Restoration of cell size by vegetative cell enlargement in Coscinodiscus wailesii (Bacillariophyceae)

Cell size reduction and restoration of the diatom <i>Eucampia zodiacus</i> in culture

“…One is auxospore formation (sexual processes) and the other is vegetative cell enlargement (asexual formation). Vegetative cell enlargement has been reported in centric diatoms such as Skeletonema costatum (Greville) Cleve (Gallagher 1983) and Coscinodiscus wailesii (Nagai & Manabe 1994, Nagai et al 1995. The method of size restoration at 50 µm observed once in the H31-C strain, such as the formation of auxospore-like spherical cells, was similar to vegetative cell enlargement seen in other diatoms such as S. costatum and C. wailesii.…”

“…The restoration of the H31-C strain therefore seemed to occur by vegetative cell enlargement rather than sexual auxospore formation. It is thought that E. zodiacus exhibits two different processes for its cell size restoration, as also reported for S. costatum (Migita 1967, Gallagher 1983 and C. wailesii (Nagai & Manabe 1994, Nagai et al 1995.…”

“…For instance, Coscinodiscus wailesii Gran, another organism causing nori seaweed bleaching, has been reported to have a minimum viable size (valve diameter) of about 70 µm (Nagai & Manabe 1994). On the other hand, restoration of cell size in natural populations of C. wailesii has been reported to occur before reaching this minimum size, when the mean valve diameter decreases to around 250 µm in the Harima-Nada (Nagai et al 1995). Nagai and Imai (2001) have suggested that restoration of cell size at a mean diameter of around 250 µm in C. wailesii is a survival strategy to avoid extermination by BacteriaPromoting Sperm Formation of C. wailesii (BPSF-Cw), or as a result of natural selection through the pressure of BPSF-Cw.…”

Tidal changes in copepod abundance and maintenance of a summer Coscinodiscus bloom in the southern San Juan Channel, San Juan Islands, USA

“…Although nutrient concentrations were not measured in this study, the tidal fluctuations in temperature and salinity profiles show that deep water is mixed into the San Juan Channel and therefore is likely to maintain relatively high nitrate concentrations throughout the summer. The abilities of C. wailesii to survive as resting cells in the dark (Nagai et al 1995a) and to attain large size through vegetative growth (Nagai et al 1995b) may be adaptations for living in areas of great turbulence, where nutrient concentrations are high but cells may be mixed into low-light environments for long periods of time.…”

Isolamento e análise química parcial de exopolissacarídeos da diatomácea marinha cultivada Coscinodiscus wailesii (Coscinodiscales, Bacillariophyta)

“…Efeitos desta espécie no ecossistema resultaram em sé-rios danos em culturas de "Nori" (Porphyra), macroalga marinha muito utilizada comercialmente como alimento, devido à absorção acelerada de nutrientes por esta diatomácea durante sua floração na costa japonesa. 2 A distribuição da espécie C. wailesii, antes restrita ao Pacífico Tropical e ao Atlântico Ocidental, ampliou-se até a Europa, Estados Unidos, Japão e Austrália, tornando-se, em algumas áreas, importante componente da comunidade fitoplanctônica. 3 No Brasil, na Baía de Paranaguá -PR, a espécie C. wailesii tem sido encontrada desde 1991 em baixas concentrações em todos os meses do ano, produzindo florações esporadicamente, durante as quais se observou uma marcada diminuição da população do fitoplâncton e zooplâncton.…”