A Comparative Study on Three Analytical Methods for the Determination of the Neurotoxin BMAA in Cyanobacteria

The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been considered a serious health threat because of its putative role in multiple neurodegenerative diseases. First reports on BMAA concentrations in cyanobacteria were alarming: nearly all cyanobacteria were assumed to contain high BMAA concentrations, implying ubiquitous exposure. Recent studies however question this presence of high BMAA concentrations in cyanobacteria. To assess the real risk of BMAA to human health, this discrepancy must be resolved. We therefore tested whether the differences found could be caused by the analytical methods used in different studies. Eight cyanobacterial samples and two control samples were analyzed by three commonly used methods: HPLC-FLD analysis and LC-MS/MS analysis of both derivatized and underivatized samples. In line with published results, HPLC-FLD detected relatively high BMAA concentrations in some cyanobacterial samples, while both LC-MS/MS methods only detected BMAA in the positive control (cycad seed sarcotesta). Because we could eliminate the use of different samples and treatments as causal factors, we demonstrate that the observed differences were caused by the analytical methods. We conclude that HPLC-FLD overestimated BMAA concentrations in some cyanobacterial samples due to its low selectivity and propose that BMAA might be present in (some) cyanobacteria, but in the low µg/g or ng/g range instead of the high µg/g range as sometimes reported before. We therefore recommend to use only selective and sensitive analytical methods like LC-MS/MS for BMAA analysis. Although possibly present in low concentrations in cyanobacteria, BMAA can still form a health risk. Recent evidence on BMAA accumulation in aquatic food chains suggests human exposure through consumption of fish and shellfish which expectedly exceeds exposure through cyanobacteria

Eutrophication management in surface waters using lanthanum modified bentonite: a review

This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The available data underline a high efficiency for phosphorus binding. This efficiency can be limited by the presence of humic substances and competing oxyanions. Lanthanum concentrations detected during a LMB application are generally below acute toxicological threshold of different organisms, except in low alkalinity waters. To date there are no indications for long-term negative effects on LMB treated ecosystems, but issues related to La accumulation, increase of suspended solids and drastic resources depletion still need to be explored, in particular for sediment dwelling organisms. Application of LMB in saline waters need a careful risk evaluation due to potential lanthanum release

Guiding principles for the development and application of solid-phase phosphorus adsorbents for freshwater ecosystems

While a diverse array of phosphorus (P)-adsorbent materials is currently available for application to freshwater aquatic systems, selection of the most appropriate P-adsorbents remains problematic. In particular, there has to be a close correspondence between attributes of the P-adsorbent, its field performance, and the management goals for treatment. These management goals may vary from a rapid reduction in dissolved P to address seasonal enrichments from internal loading, targeting external fluxes due to anthropogenic sources, or long term inactivation of internal P inventories contained within bottom sediments. It also remains a challenge to develop new methods and materials that are ecologically benign and cost-effective. We draw on evidence in the literature and the authors’ personal experiences in the field, to summarise the attributes of a range of P-adsorbent materials. We offer 'guiding principles' to support practical use of existing materials and outline key development needs for new materials

Effects of guanotrophication and warming on the abundance of green algae, cyanobacteria and microcystins in Lake Lesser Prespa, Greece

The data set contains the raw data used for the analysis in a study to the effect of guanotrophication on algae abundance in Lake Lesser Prespa Greece, as described in the research paper by Valentini et al. in PLOSONE. Lake Lesser Prespa in Greece is a vital breeding habitat for the Dalmatian and Great White Pelican. However, eutrophication processes are distressing the lake system and the outbreaks of cyanobacterial blooms during the warm months may pose a threat to aquatic organisms due to the presence of microcystins (MCs). In this study we hypothesize that nutrients (eutrophication), nutrient-rich pelican droppings (guanotrophication) and warming (climate change) can affect the algal growth and MCs production in the water layer of Lake Lesser Prespa. An experiment (bioassay) was set up where water of (three sites in) lake Lesser Prespa was incubated at two temperatures (20°C and 30°C). Five treatments were used at both temperatures to study the algal development on a short term: 1) control, 2) nitrogen addition, 3) phosphorus addition, 4) nitrogen+phosphorus addition 5) bird dropping addition. In this repository the following data are included: -Chlorophyl-a concentrations in the water (initial and end-concentrations and of additional validation experiment); -Several nutrient concentrations in the water (initial and end-concentrations); -Several nutrient concentrations in bird droppings of pelicans; -Microcystin concentrations in the water (end-concentrations)

Effect of the toxin (microcystin) content of Microcystis on copepod grazing

Although phytoplankton chemical defense may regulate plankton dynamics, demonstrating an ecologically relevant anti-grazer cue is challenging. Presented here is a novel approach to evaluate the quantitative effect of microcystin (MC), the most studied group of cyanobacterial metabolites, on grazing by the common copepod Eudiaptomus gracilis. A temperature-induced gradient in the intracellular MC concentration of three different Microcystis strains enabled the comparison of grazing pressure on cells of the same cyanobacterial strain producing different amounts of MC, in a diet with alternative food (Chlamydomonas). In all treatments, grazing pressure on Microcystis was inversely related to its MC-LR content, while selection for alternative prey was positively related to the MC-LR content of Microcystis. Moreover, grazing on Chlamydomonas also declined with increasing Microcystis MC-LR content, suggesting toxicity related inhibition of E. gracilis. The negative relation between cellular MC-LR concentration and feeding responses supported the anti-grazer hypothesis. Not all MC variants responded to temperature, and some were therefore not associated to grazing responses. Using an induced gradient in the concentration of a suspected phytoplankton defense metabolite to evaluate its quantitative relationship with grazing pressure offers an improved inference on the ecological roles of toxins. Results suggest that either MC-LR or a correlating trait may be inversely linked to the grazer pressure on Microcystis