Investigating the role of allelochemicals in the interaction between Alexandrium monilatum and other phytoplankton species.

Autor: Gaillard S; Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA 23062, USA; Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. Electronic address: sylvain.gllrd@gmail.com., Small HJ; Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA 23062, USA., Ayache N; Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA., Tanniou S; IFREMER, PHYTOX unit, F 44000 Nantes, France., Hess P; IFREMER, PHYTOX unit, F 44000 Nantes, France., Réveillon D; IFREMER, PHYTOX unit, F 44000 Nantes, France., Harris CM; Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA., Harris TM; Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA., Scott GP; Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA 23062, USA., MacIntyre A; Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA 23062, USA., Reece KS; Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA 23062, USA.
Jazyk: angličtina
Zdroj: Harmful algae [Harmful Algae] 2024 Nov; Vol. 139, pp. 102706. Date of Electronic Publication: 2024 Aug 16.
DOI: 10.1016/j.hal.2024.102706
Abstrakt: Species of the dinoflagellate genus Alexandrium can release bioactive extracellular compounds with allelopathic effects (e.g., immobilization, inhibition of growth, photosynthesis or lysis) towards other phytoplanktonic organisms. In the lower Chesapeake Bay, Virginia, US, succession or co-occurrence of blooms of Akashiwo sanguinea, Margalefidinium polykrikoides and the goniodomin-producing A. monilatum tend to be common during summer months, however the allelopathic potential of A. monilatum, and how it may affect bloom dynamics, has not be studied. We used a rapid fluorescence-based bioassay as well as flow cytometry and an assessment of immobilization to determine the potential effects of A. monilatum culture supernatants on M. polykrikoides, A. sanguinea and the diatom Chaetoceros muelleri (included as a reference strain). In addition, we also investigated the effects of standards of known A. monilatum toxins goniodomin A (GDA) and GDA seco-acid (GDA-sa). Exposure of C. muelleri to culture supernatants from two different strains of A. monilatum resulted in an inhibition of the maximum quantum yield of the photosystem II (F v /F m ) and cell lysis of the diatom, with strain-specific variation observed, highlighted by a 30-fold difference in the effective concentration resulting in 10 % inhibition (EC 10 ) and 2-fold difference in the lethal concentration resulting in 50 % mortality (LC 50 ) between the two A. monilatum strains tested. Exposure of M. polykrikoides to A. monilatum culture supernatants resulted in a decrease in motility (at ≥ 500 eq. cells mL -1 ) along with a decrease in F v /F m (at ≥ 1,500 cells mL -1 ) and altered cellular morphology (at ≥ 3,500 eq. cells mL -1 ). No effect was observed when A. sanguinea was exposed to A. monilatum culture supernatants (at the concentrations tested in these studies). When M. polykrikoides was exposed to the GDA standard, its F v /F m (at ≥ 1,951 nM) and motility (at ≥ 390 nM) decreased, and its morphology (at ≥ 975 nM) was modified. The study of supernatant time- and temperature-stability, and the absence of a relationship between observed effects and goniodomin concentrations suggested the presence of additional unknown allelochemicals distinct from goniodomins, as has been observed for other Alexandrium species. Immobilization of M. polykrikoides by A. monilatum culture supernatants and GDA standard in laboratory-based exposure experiments may indicate that A. monilatum has a competitive advantage when both species co-occur in the Chesapeake Bay and this warrants further testing.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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