Changing Trends in Paralytic Shellfish Poisonings Reflect Increasing Sea Surface Temperatures and Practices of Indigenous and Recreational Harvesters in British Columbia, Canada

Paralytic shellfish poisoning (PSP) occurs when shellfish contaminated with saxitoxin or equivalent paralytic shellfish toxins (PSTs) are ingested. In British Columbia, Canada, documented poisonings are increasing in frequency based on 62 investigations identified from 1941–2020. Two PSP investigations were reported between 1941 and 1960 compared to 31 since 2001 (p < 0.0001) coincident with rising global temperatures (r2 = 0.76, p < 0.006). The majority of PSP investigations (71%) and cases (69%) were linked to self-harvested shellfish. Far more investigations involved harvests by indigenous communities (24%) than by commercial and recreational groups. Single-case-exposure investigations increased by more than 3.5 times in the decade 2011–2020 compared to previous periods. Clams (47%); mussels (26%); oysters (14%); scallops (6%); and, in more recent years, crabs (4%) were linked to illnesses. To guide understanding of self-harvesting consumption risks, we recommend collecting data to determine when PST-producing algae are present in high concentrations, improving the quality of data in online shellfish harvest maps to include dates of last testing; biotoxin testing results; and a description of bivalve species tested. Over reliance on toxin results in biomonitored species may not address actual consumption risks for unmonitored species harvested from the same area. We further recommend introducing phytoplankton monitoring in remote indigenous communities where self-harvesting is common and toxin testing is unavailable, as well as continuing participatory education about biotoxin risks in seafoods.

Dual-Modality Imaging Microfluidic Cytometer for Onsite Detection of Phytoplankton

Phytoplankton monitoring is essential for better understanding and mitigation of phytoplankton bloom formation. We present a microfluidic cytometer with two imaging modalities for onsite detection and identification of phytoplankton: a lensless imaging mode for morphological features, and a fluorescence imaging mode for autofluorescence signal of phytoplankton. Both imaging modes are integrated in a microfluidic device with a field of view (FoV) of 3.7 mm × 2.4 mm and a depth of field (DoF) of 0.8 mm. The particles in the water flow channel can be detected and classified with automated image processing algorithms and machine learning models using their morphology and fluorescence features. The performance of the device was demonstrated by measuring Chlamydomonas, Euglena, and non-fluorescent beads in both separate and mixed flow samples. The recall rates for Chlamydomonas and Euglena ware 93.6% and 94.4%. The dual-modality imaging approach enabled observing both morphology and fluorescence features with a large DoF and FoV which contribute to high-throughput analysis. Moreover, this imaging flow cytometer platform is portable, low-cost, and shows potential in the onsite phytoplankton monitoring.

Cyanobacteria from freshwater lakes in the Azores archipelago, Portugal: data from long term phytoplankton monitoring

The Azores are oceanic islands located in the Northern Atlantic Ocean and are particularly rich in aquatic systems, ranging from freshwater, brackish, marine and thermal habitats. Due to the increase in local anthropogenic pressures and global warming, several azorean lakes began to reveal signs of eutrophication that led to the implementation of monitoring programmes and management strategies on the most impacted lakes. Later, the Water Framework Directive (2000/60/EC) demanded the establishment of biomonitoring programmes for European freshwater ecosystems and the limited Azorean monitoring programmes were extended to a larger set of lakes. Since the establishment of the aquatic systems monitoring programme in the Azores archipelago, lakes have been regularly sampled, producing innumerous unpublished records of cyanobacteria that are difficult to access. Here we present the occurrences of cyanobacteria in Azorean lakes that result from 22 years of phytoplankton monitoring in a total of 1948 cyanobacteria occurrences from 968 phytoplankton sampling events on Azorean lakes done between 1996 and 2018 as part of regional inland aquatic ecosystems monitoring programmes. Forty two cyanobacteria taxa were identified in those events, 28 species and 14 at genus level. This information is crucial for conservation, biodiversity studies and lake management, as some of the cyanobacteria species present are bloom-forming and have the ability to produce toxins. This will also allow for the identification of invasive species and possible targeted control and mitigation programmes, according to the species present in the Azorean lakes.

Phytoplankton as bioindicators of water quality in Nasarawa reservoir, Katsina State Nigeria

Aim Phytoplankton monitoring as bioindicators to assess the health of the Nasarawa reservoir and also to evaluate the relationship between phytoplankton and reservoir environmental variables. Methods Phytoplankton and water samples from Nasarawa reservoir (Nigeria) were collected and analysed for ten months (February, 2018 to November, 2018) using standard methods at five sampling sites. Results A total of 38 genera belonging to five major families such as: Bacillariophyceae (42%), Chlorophyceae (24%) Cyanophyceae (13%), Deemidiaceae (18%) and Euglenophyceae (3%) were recorded. Four Phytoplankton classes; Bacillariophyta, Chlorophyta Cyanophyta, and Desmidiaceae show positive close relation with dissolved oxygen, pH, transparency, and total dissolved solids. The overall phytoplankton density in the reservoir was higher in dry season than the wet season. Palmer pollution index was employed to study the water quality of the reservoir. The total score was calculated to be 25, showing evidence of high organic pollution. Conclusions The presence of organic pollution indicators Closterium sp, Navicula sp, Nitzschia sp, Synedra sp, Chlamydomonas sp, Cyclotella sp and Anacystis sp is a warning sign of the deteriorating condition of the water quality in the reservoir. Measures need to be enforced to reduce the rate of pollution of the reservoir arising from the human activities in the catchment of the reservoir.

INFLUENCE OF PHOSPHORUS-CONTAMINATED SEDIMENTS IN THE ABUNDANCE OF POTENTIALLY TOXIC PHYTOPLANKTON ALONG THE SFAX COASTS (GULF OF GABES, TUNISIA)

This is the first work performed in the shellfish production area located along the Sfax coasts (southern Tunisia) on the spatial and temporal patterns of toxic phytoplankton. It relates the excessive introduction of phosphorus in coastal waters from sediments contaminated with that nutrient. A multivariate approach was applyed using data derived from the National Phytoplankton Monitoring Program (REPHY) (2006-2009). We also examine if there is a direct relationship between the abundance of toxic phytoplankton and physical and chemical parameters. This study is based on phytoplankton composition and abundance, as well as physical and chemical data to evaluate the ecological status of the Sfax coasts, at shellfish farms. A total of 13 taxa included in the Intergovernmental Oceanographic Commission (IOC) toxic algae checklist and well-known bloom formers were identified in REPHY. Higher nutrient spring samples were distinguished from those of lower nutrient summer waters. The Redundancy Analysis (RDA) separated the toxic species into two groups related to nutrients availability. The large amounts of phosphorus and organic matter affected the toxic phytoplankton structure, due to the pollution of chemical origin underlining an organic load hardly biodegradable in Sfax coasts. Many of these species recorded in the water column were benthic dinoflagellates, a fact that could be explained by the resuspension of these organisms by hydrodynamics. The knowledge obtained in this study can be used to develop best management practices of the sediment compartment as well as the water column, which is crucial in the framework of any phytoplankton monitoring program. INFLUÊNCIA DE SEDIMENTOS CONTAMINADOS POR FÓSFORO NA ABUNDÂNCIA DE FITOPLANCTÔNPOTENCIALMENTE TÓXICO NAS COSTAS DE SFAX (GOLFO DE GABES, TUNÍSIA)ResumoEste é o primeiro trabalho realizado na área de produção de moluscos, situada ao longo das costas de Sfax (sul da Tunísia) que relaciona os padrões espaciais e temporais do fitoplâncton tóxico com a introdução excessiva de fósforo nas águas costeiras a partir da remobilização de sedimentos contaminados com esse nutriente. Foi usada uma abordagem multivariada com Base em dados derivados do Programa Nacional de Monitoramento de Fitoplâncton (REPHY) (2006-2009). Também foi analisada a relação entre a abundância de fitoplâncton tóxico e parâmetros físico-químicos. Este estudo baseia-se na composição e abundância de fitoplâncton, além de dados físicos e químicos para avaliar o estado ecológico das costas de Sfax, em áreas de cultivo de moluscos. Um total de 13 táxons incluídos na lista de algas tóxicas da Comissão Intergovernamental Oceanográfica e espécies geradoras de blooms de fitoplanctôn, bem conhecidas, foram identificados. Amostras de primavera, associadas a águas com mais nutrientes foram diferenciadas das amostras de verão em que a água tem teores mais baixos de nutrientes. A Análise de Redundância (RDA) separou as espécies tóxicas em dois grupos relacionados à disponibilidade de nutrientes. Os resultados revelaram que teores elevados de fósforo e matéria orgânica afetaram a estrutura do fitoplâncton tóxico, devido à poluição de origem química subjacente a uma carga orgânica dificilmente biodegradável nas costas de Sfax. Muitas das espécies encontradas na coluna de água são dinoflagelados bentônicos, fato que pode ser explicado pela ressuspensão desses organismos pelo hidrodinamismo. Os conhecimentos obtidos neste trabalho podem ser usados para desenvolver melhores práticas de gerenciamento costeiro e programas de monitoramento de fitoplâncton. Palavras Chave: Costas do sul de Sfax. Microalgas prejudiciais. Análise multivariada. Parâmetros físicos e químicos.

Molecular tools for phytoplankton monitoring samples

HABs can have severe impacts in fisheries or human health by the consumption of contaminated bivalves. Monitoring assessment (quantitative and qualitative identification) of these organisms, is routinely accomplished by microscopic identification and counting of these organisms. Nonetheless, molecular biology techniques are gaining relevance, once these approaches can easily identify phytoplankton organisms at species level and even cell number quantifications. This work tests 12 methods/kits for genomic DNA extraction and seven DNA polymerases to determine which is the best method for routinely use in a common molecular laboratory, for phytoplankton monitoring samples analyses. From our work, Direct PCR master mix for tissue samples, proved to be the most adequate by its velocity of processivity, practicability, reproducibility, sensitiveness and robustness. However, brands such as Omega Biotek, GRISP, Qiagen and MP Biomedicals also showed good results for conventional DNA extraction as well as all the Taq brands tested (GRISP, GE Healthcare Life Sciences, ThermoFisher Scientific and Promega). Lugol’s solution, with our tested kits did not show negative interference in DNA amplification. The same can be said about mechanical digestion, with no significant differences among kits with or without this homogenization step.

Isolation and characterization of algicidal bacteria and its effect on a musty odor-producing cyanobacterium Dolichospermum crassum in a reservoir

Algicidal bacteria that attack Dolichospermum crassum were isolated from the Karasuhara Reservoir in October 2010. Phytoplankton monitoring was performed from April 2010 to March 2011, and D. crassum was detected from August to November. At its peak frequency (in early October), it accounted for 23% of all phytoplankton cells. Heterotrophic bacteria were isolated from the surface water, and an algicidal assay was conducted. As a result, 3 out of 47 bacterial strains showed strong algicidal activity, and they completely destroyed the trichomes of D. crassum. An initial inoculation dose of only 1.0 × 102 cells ml−1 of these strains was enough to digest D. crassum. These strains were identified as Rheinheimera spp. according to 16S rDNA sequence analyses. This is the first report about algicidal bacteria that attack D. crassum. Algicidal bacteria could be key agents for controlling D. crassum in reservoirs.