Ecological roles of nano-picoplankton in stratified waters of an embayment in the southern Benguela.

Nano-picoplankton are the dominant primary producers during the postupwelling period in St Helena Bay, South Africa. Their dynamics on short timescales are not well-understood and neither are the community composition, structure, and potential functionality of the surrounding microbiome. Samples were collected over five consecutive days in March 2018 from three depths (1, 25, and 50 m) at a single sampling station in St Helena Bay.

Harmful algal blooms of the Benguela eastern boundary upwelling system.

The Benguela Upwelling System (BUS) is subject to a high incidence of HABs. Of the major shellfish poisoning syndromes associated with HABs, Paralytic and Diarrhetic Shellfish Poisoning (PSP and DSP) pose the greatest concern, but as documented herein there are several other HAB organisms that are also present. Blooms of Alexandrium catenella have been recognised as the typical cause of PSP since 1948.

Perceived global increase in algal blooms is attributable to intensified monitoring and emerging bloom impacts.

Global trends in the occurrence, toxicity and risk posed by harmful algal blooms to natural systems, human health and coastal economies are poorly constrained, but are widely thought to be increasing due to climate change and nutrient pollution. Here, we conduct a statistical analysis on a global dataset extracted from the Harmful Algae Event Database and Ocean Biodiversity Information System for the period 1985-2018 to investigate temporal trends in the frequency and distribution of marine harmful algal blooms. We find no uniform global trend in the number of harmful algal events and their distribution over time, once data were adjusted for regional variations in monitoring effort.

Devastating farmed abalone mortalities attributed to yessotoxin-producing dinoflagellates.

A large dinoflagellate bloom in Walker Bay (South Africa) in January 2017 impacted 3 land-based abalone farms resulting in the death of several million animals. Satellite-derived images of Chl-a from the Ocean and Land Colour Imager (OLCI) on board the European Space Agency Sentinel-3 A showed bloom initiation in late December 2016 and dispersal in mid-February 2017. The bloom was dominated by two dinoflagellate species identified by light microscopy as Gonyaulax spinifera (Claparède & Lachmann) Diesing, 1866 and Lingulodinium polyedrum (Stein) Dodge, 1989.

Pentaplacodinium saltonense gen. et sp. nov. (Dinophyceae) and its relationship to the cyst-defined genus Operculodinium and yessotoxin-producing Protoceratium reticulatum.

Strains of a dinoflagellate from the Salton Sea, previously identified as Protoceratium reticulatum and yessotoxin producing, have been reexamined morphologically and genetically and Pentaplacodinium saltonense n. gen. et sp.

Declining oxygen in the global ocean and coastal waters.

Oxygen is fundamental to life. Not only is it essential for the survival of individual animals, but it regulates global cycles of major nutrients and carbon. The oxygen content of the open ocean and coastal waters has been declining for at least the past half-century, largely because of human activities that have increased global temperatures and nutrients discharged to coastal waters.

Non-traditional vectors for paralytic shellfish poisoning.

Paralytic shellfish poisoning (PSP), due to saxitoxin and related compounds, typically results from the consumption of filter-feeding molluscan shellfish that concentrate toxins from marine dinoflagellates. In addition to these microalgal sources, saxitoxin and related compounds, referred to in this review as STXs, are also produced in freshwater cyanobacteria and have been associated with calcareous red macroalgae. STXs are transferred and bioaccumulate throughout aquatic food webs, and can be vectored to terrestrial biota, including humans.

Ocean urea fertilization for carbon credits poses high ecological risks.

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best.

A simple and rapid scanning electron microscope preparative technique for delicate "gymnodinioid" dinoflagellates.

Light microscopy (LM) is routinely used to investigate delicate (unarmoured and lightly armoured) "gymnodinioid" dinoflagellate species but at this level of resolution, morphological features such as apical grooves, apical pores, thin thecal plates, and scales are often difficult to observe, thereby necessitating the use of scanning electron microscopy (SEM). Good results were obtained when harvested cells were fixed with osmium tetroxide (OsO(4)) as the primary fixative, adhered with poly-L-lysine to round glass coverslips, dehydrated in an ethanol series, and dried with hexamethyldisilazane (HMDS). Poly-L-lysine has in the past effectively been used to adhere biological material such as human red blood cells, mouse leukemic cells, and marine dinoflagellates to glass coverslips.