetyczna samica) w 21-dniowym eksperymencie. Ustalono, że stężenia na poziomie odpowiadającym EC4.8, a nawet EC0.48 wpływają negatywnie na tempo wzrostu populacji. Temperatura silnie wpływała na toksyczność glinu. W 12-tym dniu eksperymentu stwierdzono, że zachodzi istotna interakcja pomiędzy toksycznością glinu i temperaturą, wskazująca, że w 20°C glin jest bardziej toksyczny dla wrotków niż w niższych badanych temperaturach. Mniejsza wrażliwość wrotków na glin w temperaturze poniżej 15°C może oznaczać, że łączenie tych dwóch metod zwalczania puchnięcia osadu czynnego w miesiącach zimowych może być racjonalnym i efektywnym rozwiązaniem

Use of chemometric analyses to assess biological wastewater treatment plants by protozoa and metazoa monitoring

Protozoa and metazoa biota communities in biological wastewater treatment plants (WWTP) are known to be dependent of both the plant type (oxidation ditch, trickling filter, conventional activated sludge, among others) and the working operational conditions (incoming effluent characteristics, toxics presence, organic load, aeration, hydraulic and sludge retention times, nitrification occurrence, etc.). Thus, for analogous WWTP operating in equivalent operating conditions, similar protozoa and metazoa communities can be found. Indeed, the protozoa and metazoa biota monitoring can be considered a quite useful tool for assessing the functioning of biological WWTP. Furthermore, the use of chemometric techniques in WWTP monitoring is becoming widespread to enlighten interrelationships within the plant, especially when a large collection of data can be obtained. In the current study, the protozoa and metazoa communities of three different types of WWTP, comprising one oxidation ditch, four trickling filters, and three conventional activated sludge plants, were monitored. For that purpose, metazoa, as well as the main protozoa groups (flagellates, free-swimming, crawling and sessile ciliates, and testate amoeba) were determined in terms of contents and relative abundance. The collected data was further processed by chemometric techniques, such as cross-correlation, principal components, multivariate ANOVA, and decision trees analyses, allowing to successfully identify, and characterize, the different studied WWTP, and thus, being able to help monitoring and diagnosing operational problems.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 — Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio