Responses of Freshwater Zooplankton as Biological Indicators to the Aquatic Chemical Properties

Zooplankton are found very sensitive to even slight aquatic pollution due to a number of chemical imbalances in freshwater bodies. As an amazing tiny creature zooplankton play a very crucial role in the aquatic food chain by transferring energy from primary levels to tertiary organisms. For many years it has been well established that zooplankton act as promising biological indicators to continuously fluctuating aquatic environments and subsequently to global warming. While reacting to these aquatic environmental fluctu-ations, zooplankton population growth can either be stimulated or inhibited. The presence or absence of particular zooplankton species can reveal the trophic status of the water body. Moreover, in a harsh env-ironment, algal toxins may have drastic effects on the behavioral characteristics of zooplankton.

Substances of emerging concern in Baltic Sea water: Review on methodological advances for the environmental assessment and proposal for future monitoring

The Baltic Sea is among the most polluted seas worldwide. Anthropogenic contaminants are mainly introduced via riverine discharge and atmospheric deposition. Regional and international measures have successfully been employed to reduce concentrations of several legacy contaminants. However, current Baltic Sea monitoring programs do not address compounds of emerging concern. Hence, potentially harmful pharmaceuticals, UV filters, polar pesticides, estrogenic compounds, per- and polyfluoroalkyl substances, or naturally produced algal toxins are not taken into account during the assessment of the state of the Baltic Sea. Herein, we conducted literature searches based on systematic approaches and compiled reported data on these substances in Baltic Sea surface water and on methodological advances for sample processing and chemical as well as effect-based analysis of these analytically challenging marine pollutants. Finally, we provide recommendations for improvement of future contaminant and risk assessment in the Baltic Sea, which revolve around a combination of both chemical and effect-based analyses.

Monitoring the Emergence of Algal Toxins in Shellfish: First Report on Detection of Brevetoxins in French Mediterranean Mussels

In France, four groups of lipophilic toxins are currently regulated: okadaic acid/dinophysistoxins, pectenotoxins, yessotoxins and azaspiracids. However, many other families of toxins exist, which can be emerging toxins. Emerging toxins include both toxins recently detected in a specific area of France but not regulated yet (e.g., cyclic imines, ovatoxins) or toxins only detected outside of France (e.g., brevetoxins). To anticipate the introduction to France of these emerging toxins, a monitoring program called EMERGTOX was set up along the French coasts in 2018. The single-laboratory validation of this approach was performed according to the NF V03-110 guidelines by building an accuracy profile. Our specific, reliable and sensitive approach allowed us to detect brevetoxins (BTX-2 and/or BTX-3) in addition to the lipophilic toxins already regulated in France. Brevetoxins were detected for the first time in French Mediterranean mussels (Diana Lagoon, Corsica) in autumn 2018, and regularly every year since during the same seasons (autumn, winter). The maximum content found was 345 µg (BTX-2 + BTX-3)/kg in mussel digestive glands in November 2020. None were detected in oysters sampled at the same site. In addition, a retroactive analysis of preserved mussels demonstrated the presence of BTX-3 in mussels from the same site sampled in November 2015. The detection of BTX could be related to the presence in situ at the same period of four Karenia species and two raphidophytes, which all could be potential producers of these toxins. Further investigations are necessary to understand the origin of these toxins.

Algal Toxic Compounds and Their Aeroterrestrial, Airborne and other Extremophilic Producers with Attention to Soil and Plant Contamination: A Review

The review summarizes the available knowledge on toxins and their producers from rather disparate algal assemblages of aeroterrestrial, airborne and other versatile extreme environments (hot springs, deserts, ice, snow, caves, etc.) and on phycotoxins as contaminants of emergent concern in soil and plants. There is a growing body of evidence that algal toxins and their producers occur in all general types of extreme habitats, and cyanobacteria/cyanoprokaryotes dominate in most of them. Altogether, 55 toxigenic algal genera (47 cyanoprokaryotes) were enlisted, and our analysis showed that besides the “standard” toxins, routinely known from different waterbodies (microcystins, nodularins, anatoxins, saxitoxins, cylindrospermopsins, BMAA, etc.), they can produce some specific toxic compounds. Whether the toxic biomolecules are related with the harsh conditions on which algae have to thrive and what is their functional role may be answered by future studies. Therefore, we outline the gaps in knowledge and provide ideas for further research, considering, from one side, the health risk from phycotoxins on the background of the global warming and eutrophication and, from the other side, the current surge of interest which phycotoxins provoke due to their potential as novel compounds in medicine, pharmacy, cosmetics, bioremediation, agriculture and all aspects of biotechnological implications in human life.

Microfluidic Flow Injection Immunoassay System for Algal Toxins Determination: A Case of Study

A novel flow injection microfluidic immunoassay system for continuous monitoring of saxitoxin, a lethal biotoxin, in seawater samples is presented in this article. The system consists of a preimmobilized G protein immunoaffinity column connected in line with a lab-on-chip setup. The detection of saxitoxin in seawater was carried out in two steps: an offline incubation step (competition reaction) performed between the analyte of interest (saxitoxin or Ag, as standard or seawater sample) and a tracer (an enzyme-conjugated antigen or Ag*) toward a specific polyclonal antibody. Then, the mixture was injected through a “loop” of a few μL using a six-way injection valve into a bioreactor, in line with the valve. The bioreactor consisted of a small glass column, manually filled with resin upon which G protein has been immobilized. When the mixture flowed through the bioreactor, all the antibody-antigen complex, formed during the competition step, is retained by the G protein. The tracer molecules that do not interact with the capture antibody and protein G are eluted out of the column, collected, and mixed with an enzymatic substrate directly within the microfluidic chip, via the use of two peristaltic pumps. When Ag* was present, a color change (absorbance variation, ΔAbs) of the solution is detected at a fixed wavelength (655 nm) by an optical chip docking system and registered by a computer. The amount of saxitoxin, present in the sample (or standard), that generates the variation of the intensity of the color, will be directly proportional to the concentration of the analyte in the analyzed solution. Indeed, the absorbance response increased proportionally to the enzymatic product and to the concentration of saxitoxin in the range of 3.5 × 10–7–2 × 10–5 ng ml−1 with a detection limit of 1 × 10–7 ng ml−1 (RSD% 15, S N−1 equal to 3). The immunoanalytical system has been characterized, optimized, and tested with seawater samples. This analytical approach, combined with the transportable and small-sized instrumentation, allows for easy in situ monitoring of marine water contaminations.

Contaminants of Emerging Concern in African Wastewater Effluents: Occurrence, Impact and Removal Technologies

Worldwide, the pollution of water bodies by contaminants of emerging concern (CECs) such as pharmaceuticals, endocrine disrupting compounds, flame retardants including brominated flame retardants (BFRs) and perfluorochemicals (PFCs), micro plastics, nanomaterials, and algal toxins, to name just a few, is creating a new set of challenges to the conventional wastewater treatment facilities, which demonstrate inefficiency in removing/degrading many CECs. As a consequence, environmentalists started to detect the presence of some of those contaminants at alarming levels in certain countries, with possible negative effects on aquatic species and often increased potential for human health risks through the exposure to the contaminated waters, or the reuse of treated wastewater in agriculture and household use. Such issues are more accentuated in the African continent due to various socio-economic problems giving rise to poor sanitation systems and serious shortages in wastewater treatment plants in many regions, making it difficult to tackle the problem of conventional pollutants, let alone to deal with the more challenging CECs. Thus, in order to effectively deal with this emerging environmental threat, African researchers are working to develop and optimize sound sampling and analytical procedures, risk assessment models, and efficient remediation technologies. In this review, related recent research efforts conducted in African universities and research institutions will be presented and discussed with respect to the occurrence and assessment of CECs in African wastewater effluents, the potential risks to aquatic ecosystems and humans, the tailored remediation techniques, along with some knowledge gaps and new research directions.