The role of macroalgae in epiphytism of the toxic dinoflagellate Gambierdiscus toxicus (Dinophyceae)

Abstract

Populations of the toxic, epiphytic dinoflagellate Gambierdiscus toxicus Adachi et Fukuyo are associated closely with Jania sp. on Hitiaa and Papara fringing reefs in Tahiti. Small populations were also observed to be associated with Amphiroa sp. and Halimeda opuntia (L.) Lamouroux. The cells attached themselves to the thallus by means of a short thread. When the thalli were irradiated, the cells began to detach from them and swim around the branches. The swimming cells stopped and attached to substrata when a disturbance occurred. The attached cells began to swim within a short time under light conditions when the thallus of Jania sp. were placed near the attached cells. Amphiroa sp. and H. opuntia also induced this re-commencement of swimming of the attached cells. These observations suggest that G. toxicus usually swims around macroalgal thalli on coral reefs. When sudden disturbance or strong water motion occurs, they attach to the surface of macroalgae and are not dispersed. Soon after water motion becomes slow, the cells begin to swim into the water around the thalli. The epiphytism of G. toxicus is different from epiphytic pennate diatoms, most of which adhere to the thallus all the time. The population of G. toxicus is maintained as an association to a limited number of species of macroalgae which support the re-commencement of swimming after disturbance.

Ciguatera-Causing Dinoflagellates in a Coral-reef Mangrove Ecosystem, Belize

“…In contrast, on macrophytes bloom populations of G. toxicus were high at the fringing reefs in Tahiti, Yasumoto et al, (1979), Papara reef (Nakahara et al, 1996), and Hitiaa reef (Bagnis et al, 1990). Yasumoto et al, (1980);and Ballantine et al, (1988) illustrated that G. toxicus cells formed a mucilaginous matrix over the macroalgal surface.…”

“…Yasumoto et al, (1980);and Ballantine et al, (1988) illustrated that G. toxicus cells formed a mucilaginous matrix over the macroalgal surface. Nakahara et al, (1996) observed G. toxicus cells attached or cells swimming around on the thallus of Janina sp. ; and Coolia canariensis species attached to epiphytes on rocks at the tidal pools in the Canary Islands (Fraga et al, 2008).…”

“…Harmful blooms were observed of O. lenticularis, C. monotis, and G. toxicus on associated macroalgae (Ballantine et al, 1988;Fukuyo, 1981;Nakahara et al, 1996), and on dead corals (Carlson and Tindall, 1985). This study supports the finding that inshore localized area of sand at South Water may serve as a nursery for harmful-dinoflagellates.…”

“…The association of CFP-dinoflagellates with a specific macroalgae indicated substrate specificity, as recognized by Yasumoto et al, (1979), but in other areas numerous dinoflagellate species occupied red, brown, and green algae (Bomber et al, 1988a). The flexibility of the thallus which provides nutrients for dinoflagellates may be another regulatory factor (Nakahara et al, 1996). Populations of G. toxicus have a distinct seasonal pattern in Florida (Bomber et al, 1988b) and are most abundant in the warm season.…”

Composición de dinoflagelados epífitos y forófitos en la Costa norte del golfo de Morrosquillo, Sucre, Colombia

“…Una de las posibles causas que pudieron afectar son las características de los sitios, ya que estos están compuestos principalmente por rompeolas, los cuales cumplen la función de disminuir la fuerza de llegada del oleaje a la costa. No obstante, estos ocasionan que incremente la turbulencia dado el choque de estas corrientes hacia las rocas, de tal forma que es posible que la adhesión efectiva de los dinoflagelados epífitos sobre las macrófitas disminuya, haciendo que se suspendan en la columna de agua (NAKAHARA et al, 1996;RICHLEN y LOBEL, 2011). Además, se observó una fuerte deposición de sedimento sobre la mayoría de macrófitas, que también afecta la colonización de estos microorganismos (DELGADO et al, 2006).…”