Cyst morphology, germination characteristics, and potential toxicity of Pyrodinium bahamense in the Gulf of California

Abstract

Pyrodinium bahamense is a meroplanktonic dinoflagellate that produces paralytic shellfish toxins that cause human poisoning along tropical and subtropical coasts. Cyst morphology, germination characteristics, and toxicity were investigated using samples from Isla San José in the Gulf of California. Morphology was observed through light and scanning electron microscopy. Germination was tested at different temperature (15°C-35°C) and salinity (15-35) conditions in different culture media (natural seawater, GSe, and f/2). To elucidate toxicity of vegetative cells grown from cyst germination, nine strains were subject to toxin analyses through fluorescence high-performance liquid chromatography. Morphological features and size of cysts generally agree with previous descriptions, particularly morphotypes found in the subtropical North Atlantic, where P. bahamense var. bahamense occurs. Cysts exhibit thermophilic and euryhaline characteristics. Highest germination occurred from 20°C to 35°C with the peak between 25°C and 30°C. Excystment occurred at salinities from 20 to 35. Germination occurred in the three culture media, but was highest in the optimal temperature range in the culture medium that included terrestrial soil extract and selenium. Only one strain exhibited toxicity with high saxitoxin concentration (95 pg STX eq cell -1 ).

Distribusi dan Kelimpahan Kista Pyrodinium bahamense di Perairan Rawan Marak Alga Berbahaya di Indonesia

“…Kista yang telah diekstraksi kemudian diidentifikasi dan dienumerasi menggunakan phase-contrast inverted microscope Nikon Diaphot pada perbesaran antara 100-400X. Enumerasi kista P. bahamense dilakukan dengan modifikasi metode analisis fraksi sampel (sample fraction) menggunakan Sedgewick Rafter Counting Chamber (SRCC) LeGresley & McDermott (2010), sedangkan identifikasi kista P. bahamense dilakukan berdasarkan karakter morfologi dan morfometri kista menurut Matsuoka (1989), Matsuoka et al (1999), dan Morquecho et al (2014). Sebagai catatan, semua sampel kista yang dikoleksi dalam penelitian terdahulu dari perairan Teluk Lampung (2014), Teluk Ambon (2014), Teluk Jakarta (2014 dan 2019), dan pesisir Cirebon (2017) telah melalui proses ekstraksi, enumerasi, dan identifikasi yang sama.…”

Co-ocurrence of two toxic dinoflagellates in Acapulco Bay, Guerrero, Mexico: an opportunity to quantify their biology and ecology

“…Continue studying this species is imperative because there are still many issues to elucidate with respect to its sexuality. Mertens et al (2015) point out that the species is heterothallic, and Morquecho et al (2014) indicate that the cysts are homothallic, suggesting that cultured populations of strains derived from the germination of cysts cannot undergo sexual reproduction or form hypnozygotes unless they are crossed. There is also no certainty about its dormancy time (regulated by an internal clock) and quiescence (reg-ulated by environmental conditions), and the morphology of its different states of life in the sexual cycle (gametangia, gametes, planozyygotes and planomeiocytes).…”

Pyrodinium bahamense One the Most Significant Harmful Dinoflagellate in Mexico

“…Ecophysiological studies with regional P. bahamense strains are insufficient in México, and so far, strains from Isla San José, Gulf of California have only been studied. To elucidate the toxicity of vegetative cells grown from cyst germination, Morquecho et al (2014) analyzed nine strains through fluorescence highperformance liquid chromatography, and only one exhibited toxicity with high saxitoxin concentration (95 pg STX eq cell −1 ). Additionally, morphological features and size of cysts agreed with previous descriptions, particularly morphotypes found in the subtropical North Atlantic.…”

“…The colorless wall is bi-layered, with a scabrate outer surface and a smooth inner surface. In living cysts, the yellow-green cytoplasm encloses a red accumulation body ( Figure 1D) and numerous starch grains (Morquecho et al, 2014). Vegetative stage is easy to identify with basic microscopy equipment, and it could hardly be confused with other species.…”