Multidecadal time series of satellite-detected accumulations of cyanobacteria in the Baltic Sea

Cyanobacteria, primarily of the species \textit{Nodularia spumigena}, form extensive surface accumulations in the Baltic Sea in July and August, ranging from diffuse flakes to dense surface scums. The area of these accumulations can reach ~ 200 000 km². We describe the compilation of a 35-year-long time series (1979–2013) of cyanobacteria surface accumulations in the Baltic Sea using multiple satellite sensors. This appears to be one of the longest satellite-based time series in biological oceanography. The satellite algorithm is based on remote sensing reflectance of the water in the red band, a measure of turbidity. Validation of the satellite algorithm using horizontal transects from a ship of opportunity showed the strongest relationship with phycocyanin fluorescence (an indicator of cyanobacteria), followed by turbidity and then by chlorophyll <i>a</i> fluorescence. The areal fraction with cyanobacteria accumulations (FCA) and the total accumulated area affected (TA) were used to characterize the intensity and extent of the accumulations. The fraction with cyanobacteria accumulations was calculated as the ratio of the number of detected accumulations to the number of cloud-free sea-surface views per pixel during the season (July–August). The total accumulated area affected was calculated by adding the area of pixels where accumulations were detected at least once during the season. The fraction with cyanobacteria accumulations and TA were correlated (<i>R</i>² = 0.55) and both showed large interannual and decadal-scale variations. The average FCA was significantly higher for the second half of the time series (13.8%, 1997–2013) than for the first half (8.6%, 1979–1996). However, that does not seem to represent a long-term trend but decadal-scale oscillations. Cyanobacteria accumulations were common in the 1970s and early 1980s (FCA between 11–17%), but rare (FCA below 4%) during 1985–1990; they increased again starting in 1991 and particularly in 1999, reaching maxima in FCA (~ 25%) and TA (~ 210 000 km²) in 2005 and 2008. After 2008, FCA declined to more moderate levels (6–17%). The timing of the accumulations has become earlier in the season, at a mean rate of 0.6 days per year, resulting in approximately 20 days advancement during the study period. The interannual variations in FCA are positively correlated with the concentration of chlorophyll <i>a</i> during July–August sampled at the depth of ~ 5 m by a ship of opportunity, but interannual variations in FCA are more pronounced as the coefficient of variation is over 5 times higher

Changing seasonality of the Baltic Sea

Changes in the phenology of physical and ecological variables associated with climate change are likely to have significant effect on many aspects of the Baltic ecosystem. We apply a set of phenological indicators to multiple environmental variables measured by satellite sensors for 17–36 years to detect possible changes in the seasonality in the Baltic Sea environment. We detect significant temporal changes, such as earlier start of the summer season and prolongation of the productive season, in several variables ranging from basic physical drivers to ecological status indicators. While increasing trends in the absolute values of variables like sea-surface temperature (SST), diffuse attenuation of light (Ked490) and satellite-detected chlorophyll concentration (CHL) are detectable, the corresponding changes in their seasonal cycles are more dramatic. For example, the cumulative sum of 30 000 W m−2 of surface incoming shortwave irradiance (SIS) was reached 23 days earlier in 2014 compared to the beginning of the time series in 1983. The period of the year with SST of at least 17 °C has almost doubled (from 29 days in 1982 to 56 days in 2014), and the period with Ked490 over 0.4 m−1 has increased from about 60 days in 1998 to 240 days in 2013 – i.e., quadrupled. The period with satellite-estimated CHL of at least 3 mg m−3 has doubled from approximately 110 days in 1998 to 220 days in 2013. While the timing of both the phytoplankton spring and summer blooms have advanced, the annual CHL maximum that in the 1980s corresponded to the spring diatom bloom in May has now shifted to the summer cyanobacteria bloom in July

Toxicity of five anilines to crustaceans, protozoa and bacteria

Aromatic amines (anilines and related derivates) are an important class of environmental pollutants that can be released to the aquatic environment as industrial effluents or as breakdown products of pesticides and dyes. The toxicity of aniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline and 3,5-dichloroaniline towards a multitrophic test battery comprised of bacteria Aliivibrio fischeri (formerly Vibrio fischeri), a ciliated protozoan Tetrahymena thermophila and two crustaceans (Daphnia magna and Thamnocephalus platyurus) were investigated. Under the applied test conditions, the toxicity of the anilines notably varied among the test species. The bacteria and protozoa were much less sensitive towards the anilines than the crustaceans: EC50 values 13–403 mg L-1 versus 0.13–15.2 mg L-1. No general tendency between toxicity and the chemical structure of the anilines (the degree of chloro-substitution and the position of the chloro-substituents) was found in the case of all the tested aquatic species. The replacement of the artificial test medium (ATM) by the river water remarkably decreased the toxicity of anilines to crustaceans but not to protozoa. This research is part of the EU 6th Framework Integrated Project OSIRIS, in which ecotoxicogenomic studies of anilines (e.g., for Daphnia magna) will also be performed that may help to clarify the mechanisms of toxicity of different anilines

An inverse relationship between production and export efficiency in the Southern Ocean

Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 40 (2013): 1557–1561, doi:10.1002/grl.50219.In the past two decades, a number of studies have been carried out in the Southern Ocean to look at export production using drifting sediment traps and thorium-234 based measurements, which allows us to reexamine the validity of using the existing relationships between production, export efficiency, and temperature to derive satellite-based carbon export estimates in this region. Comparisons of in situ export rates with modeled rates indicate a two to fourfold overestimation of export production by existing models. Comprehensive analysis of in situ data indicates two major reasons for this difference: (i) in situ data indicate a trend of decreasing export efficiency with increasing production which is contrary to existing export models and (ii) the export efficiencies appear to be less sensitive to temperature in this region compared to the global estimates used in the existing models. The most important implication of these observations is that the simplest models of export, which predict increase in carbon flux with increasing surface productivity, may require additional parameters, different weighing of existing parameters, or separate algorithms for different oceanic regimes.This work was supported by NASA award number NNX08AB48G.2013-10-2

LuxCDABE—Transformed Constitutively Bioluminescent Escherichia coli for Toxicity Screening: Comparison with Naturally Luminous Vibrio fischeri

We show that in vitro toxicity assay based on inhibition of the bioluminescence of recombinant Escherichia coli encoding thermostable luciferase from Photorhabdus luminescens is a versatile alternative to Vibrio fischeri Microtox™ test. Performance of two luxCDABE-transformed E. coli MC1061 constructs (pDNlux) and (pSLlux) otherwise identical, but having 100-fold different background luminescence was compared with the performance of V. fischeri. The microplate luminometer and a kinetic Flash-Assay test format was used that differently from Microtox test is also applicable for high throughput analysis. Toxic effects (30-s till 30-min EC50) of four heavy metals (Zn, Cd, Hg, Cu) and three organic chemicals (aniline, 3,5-dichloroaniline and 3,5-dichlorophenol) were studied. Both E. coli strains had comparable sensitivity and the respective 30-min EC50 values highly correlated (log-log R2 = 0.99; p < 0.01) showing that the sensitivity of the recombinant bacteria towards chemicals analyzed did not depend on the bioluminescence level of the recombinant cells. The most toxic chemical for all used bacterial strains (E. coli, V. fischeri) was mercury whereas the lowest EC50 values for Hg (0.04–0.05 mg/L) and highest EC50 values for aniline (1,300–1,700 mg/L) were observed for E. coli strains. Despite of that, toxicity results obtained with both E. coli strains (pSLlux and pDNlux) significantly correlated with V. fischeri results (log-log R2 = 0.70/0.75; p < 0.05/0.01). The use of amino acids (0.25%) and glucose (0.05%)-supplemented M9 medium instead of leucine-supplemented saline significantly (p < 0.05) reduced the apparent toxicity of heavy metals to both E. coli strains up to three orders of magnitude, but had little or no complexing effect on organic compounds. Thus, P. luminescens luxCDABE-transformed E. coli strains can be successfully used for the acute toxicity screening of various types of organic chemicals and heavy metals and can replace V. fischeri in certain cases where the thermostability of luciferase >30 °C is crucial. The kinetic Flash Assay test format of the bioluminescence inhibition assay facilitates high throughput analysis. The assay medium, especially in case of testing heavy metals should be a compromise: optimal for the viability/luminescence of the recombinant test strain and of minimum complexing potential

SUSY a consequence of smoothness?

The consequences of certain simple assumptions like smoothness of ground state properties and vanishing of the vacuum energy (at least perturbatively) are explored. It would be interesting from the point of view of building realistic theories to obtain these properties without supersymmetry. Here we show, however, at least in some quantum mechanical models, that these simple assumptions lead to supersymmetric theories.Comment: 26 pages; revised version of paper (November 15 2000

Satellite detection of increased cyanobacteria blooms in the Baltic Sea: Natural fluctuation or ecosystem change?

Using data from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA series of satellites, an increase in the area covered by cyanobacteria blooms in the Baltic Sea was detected. The time series of satellite data covers a period of 12 years from 1982 to 1993. The total area covered by surface-floating cyanobacteria (blue-green algae) has increased in the 1990s, reaching over 62 000 km in 1992. From 1992, visible accumulations appeared for the first time in the Gulf of Riga and reappeared, in the western Gulf of Finland, after being absent from 1984. Conspicuous surface blooms were also present in the early 1980s, coincident with a period of sunny and calm summers. However, when the influence of variable sunshine duration is taken into account, the increase in 1991-1993 is still distinct, indicating significant changes in the Baltic environment. The causal factors for the increased cyanobacteria blooms are still not clear

Ligand-Doped Copper Oxo-hydroxide Nanoparticles are Effective Antimicrobials.

Bacterial resistance to antimicrobial therapies is an increasing clinical problem. This is as true for topical applications as it is for systemic therapy. Topically, copper ions may be effective and cheap antimicrobials that act through multiple pathways thereby limiting opportunities to bacteria for resistance. However, the chemistry of copper does not lend itself to facile formulations that will readily release copper ions at biologically compatible pHs. Here we have developed nanoparticulate copper hydroxide adipate tartrate (CHAT) as a cheap, safe and readily synthesised material that should enable antimicrobial copper ion release in an infected wound environment. First, we synthesised CHAT and showed that this had disperse aquated particle sizes of 2-5 nm, and mean zeta potential of -40 mV. Next, when diluted into bacterial medium, CHAT demonstrated similar efficacy to copper chloride against Escherichia coli and Staphylococcus aureus, with dose-dependent activity occurring mostly around 12.5-50 mg/L of copper. Indeed, at these levels, CHAT very rapidly dissolved and, as confirmed by a bacterial copper biosensor, showed identical intracellular loading to copper ions derived from copper chloride. However, when formulated at 250 mg/L in a topically-applied matrix, namely hydroxyethyl cellulose, the benefit of CHAT over copper chloride was apparent. The former yielded rapid sustained release of copper within the bactericidal range but the copper chloride, which formed insoluble precipitates at such concentration and pH, achieved a maximum release of 10 ± 7 mg/L copper by 24 hours. We provide a practical formulation for topical copper - based antimicrobial therapy. Further studies, especially in vivo, are merited