Red tide of the Lingulodinium polyedrum (Dinophyceae) in Odessa Bay (Black Sea)

One of the most massive red tides at the Odessa Bay was observed in September October 2020. It was caused by a toxic dinoflagellate Lingulodinium polyedrum (Stein) Dodge. The maximum abundance (56.1 x 106 cells L-1) of L. polyedrum was registered at the Odessa port area on October 6 when a water temperature and a salinity were 19.7°C and 14.3 ‰ respectively. The red tide was so huge and dense that the water glowed at night due to the bioluminescence characteristic of this species. The article briefly describes the history of the study of L. polyedrum in this area and provides a detailed morphological description with original photographs of this species sampled from bloom. We associate the appearance of the red tide with an increased temperature of sea water and air, a high content of nutrients, the presence of viable L. polyedrum cysts, and a slight decrease in salinity in the bay during the period of a mass development of the species in autumn of 2020. The red tide was accompanied by Protoperidinium steini, P. divergens, Prorocentrum cordatum, P. minimum, P. micans, Gonyaulas scrippsae, Diplopsalis lenticula, Azadinium spinosum, Dinophysis rotundata, D. acuminata, Oblea rotunda, Scrippsiella trochoidea, Ceratium furca.

Dinoflagellate cysts production in the north-western Adriatic Sea

A sediment trap study was conducted in the Gulf of Venice, north-western Adriatic Sea, from April to December 2005 to assess relationships between planktonic dinoflagellates and cyst production. Every month, CTD profiles and discrete samplings for phytoplankton, nutrients and particulate matter were conducted. Cyst fluxes spanned from 90 to 127,600 cysts m-2 d-1 and major peaks were due to a small cyst attributed to cf. Biecheleria and to calcareous cysts of Scrippsiella trochoidea. A good correspondence between cyst fluxes in sediment traps and the presence of the corresponding vegetative cells in the water column was detected for Lingulodinium polyedrum, and species of the genera Spiniferites,Gonyaulax and Protoperidinium. A PCR method applied to surface sediment samples allowed the identification of a number of potentially harmful dinoflagellate cysts (Alexandrium minutum, A. tamutum, A. taylorii, Lingulodinium polyedrum and Protoceratium reticulatum).

The inhibitory effect of a non-yessotoxin-producing dinoflagellate, Lingulodinium polyedrum (Stein) Dodge, towards Vibrio vulnificus and Staphylococcus aureus

<p>The increased bacterial resistance to antibiotics has caused global concern, prompting the search for new compounds. Because of their abundance and diversity, marine phytoplankton are an important potential source of such compounds. Research on dinoflagellates has led to the discovery of inhibitors of bacterial growth. The marine dinoflagellate <em>Lingulodinium polyedrum</em> blooms in different regions of the world, including Mexico, and is also known to regulate the growth of other species in coastal waters. Here, we investigate the taxonomy of this dinoflagellate and characterize the ability of its extracts to inhibit the growth of two bacteria of medical importance (<em>Vibrio</em> <em>vulnificus</em> and <em>Staphylococcus</em> <em>aureus</em>) on agar culture plates. Taxonomic characterization was performed by PCR and gene amplification of ITS, and confirmed that the species isolated off the Pacific coast of Mexico was <em>L.</em> <em>polyedrum</em>. To prove the inhibitory effect of <em>L. polyedrum</em> extracts, cultures were harvested by centrifugation. Pellets from three cellular abundances were extracted with water, methanol, hexane and chloroform. The experiments on <em>V. vulnificus</em> showed a high growth inhibition for the four extracts, ranging from 77 to 98%. Surprisingly, the growth inhibition was lower when the extracts originated from a higher <em>L. polyedrum</em> cell abundance, ranging from 0 to 34%. For <em>S. aureus</em>, the growth inhibition was also high, but not statistically different for all extracts and cell abundances, ranging from 62 to 99%. This shows promise for future pharmacological applications. Our Mexican strain of <em>L. polyedrum</em> did not produce any detectable yessotoxins.</p>